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ELEMENTS 
 
 OF 
 
 MEDICAL CHEMISTRY. 
 
 BY 
 
 B. HOWARD RAND, M.D., 
 
 PROFESSOR OF CHEMISTRY IN JEFFERSON MEDICAL COLLEGB. 
 
 PHILADELPHIA: 
 
 T. ELLWOOI) ZELL & CO., 
 
 17 and 19 South Sixth Street. 
 
 1867. 
 
Entered according to Act of Congress, in the year 1866, by 
 
 B. HOWARD RAND, M.D., 
 
 in the Clerk's Office of the District Court of the United States for the Eastern 
 District of Pennsylvania. 
 
 («) 
 
 PRINTED BY SMITH & PETERS, 
 
 Frauklm Buildings, Sixth Street, below Arch, 
 
 Philadelphia. 
 
2tf 
 
 PREFACE. 
 
 This work is intended chiefly for the use of 
 Students of Medicine during their attendance upon 
 lectures; it is believed that it will also be found of 
 service to the practitioner. 
 
 The volume may be regarded as a full set of notes 
 of the author's course of lectures in the Jefferson 
 Medical College. 
 
 The immense extent of the subjects comprised 
 under the general head of Chemistry and Physics, 
 together with the limited time which the student is 
 able to devote to them, rendered a careful selection 
 of topics necessary. In doing this, it has been the 
 author's aim to discuss thoroughly general principles 
 and their application to medicine, leaving more mi- 
 nute details to be gathered at leisure from the larger 
 text-books. The consideration of purely theoretical 
 points, of disputed facts, or of applications of chemis- 
 try not directly connected with medicine, has been, as 
 a general rule, omitted. Chemical affinity, symbols, 
 and nomenclature have been particularly dwelt upon, 
 as they constitute the points of most difficulty to the 
 beginner, while, if they are not clearly understood,, 
 no satisfactory progress can be expected. Convinced 
 
 (Hi) 
 
IV PREFACE. 
 
 that familiarity with the use of chemical symbols 
 is of the utmost importance, and that it is readily 
 acquired, the author has employed them profusely, 
 preferring in many cases to write the symbol of an 
 element or compound in preference to its name. The 
 older notation, nomenclature, and equivalents have 
 been retained as best adapted for elementary instruc- 
 tion. 
 
 Believing in the necessity of a rigid adherence to 
 the U. S. Pharmacopoeia, not only as regards the for- 
 mulae, but also the titles of preparations, the officinal 
 names have been always used ; as often as possible 
 the Latin title has been given, and the formulae writ- 
 ten in prescription style as a useful exercise for the 
 student. 
 
 It would have been an easier task to have pro- 
 duced a larger volume ; much time and thought have 
 been expended in the selection and condensation of 
 subjects, and it is hoped that the labour thus be- 
 stowed will be found to lessen that of the overworked 
 student. 
 
 As all the apparatus described is exhibited in oper- 
 ation during the course of lectures, it has not been 
 thought necessary to use many illustrative cuts. 
 
 1615 Summer Street, Philadelphia. 
 3d August, 1866. 
 
TO THE STUDENT. 
 
 The numbers in parentheses refer to the paragraph to 
 be consulted. 
 
 When the Latin title of a preparation is given, the 
 officinal U. S. P. compound is always referred to. 
 
 The following are the principal signs and abbreviations 
 used in prescriptions, and also employed in many of the 
 pharmaceutical formul-ae in this work. 
 
 R, Recipe — Take; ^, troyounce ; f^, fluidounce ; f,5, 
 fluidrachm ; n\, , minim ; gtt, gutta, guttse, drop or drops ; 
 gr, granum, grana, grain or grains ; O, octarius, a pint ; 
 M, misce, mix ; ft, fat, let there be made ; chart., chartula 
 or chartulse, a packet or packets ; aa, of each ; t. d., ter 
 die, thrice daily ; q. s., quantum sufficiat, as much as is 
 sufficient. The Roman numerals, ss one-half, j one, v 
 five, x ten, 1 fifty, c one hundred, are usually employed 
 in prescriptions, being placed after the sign. The scruple 
 B, drachm 3, pound lb, and gallon, Gong., are not used in 
 the U. S. Pharmacopoeia. 
 
 A table of weights and measures, American, English, 
 and French ; general rules in regard to incompatibles and 
 antidotes ; a series of reactions for practice ; a list of the 
 more important minerals, and a glossary of terms and 
 synonyms, will be found in the Appendix. 
 
 (v) 
 
TABLE OF CONTENTS. 
 
 PAGE 
 
 Introduction 15 
 
 Properties and Qualities of Matter , 15 
 
 Of Force 16 
 
 PAET L — PHYSICS. 
 Gravitation. 
 
 Specific Gravity 18 
 
 Of Solids 19 
 
 soluble in Water 19 
 
 lighter than Water 20 
 
 in Powder...., 20 
 
 Of Liquids. By Displacement, Hydrometers, and S. G. Bottle... 20 
 
 Of Gases 21 
 
 Light. 
 
 Nature of Light 22 
 
 Definitions 22 
 
 Reflection. 
 
 from Plane Surfaces 23 
 
 from Curved Surfaces 23 
 
 Applications. — Specula, Mirrors, etc 24 
 
 Transmission. 
 
 Refraction 24 
 
 Index of Refraction 24 
 
 Optical Illusion 25 
 
 Prisms and Lenses 26 
 
 Images formed by Lenses 27 
 
 the Eye 27 
 
 Aberrations 28 
 
 the Microscope 28 
 
 Analysis of Light; Solar Spectrum 29 
 
 Complementary Colours 29 
 
 Absorption 30 
 
 Physical Optics 30 
 
 Heat. 
 
 Nature of Heat 30 
 
 Heat a Mode of Motion 31 
 
 Mechanical Equivalent of Heat 32 
 
 Temperature 32 
 
 Thermoscopes 32 
 
 Thermometers 32 
 
 Pyrometers 33 
 
 Thermo-Multiplier 34 
 
 Sources of Heat 34 
 
 Physical 34 
 
 Mechanical 35 
 
 Chemical : >^ 
 
 (vii) 
 
V1U TABLE OF CONTENTS. 
 
 PA<JS 
 
 Communication of Heat 35 
 
 Radiation 35 
 
 Emission v 36 
 
 Absorption ^., r 36 
 
 Reflection ..>. 37 
 
 Transmission; Diathermacy 37 
 
 Refraction ." 38 
 
 Conduction 38 
 
 Convection 39 
 
 Effects of Heat 40 
 
 Expansion . 40 
 
 of Solids 40 
 
 of Liquids 41 
 
 Maximum Density of "Water 42 
 
 of Gases 42 
 
 Formulae for Varying Volume 43 
 
 Change of State 43 
 
 Fusion and Solidification 43 
 
 Evaporation ; Tension of Vapours 44 
 
 Vapourisation; Boiling-Point 46 
 
 Condensation, Distillation 47 
 
 Spheroidal State 48 
 
 Latent Heat 49 
 
 Freezing Mixtures 50 
 
 Freezing by Evaporation 50 
 
 Specific Heat. 
 
 of Solids and Liquids; Equal "Weights 51 
 
 " " Atomic " 52 
 
 of Gases; Constant Volume 52 
 
 " " Pressure 52 
 
 Agency of Heat in Natural Phenomena 52 
 
 Climate and Season 53 
 
 Winds, periodical and others 53 
 
 Dew, Clouds, etc 53 
 
 ELECTRICITY. 
 
 I. Magnetism. 
 
 Magnets 54 
 
 Directive Tendency 54 
 
 Induction 54 
 
 Variation and Dip 55 
 
 Diamagnetism 55 
 
 II. Statical Electricity. 
 
 Elementary Phenomena 55 
 
 Hypotheses 56 
 
 Conductors and Insulators 56 
 
 Electroscopes, Electrometers 57 
 
 Electrical Tension 57 
 
 Distribution 58 
 
 Induction 58 
 
 Electrophorus 60 
 
 Electrical Machine 60 
 
 Leyden Jar 61 
 
 Effects of Statical Electricity 62 
 
 Physical 02 
 
TABLE OF CONTENTS. IX 
 
 PAGE 
 
 Chemical 62 
 
 Physiological 62 
 
 At 'ospheric Electricity 62 
 
 III. P " ^amical Electricity. 
 
 Elementary Phenomena 64 
 
 Theoretical Considerations 65 
 
 Quantity and Intensity 66 
 
 Resistances and Defects 67 
 
 Imperfect Conduction 67 
 
 Adhesion of Hydrogen 68 
 
 Local Action „ 68 
 
 Forms of Voltaic Cell 68 
 
 Volta's Pile 68 
 
 Hare's Trough 69 
 
 Smee's Cell 69 
 
 Sulphate of Copper Cell 69 
 
 Daniel's Cell 70 
 
 Grove's Cell 70 
 
 Bunsen's Cell 70 
 
 Maynooth Cell 71 
 
 Combination of Cells ; Ohm's Law 71 
 
 Effects of Dynamical Electricity 72 
 
 (1) Physical 72 
 
 (a) Heating Effects 72 
 
 (b) Electro-Magnetism 73 
 
 Ampere's Theory 74 
 
 Electro-Magnets ; the Telegraph 75 
 
 (c) Induced Currents 76 
 
 Electro-Magnetic Machines 76 
 
 Ruhmkorff Coil 77 
 
 (2) Chemical 79 
 
 (3) Physiological 79 
 
 IV. Magneto-Electricity. 
 
 Magneto-Electric Machines 80 
 
 V. Thermo-Electricity. 
 
 VI. Animal Electricity. 
 
 Medical Applications of Electricity 84 
 
 Correlation and Conservation of Force 85 
 
 PART II. — PRINCIPLES OF CHEMISTRY. 
 
 I. Cohesion. 
 
 Nature of Cohesion 87 
 
 Properties depending upon it S8 
 
 Crystallography 88 
 
 Formation of Crystals 91 
 
 Useful Applications 91 
 
 II. Adhesion. 
 
 («) Between Solids. Striction Cements , 92 
 
 (6) " " and Liquids. Wetting, Capillary Attraction, 
 
 Solution, Dialysis 92-95 
 
 (c) Between Solids and Gases. Absorption 95 
 
 (d) " Liquids. Solution, Diffusion, Osmose 96 
 
 (e) " " and Gases. Absorption 97 
 
 (/) " Gases. Diffusion, Atmosis 97 
 
X TABLE OF CONTENTS. 
 
 PAGE 
 
 III. Chemical Affinity. 
 
 Nature of 98 
 
 Admixture and Combination 98 
 
 Influence of Cohesion, Light, Heat, Electricity, Catalysis, the 
 
 Nascent State, and Mechanical Force on Combination 98-100 
 
 Laws of Chemical Combination, Equivalents,Combining Weights, 101 
 
 Atomic Theory 104 
 
 Combination by Volume 104 
 
 Notation. Symbols 105 
 
 Nomenclature of Chemical Compounds 107 
 
 List of Oxygen Acids 109 
 
 IV. Decomposition. 
 
 (a) Decomposition proper , 110 
 
 Effect of Light, Heat, Electricity, Catalysis, Example, 
 
 and Chemical Force 110-112 
 
 Electro-Chemistry 112 
 
 Electrical Table of Elements 113 
 
 Voltaic Protection of Metals 114 
 
 Electro-Plating 114 
 
 (&) Decomposition by Superior Affinity 115 
 
 (1) Single. 115 
 
 (2) Double 116 
 
 Influence of Insolubility, Volatility, Mass, etc 116, 117 
 
 Analysis « 117 
 
 Qualitative 117 
 
 Spectral Analysis 119 
 
 Quantitative 119 
 
 by Weight and Volumetric, Cupellation 120 
 
 PART III. — CHEMISTRY OF THE ELEMENTS. 
 Table of Elements, -with their Symbols and Combining Weights. 
 
 Oxygen and Ozone. 
 
 Manipulation of Gases 125 
 
 Hydrogen. 
 
 Water 129 
 
 Impurities, Tests, and Purification of. 130-131 
 
 Aqua, Aqua Destillata, Aquse Medicatse 131 
 
 Maceration, Digestion, Infusion, Decoction, Filtration, Displace- 
 ment, Lixiviation, Levigation, Elutriation, Decantation 133 
 
 Nitrogen. 
 
 The Atmosphere 134 
 
 Physics of. — Density, Weight, Pressure, the Barometer, Mariotte's 
 Law, the Syphon, Pipette, Wash Bottle, Safety Tubes, Atomiser, 
 
 Temperature and Moisture; Chemistry of. 135-138 
 
 Effects of Respiration ; Air Test ; Antiseptics, Deodorisers, and 
 
 Disinfectants; Ventilation 138, 140 
 
 Nitric Acid 143 
 
 Acidum Nitricum, Acidum Nitricum dilution 145 
 
 Hyponitric (nitrous) Acid 145 
 
 Nitrous (hyponitrous) Acid 145 
 
 Nitric Oxide... 146 
 
 Nitrous Oxide... . 146 
 
 Ammonia 146 
 
TABLE OP CONTENTS. xi 
 
 PAGE 
 
 Carbon. 
 
 Diamond, Graphite, Graphine, Charcoal, Lampblack 146 
 
 Carlo Ligni, Carlo Animalis, Carlo Animalis purificatus 147 
 
 Carbonic Acid 148 
 
 Aqua Acidi Carlonici (Mineral Water) 149 
 
 Carbonic Oxide 150 
 
 Oxalic Acid 150 
 
 Hydrocarbons. Nature and Structure of Flame; the Blowpipe...l51-153 
 Sulphur. 
 
 Sulphur Sullimatum, Sulphur Lotum, Sulphur Praecipitatum (Lac 
 
 sulphuris) 153-155 
 
 Sulphuric Acid 155 
 
 Acidum Sulphuricum , Acidum Sulphuricum dilutum, Acidum 
 
 Sulphuricum aromaticum (Elixir of Vitriol) 155-157 
 
 Sulphurous Acid, Acidum Sidphurosum 157 
 
 Hyposulphurous Acid 158 
 
 Sulphuretted Hydrogen, Hydrosulphuric Acid 158 
 
 Bisulphide of Carbon, Sulphocarbonic Acid 159 
 
 Phosphorus 160 
 
 Phosphoric Acid 162 
 
 Acidum Phosphoricum glaciate, Acidum Phosphoricum dilutum 163 
 
 Phosphorous Acid, Hypophosphorous Acid, Phosphuretted Hy- 
 drogen 163 
 
 Chlorine. 
 
 Aqua Chloriuii 164 
 
 General Chemistry of the Halogens 165 
 
 Perchloric Acid,. Chloric Acid, Hypochloric Acid, Chlorous Acid, 
 
 and Hypochlorous Acid 166 
 
 Hydrochloric Acid, Muriatic Acid, Acidum Jfuriaticum, Acidum 
 Ifuriaticum dilutum, Acidum Nitromuriaticum (Aqua Regia) 167, 168 
 
 Other Compounds of CI 168 
 
 Bromine. 
 
 Brominium If 9 
 
 Iodine. 
 
 Iodinium, Tinctura Iodinii, Tinctura Iodinii composita, Liquor 
 Todinii compositus, Unguentum Iodinii, JJng. Iodinii composi- 
 tum, Sulphuris Iodidum, Ung. Sidphuris Iodidi, Acidum Hy- 
 
 driodicum dilutum 169-172 
 
 Fluorine. 
 
 Hydrofluoric Acid, HF 172 
 
 Cyanogen. 
 
 Chemical Relations 173 
 
 Oxygen Compounds 174 
 
 Hydrocyanic Acid, HCy; Acidum Hydrocyanicum dilutum 174 
 
 Ferrocyanogen, Ferricyanogen, Sulphocyanogen 176 
 
 Boron. 
 
 Boracic Acid 177 
 
 Stlicon. 
 
 Silicic Acid, Silica 178 
 
 The Metals. 
 
 Sources and Extraction..... 178 
 
 Chemical Relation 180 
 
 Constitution of Salts 180 
 
 General Rules 182 
 
 Isomorphism 182 
 
Xll TABLE OF CONTENTS. 
 
 PAGX 
 
 Potassium. 
 
 Potassa, Liquor Potassse, Potassii Sulphur et urn, Patassii Iodidicm, 
 Potassii Bromidum, Potassii Cyanidum, Potassii Ferrocyani- 
 dum, Potassse Nitras, Potassse Carbonas impura, Potassse Car- 
 bonas, Potassse Oarb. pura, Potassse Bicarbonas, Potassse Sul- 
 phas, Potassse Chloras, Potassse Tartras, Potassse Bitartras, 
 Potassse et Sodse Tartras, Potassse Citras, Liquor Potassse Citratis, 
 
 Ilistura Potassse Citratis 1S4— 196 
 
 SODIUM. 
 
 Liquor Sodse, Sodii Chloridum, Sodse Carbonas, Sodse Carb. 
 exsiccata, Sodse Bicarbonas, Sodse Sulphas, Sodse Sulphis, Sodse 
 Phosphas, Liquor Sodse Chlorinatse, Sodse Boras, Sodse Acetas, 
 
 Sodse Valerianate 197-204 
 
 Lithium. 
 
 Lithise Carbonas 20-4 
 
 Ammonium. 
 
 Aquse Ammonise fortior, Aquse Ammonise, Spiritus Ammonise, Spi- 
 ritus Ammonise aromaticus, Linimentum Ammonise, Ammonise Mu- 
 rias, Nitrate, Ammonise Sulphas, Sulphydrate, Liquor Ammonise 
 
 acetatis, Ammonise Yalerianas 20-4-210 
 
 Calciuji. 
 
 Calx, Liquor Calcis, Linimentum Calcis, Calcii Chloridum, Li- 
 quor Calcii Chloridi, Sulphide, Creta prseparata, Testa jjrsepa- 
 rata, Calcis Carbonas jjrsecijjitata, Sulphate, Calcis Phosphas 
 
 prsecipitata, Hypophosphites, Calx Chlorinata 210-215 
 
 Magnesium. 
 
 Magnesia, Magnesise Carbonas, Jfagnesise Sulpliaa, Liquor Jfagne- 
 
 sise Citratis 216-219 
 
 Barium. 
 
 Liquor Barii Chloridi 219 
 
 Strontium 219 
 
 Aluminum. 
 
 Alumina, Mordants, Aluminse Sulphas, Alums, Alumen, Alumen 
 ex8iccatum, Aluminse et Ammonise Sulphas, Silicates, Clay, Glass, 
 
 and Porcelain 220-222 
 
 Manganese. 
 
 Manganesii Oxidum nigrum, Manganesii Sulphas, Chameleon Min- 
 eral, Potassie Permanganas 226, 227 
 
 Iron. 
 
 Ferritin, Ferrum Redactum, Ferri Oxidum hydratum, Ferri Sul- 
 phuretum, Ferri Chloridum, Tinctura Ferri Chloridi, Syriqius 
 Ferri Iodidi, Pilulse Ferri Iodidi, Ferri Ferrocyanidum, Liquor 
 Ferri Nitratis, Pilulse Ferri composita, Ferri Subcarbonas, 
 Trochisci Ferri Subcarbonatis, Ferri Sulphas, Ferri Sulphas 
 exsiccata, Liquor Ferri Tersulphatis, Liquor Ferri Subsulphatis, 
 Ferri et Ammonise Srdphas, Ferri Phosphas, Ferri Pyrophos- 
 phas, Ferri Lactas, Ferri et Potassse Tartras, Ferri et Ammonise 
 Tartras, Ferri Citras, Liquor Ferri Citratis, Ferri et Ammonise 
 
 Citras, Ferri et Quinise Citras 228-243 
 
 Chromium. 
 
 Acidum Chromicum, Potassse Bichromas 243, 214 
 
 Nickel and Cobalt 244 
 
 Copper. 
 
 Cupri Sulphas, Cupri Subacetas, Cuprum Ammoniatum, Chlorides, 
 Carbonates 245, 246 
 
TABLE OF CONTEXTS. Xlll 
 
 PAGE 
 
 Zinc. 
 
 Zincam, Zinci Oxidant, Zinci Chloridum, Oxychloride, Zinci 
 Carbonas prsecipitata, Cera tain Zinci Carbonatis, Zinci Sul- 
 phas, Zinci Acetas, Zinci Valeriana* 247-251 
 
 Cadmium. 
 
 Cadmii Sulphas 252 
 
 Bismuth. 
 
 Bismutham, Bismuthi Subnitras, Bismuthi Sabcarbonas 253-255 
 
 Lead. 
 
 Plumbi Oxidant, Emplastrum Plumbi, Plumbi Todidum, Plumbi 
 Carbonas, Unguentum Plumbi Carbonatis, Plumbi Nitras, 
 Plumbi Acetas, Liquor Plumbi Subacefatis, Liquor Plumbi Sub- 
 
 acctatis dilutus, Ccratum Plumbi Subacetatis 255-260 
 
 Tin 260 
 
 ^RSENIC. 
 
 Arsenicum, Acidum Arseniosum, Liquor Pvtassse Arsenitis, Arsenici 
 Iodidum ; Scheele's Green, Schvveinfurth Green, Realgar, Or- 
 
 piment 261-269 
 
 Antimony. 
 
 Antimonii Oxidum, Antimonii Salphuretum, Antimonii Oxy sul- 
 phur etum, Antimonium Sulphuratum, Antimonii et Potassse 
 
 Tartras ., 269-272 
 
 Cerium. 
 
 Oxalate 273 
 
 Mercury. 
 
 Hydrargyrum, Pilulie Hydrargyri, Unguentum Hydrargyri, Em- 
 plastrum Hydrargyri, Hydrargyrum cum Cretd, Hydrargyri Oxi- 
 dum rubrum, Unguentum Hydrargyri Oxidi rubri, Hydrargyri 
 Sulphuretum rubrum, Hydrargyri Chloridum mite, Hydrargyri 
 Chloridum corrosivum, Hydrargyrum Ammoniatum, Unguentum 
 Hydrargyri Ammoniati, Hydrargyri Iodidum viride, Hydrargy- 
 rum Iodidum rubrum, Liquor Arsenici et Hydrargyri lodidi, Hy- 
 drargyrum Cyanidum, Liquor Hydrargyri Nitratis, Unguentum 
 
 Hydrargyri Nitratis, Hydrargyri Sulphas flava 273-281 
 
 Silver. 
 
 Argentum, Argenti Oxidum, Argenti Cyanidum, Argenti Nitras, 
 
 Argenti Nitras fusa 283-285 
 
 Gold , 285 
 
 Platinum, Iridium, Osmium 286 
 
 PART IV. — ORGANIC CHEMISTRY. 
 
 Constitution of Organic Bodies , 287 
 
 Decompositions 288 
 
 Analysis 288 
 
 Theoretical Considerations 289 
 
 Isomeric, Metameric, and Homologous Bodies 291 
 
 Classification 291 
 
 I. Starch Group. 
 
 Cellulose, Starch, Dextrin, Gum, Pectin : Cane, Grape, Fruit, and 
 
 Milk Sugars 292-300 
 
 Fermentation. 
 
 Vinous, Lactic, Butyric, Viscous 300-306 
 
 II. Radicals of thk General Formula C^nl^n-l-l. 
 
 Theoretical Considerations 306 
 
XIV TABLE OF CONTENTS. 
 
 PAGE 
 
 Methyl Alcohol, Formic Acid, ChloroformumVenale, Chloroformum 
 purificatum, Mistura Chloroformi, Linimentum Chloro/ormi, 
 Liquor Guttx perchse 307-310 
 
 Ethyl Alcohol, Alcohol, Alcohol fortior, JEther, JEther fortior, 
 Spiritus uEtheris compositus, Spiritus JEtheris Nitrosi, Chloride 
 of Ethyl 310-314 
 
 Acetic Acid, Acetum, Acetum destillatum, Acidum aceticum, Acid. 
 Acetic, dilutum, Butyric Acid, Butyric Ether 314-316 
 
 Alcohol Amylicnm, Acidum Yalerianicum, Valeriate of Amyl Oxide, 
 Flavouring Ethers . 317 
 
 III. Radicals not Homologous with Ethyl. 
 
 Benzoyl, Oleum Amygdatse o.marse, Acidum Benzoicum, Nitroben- 
 
 zole, Benzonitrile, Benzole, Phenic or Carbolic Acid 317-320 
 
 Cinnamyl, Salicyl 320 
 
 Kakodyl, Oxide, Cyanide, Kakodylic Acid , 321 
 
 IV. Organic Acids not Otherwise Classified. 
 
 Acidum Tartaricum, Racemic, Acidum Citricum, Malic, Acidum 
 Tannicum, Acidum Gallicum, Pyro- and Metagallic Acids... 322-325 
 
 V. Artificial Organic Bases. 
 
 Substitution Ammonias and Ammoniums. Aniline, Propylamine 
 
 325-327 
 
 VI. The Alkaloids and Allied Principles. 
 
 Analysis in Cases of Poisoning 329 
 
 Morphia, llorphise Sulphas, Iforphise 3/urias, Uorphise Acetas, 
 
 Valerianate of Morphia 330-332 
 
 Other Alkaloids of Opium , 332 
 
 Quinia, Quinise Sulphas, Quinise Valerianas, Quinidia, Cinch oniae 
 Sulphas, Cinchonidia, Strychnia, Strychnise Sulphas, Brucia, 
 Igasuria, Veratria, Aconitia, Atropia, Emetia, Berberina, Be- 
 beerina, Delphia, Piperina, Caffeine, Theobromina, Conia, Con- 
 hydrina, Nicotina, Substitution Products of the Alkaloids, 
 Neuter and Acid Bitter Principles 332-340 
 
 VII. Fats and Oils. 
 
 Saponification 341 
 
 Fatty Acids 341 
 
 Glycerina 343 
 
 Volatile Oils 345 
 
 Camphors and Resins 347 
 
 VIII. Colouring Matters. 
 
 Indigo, Aniline, Picric Acid, Litmus, Rubia, Hsematoxylon, Car- 
 thamine, Lac, Coccus, Chlorophylle, etc 347-350 
 
 IX. Proximate Principles not Otherwise Classified. 
 Albumen, Fibrin, Casein, Protein, Gelatin, Kreatin, Kreatinine, 
 
 Inosic Acid, Inosite 350-355 
 
 Blood, Saliva, Milk, Gastric Juice, Pepsin, Sweat, Bile, Urine.. 356-359 
 Urinary Calcidi 364 
 
 APPENDIX. 
 
 "Weights and Measures 367 
 
 Incompatibility 370 
 
 Antidotes and Precautions in Medico-Legal Examinations 371 
 
 Reactions for Practice 373 
 
 List of Minerals, with their Chemical Composition 376 
 
 Glossary 381 
 
MEDICAL CHEMISTRY. 
 
 INTKODUCTION. 
 
 1. Chemistry investigates the reaction of the particles 
 
 of matter. Reaction is mutual or reciprocal action, and is 
 
 due to force. Action and reaction are equal and opposite. 
 
 In common language we frequently overlook the reaction, and 
 speak of action alone. Thus, vinegar spilled on a polished mar- 
 ble table is said to corrode or damage it, but the vinegar is at 
 the same time neutralised and spoiled for use. 
 
 2. Particles are the exceedingly minute portions of mat- 
 ter which go to make up a mass. They may be atoms 
 (Gt. a, not, and temno, I cut), which are the ultimate por- 
 tions of an elementary body ; or molecules (Lat. molecula, 
 a particle), the ultimate portions of a compound body. 
 Molecules are composed of two or more atoms. 
 
 3. Matter is anything that can be grasped in the hand. 
 It may be elementary or compound. All substances known 
 to us are composed of sixty-four bodies, which, having not 
 as yet been decomposed, are termed elements. Like the 
 letters of the alphabet, which, variously combined, give us 
 thousands of words, these elements, in various forms and 
 grades of combination, make up the apparently infinite 
 variety of forms of matter 
 
 4. Matter is Indestructible. — What we term destruction 
 is merely a new combination of elements. Solid bodies 
 sometimes become gaseous when burned, and thus, being 
 invisible, are supposed to be destroyed. Experiment shows 
 
 (15) 
 
16 MEDICAL CHEMISTRY. 
 
 this not to be true. When a piece of gun-cotton is burned 
 
 in a counterpoised exhausted globe, it disappears, but the 
 
 weight of the globe and its now gaseous contents is 
 
 unchanged. 
 
 AVood, when burned, gives off carbonic acid and water, which 
 pass into the atmosphere ; the water falls to the earth, and may 
 be absorbed by some growing vegetable^to assist in forming 
 again wood. The carbonic acid consists of the elements carbon 
 and oxygen. When absorbed by plants, it is, under certain cir- 
 cumstances, decomposed, the oxygen given out and the carbon 
 assimilated going to form new wood. Hence it would be possible 
 to burn the same combustible twice or more. 
 
 5. Matter is incapable of Spontaneous Change. — All 
 change is due to force. This property is called inertia. 
 The inertia of a body depends upon the number of its 
 particles or its mass. Time is required to communicate 
 motion to all these particles, or to abstract it from them ; 
 hence all change in matter is gradual. 
 
 6. Weight is due to the action of gravitation upon a 
 body, and depends also on the mass. The same mass has 
 not always the same weight, as the force of gravitation 
 varies in different localities. Practically, however, the 
 terms may be used as synonymous. 
 
 7. Force is anything capable of causing change in matter. 
 Of its nature we are utterly ignorant. Although mani- 
 festing itself in the various phenomena of gravitation, 
 light, heat, electricity, magnetism, cohesion, adhesion, 
 chemical affinity, and vital force, there can be little doubt 
 that it is in all these essentially the same agent, 
 
 8. Force acts to produce either attraction or repulsion. 
 The particles of matter are not in actual contact ; the spaces 
 between them are called physical pores, and although ex- 
 ceedingly minute, are believed to be much greater in pro- 
 portion than the particles themselves. 
 
 Newton calculated that if there were no pores, the earth and 
 its inhabitants could be comprised within the space of a cubic 
 inch. What are usually known as pores, as in the sponge, 
 
INTRODUCTION. It 
 
 pumice-stone, etc., are not true physical pores, but rather canals 
 or tubes traversing the body ; they are distinguished as sensible 
 pores. 
 
 The force of attraction tends to bring together the par- 
 ticles of matter, and, were there no antagonistic agencies, 
 would do so ; the force of repulsion tends to separate these 
 particles. The phenomena of expansion, of contraction, 
 and of change of state are all due to the preponderance 
 of one or the other of these agencies. The great agent of 
 repulsion is heat. We have also electrical and magnetic 
 repulsions. This part of the subject will be more fully 
 considered hereafter. 
 
 2* 
 
PART I. 
 
 PHYSIOS. 
 
 GRAVITATION. 
 
 9. Is but little connected with Chemistry. The law of 
 gravitation is that every particle of matter attracts every 
 other particle in the direct ratio of its mass, and the inverse 
 ratio of the square of the distance. 
 
 10. Terrestrial Gravitation — Is the action of the 
 mass of the earth upon bodies on or near its surface. It 
 may be considered as proceeding from its centre (nearly). 
 It is greater at the poles than at the equator, and is less 
 when a body is carried above or below the surface of the 
 earth. 
 
 Thus, a mass of iron weighing 1000 lbs. at the equator, would 
 weigh 1005 at the poles; 500 lbs. at 2000 miles below the surface 
 of the earth, or at 1650 miles above it.* 
 
 The action of bodies on the earth's surface is reciprocal, and 
 the earth rises to meet a falling body, but the mass of the former 
 is so immense compared with any body which has ever been 
 known to fall through our atmosphere, that the effect is imper- 
 ceptible. 
 
 11. Specific Gravity. — By the term density we mean 
 the relation of the mass of a body to its volume, or the 
 number of particles in a given space. By specific gravity 
 we mean the relative weights of equal volumes of different 
 bodies, assumed to be at the same temperature and press- 
 ure. The term density is often used to express specific 
 gravity. 
 
 * Sillima.v. Principles of Physics, 2d ed., p. 67. 
 (18) 
 
GRAVITATION. 19 
 
 A quart of oxygen, at ordinary pressure and temperature, if 
 forced into the space of a pint, would have its density doubled. 
 The specific gravity of oxygen — compared with air as unity — is, 
 when taken at a fixed temperature and pressure, 1*106 ; that is, 
 that if a certain bulk of air weigh 1000 grains, an equal bulk of 
 oxygen will weigh 1106 grains. 
 
 In order to compare the weights of equal volumes of 
 
 different bodies, arbitrary standards are assumed. For 
 
 solids and liquids, water at 60° F. is chosen as unity; and 
 
 for gases, air at ordinary atmospheric pressure (30 in. 
 
 barometer), and 60° F. is assumed as 1000. 
 
 Solids and liquids do not perceptibly alter in bulk by ordinary 
 change of atmospheric pressure. All matter varies in bulk by 
 change of temperature, hence the necessity of carefully bringing 
 the bodies to a fixed degree by trial or calculation. 
 
 12. The specific gravity Of a solid is determined on the 
 principle that a body immersed in a liquid, displaces a 
 volume equal to its own. Hence by a known hydrostatic 
 law the immersed body loses weight equal to that of an 
 equal bulk of the liquid. In practice, a solid is first weighed 
 in air, and then in water, and the loss noted. The weight 
 in air divided by the loss of weight in water gives the spe- 
 cific gravity. Or the solid may be put into a vessel with 
 a spout and brimful of water. The quantity which runs 
 out is weighed, and the weight of the body divided by it. 
 
 Thus, a piece of iron weighed in air 460 grains, in water 406*16 
 grains, 460— 406-1 6=58'84 grains; the loss in water, 460H-58-84 
 =7*8, equal the S.G. of the iron. 
 
 13. When the solid is soluble in water, its specific grav- 
 ity is taken in reference to some other liquid. The quan- 
 tity thus obtained, multiplied by the S, Gr. of the liquid, 
 gives the S. G. of the solid. 
 
 Thus, a piece of sugar weighed in air 400 grains, it lost in oil 
 of turpentine 217"5 grains, 400 -*- 217'5 = 1-84. The S. G. of the 
 turpentine is '87, 1'84 X '87 = 1*6, equal the S. G. of the sugar. 
 
 1 4. When the solid is lighter than water, it is weighed 
 and attached to a body (the weight of which in air and 
 
20 MEDICAL CHEMISTRY. 
 
 water is known) sufficient to sink it. This compound 
 mass or system is weighed in air, and its loss in water de- 
 termined. The loss of the heavy body being known, that 
 of the light body is easily determined by subtraction, and 
 the S. G. obtained as before. 
 
 Thus, a piece of wood weighed in air 200 grains; attached to a 
 bit of copper the system weighed 2247 grains in air, and 1620 
 grains in water, losing 627 grains. The copper alone loses in 
 water 230 grains, 627 — 230 = 397, equal the loss of the wood 
 alone, 200-7-397 = -504, the S.G. of the wood. 
 
 15. When the solid is in powder, it is introduced into a 
 counterpoised bottle full of water, the weight of the water 
 being known (specific gravity bottle [16]). Were no water 
 displaced, the weight of the bottle would be increased by 
 that of the powder, but as a bulk of water equal to that 
 of the powder overflows, the new weight is less than the 
 sum by the weight of that water ; which quantity, divided 
 into the weight of the powder, gives the S. Gr. 
 
 Thus, the bottle holds 1000 grains of water ; 150 grains of sand 
 being introduced, the total weight, instead of being 1150 grains, 
 is but 1096 grains ; hence 54 grains of water have been displaced, 
 150-7- 54=2-764, S.G. of the sand. 
 
 16. The specific gravity of a liquid may be ascertained 
 by the bottle, the hydrometer, or by displacement. The 
 specific gravity bottle is made to hold 100 or 1000 grains 
 of distilled water, and is furnished with a counterpoise. 
 The weight in grains of the liquid introduced into the 
 counterpoised bottle gives its S. Gr. A common light flask 
 may be used by noting its weight when empty, when filled 
 with water to a mark made on the neck by a file, and when 
 filled to the same point with the liquid to be tested. The 
 weight of the latter, divided by that of the water, gives 
 its S.G. 
 
 17. Hydrometers have a graduated stem, counterpoised 
 below so as to make it float upright. As the instrument 
 sinks deeper in a liquid lighter than water, and less in a 
 heavier liquid, it may be graduated to indicate S. G. 
 
LIGHT. 21 
 
 Usually several hydrometers are employed for liquids lighter 
 or heavier than water, so as to avoid the inconvenience of a long- 
 stem, and to have the divisions of the scale larger. The gradua- 
 tion may be arbitrary, as in Beaume's ; may indicate percentage 
 by weight or volume in a mixture, as in Tralles' or Richter's, for 
 spirits ; may test for comparative purity, as in the lactometers ; or 
 may be graduated to the true specific gravity, as in urinometers. 
 The instruments for specific gravity made by Dr. Wilson H. Pile, 
 of Philadelphia, leave nothing to be desired in point of conven- 
 ience and accuracy. Those with Beaume's scale have also the 
 corresponding S. G. marked upon them. In using a hydrometer, 
 it should never be dropped into a liquid, as the weight of that 
 adhering when it rises above the surface will render its indica- 
 tions faulty. 
 
 18. By Displacement. — Weigh a solid in air, in water, 
 
 and in the liquid to be tested ; note the loss in each case. 
 
 The loss being the weight of an equal bulk of the two 
 
 liquids, by dividing the loss in the latter by that in the 
 
 water, we get the S. G. 
 
 Thus, a glass rod loses in water 171 grains, in alcohol 143 
 grains, 143 — 171 = -836=: S. G. of the alcohol. 
 
 19. The Specific Gravity of Gases is determined by ad- 
 mitting the gas into an exhausted counterpoised globe, 
 capable of containing a known weight of air, and compar- 
 ing the two. 
 
 LIGHT. 
 
 The subject of light is but little connected with ele- 
 mentary chemistry. A knowledge of its most important 
 laws, however, is indispensable to a correct understanding 
 of the physiology of vision, and an intelligent use of the 
 various optical instruments used by the physician. 
 
 20. Sources and Velocity of Light. — The sources of 
 light are the sun, fixed stars, incandescence, phosphores- 
 cence, and electricity. The velocity of light varies with 
 
22 MEDICAL CHEMISTRY. 
 
 the medium, being less as that is more dense. In air it is 
 estimated at 190,000 miles per second. — (Foucault.) 
 
 21. Nature of Light - Theories. — 1. The corpuscular 
 supposes that luminous corpuscles are thrown off from 
 luminous bodies, each particle producing in its flight in 
 the surrounding ether undulations similar to those pro- 
 duced by a stone falling into water. 2. The undulatory 
 theory supposes light to consist of vibrations of an ethe- 
 real medium of extreme tenuity, without the onward pro- 
 gress of any substance whatever. The latter theory is 
 now generally accepted, but the language of the former is 
 still retained in explaining the simpler phenomena of the 
 reflection and refraction of light. 
 
 22. Definitions. — A ray is a single (imaginary) line 
 of light. A beam is a collection of parallel rays, as from 
 the sun. A pencil is a collection of divergent or conver- 
 gent rays, as the light from a candle, or the sun's rays 
 brought to a focus by a burning-glass. Luminous bodies 
 are those from which light proceeds. Transparent or dia- 
 phanous permit light to pass through them; so that bodies 
 on the other side are visible. Translucent bodies permit 
 a portion of light to pass in an irregular manner, so that 
 bodies on the other side are indistinctly seen; such are 
 porcelain, oiled paper, and horn. Opaque bodies cut off 
 the rays of light ; when in very thin leaves, they may be- 
 come translucent. The intensity of light is inversely as 
 the square of the distance. Thus, if two lights, one at a 
 distance twice as great as the other, cast equal shadows, 
 then the more distant light is four times as intense as the 
 other. Instruments for measuring the relative intensity 
 of light from different sources are called photometers. 
 
 Properties of Light. — A ray of light falling upon a sur- 
 face may be reflected, transmitted, or absorbed. 
 
 23. 1. Reflection. — When a surface reflects regularly, it 
 becomes invisible, and an image of an object placed in 
 
LIGHT. 23 
 
 front of it is seen ; if it reflects irregularly, the surface is 
 visible, and the image is more or less lost. Thus, a bright 
 looking-glass reflects regularly ; covered with dust or 
 grease, irregularly. We see bodies then only by this irreg- 
 ular reflection. 
 
 (a) When a ray of light falls upon a plane surface, 
 such as an ordinary mirror, it is reflected at an angle 
 equal to that at which it fell. The law, as ordinarily ex- 
 pressed, is that "the angles of incidence and of reflection 
 are equal, and are in the same £fe- *• 
 
 plane with the normal. 
 
 Thus, in the figure, I A and R A 
 form equal angles with N A, the nor- 
 mal or perpendicular ; they are more- 
 over all in the same plane. 
 
 (p) Curved surfaces are considered as being made up of 
 an infinite number of plane surfaces, and the effects of such 
 are easily deduced from simple geometric laws. The fol- 
 lowing are some of the general facts : — Concave mirrors 
 cause rays of light falling upon them to converge (approach 
 each other) ; convex mirrors render these rays divergent ; 
 parallel rays falling upon a concave mirror are brought to 
 a point midway between the centre of curvature and the 
 surface, called the principal focus ; conversely a luminous 
 body, at the principal focus has its pencil converted into a 
 beam. The image seen in a concave mirror is erect and 
 larger than the object when the latter is near the mirror 
 (nearer than the principal focus) ; when more distant, it is 
 inverted and smaller. The image seen in a convex mirror 
 is always erect and smaller than the object. 
 
 These remarks are true only within certain limits. The subject 
 of the aberration of spherical mirrors, the effect of cylindrical 
 and other forms, need not be discussed in an elementary work. 
 
 24. Applications. — The speculum is a tube with a 
 polished interior surface, intended for the exploration of 
 
24 MEDICAL CHEMISTRY. 
 
 the natural canals, as the nostril, the meatus auditorius, 
 the vagina, and the rectum ; the tube distends or keeps 
 open the natural canal, while the polished interior reflects 
 light within. Plane mirrors are used for obtaining images 
 of parts out of the direct view, as in the laryngoscope and 
 endoscope, by means of which the condition of the larynx 
 or urethra may be thoroughly studied and applications 
 made directly to it. Concave mirrors are used to concen- 
 trate light, as in the ophthalmoscope, where the light is 
 thrown through the pupil ; or in the use of the laryngo- 
 scope, where light is thrown into the fauces by means of a 
 concave mirror fastened to the forehead of the operator, or 
 placed in some other convenient position, while the organ 
 itself is reflected in a plane mirror. 
 
 25. Transmission. — Light falling upon a transparent 
 medium passes through it ; practically, a portion is re- 
 flected, and this amount increases with the aDgle of inci- 
 dence. When it falls perpendicularly, the ray passes 
 through without change ; when obliquely, it is refracted or 
 bent. In passing from a rarer to a denser medium, the 
 refraction is towards the normal, and vice versa. The 
 relation between the angles formed by the incident and 
 refracted ray with the normal, which expresses the refract- 
 ing power of the body, is termed the index of refraction. 
 
 pig. 2. Thus in Fig. 2 we have, A B D 
 
 the angle of incidence, X Y the 
 surface of the medium (water 
 for instance), B G the refracted 
 ray, D B E the normal; D g is 
 the sine (or measure) of the angle 
 of incidence, and /of the angle 
 
 of refraction, G BE. --| = index 
 
 of refraction, which, for water 
 is about |, or 1*33. Hence, as 
 the eye always sees an object in the direction in which the ray 
 of light enters it, objects viewed obliquely in water (or other 
 media) are not seen in their true position. In denser media 
 they seem nearer the surface, as in an oar in water. This 
 
LIGHT. 
 
 25 
 
 can be understood by the ac- Fig. 3; 
 
 companying figure. The ray 
 
 proceeding from the coin C, at 
 
 the bottom of a dish of water, 
 
 passing into the rarer medium, 
 
 air is refracted from the normal 
 
 and takes the direction A D ; 
 
 the eye at D traces the ray back 
 
 in the direction of the dotted line, 
 
 and sees the coin at E nearer 
 
 the surface. 
 
 26. Prisms, Lenses. — When a ray of light passes through 
 a triangular prism, it is re- Fig. 4. 
 
 fracted toward the normal 
 on entering, and from the 
 normal on leaving. 
 
 Thus in Fig. 4 the incident 
 ray I R is refracted in the di- 
 rection R E on entering the 
 prism, and E F on leaving it. 
 The effect of two prisms base to base, or edge to edge, is seen in 
 Fig. 5. 
 
 Fig. 5. 
 
 Lenses are of various forms, the most important of which 
 are the doubly convex and doubly concave. 
 
 The action of lenses is easily understood by considering 
 them as made up of prisms arranged as in Fig*. 5. 
 
 Kays of light, falling upon a convex lens, will be con- 
 verged. Parallel rays, falling upon a doubly convex lens, 
 are brought to a point called the principal focus, which 
 3 
 
26 
 
 MEDICAL CHEMISTRY. 
 
 coincides with the centre of curvature; Fig. 6, 
 cave lens causes parallel rays to diverge ; Fig. f . 
 
 Fig. 6. 
 
 A con- 
 
 Fig. 7. 
 
 Images formed by Lenses. Each point of the object may- 
 be considered as giving off a pencil of rays, which are re- 
 fracted to a focus ; the assemblage of these foci gives the 
 image of the body 
 
 When the object is beyond the principal focus of a 
 convex lens, the image will be on the other side real and 
 
 inverted) Fig. 8. 
 
 Its size will depend upon the relative 
 
 Fig. 8. 
 
 distances of the object, the lens, and the screen. The 
 nearer the object to the lens, and the more distant the 
 
LIGHT. 27 
 
 screen, the larger the image. When the object is nearer 
 the lens than the principal focus, the image will be virtual 
 (that is, it cannot be thrown upon a screen) on the same 
 side as the object, and larger; the lens then constitutes a 
 magnifying-glass. The image formed by a concave lens 
 is virtual and smaller than the object. 
 
 Thus, in Fig. 9 the rays of light from the various points of the 
 small arrow, a b, are' Fte 9 
 
 refracted in passing 
 through the doubly con- 
 vex lens, the eye traces 
 them backwards, and 
 the image formed on 
 the retina is the same 
 as that of the object in- 
 creased in its dimen- 
 sions to AB, and viewed 
 by the unassisted eye. 
 
 27. The Eye contains a series of lenses which cause the 
 image of objects to be thrown inverted upon the retina. 
 As we see bodies in the direction in which the ray comes, 
 this does not interfere with vision. 
 
 When the eye is too convex, the image is formed in front 
 of the retina, and near-sightedness results. It is palliated 
 by the use of concave spectacles, which cause the rays of 
 light to diverge before entering the pupil. When the eye 
 is not sufficiently convex, the rays do not come to a focus 
 upon the retina, but would form an image behind it ; con- 
 vex lenses are used in these cases. Sometimes the eye is 
 flattened vertically or at the sides, when objects are dis- 
 torted, being elongated or rendered broader, as the case 
 may be ; some eyes are unable to distinguish the upright 
 lines of a brick wall ; others, those which are horizontal. 
 Similar effects are often seen in looking through a window 
 of common (cylinder) glass. In these cases cylindrical 
 lenses are to be employed. 
 
 The first or second defect is often combined with the third. 
 
28 
 
 MEDICAL CHEMISTRY. 
 
 Care should be taken, in selecting lenses to remedfy defects of 
 vision, that the eye is not still further injured by the use of spec- 
 tacles of improper curve. Lenses with the cylindrical and con- 
 cave or convex surface combined are made by Mr. Lentmeyer of 
 this city. 
 
 28. Aberrations. — Simple lenses are subject to spherical 
 Fi ff . ] o. and chromatic aberrations. The 
 
 former produces indistinctness 
 of form, the latter gives fringes 
 of colour to the image. The 
 causes and remedies of these 
 will not be discussed here. 
 
 29. Microscopes.— The sim- 
 plest form of microscope is the 
 doubly convex lens, the object 
 being placed within the princi- 
 pal focus (30). Sometimes the 
 lens is mounted on a stand, with 
 a stage to hold the object, and 
 a concave mirror below to con- 
 centrate the light upon trans- 
 parent bodies, or a convex lens 
 above to illuminate those which 
 are opaque. 
 
 1 The compound microscope con- 
 sists of two sets of lenses, by the 
 first of which (the object-glass) 
 a real inverted image of the ob- 
 ject is made, which is received 
 at the focus of the second set of 
 lenses (the eye-piece), and again 
 magnified. The principle is seen in Fig. 10. When the 
 arrow, s r, placed before the lens, a b, but without its prin- 
 cipal focus, forms a real enlarged image, R S, which being 
 again magnified by the eye lens, c d, the eye traces the 
 
LIGHT. 29 
 
 rays back in the direction C R' and D S', giving the greatly 
 enlarged image R' S'. In practice, the instrument is made 
 more complex, to avoid aberrations. 
 
 30. Analysis of Light; Spectrum.— If a beam of light, 
 B, Fig. 11, be admitted into a dark room, through a cir- 
 cular opening, H, it will form a Fig. n. 
 white spot upon the wall, W. 
 If .the triangular prism, P, be in- 
 terposed, the beam will be twice 
 bent (28) ; but instead of forming 
 only a circular spot upon the 
 wall, it will be elongated, forming what is termed the 
 prismatic spectrum. The colours beginning at the top 
 are violet, indigo, blue, green, yellow, orange, and red. 
 By means of a lens or a second prism these may be re-com- 
 bined, forming white light. These colours cannot be fur- 
 ther decomposed; they are therefore termed primary. 
 The violet, being the most deflected from the course of the 
 beam, is the most refrangible, and the red the least so. 
 The greatest illuminating power is in the yellow ; the 
 greatest heating power in and beyond the red, and the 
 greatest chemical power in and beyond the violet. The 
 lengths of the waves of the different colours, and their 
 number of vibrations per second, have been calculated. 
 The number of vibrations of the extreme violet is 
 721,000,000,000,000, and their length ^^ of an inch ; the 
 extreme red vibrates 458,000,000,000,000 times per second, 
 and the vibrations are -gihio °f an mcn m length. This 
 subject will be further discussed under the head of Chemi- 
 cal Affinity, and Decomposition. 
 
 Complementary Colours. Any two colours which by their 
 union would produce white light are said to be complementary. 
 If we. take from the solar spectrum any colour whatever, we may 
 unite all the remaining colours by means of a lens or prism, and 
 the resulting tint will be complementary to the one removed, 
 
30 MEDICAL CHEMISTRY. 
 
 being just what is wanted to make white light. The following 
 are examples: red, green; violet, yellow ; blue, orange. Com- 
 plementary colours brighten each other by contrast. 
 
 31. Absorption of Light. — When light is reflected or 
 transmitted, a portion is absorbed by the surface or 
 medium. When all the rays are absorbed by a surface, it 
 is black, or more properly invisible ; when all are irregu- 
 larly reflected, it is white, or if regularly reflected, invisible 
 (23). If a portion be absorbed, the colour will be due to 
 those rays reflected or transmitted ; thus blue glass absorbs 
 all but the blue ray, and red cloth absorbs all but the red 
 ray. The cause of this selection of colours of bodies is 
 wholly unknown. 
 
 32. Physical Optics includes the subjects of interference, 
 diffraction, polarisation, and fluorescence. These phenomena 
 are complex in their character ; they are usually explained 
 upon the undulatory theory, although in some cases it 
 fails. The student is referred to more elaborate works for 
 their consideration 
 
 HEAT. 
 
 I. PRELIMINARY, 
 
 33. Nature of Heat. — Two theories have prevailed: 
 First, that a subtile imponderable body, termed caloric, 
 enters into the pores (8) of bodies, and by its varying 
 quantity and the changes produced upon its entering or 
 leaving, the phenomena observed are caused. In cer- 
 tain cases it was supposed to become latent (Lat. lateo, 
 I lie hidden), and was then inappreciable to ordinary 
 Observation. The second considers heat as a "mode of 
 
HEAT, 81 
 
 motion,"* but the exact manner in which this motion pro- 
 duces the various phenomena is yet a matter of discussion. 
 The latter view of the subject is generally adopted, al- 
 though, as in the case of light, the language of the mate- 
 rial theory is yet employed for convenience. 
 
 34. Relations of Heat and Motion. — Apart from any 
 theoretical consideration, the mutual convertibility of mo- 
 tion and heat has been settled by experiment. It has long 
 been known that heat would produce motion, as in the 
 steam-engine, or the expansion of a liquid in a ther- 
 mometer tube, and that arrested motion would produce 
 heat, as in friction-matches, or iron rendered red-hot by 
 hammering. It has been ascertained that when heat is 
 doing work, it is no longer sensible as heat, and that the 
 amount of heat developed by arrested motion is exactly 
 equivalent to the force employed ; which force is equal 
 to that which would be developed by the amount of heat 
 given out by its arrest. 
 
 35. Mechanical Equivalent of Heat— The independent 
 researches of Joule and Von Meyer have given us the 
 mathematical relation between heat and work. The unit 
 of work (dynamical unit) is one pound raised- one foot, or 
 one foot-pound ; the unit of heat is the amount necessary 
 to raise one pound of water from 32° to 33° F. or less, 
 accurately that required to raise a pound of water one 
 degree of Fahrenheit's scale. One thermal unit is equiva- 
 lent to 712 dynamical units. 
 
 36. Temperature. — We judge of the intensity of heat 
 by our sensations, and speak of bodies as being hot or 
 cold. These sensations are fallacious, those produced by 
 extreme cold and heat being similar. The terms high and 
 low temperature are applied to signify the conditions ex- 
 pressed in ordinary language by hot and cold. The tem- 
 
 * Tyndaxl. Heat considered as « Mode of Motion. 1863. 
 
32 MEDICAL CHEMISTRY. 
 
 perature of a body simply indicates the intensity of its 
 heat, and gives no idea of the quantity. Thus a ther- 
 mometer in a teacupful of boiling water marks the same 
 temperature as if plunged into a vat of the same contain- 
 ing a thousand gallons, yet we know that the quantity of 
 heat given out during the cooling of the latter is as many 
 times greater than that which the former gives out, in 
 falling to the same temperature, as the amount of liquid 
 is greater. Again, suppose a thermometer at 50° F. and 
 100° F. in equal quantities of liquid, it would be a mistake 
 to suppose that in the latter case the water was twice as 
 hot as in the former. The zero of the thermometric scale 
 is entirely arbitrary and does not indicate the complete 
 absence of heat, which may be yet abstracted from bodies 
 which have been cooled to 0. The absolute of heat has 
 been calculated to be — 459° F. 
 
 37. Measurement of Temperature. — The instruments for 
 indicating changes of temperature, or for measuring them, 
 are thermoscopes, thermometers, pyrometers, and thermo- 
 multipUers. In all cases their graduations are arbitrary. 
 
 Thermoscopes (Gr. therme, heat, and scopeo, I view) 
 merely indicate changes of temperature. The most com- 
 mon form is a bulb containing air attached to a stem con- 
 taining liquid; on an increase of temperature the air 
 expands, driving the liquid upwards or downwards, (Sanc- 
 torius' thermometer.) This instrument is imperfect, be- 
 cause the volume of air in the bulb may be varied by 
 changes of atmospheric pressure. In the differential 
 thermometer two bulbs containing air are united by a U- 
 shaped tube containing liquid ; any change in the temper- 
 ature of one of the bulbs, the other being unaffected, is 
 made manifest by the motion of the liquid from the 
 warmer bulb. 
 
 Thermometers (Gr. tJierme, heat, and metron, measure) 
 
HEAT. 33 
 
 serve both to indicate and compare changes of temperature. 
 Their indications are derived from the expansion of a 
 liquid in a closed tube. Mercury is the liquid preferred 
 because of its low specific heat (69), its uniformity of ex- 
 pansion (51), its low freezing and high boiling point, and 
 its property of not adhering to glass. The tube has a bulb 
 blown on it, which with part of the stem is filled with 
 mercury ; the air is expelled by boiling the mercury, and 
 the end of the tube hermetically sealed, (melted together.) 
 The instrument is then immersed in the vapour of boiling 
 water, (the barometer being at 30 in.,) and the height of 
 the column marked ; afterwards it is plunged into melting 
 ice and the height again noted. The space between 
 these two points is divided into degrees, which vary ac- 
 cording to the scale adopted. On the centigrade scale 
 (C.) the melting point of ice is marked 0, the boiling point 
 of water 100°. Reaumur's scale (R.) has the same 0, but 
 the boiling point is 80°. Fahrenheit (F.) marks the lower 
 point 32°, the upper 212°. Thus the same space is divided 
 into 100, 80, and 180 degrees on the different scales. 
 
 Hence (dividing by 20) 9 degrees F.=5 C.=4 R. To convert 
 O; degrees to F M multiply by 9, divide by 5, and add 32. To con- 
 vert R. to F., multiply by 9, divide by 4, and add 32. The fol- 
 lowing formulas include all the necessary conversions : F. to C, f 
 (F.~32)=C; C. toF., §C + 32 = F.; R. to F., f R.-f 32 = F. ; 
 F. toR., |(F.— 32) = R. 
 
 Pyrometers (Gr. pur, fire, and metron, measure) are 
 instruments used for measuring high temperatures by 
 means of the expansion of a solid body, which it is diffi- 
 cult to soften or melt. Saxton's reflecting pyrometer 
 measures very slight changes at ordinary temperatures by 
 communicating, by means of compound levers, the motion 
 produced by the expansion of a bar of metal to a mirror 
 which reflects a scale placed at a distance ; the image of 
 the scale in the mirror is examined by a telescope. 
 
34 MEDICAL CHEMISTRY. 
 
 An idea of the effect of the mirror in magnifying the changes 
 of the bar, may be obtained by throwing a beam of light from a 
 email looking-glass upon a distant wall ; an almost imperceptible 
 change in the position of the mirror is followed by a motion of 
 the spot of reflected light through several feet. 
 
 Thermo-Multiplier. This instrument is by far the most 
 sensitive to minute changes of temperature yet devised. 
 A number of small bars of bismuth and antimony are 
 soldered at alternate ends and kept apart by slips of paste- 
 board ; to the end bars of the arrangement a copper wire 
 is fastened, this passes several times around a delicately 
 suspended magnetic needle ; when one end of the pile of 
 bars is warmed, a current of electricity passes through the 
 wire and causes the needle to move over a graduated scale. 
 
 E. SOURCES OP HEAT. 
 
 1. Physical; 2. Mechanical; 3. Chemical. 
 
 38. (1) Physical. — These are the heat of the sun and 
 stars, the internal heat of the earth, and atmospheric elec- 
 tricity. The two last are comparatively unimportant. 
 
 Amount of Heat Emitted by the Sun. — According to the 
 observations of Pouillet,* the amount of heat annually re- 
 ceived from the sun would melt a layer of ice surrounding 
 the earth 101 feet thick. Yet the earth receives less than 
 the two thousand millionths of the heat emitted by the 
 sun. The fixed stars, the suns of other systems, are esti- 
 mated to furnish to the earth four-fifths as much heat as 
 the sun itself, f 
 
 The heat emitted by the sun would boil 700,000,000,000 of 
 cubic miles of ice-cold water per hour ; its volume is 1,400,000 
 times greater than that of the earth, yet if made of coal, and oxy- 
 gen furnished in quantity sufficient to enable it to supply the 
 observed emission, it would be utterly consumed in 5000 years. J 
 
 * Physique, tome 2de, p. 681. f Silliman, op. cit. 493. 
 
 X Tyndall, op. cit. 434, 435. 
 
HEAT. 35 
 
 The cause of the sun's heat is supposed by Von Meyer * to be 
 due to the percussion of asteroids falling upon it. Should the 
 earth be drawn into the sun, the heat developed by the shock 
 and the arrest of the earth's rotation would supply the sun's 
 emission for ninety-five years.f 
 
 39. (2) Mechanical Sources of Heat. — Force is never 
 
 lost. When motion is arrested, enough heat is developed 
 
 to reproduce that motion, if properly applied. Friction 
 
 compression, and percussion are methods of converting 
 
 motion into heat. 
 
 A match is lighted by the heat developed by friction ; a piece 
 of cold metal passed between rollers becomes hot ; iron may be 
 heated red-hot by hammering. 
 
 40. (3) Chemical Sources of Heat. — Chemical combina- 
 tion is accompanied by heat. "When the heat thus pro- 
 duced is sufficiently intense to produce light, the phenom- 
 enon is called combustion. This subject will be more 
 fully considered under the heads of Chemical Affinity, 
 and Oxygen. 
 
 In an ordinary fire the heat developed is due to the'union of 
 the oxygen of the air with the carbon and hydrogen of the fuel. 
 The amount of heat developed will depend chiefly upon the 
 quantity of oxygen consumed. 
 
 The cause of animal heat is supposed to be the union of 
 the carbon, and perhaps of the hydrogen of the food, with 
 the oxygen of the inspired air. This probably takes place 
 in the capillaries. — (Liebig.) This view is not adopted 
 by all physiologists. 
 
 m. COMMUNICATION OF HEAT. 
 
 1. Radiation ; 2. Conduction ; 3. Convection. 
 41. (1) Radiation. — The phenomena of radiant heat 
 closely resemble those of light. It is propagated in rays 
 
 * Celestial Dynamics, Am. ed., p. 271. 
 
 •J- Prof. Thompson, cited in Tyndall, pp. 441, 442. 
 
oo MEDICAL CHEMISTRY. 
 
 with immense velocity, and is reflected, transmitted, or 
 absorbed by the surface upon which it falls. It is not 
 affected by currents of air. Its intensity is directly pro- 
 portional to the temperature of the source, and inversely 
 as the square of the distance. It is supposed to be con- 
 stantly taking place from the surfaces of all bodies ; when 
 a body is warmer than those surrounding, it emits more 
 than it receives, and vice versa. Hence the apparent radi- 
 ation of cold, as in the lowering of the thermometer hung 
 over the side of a vessel on the approach of an iceberg. 
 The heat accompanying light is termed luminous; that 
 from a dark body, as a vessel of hot water, obscure. 
 
 42. Emission. — The rate at which heat passes from a 
 body depends upon the temperature and nature of the sur- 
 face. Rough surfaces emit most rapidly. The following 
 examples will show the emissive power of different sur- 
 faces for non-luminous heat: Lampblack (the highest) 
 assumed as 100; white lead, 100; writing-paper, 98; 
 glass, 90 ; ice, 85 ; tarnished lead, 45 ; polished silver, 3. 
 It is independent of colour. 
 
 Water is easily boiled in a glass, or rough or smoked metallic 
 vessel ; it is kept warm in a vessel of polished metal. A pol- 
 ished metallic vessel, filled with hot water, will cool more rapidly 
 if covered with a tightly fitting muslin jacket. The high radi- 
 ating power of glass causes windows, in winter, to cool the air 
 of rooms rapidly, resulting in loss of fuel and the production of 
 downward currents of cold, foul air, which interfere with venti- 
 lation. Water has a high radiating power, and will freeze, 
 under favourable circumstances, when the temperature of the 
 surrounding air is not below 40° F. 
 
 43. Absorption. — The absorbing power of a surface is 
 the same as its emissive power when the source is at 
 212° F.; at other temperatures they coincide nearly, but 
 not exactly. It also varies with the nature of the source 
 Lampblack is the only substance which absorbs all the 
 rays of heat, no matter what the source. Absorption of 
 
HEAT. 3t 
 
 obscure rays is independent of the colour of the surface ; 
 of luminous rays the greatest number are absorbed by 
 black ; then in the following order : violet, indigo blue, 
 green, red, yellow, and white. The rays of heat are more 
 largely absorbed in proportion as they fall more nearly 
 perpendicularly upon the surface. Hence the less ap- 
 parent warmth of the sun's rays in winter. 
 
 44. Reflection. — The laws of the reflection of radiant 
 heat agree with those of light (23). The reflecting power 
 of a surface is inversely as its radiating power. Polished 
 metallic surfaces form the best reflectors ; glass silvered on 
 the back, while an excellent reflector of light, is almost 
 useless in the case of heat; but a film of gold tjxjtjutjtj °f 
 an inch in thickness, placed on the front of the glass, will 
 reflect almost as well as a solid metallic plate. 
 
 45. Transmission. — The laws of the transmission of 
 radiant heat accord closely with those of light. Bodies 
 which allow heat to pass through them are termed 
 diathermous (Gr. dia, through, and thermaino, to heat). 
 There is no direct relation between the transparency of a 
 medium and its power to transmit heat. Rock-salt is the 
 most diathermous body known; when smoked so as to 
 become opaque, it still transmits heat ; alum which may 
 be obtained quite transparent, almost entirely cuts off the 
 heat-rays; glass transmits them imperfectly. The pro- 
 portion of heat-rays transmitted also depends upon the 
 source ; at high temperatures a larger proportion is trans- 
 mitted, and the difference of the diathermacy of various 
 media is less marked than for the obscure rays. Gases 
 vary exceedingly in their transmitting power, pure dry air 
 being almost absolutely diathermous, while ammonia, 
 olefiant gas, odours of essential oils, and watery vapour 
 obstruct to a greater or less degree.* The radiating and 
 absorbing powers of media are proportional. 
 
 * Tvndall, op. eft. pp. 361> 374, 399. • 
 
38 MEDICAL CHEMISTRY. 
 
 Calling the absorptive power for obscure rays, under atmo- 
 spheric pressure, of pure dry air 1, that of ammonia is 1195 ; 
 olefiant gas, 970 ; humid air, 96 ; essential oils, 30 to 372. A 
 stratum of ammonia as thick as a sheet of paper will cut off 
 obscure heat-rays as effectually as a metal screen. The im- 
 portance of these discoveries to the science of meteorology is 
 obvious. 
 
 Sifting of Rats. — When the rays from any source pass 
 through a medium, a certain portion is arrested. Of those which 
 go through a much larger proportion will pass through a second 
 similar medium. For example, a plate of alum transmitted but 
 9 per cent, of heat-rays, arresting 91 ; of these 9 a second plate 
 transmitted 90 per cent., arresting but 10 per cent. The heat 
 which has passed through the first plate is said to be sifted of 
 those rays which are most easily arrested. This principle 
 explains why glass readily transmits solar heat, but arrests that 
 from other sources. The heat of the sun in its passage through 
 the atmosphere (which contains watery vapour, ammonia, and 
 odours) is strained of the rays which could be stopped by the 
 glass. 
 
 46. Refraction Of Heat. — The rays of heat obey the 
 laws of light in regard to refraction. The ordinary burn- 
 ing-glass causes the rays of the sun to be concentrated 
 upon a spot, the focus (26). The intensity of the heat at 
 the focus compared with that of the sun is as the area of 
 the glass compared with that of the focus. Heat passed 
 through a prism forms a thermal spectrum analogous to 
 the solar spectrum, but differing in many important points. 
 Heat, like light, may be polarized. 
 
 4t. Conduction. — Heat passes slowly through bodies, it 
 is supposed by radiation from particle to particle. The 
 conducting power of liquids is very slight, that of gases 
 inappreciable. Of solid bodies, the metals are the best 
 conductors. The following list assumes the best con- 
 ductor at 100 : Silver, 100; gold, 98; copper, 73 ; brass, 22; 
 tin, 23; iron, 13; lead, 11; platinum, 10; German silver, 
 6 ; bismuth, 2. Solids generally conduct equally in all 
 directions. This is not the case with certain crystals and 
 with wood. Porous or fibrous bodies, as sawdust, pow- 
 
HEAT. 39 
 
 dered charcoal, and down, are bad conductors on account 
 of the air and gases enclosed. 
 
 Illustrations. — If a rod of iron be held with one end in the 
 fire, an appreciable time will elapse before the hand receives heat 
 through it, although the radiant heat of the sun, at 95,000,000 of 
 miles distant, is felt as soon as his light is seen. 
 
 If a pin be thrust into a candle-flame, it will soon become too 
 hot to be held ; a wooden match, if held upwards, may be burned 
 almost to the fingers without heat being communicated by the 
 wood. 
 
 Metal at 120° F. will burn the hand ; water may be borne at 
 150° if the hand be kept still and the temperature gradually 
 raised ; dry air may be endured above 300°, at which tempera- 
 ture eggs may be roasted and steaks cooked. Moist air con- 
 ducts better than when dry ; hence the feeling of chilliness it pro- 
 duces. Fire-proof safes, ice-houses, water-pitchers, are made 
 double with porous material interposed to prevent the com- 
 munication of heat from without. A bed of ice several centuries 
 old exists on the flanks of Mount iEtna, preserved by having 
 been first covered with a layer of sand and ashes, and then with 
 a stream of lava. 
 
 The order of conducting power of clothing materials is as fol- 
 lows: linen, cotton, silk, wool, furs, eider-down. Fine fabrics 
 are warmer than coarse ones. 
 
 48. Convection or Circulation. — Liquids and gases can, 
 in practice, be warmed only by heat applied below. The 
 particles of. fluid in contact with the heated portion of the 
 containing vessel become expanded and are forced upwards 
 by the descending cooler and heavier ones. A circulation 
 is thus set up by which each particle in turn receives heat 
 from the source. The presence of any viscid matter will 
 prevent this circulation; hence, in boiling starch, gum, 
 etc., the fluid requires to be constantly stirred to prevent 
 burning. 
 
 Winds and currents in the atmosphere (193) are thus caused. 
 The gulf-stream is due to the heated water of the tropics flowing 
 off toward the poles. 
 
40 MEDICAL CHEMISTRY. 
 
 IV. EFFECTS OF HEAT. 
 
 49. In considering the effects of heat, it should be 
 borne in mind that bodies consist of particles with dis- 
 proportionately large spaces or pores between them (8). 
 These particles are under the constant influence of two 
 forces, that of attraction tending to bring the particles into 
 contact, and that of repulsion (due principally, if not 
 wholly, to heat) tending to drive them asunder. When 
 the first preponderates greatly, bodies are solid ; when in 
 a less degree, liquid; and when the latter is stronger, they 
 are in the state of gas or vapour. Moreover, as the dis- 
 tance of the particles increases, the attractive force dimin- 
 ishes in a rapid ratio, and the repulsive force acts with 
 an energy correspondingly greater (9). The effects of 
 heat may be considered under the heads of Expansion, 
 and Change of State. 
 
 50. 1. EXPANSION (a) of Solids, (b) of Liquids, (c) 
 of Gases. 
 
 (a) Of Solids. — All solids (except caoutchouc*) expand 
 by heat. The expansion is equal in all directions; the 
 solid resumes its original form and volume on returning 
 to the original temperature. When expansion is measured 
 in length only, it is called linear ; when in all dimensions, 
 it is called cubical. The coefficient of expansion is the 
 small increase in dimensions observed in passing from 32° 
 to 33° F. The rate of expansion of solids varies with the 
 body and increases with the temperature. The force 
 exerted by an expanding or contracting body is equal to 
 that required to extend or compress it an equal amount, 
 and is practically irresistible. A bar of iron one inch 
 
 * Tyndall, op. tit. p. 102. 
 
HEAT. 41 
 
 square, heated from 10° to 90° F., exerts a pressure of 
 about f tons. 
 
 Certain crystals do not expand equally in all directions. 
 Wood expands more in the breadth than in the length of its 
 fibres ; lead sometimes expands permanently, causing the leaden 
 lining of bath-tubs, etc., to become wrinkled. 
 
 Cubical expansion may be derived from the linear by cubing 
 the coefficient. The increase of capacity of hollow vessels is 
 equal to that of a solid mass of the same size and material for a 
 like change of temperature. 
 
 The amount of expansion of solids is small, being for zinc, 
 which is the most expansible of the metals, only 5 ^th of its 
 length, between 32° and 212° F. The following list gives the 
 relative dilatability of the bodies named: Zinc, lead, tin, silver, 
 brass, gold, copper, bismuth, iron, steel, antimony, platinum, 
 glass. Ice and certain minerals are more expansible than the 
 metals. Platinum wires may be fastened in glass, as the two 
 expand and contract nearly alike ; other metals will expand and 
 contract more than the glass, causing them to split it or become 
 loose. 
 
 Compound bars. — If two metals, as silver and platinum, be 
 riveted together, the bar will bend on change of temperature; 
 the more expansible metal forming the convex front of the curve 
 when heated, and vice versa. Such an arrangement is employed 
 in BregueVs thermometer, and is applied, among others, to the 
 compensation of the pendulums of clocks and balance-wheels of 
 watches. 
 
 The force of expansion and contraction of solids is often 
 
 usefully employed, as in shrinking tires on wheels, reinforce 
 rings on cannon, or in drawing up the walls of buildings by the 
 contraction of rods passed through the walls. Glass stoppers 
 may be loosened by heating the neck of the bottle; the neck 
 becomes warmed sooner than the stopper, and, expanding, re- 
 leases it. Heat, applied to a thick glass vessel, will crack it, 
 because of the more rapid expansion of the part heated, owing 
 to the bad conducting power of the glass. Chemical flasks are 
 made thin, and will safely bear sudden changes of temperature. 
 
 51. (6) Of Liquids. — Liquids expand more than solids 
 for an equal increase of temperature, because in them the 
 cohesive force is weaker. Between 32° and 212° F. the 
 expansion (cubical) of mercury is ^, of water 3^.3, alco- 
 hol i. They expand more irregularly than solids, the rate 
 being greater at higher temperatures. Mercury is the most 
 uniform in its rate of expansion, which is one reason for 
 4* 
 
42 MEDICAL CHEMISTRY, 
 
 its use in thermometers (37). The rate of expansion of a 
 liquid in glass (which at the same time expands) is called 
 its apparent, in contradistinction to its absolute or real ex- 
 pansion. The force exerted by the expansion of a liquid 
 is, like that of a solid, practically irresistible. Mercury, 
 heated 10°, exerts a force of 2850 lbs. per square inch. 
 When kept under pressure, and heated above their boiling- 
 point, the rate of expansion of liquids increases rapidly, 
 and even exceeds that of gases. Liquid carbonic acid ex- 
 pands more than air for an equal increase of temperature. 
 
 52. Maximum Density of Water. — Water, cooled below 
 
 39-2° F., no longer contracts, but expands until it reaches 
 
 the freezing-point 32° F. Hence at that point any increase 
 
 or diminution of temperature causes an increase of bulk, 
 
 and the liquid is said to be at its temperature of maximum 
 
 (greatest) density 
 
 Owing to this fact, our streams and lakes never freeze to any 
 great depth. Water exposed to cold loses its heat by radiation 
 (41) and convection (48), until it reaches 39*2° F. ; after this, 
 circulation ceases, the colder water, being lighter, no longer sinks 
 to the bottom, but remains like a film of oil on the surface until 
 it freezes. Ice, being lighter than water floats, and as it is a bad 
 conductor of heat, acts to protect the stream from further loss. 
 The temperature of maximum density of sea-water is 25*7° F. 
 
 53. (c) Of Gases. — In gases the cohesive force is inap- 
 preciable; they therefore expand more than liquids. All 
 gases expand alike, and the rate is not altered by tempera- 
 ture nor pressure. The increase of bulk of a gas for 1° F. 
 is % \-q of its bulk at 0° F., or T ^ of its bulk at 32° F. 
 This is equal to rather more than one-third of the bulk 
 between 32° and 212° F. 
 
 The above statements, although practically true, are not strictly 
 so Certain liquefied gases, as carbonic acid, expand more than 
 the gases themselves. All gases do not absolutely expand alike, 
 nor is the rate of expansion entirely uninfluenced by pressure. 
 
 In order to calculate the volume of a given quantity of 
 gas of known temperature and pressure at any other tern- 
 
HEAT. 43 
 
 perature and pressure, the following simple formulae will 
 be sufficient. Calling t the original temperature in degrees 
 F., p the original pressure, t' the observed temperature, and 
 p f the observed pressure. Then, as a gas increases ? J V of 
 its bulk for each degree F., and its volume is inversely at 
 the pressure (194), we have 
 
 460-H : 460-f ^ : : V : V : and 
 p' : p : ::V:V 
 where V and V are the original and observed volumes. 
 
 Thus, 100 cubic inches of a gas at 60° F., and 30 in. bar., 
 become at 90° F., and 29 in. bar., — 109-2 c. in. 
 520 : 550 : : 100 : 105-7 
 29 : 30 : : 100 : 103*5 
 
 54. 2. Change of State includes the phenomena of (a) 
 fusion, congelation, or solidification; (6) evaporation, 
 vapourisation, condensation; and (c) latent heat. All 
 matter (with certain exceptions) may exist either as solid, 
 liquid or gas, the state depending upon the temperature 
 and pressure. By lowering temperature and increasing 
 pressure, thus aiding cohesion, we convert gases and 
 vapours into liquids, and finally into solids, and vice versa. 
 
 As yet, some solids have not been satisfactorily fused or vapour- 
 ised, and the following gases have resisted all attempts to liquefy 
 them : oxygen, hydrogen, nitrogen, carbonic oxide, nitric oxide, 
 and marsh gas. 
 
 When we speak then of a body as a solid, or liquid, or gas, 
 we refer to ordinary temperatures. To an inhabitant of a cli- 
 mate of a fixed temperature of 0° F., sulphurous acid would be a 
 liquid and water a solid ; were the planet Mercury habitable, 
 iron would be described as a gas 
 
 55. (a) Fusion and Solidification. — Bodies melt at a 
 certain temperature fixed for each, at which temperature 
 they also solidify. During the processes of fusion or of 
 solidification, the temperature remains constant. Some 
 bodies, as ice, pass at once to the liquid state; others, 
 as butter, soften gradually ; others, as camphor and arsenic, 
 
44 MEDICAL CHEMISTRY. 
 
 pass at once into the state of vapour, unless under more 
 than atmospheric pressure. 
 
 The following are some of the more important fusing points in 
 degrees (F.) : Mercury — 39, bromine — 4, phosphorus X 111, iodine 
 + 224, sulphur + 239, tin + 455, bismuth -f 518, lead -f 630, zinc 
 + 761, silver + 1873, copper + 2143, gold + 2016. 
 
 The temperature of the liquid remains constant during fusion 
 because the heat applied goes to melt the body, not to raise the 
 temperature of that already melted. It is then doing work (34) 
 and is not sensible to the thermometer; (Latent Heat.) Con- 
 versely, when heat is abstracted from a liquid, a portion becomes 
 solid, and the heat of fusion is thus liberated, and the tempera- 
 ture cannot fall so long as any liquid remains. 
 
 Bodies which are difficult of fusion, as carbon, fire-clay, lime, 
 magnesia, silica, etc., are termed refractory. Even carbon, how- 
 ever, has been softened and partially fused in the voltaic arch. 
 
 56. Change of Volume during Solidification. — Mercury 
 and most metals contract on solidification, and do not 
 therefore make good casts. Hence coins and medals are 
 stamped. Certain alloys, as type-metal (lead and anti- 
 mony), expand and take sharp impressions of a matrix. 
 Water expands about one-eleventh of its bulk on freezing, 
 and will burst strong iron vessels. 
 
 Water does not always freeze at 32° F., but invariably melts 
 at that temperature. By keeping it perfectly still, deprived of 
 carbonic acid, or under great pressure, or in capillary tubes, its 
 temperature may be lowered 10° or more below its normal freez- 
 ing-point. 
 
 57. (6) Evaporation and Vapourisation. — Liquids on 
 the application of heat become vapours. Physically, 
 vapours (remote from their condensing points) and gases 
 are identical 
 
 Evaporation takes place gradually, at all temperatures, 
 
 and from the surface of the liquid only. When solids pass 
 
 at once into the state of vapour, it is termed sublimation, 
 
 although this word has a more extended meaning 
 
 Ice and snow evaporate below 32° F. Some liquids do not 
 evaporate below a certain point, as mercury below 40° F., and 
 sulphuric acid at common temperature. 
 
HEAT. 45 
 
 58. Tension of Vapours. — If a barometer tube be filled 
 and inverted over mercury, there will be above the mer- 
 cury, in the tube, a vacuum (Torricellian vacuum [193] ). 
 If into a series of such tubes small equal quantities of 
 different liquids be introduced at the same temperature, it 
 will be noticed that the liquid will volatilise instantly, and 
 that the mercury will be forced down in the tube to a 
 greater distance in proportion as the liquid is more vola- 
 tile. This elastic force or spring of the vapour is called 
 its tension. If an additional quantity of liquid be intro- 
 duced, further depression takes place, until it will be found 
 that the liquid will no longer volatilise, nor the column be 
 depressed by its vapour. The space has become saturated 
 with the vapour and ean receive no more ; this is called 
 the point of saturation or maximum (greatest) tension of 
 the vapour for that temperature. By increasing the tem- 
 perature, more liquid is volatilised and further depression 
 takes place ; by reducing it, a portion of the vapour is 
 condensed, and the column rises. When the temperature 
 rises to the boiling-point of the liquid, the mercury is 
 driven out of the tube, and will stand at the level of the 
 cistern. When the tube contains both vapour and liquid, 
 by raising it so as to diminish the pressure, further evapo- 
 ration takes place ; by depressing it into the cistern so as 
 to increase the pressure, more liquid is formed. Hence 
 the point of saturation or maximum tension varies with 
 the temperature, and is independent of the pressure. The 
 tension of vapours in communicating vessels unequally 
 heated is equal, and is that due to the lower temperature. 
 
 59. Circumstances influencing Evaporation.— The greater 
 the extent of surface, the higher the temperature (up to a 
 certain point [64] ) and the less the pressure, the more 
 rapid the evaporation. Rapid removal of air, by present- 
 ing a fresh space instead of one partially saturated, also 
 aids it, 
 
46 MEDICAL CHEMISTRY. 
 
 In the arts, evaporation is carried on in flat dishes ; some- 
 times in salt-making the brine is allowed to trickle over twigs, 
 to increase the extent of surface. Medicinal extracts are pre- 
 pared in vacuo. Draughts of air produce a sensation of coolness 
 by promoting evaporation (68). 
 
 60. Vapourisation, or Ebullition, takes place rapidly at 
 the boiling-point and from the whole of the liquid. A 
 liquid boils when the tension of its vapour exceeds its co- 
 hesive force and the pressure on its surface. When water 
 is exposed to heat, we notice that the air is first driven 
 out, then simmering is heard. This is due to the con- 
 densation of the bubbles of steam formed at the lower part 
 of the vessel by the cooler liquid above. As soon as the 
 whole reaches the boiling-point, the bubbles pass to the 
 surface and the steam escapes ; ordinarily it is partly con- 
 densed into minute bubbles or drops forming a cloud. 
 True steam is transparent and invisible, as air. The boil- 
 ing-points of liquids will be given as their properties are 
 described. By reducing the pressure the boiling-point is 
 lowered, by increasing it it is raised, so that water may be 
 made to boil in vacuo at 10°, or in a strong boiler be 
 heated red-hot. The temperature of water in an ordinary- 
 locomotive boiler is 340° F. 
 
 Adhesion also modifies the boiling-point. In a perfectly clean 
 glass vessel water may be raised to 221°, and then bursts irregu- 
 larly into steam ; a little clean sand or platinum wire causes the 
 liquid to boil regularly at its normal temperature. This expe- 
 dient is often used in distilling heavy liquids, which by their 
 thumping would break the retort. Water entirely deprived of 
 air may be heated to 360°, and then bursts into steam with ex- 
 plosive violence. — (Donn^.) 
 
 As the boiling-point varies with the pressure, the barometric 
 height of 30 inches (193) is assumed as the standard. 
 
 Solutions of solids raise the boiling-point ; a saturated solution 
 of common salt boils at 227° F. Such solutions are sometimes 
 used as water-baths or in tempering steel. The water-bath con- 
 sists of two concentric vessels having the intervening space filled 
 with water, but open to the atmosphere. A body placed in the 
 inner vessel will be subjected to a temperature not exceeding 
 
HEAT. 47 
 
 that of the boiling-point of the liquid. The common glue-pot is 
 an example. 
 
 Sugar is made in vacuum pans, by means of which it is boiled 
 at a lower temperature. In Papin's digester, a strong boiler of 
 peculiar form, water is heated above its boiling-point, and its 
 solvent action on certain bodies much increased. 
 
 61. Mechanical Force developed during Evaporation. — 
 A cubic inch of water yields nearly a cubic foot of steam. 
 Hence the evaporation of water is a convenient method of 
 converting heat into motion (34). Although some other 
 liquids boil at a much lower temperature, ether, for in- 
 stance, at 94*8°, yet at their boiling-points, the space occu- 
 pied by their vapour is less than that of steam, and they 
 require the same amount of heat to produce the same 
 volume. Hence there would be no advantage in substi- 
 tuting them for water in engines. The expansion of air 
 is employed for the same purpose. As air only increases 
 about one-third of its volume by being heated from 32° to 
 212° R, its usefulness is limited to engines of moderate 
 power. Its advantages over steam are: (1) Greater 
 economy. The specific heat of air (70) is but one-fourth 
 that of water. In engines working into the atmosphere, 
 the agent (steam or air) is thrown away after doing work, 
 and the residual heat wasted. Air wastes but one-fourth 
 as much as steam. (2) Safety. In air-engines there is 
 no boiler, can be no explosion, and an attendant is only 
 needed to replenish the fire and keep the machinery in 
 order. 
 
 62. Condensation of vapours is accomplished by cold, 
 aided in some cases by pressure. Pressure alone cannot 
 liquefy a vapour, as the heat developed by the condensa- 
 tion is equivalent to the force producing it (34). By 
 combined pressure and cold most of the gases known to 
 us have been liquefied, and many solidified. Those which 
 are known to us only as gases, to wit : oxygen, hydrogen, 
 
48 MEDICAL CHEMISTRY. 
 
 nitrogen, carbonic oxide, nitric oxide, and marsh gas, are 
 termed permanently elastic gases. 
 
 63. Distillation is the successive evaporation and con- 
 densation of a liquid. It is employed to separate a liquid 
 from a dissolved solid, or to separate liquids of different 
 volatility from each other (fractional distillation). An 
 example of the first is in the distillation of water to free it 
 from impurities ; of the second, the separation of alcohol 
 and water in the manufacture of spirits. 
 
 Fractional distillation cannot be relied on to separate entirely 
 liquids of different volatility, because evaporation takes place 
 below the boiling-point of the less volatile liquid. Ilence chemi- 
 cal means are resorted to after the distillation. See Alcohol. 
 
 The form of condenser used on the large scale is a coiled pipe 
 or worm immersed in a cistern in which water is admitted be- 
 low, and passes out above. Liebig's condenser is a tube sur- 
 rounding that leading from the retort, closed at the ends, and 
 having a lateral tube for the admission of cold water below, and 
 one for its exit above. 
 
 When the distillate is not very volatile, it is sufficient to keep 
 the neck of the retort and the receiver cool by means of wetted 
 paper or cloth. 
 
 64. Spheroidal State. — A liquid dropped upon a polished 
 plate heated considerably above its boiling-point, does not 
 wet the plate, but assumes the form of a flattened sphere 
 resting quietly upon it. The evaporation of the spheroid 
 is slow, its temperature is always below the boiling-point 
 of the liquid (205'T° F. for water), that of its vapour 
 nearly that of the plate. It does not touch the plate. 
 The phenomenon takes place in vacuo, on the surface of 
 most solids and of liquids. The chemical action of a liquid 
 upon the plate is suspended while the former is in the 
 spheroidal state. The causes assigned for this phenome- 
 non are four. (1) The repulsive force which heat exerts 
 between bodies which are nearly in contact with each 
 other. (2) A cushion of vapour is formed on which 
 the spheroid rests. (3) This vapour is a bad conductor, 
 
HEAT. 49 
 
 and prevents the rapid transmission of heat from the plate 
 to the globule. The radiant heat of the plate is reflected 
 from the globule. (4) The evaporation from the surface 
 of the spheroid carries off the heat as it arrives, and pre- 
 vents the liquid from boiling. 
 
 Certain remarkable phenomena are connected with this state. 
 A white-hot poker may be licked with impunity ; the hand 
 (moist) may be safely plunged into molten iron or lead. By the 
 aid of liquid sulphurous or solid carbonic acids, water and mer- 
 cury may be frozen in red-hot capsules. 
 
 65. (c) Latent Heat. — When heat causes a solid to 
 liquefy, or a liquid to vapourise, it is doing work in over- 
 coming or resisting the cohesive force of the particles. It 
 cannot at the same time then do other work in expanding 
 the liquid of a thermometer, or in producing those changes 
 which give us the sensation of heat. It is therefore insen- 
 sible or latent (lateo, lie hidden). 
 
 If we expose a pound of water and one of ice, each at 
 32° F., in vessels provided with thermometers, to an uni- 
 form source of heat, the ice will gradually melt, but the 
 thermometer will remain at 32° until the last solid parti- 
 cle has disappeared (55). If at this instant the ther- 
 mometer in the other vessel be examined, the water will 
 be found to have risen to 114° F. It is evident that 142 
 thermal units (35) have been expended in converting ice 
 into water of the same temperature. 
 
 If we expose a pound of water at 212° F., and 96 f 
 pounds at 60° F., to an uniform source of heat, the boil- 
 ing water will pass into steam of the same temperature 
 (212° F). When it has all vapourised, the 96? pounds of 
 water will be found to have risen 1° F., to wit, to 61° F. 
 Hence 96 T thermal units are required to convert water 
 into steam of the same temperature. On condensing the 
 steam, by passing it into water below 212°, this heat is 
 again given out. 
 5 
 
50 MEDICAL CHEMISTRY. 
 
 Water is the great regulator of changes of the earth's tempe- 
 rature. From its high specific heat (09), it absorbs heat in hot 
 seasons or localities, and gradually gives it out as the tempera- 
 ture falls. Ice and snow give out their latent heat to moderate 
 sudden frosts, and again absorbing it, reduce the temperature 
 during rapid thaws. By their bad conducting powers they 
 protect the earth from extremes of cold. Evaporation from the 
 surface of the earth moderates the intensity of the sun's rays. 
 
 Steam is used as a source of heat, both from its convenience 
 and in cases where the direct action of fire would be unsafe. It 
 gives out both its sensible and latent heat when condensed. The 
 sum of the sensible and latent heat is nearly constant ; that is, 
 as we increase the temperature of steam by means of a high- 
 pressure boiler (60), we compress it into a less volume, and thus 
 liberate a portion of the latent heat. Hence there is no economy 
 in the use of high-pressure steam for heating purposes. 
 
 66. Freezing Mixtures. — If we mix two solids capable 
 of rendering each other liquid by chemical or mechanical 
 force, the particles are torn asunder by this force, and the 
 heat which would be necessary to liquefy them must be 
 supplied from surrounding bodies. The same is true of a 
 solid and liquid. The most common and convenient freez- 
 ing mixture is composed of salt one part, snow or pounded 
 ice two parts. A temperature of 0° F. may thus be pro- 
 duced and maintained for some time. By means of a bath 
 of solid carbonic acid and ether, Mitchell (J. K.) obtained 
 a temperature of — 146° F. Natterer, by means of liquid 
 nitrous oxyde and bisulphide of carbon, reached — 220° F. 
 In the latter cases the low temperature was partly due to 
 evaporation. The cold produced by solution, as of epsoni 
 salt or nitre, is explained on the same principle. 
 
 67. Cold produced by Evaporation. — The heat required 
 to evaporate or vapourise a liquid is abstracted from sur- 
 rounding bodies, or from the liquid itself. The more vola- 
 tile the liquid, the more rapid the reduction of tempera- 
 ture. 
 
 . The cooling effects of the rapid evaporation of perspiration, 
 especially in draughts of air, of cologne, etc., are well known. 
 
HEAT. 51 
 
 The evaporation of ether has been employed on the large scale 
 in Twining's apparatus for the production of ice in hot climates. 
 Water may be frozen by its own evaporation in an exhausted 
 receiver, or the cryophorus of Wollaston. In Carre's apparatus 
 a solution of ammonia in water (which takes up over 700 vol- 
 umes of the gas) is heated in a strong boiler until the gas is 
 expelled. This gas passes by a tube into a communicating con- 
 denser, where it is liquefied by its own pressure, aided by the 
 abstraction of heat by means of a current of water. If the 
 boiler be now placed in water, and cooled, the liquid ammonia 
 (which boils at — 40° F.) passes rapidly into vapour, which is 
 absorbed by the now cool water in the boiler, and the water in 
 contact with the condenser, giving heat to the boiling ammonia, 
 freezes. The cold produced by the evaporation of the spray of 
 ether or rhigolene has been used for the production of local 
 anaesthesia. — (Richardson, Bigelow.) 
 
 68. SPECIFIC HEAT. — Equal weights of different 
 substances submitted for the same time to the same source 
 of heat do not acquire the same temperature. Some take 
 longer than others to warm through. Thus if two vessels, 
 one containing a pound of water, the second a pound of 
 mercury, be exposed to the same source of heat, it will be 
 found that while the water rises 1°F., the mercury will rise 
 33° F. The water is thus said to have a capacity for heat 
 33 times greater than that of mercury. As water has 
 the greatest capacity for heat of any known body, it is 
 assumed as the standard. The specific heat of a body is 
 the amount required to raise it 1° F., compared with an 
 equal weight of water. Thus the specific heat of mer- 
 cury is 0.033. It is not necessary here to detail the 
 various methods of determining accurately the specific 
 heats of bodies. The specific heat of a substance is 
 greater in the liquid than in the solid form. 
 
 A common experiment to show the different relative expansi- 
 bility of liquids is to take three tubes of equal diameters 
 furnished with bulbs of equal capacity, one filled with mercury, 
 a second with water, and a third with alcohol, to the same mark 
 on a scale. These are inserted in boiling water. At the end of a 
 few minutes the alcohol will stand highest, the water next, and 
 the mercury lowest, indicating their relative apparent expansi- 
 
52 MEDICAL CHEMISTRY. 
 
 bility. At first, however, the mercury rises higher than either 
 the water or the alcohol, owing to its small specific heat. This 
 is one of the properties which renders mercury especially 
 adapted for thermometers. The high specific heat of water 
 serves to moderate vicissitudes of climate (65). 
 
 69. Specific Heat of Gases. — This may be considered, 
 (1) when the gas is kept in a close vessel, so that its 
 volume cannot increase (specific heat under constant 
 volume) ; (2) when the gas is allowed to expand freely 
 (specific heat under constant pressure). The specific heat 
 of gases does not vary with the temperature or with the 
 pressure. When air is allowed to expand freely, about 
 fths of the heat applied is expended in producing ele- 
 vation of temperature, the remaining § ths being employed 
 in expanding the air, or in work. This is given out upon 
 compressing the air. The heat evolved by suddenly com- 
 pressing air is sufficient to ignite tinder. 
 
 70. Relation between Specific Heat and Atomic Weight. 
 If instead of comparing equal weights of elementary 
 bodies we take atomic weights (147), we shall find that 
 their capacity for heat is equal, or nearly so. In other 
 words, the specific heat of elementary bodies is inversely 
 as their atomic weights. There are certain important 
 exceptions to this law. This law also holds good in 
 regard to compound bodies of similar chemical consti- 
 tution, and containing the same number of atoms. 
 
 71. Agency of Heat in Natural Phenomena. — The 
 change of season depends upon the fact that in summer 
 the sun is longer above the horizon, and his rays are more 
 nearly vertical (43). Climate is modified by the presence 
 of large bodies of water, which render the temperature 
 more uniform (65) ; by the gulf-stream, which conveys 
 northward the warmer water of the tropics. The presence 
 of snow-clad mountains, and of large forests which hide 
 the earth from the sun's rays, render a climate colder. 
 
. HEAT. 53 
 
 The latitude, elevation, and prevailing winds also exert a 
 marked influence. Winds, draughts, and currents depend 
 upon the ascent of heated air, from the greater weight of 
 a column of cooler air of equal height. The trade-winds 
 and monsoons are periodical. The former are due to the 
 ascent of heated air from the equator, and the inflow from 
 the poles. They blow from the northeast and southeast ; 
 this obliquity being due to the rotation of the earth. The 
 latter are caused by the alternate heating of the earth on 
 opposite sides of the equator by the sun. 
 
 72. Sea and Land-Breeze. — When the sun shines on the 
 sea and adjacent coast, the latter becomes raised in tem- 
 perature, while the former remains nearly constant from 
 its vast volume and great specific heat (68). Hence the 
 cooler air from over the water gravitates and drives up 
 the lighter warmer air over the land, giving rise to the 
 sea-breeze. At night the land cools by radiation rapidly, 
 while the sea maintains its uniform temperature, and a 
 reverse current, the land-breeze, is produced. 
 
 Dew.— During the day the sun causes rapid evaporation 
 of the surface moisture of the earth, which diffuses through 
 the atmosphere ; at night the earth cools by radiation, and 
 this moisture is condensed upon its surface jjist as in sum- 
 mer it is seen on the surface of a vessel of iced water. 
 Clouds prevent the formation of dew by reflecting the 
 radiant heat to the earth; winds carry it off as fast as 
 deposited, Clouds, fog, rain, snow, and hail, are formed 
 from the condensed moisture of the atmosphere, but under 
 conditions too complex to be fully discussed in an ele- 
 mentary work. See The Atmosphere (193). 
 
 5* 
 
54 MEDICAL CHEMISTRY. 
 
 ELECTRICITY. 
 
 Is supposed to exist naturally in all bodies in a state of 
 equilibrium, and to manifest itself when this is disturbed 
 It is developed by mechanical means (statical or frictional 
 electricity), by chemical action (dynamical electricity, gal- 
 vanism, voltaic electricity), by heat (thermo-electricity), 
 by magnetism (magneto -electricity), by nervous force 
 (animal electricity). Magnetism being but a manifestation 
 of electricitv, is conveniently considered first. 
 
 MAGNETISM. 
 
 73. Magnets. — Magnetic iron ore, Fe 3 4 , (loadstone,) 
 possesses the property of attracting iron and certain other 
 metals (nickel, cobalt, and perhaps manganese), and of 
 communicating its powers to them ; a bar of iron or steel 
 thus magnetised is called an artificial magnet. Iron re- 
 ceives and loses magnetism readily, steel with difficulty. 
 
 A magnet is found to possess attractive powers princi- 
 pally at its ends, which are called its poles. 
 
 74. Directive Tendency. — If a magnet be suspended 
 freely, it assumes a position nearly north and south. The 
 end which invariably points north, is called the north pole, 
 and vice versa. One pole cannot exist without the other; 
 the fragments of a magnet each have poles. The north 
 pole of a second magnet repels that of the first, and attracts 
 its south pole, and vice versa. A magnet thus freely sus- 
 pended forms a compass-needle. When two magnets are 
 joined with the N.pole of one above the S.pole of the other, 
 it constitutes an astatic needle. 
 
 75. Induction. — A piece of iron brought near a magnet 
 has magnetic polarity induced in it, and is attracted; the 
 
ELECTRICITY. 55 
 
 intensity of the attraction depends upon the distance, and 
 is not interfered with by the interposition of neutral sub- 
 stances. This second magnet is capable of inducing mag- 
 netism in a third in a less degree, and so on. 
 
 76. Variation and Dip. — The line of direction of the 
 magnet, called the magnetic meridian, varies from the true 
 meridian. This deflection, which is not constant, is called 
 the variation of the needle. A magnet free to move in a 
 vertical plane will have a dip, which increases as we go 
 from the equator towards the poles. The earth is supposed 
 to be a great magnet, and the poles have been discovered, 
 that is, points where the dipping needle was vertical, and 
 the horizontal needle ceased to traverse. 
 
 11. Diamagnetism. — Researches with very powerful 
 magnets (electro-magnets, 104) have shown that all bodies 
 are probably more or less influenced by the magnet. Bodies 
 which are attracted arrange themselves in a line joining 
 the poles (axially), those which are repelled in a line at 
 right angles to this (equatorially). The former are called 
 magnetics or paramagnetics, the latter diamagnetics. Oxy- 
 gen is highly magnetic. 
 
 STATICAL ELECTRICITY. 
 
 IS. Elementary Phenomena. — If a tube or rod of dry 
 glass be rubbed with a cat's fur, it will be found to attract 
 light bodies, such as bits of paper. In the dark, a feeble 
 bluish light is seen in the path of the rubber, and a crack- 
 ling sound is heard; on presenting the knuckle, a slight 
 spark will pass to it. Brought near the face, either the 
 rod or rubber communicates a sensation as if cobwebs 
 were in contact with the skin. A body thus affected is said 
 to be excited or electrified. Electricity does not increase 
 or diminish the weight of bodies under its influence. The 
 
56 MEDICAL CHEMISTRY. 
 
 same phenomena may be observed (with proper precau- 
 tions) in all bodies. Electricity readily passes from an 
 excited body to a neutral one, and may be stored up for 
 purposes of experiment. 
 
 79. Two Kinds of Electricity. — If a pith-ball be sus- 
 pended by a silk string, it will be attracted by an excited 
 glass rod. On touching the rod, it is repelled, but is then 
 attracted by the rubber ; or if touched by the finger, is dis- 
 charged, and will then be attracted by either the rod or 
 rubber. Similar phenomena in every respect are seen 
 when the rod is composed of resinous matter or sulphur. 
 A ball repelled by the glass will be attracted by the sul- 
 phur as by its own rubber, and vice versa. 
 
 80. Hypotheses. — Two hypotheses have been suggested 
 to account for these and other electrical phenomena. Both 
 involve the assumption of a subtile, ethereal, imponderable 
 fluid pervading all nature, and existing in a state of quies- 
 cence or combination in bodies in their natural state. 
 Franklin supposed that, when the electrical equilibrium 
 was disturbed by friction, that one body received from 
 the other a portion of this fluid, becoming positive -f, 
 while the other, having relatively less, was termed nega- 
 tive — . In case of glass, the rubber loses, while in that 
 of resin the rod loses. Du Fay supposed the existence of 
 two mutually attractive fluids, the vitreous and resinous, 
 equal in amount but opposite in tendency ; when associ- 
 ated together in equal quantity, they mutually neutralise. 
 When disturbed, they are separated, one going to the rub- 
 ber and the other to the body rubbed. 
 
 As neither hypothesis is probably true, that of Franklin is 
 preferred from its simplicity. Either U competent to explain 
 most of the phenomena. 
 
 Bodies similarly excited repel each other, and those of 
 
 unlike excitement mutually attract, 
 
ELECTRICITY. 57 
 
 81. Conductors; Insulators. — When a body is excited, 
 the rate at which it will return to its normal condition 
 depends upon the substances in contact with it. In dry 
 air, the excitement will continue a long time ; touched with 
 a neutral rod of glass or resin, no sensible change is pro- 
 duced. In damp air, the excitement soon vanishes, and a 
 touch of the finger or of a rod of metal instantly causes 
 the discharge. Bodies which thus allow the electricity to 
 pass through them are called conductors; those which 
 do not, insulators. Bad conductors receive and part with 
 electricity very slowly; if touched by an excited body, 
 they receive electricity only at the point of contact, and if, 
 when excited, they are touched, they lose electricity only 
 at the point touched. Good conductors can only be 
 excited when their communication with the earth is cut 
 off. A metal rod shows no signs of electricity when 
 rubbed, unless provided with a glass handle or otherwise 
 insulated. 
 
 The following list will give a general idea of the position of 
 the most important bodies as respects their conducting powers, 
 beginning with the worst: Dry gases, gutta-percha, vulcanite, 
 collodion, shellac, sulphur, amber, resins, silk, dry fur, glass, ice, 
 volatile oils, fixed oils, vegetable fibres (string), animal bodies, 
 water, saline solutions, flame, melted salts, charcoal, the metals. 
 The relative conducting power of metals for electricity and for 
 heat (47) is nearly the same. The most perfect insulators allow 
 electrical influence to traverse them but by induction (85), not 
 by conduction. The earth is the great common reservoir whence 
 all electrical excitements proceed, and to which they all tend. 
 
 82. Electroscopes serve to indicate the presence of excite- 
 ment by the divergence of light bodies similarly charged. 
 One of the best is Bennett's, composed of two slips of 
 gold leaf attached to the brass cap of a jar. On the ap- 
 proach or contact of an excited body, the leaves diverge. 
 In order to determine the kind of excitement, it is only 
 necessary to charge the instrument with electricity of 
 known character. As opposite electricities attract, tho 
 
58 MEDICAL CHEMISTRY. 
 
 movement of the light bodies, will at once indicate that 
 of the substance to be tested. 
 
 Electrometers measure the relative amounts of electrical 
 force. It is found that the force of attraction and repul- 
 sion is directly as the amount of electricity, and inversely 
 as the square of the distance of the bodies. 
 
 83. Electrical Tension. — The tendency of excited bodies 
 to equilibrium is called their tension, and may be com- 
 pared to a stretched spring. The equilibrium is restored, 
 (1) By conduction. (2) By disruptive discharge (spark). 
 (3) By convection, in which a body, as air, in contact with 
 the excited object receives electricity, is repelled, and trans- 
 mits it to a neutral body or one of opposite excitement. The 
 velocity of electricity of high tension is as great as that 
 of light, when of low tension it is much less. The dura- 
 tion of the electric spark is inconceivably short. It takes 
 always the path of least resistance, which may not always 
 be the shortest; hence the zigzag form sometimes seen. 
 When electricity passes continuously, it is called a current. 
 
 84. Distribution of Electricity. — Electricity of high ten- 
 sion resides only on the outside surfaces of bodies ; when 
 of feeble tension, it may pass through the whole mass (as 
 in a wire carrying a feeble current). 
 
 When the surface is a sphere, the electricity is uniformly 
 distributed ; on departing from this form, it tends to accu- 
 mulate at the smaller portion, and will pass rapidly and 
 quietly to and from points or sharp edges. The greater 
 the surface over which a given quantity of electricity is 
 distributed, the less its intensity. 
 
 85. Induction of Electricity. — An excited body may 
 disturb the equilibrium of a neutral one without contact, 
 its influence being transmitted through the intervening 
 insulator (dialectric). In this case the second body nei- 
 ther gains nor loses electricity, and returns to its normal 
 
ELECTRICITY. 
 
 59 
 
 condition as soon as the excited body is removed. If, 
 however, while excited it be touched, a portion of elec- 
 tricity of the same name as that of the excited body will 
 pass to the earth, and the body will remain excited after 
 the removal of the disturbing object, but with electricity 
 of an opposite name. This action takes place by a polar- 
 isation of the particles of the intervening dialectric. 
 The thinner the dialectric the more decided the induction. 
 All insulators are not alike in the power of thus transmit- 
 ting the excitement. A plate of shellac offers only one 
 half as much resistance as one of air of equal thickness. 
 The relative facility of induction of bodies compared with 
 air as a standard, is called their specific inductive capacity. 
 
 If a positively excited rod be approached to the Bennett's elec- 
 troscope (82), the leaves will diverge ; the cap will be found to be 
 negative, the lower ends of leaves positive. On withdrawing the 
 rod, the leaves fall, and all excitement disappears. If, however, 
 while the leaves are divergent, and the excited rod is near the 
 instrument, the cap be touched with the finger, the leaves will 
 fall, and all will be quiet. On now removing the rod, the leaves 
 diverge, the cap will be found to be negative, and the lower ends 
 of the leaves positive. If we had touched the rod to the cap, 
 the whole would have been charged with positive electricity by 
 contact. 
 
 The action of polarisation may be understood by the accom- 
 panying figure (12). Let A represent the positively excited 
 body ; the positive elec- 
 tricity of the particle, 
 
 B, of air is repelled, 
 leaving the side next 
 the rod negative. This 
 particle acts in a simi- 
 lar manner on C, and 
 so on with diminished 
 intensity through the 
 chain ; the last particle, 
 
 C, acts upon the second 
 body, driving the + 
 electricity from the side 
 B, and causing it to ac- 
 cumulate on C.^ It is obvious that, on the removal of A, all cause 
 of excitement is withdrawn, and equilibrium is restored. On 
 
 Fig. 12. 
 
60 MEDICAL CHEMISTRY. 
 
 touching C, however, a portion of + electricity passes to the 
 earth, leaving A and B in opposite conditions, and attracting 
 each other. This removes all signs of excitement. On taking 
 away A, the negative electricity in B becomes manifest. 
 
 86. Means of Accumulating Electricity.— The electroph- 
 orus, electrical machine, and Leyden jar will be consid- 
 ered. The hydro-electric machine is not now used, and 
 the induction coil will be described hereafter (108). 
 
 87. The Electrophorus, in its usual form, consists of a 
 cake of resin and a metallic plate of nearly the same size, 
 furnished with a glass handle. The resin is excited, and 
 its upper surface becomes negative ; the plate is laid on it, 
 touched with the finger, and lifted. The negative elec- 
 tricity having escaped, it is charged positively by induc- 
 tion, and will give a spark. The disc of metal receives a 
 little negative electricity by contact; but as it touches 
 the resin in but a few points, and the latter is a bad con- 
 ductor, the principal effect is by induction. This is a con- 
 venient instrument for the laboratory ; jars may be charged 
 by it, and gases exploded. 
 
 Messrs. Cornelius & Baker have introduced successfully a neat 
 and portable form of electrophorus for lighting gas-burners. 
 
 88. The Electrical Machine consists of a plate or cylin- 
 der of glass, mounted on a shaft, and pressed by felt rub- 
 bers. The electricity excited by the friction is collected 
 by points and conveyed to an insulated brass cylinder 
 with rounded ends, called the prime conductor. The rub- 
 bers are attached to a similar negative conductor. As the 
 electricity of the rubbers is imparted to the glass, more is 
 supplied from the earth by means of a chain attached to 
 them. A small quantity of an amalgam of zinc, tin, and 
 mercury is applied to the rubbers. It greatly adds to the 
 efficiency of the machine, probably by becoming chemi- 
 cally changed. 
 
 A cheap machine may be made by casting the plate of red 
 
ELECTRICITY. 61 
 
 sulphur. The skin of a cat, without amalgam, serves to excite 
 it. Red sulphur is made by heating ordinary sulphur three 
 times in an iron vessel to a temperature between 482° and 580° 
 F., allowing it to cool thoroughly after each fusion. — (E. Bec- 
 
 QUEREL.) 
 
 89. The Leyden Jar consists of a jar coated inside and 
 out to within about three inches of the top with tin foil. 
 A baked wood stopper is furnished with a rod having a 
 chain at its lower end in contact with the inside of the 
 jar, and a knob on its upper extremity. When the knob 
 is approached to the prime conductor, a spark passes into 
 the jar, and one of the same name will pass to a conductor 
 placed near the outer coating. When charged, either the 
 inner or outer coating may be touched separately with 
 impunity, but on touching both, a shock is felt. If a 
 jointed rod with a glass handle be used to make the com- 
 munication, a vivid spark will be seen, accompanied by a 
 snap. By connecting together a number of such jars, a 
 large amount of electricity may be accumulated, and 
 effects approaching those of lightning produced. 
 
 If the jar be insulated, but little electricity will pass into it, 
 as the tension of the inner coating soon equals that of the prime 
 conductor. If, however, the outer coating be in communication 
 with the earth, the electricity received from the machine by the 
 inner coating drives by induction an equal amount of the same 
 name to the earth, leaving the outer coating negative. This 
 attracts the + electricity so strongly that it cannot manifest 
 itself by its action on any outside neutral body, and will not 
 produce spark or shock (latent or disguised electricity). Still, 
 the positive electricity is prevented from passing to the negative 
 by the glass. If a communication be opened between the coat- 
 ings, equilibrium is instantly restored. Owing to the resistance 
 of the dialectric (85) the attraction of the -f* and — electricity is 
 not quite sufficient to cause them to hold each other in a per- 
 fectly quiescent state, and a slight manifestation will be per- 
 ceived on touching either coating ; indeed, a jar may be dis- 
 charged slowly by alternately touching the coatings. The thicker 
 the glass, the more manifest is this condition of things. The 
 electricity resides in the glass ; the use of the coatings is merely 
 to distribute it. 
 6 
 
62 MEDICAL CHEMISTRY. 
 
 Effects of Electricity. — (1) Physical; (2) Chemical; (3) 
 Physiological. 
 
 90. (1) The physical effects of electricity of high tension 
 are familiar. The disruption of solids, magnetisation of 
 iron, fusion of wires, ignition of combustibles, result from 
 thunder-stroke. Some of these physical effects are indirect, 
 being due to the heat developed by the resistance of an 
 imperfect conductor. Sparks are seen only in a resisting 
 medium, as air; in vacuo there is simply an ovoidal tuft 
 of light passing between the conductors resembling the 
 aurora borealis. The colour of the spark depends upon 
 the medium, being blue in nitrogen, crimson in hydrogen, 
 and green in carbonic acid. A point giving off -f elec- 
 tricity presents a distinct brush, a — point simply a small 
 star. 
 
 91. (2) Many of the chemical actions of static electricity 
 are indirect, such as the explosion of mixed gases (101). 
 Among the direct effects may be mentioned the decompo- 
 sition of water, of iodide of potassium, hydrochloric acid, 
 ammonia, and nitrous oxide. The oxygen and nitrogen 
 of the air unite under the influence of the electric spark, 
 forming nitric acid, which is found in rain-water after thun- 
 der-storms.* Oxygen is converted into ozone (185). 
 
 92. (3) Physiological. — The shock of electricity is fa- 
 miliar to all, the spark from the prime conductor produces 
 stinging and rupefaction. A person charged on an insu- 
 lating stool feels a prickly heat and glow of the skin re- 
 sulting in perspiration. Statical electricity is but little 
 employed in medicine. 
 
 93. Atmospheric Electricity. — The electricity of the air 
 is usually -f , as may be shown by raising an insulated 
 conductor upon a pole and connecting it with a delicate 
 
 * It is possible that the nitric acid found in rain-water may be due to 
 other causes. 
 
ELECTRICITY. 63 
 
 electroscope. The earth is negative. Clouds, fogs, and 
 rain disturb the electricity of the atmosphere in a marked 
 manner. 
 
 Thunder-storms are more frequent in lower latitudes; 
 beyond 70° they are unknown. They are generally con- 
 fined to the lower strata of the atmosphere. In some 
 localities, as California, they are very rare. A cloud 
 charged with electricity induces an opposite condition in 
 a second cloud, or on the earth. It is thus attracted (85), 
 and when the distance is such that the tension of the elec- 
 tricity (83) can overcome the resistance of the atmosphere, 
 a spark passes accompanied by thunder. This latter phe- 
 nomenon is probably due to the noise produced by the rush- 
 ing of the atmosphere into the space rendered rare by the 
 passage of the spark. Lightning without thunder is due 
 to clouds below the horizon, or in the highly rarefied upper 
 regions of the atmosphere. When a cloud is of consider- 
 able extent, a flash passing to the earth is instantly fol- 
 lowed by one in the opposite direction at its distant end 
 (return stroke). 
 
 Precautions against Thunder-stroke. — Trees, from their 
 height and comparatively good conducting power, attract 
 lightning ; so with rarefied air, as from barns and chimneys. 
 These should be avoided. Gas and water pipes carry off 
 electricity when it has fallen on a building, and thus often 
 prevent serious damage. A metallic roof protects a build- 
 ing by diffusing the electricity over a large surface, dimin- 
 ishing its intensity proportionately, and allowing of its 
 escape from the edges and corners of the metal. 
 
 Lightning-rods should be buried sufficiently deep to be 
 always in moist earth or charcoal, or connected with a gas 
 or water pipe. They are apt to rust off at the surface of the 
 ground ; a zinc ball or cylinder will protect from this for a 
 long time (165). Copper is the best material, being about 
 
G4 MEDICAL CHEMISTRY. 
 
 three times as good a conductor as iron, and less liable to 
 corrode. The point is tipped with platinum, gold, or sil- 
 ver ; the first is commonly used, but is apt to be defective 
 from imperfect welding. Perhaps the best point is that 
 of Dr. Hare, consisting of a solid copper point imbedded 
 in a zinc ball, into which are also inserted pointed copper 
 wires, forming a brush. The rod should be continuous 
 and solid, as when electricity is being quietly carried off it 
 is of low tension and passes through the body of the rod. 
 Insulators are unnecessary. Large masses of metal in a 
 building should be connected with the rod to avoid the 
 lateral stroke. 
 
 Treatment after Thunder-stroke. — The patient should be 
 stripped, freely affused with cold water, alternating with 
 brisk frictions. Any subsequent symptoms to be treated 
 pro re nata. 
 
 DYNAMICAL ELECTRICITY. 
 
 94. Elementary Phenomena. — If a plate of pure or 
 amalgamated (9*7) zinc, and one of copper, be plunged into 
 water acidulated with sulphuric acid, no action will be 
 noticed. By delicate instruments it will be found that 
 the lower portion of the zinc is positive, and that of the 
 copper negative, while the portions above the liquid, or 
 wires connected therewith, will be of an opposite polarity. 
 By combining a large number of such cups, shocks may 
 be felt, and feeble sparks seen. If now the plates be con- 
 nected by a ware, or by touching their upper edges, all 
 signs of electrical excitement cease, bubbles of hydrogen 
 arise from the surface of the copper plate, while the zinc 
 is gradually dissolved ; no gas, however, is seen on its 
 surface. The copper plate remains bright and uncorroded 
 as long as any zinc is present. The connecting wire rises 
 
ELECTRICITY. 65 
 
 in temperature, and is found to deflect the magnetic 
 needle, and to cause magnetism in a rod of soft iron, if 
 coiled around it. If the ends of the wire be tipped with 
 platinum, and plunged into acidulated water, the latter is 
 decomposed, oxygen arising at the end of the wire con- 
 nected with the copper plate, and hydrogen from the other. 
 The electricity passes from the zinc (positive) to the 
 copper (negative) in the liquid, and from the copper to 
 the zinc out of it, thus forming the simple voltaic circuit. 
 The portions of the plates out of the liquid are termed 
 poles or electrodes, and their polarity is the reverse of 
 that of the plates, the positive pole being on the copper, 
 and the negative pole on the zinc. The liquid is termed 
 the electrolyte, and must be capable of conducting elec- 
 tricity, and of being decomposed by it. 
 
 The above experiment constitutes a single case of a very 
 extended series of phenomena. We may have a single plate 
 and two distinct fluids ; we may reverse the direction of the 
 current by reversing the chemical action. The general fact is, 
 that all chemical action is attended by the development of an 
 equivalent quantity of electricity ; the course of the electricity 
 being within the electrolyte from the body most acted on to the 
 other. 
 
 95. Theoretical Considerations. — The explanation of the 
 foregoing phenomena usually accepted may be briefly 
 stated as follows, taking water as the electrolyte, and 
 zinc and platinum as the plates. Zinc and oxygen tend 
 to combine ; hydrogen will not unite with zinc. When the 
 plates are introduced, without touching, a polarisation 
 (85) takes place, the atoms of oxygen turning towards 
 the zinc, which at the same time becomes positive, while 
 the platinum becomes negative by induction (Fig. 13). 
 Upon making contact between the two metals, electrical 
 equilibrium is instantly restored throughout the whole 
 polar chain. At the same time the oxygen unites with 
 
66 
 
 MEDICAL CHEMISTRY. 
 
 the zinc, forming a particle of oxide of zinc, ZnO, which 
 unites with the acid ; the hydrogen thus set free does not 
 
 Fig. 13. 
 
 Pig. 14. 
 
 pass off, but unites with the oxygen of the next molecule ; 
 and so through the whole polar chain, the last-}- hydrogen 
 is attracted by the negative platinum, but not being 
 capable of combining with it, is set free (Fig. 14). This 
 action is repeated until all the zinc is consumed. As the 
 electrical equilibrium is restored as fast as it is disturbed, 
 it is obvious that in such an arrangement no evidences of 
 electrical tension (83) can be observed. It may be com- 
 pared to an ordinary electrical machine, in which the 
 prime conductor and rubber are connected by a wire. 
 The same amount of electricity is developed by turning 
 the plate as when the prime conductor is insulated, but 
 equilibrium being instantly restored, no sparks or shocks 
 can be perceived. 
 
 The above explanation is imperfect in some respects, and phy- 
 sicians are not yet decided upon the theory of the voltaic circuit. 
 Faraday regards the chemical change as the cause, Schonbein as 
 the effect of the action. 
 
 96. Quantity and Intensity. — These terms are much 
 
ELECTRICITY. 67 
 
 employed in speaking of voltaic arrangements and phe- 
 nomena, yet it is difficult at first to get a clear idea of 
 their meaning. An illustration drawn from the subject of 
 heat may aid the student. A grain of platinum wire 
 heated to intense whiteness, if plunged into a pint of 
 water at 40° F., would only raise its temperature about 
 ^ of a degree ; its quantity of heat is therefore small, 
 while its intensity is great. Ten pints of warm water, in 
 which the hand may be comfortably immersed, would raise 
 the same to about 94° F., or 54°; yet, although the quan- 
 tity of heat is relatively much greater, its intensity is 
 less, and by no known means can we convert heat of low 
 into that of high intensity. 
 
 Electricity of small quantity and great tension, gives 
 sparks and shocks, and can overleap obstacles. Electric- 
 ity of quantity and low intensity develops much heat, mag- 
 netises powerfully, and causes a proportionately greater 
 amount of chemical decomposition. The former is charac- 
 teristic of the machine electricity, the latter of the voltaic 
 or current electricity. The method of arranging voltaic 
 cells in order to attain the maximum effect will be con- 
 sidered hereafter (99). 
 
 Faraday and Becquerel have shown by actual experiment that 
 the quantity of electricity developed during the decomposition of 
 a single drop of water equals that of a coated surface of Leyden 
 jar of 32 acres, or that of a powerful flash of lightning; yet so 
 feeble is its intensity, that it could not pass through a film of air 
 the yoW °f an * nc h * n thickness. 
 
 97. Resistances and Defects. — These may be stated as 
 (1) Imperfect conduction, (2) Adhesion of hydrogen to the 
 negative plate, (3) Local action. 
 
 (1) Imperfect Conduction. — The electrolyte opposes 
 resistance depending on its nature, and increasing with 
 the distance between the plates. The plates themselves 
 are imperfect conductors, and so are the connecting wires; 
 
68 MEDICAL CHEMISTRY. 
 
 the resistance of a wire being directly as its length, and 
 inversely as the area of its cross section. We should 
 therefore use thick plates, place them as near together as 
 possible, and make the connections with short and thick 
 copper wires or ribbands. 
 
 (2) Adhesion of Hydrogen. — In the arrangement before 
 described the hydrogen arising from the negative plate 
 adheres in bubbles, and thus cuts off a large portion of its 
 surface ; the gas also acts by reason of its electro-positive 
 character (164) to diminish the difference of electrical con- 
 dition of the two plates upon which the voltaic action 
 depends. It adheres less to rough surfaces, and may be 
 chemically consumed or burned (98). 
 
 (3) Local Action. — Commercial zinc contains other 
 metals, as lead, tin, cadmium, also carbon. These act as 
 small negative plates, causing circuits to be set up on the 
 surface of the zinc, eating it into holes, and injuring the 
 action of the cell. It is prevented by amalgamation ; the 
 zinc is washed with dilute sulphuric acid, and plunged into 
 mercury — the deeper the better, — or mercury is rubbed 
 over it. The action of the mercury is not clearly under- 
 stood. 
 
 98. Forms Of Voltaic Cells. — Volta's original pile con- 
 sisted of discs of copper, zinc, and cloth moistened with 
 dilute acid or a solution of common salt ; the arrangement 
 being copper, cloth, zinc. A sufficient number of these 
 were arranged in a pile or column, the terminal zinc and 
 copper provided with wires, and the whole insulated. The 
 electroscope shows the zinc end to be positive, and the 
 copper negative. On touching the ends, a slight shock is 
 felt, and a spark is seen on breaking contact of the wires. 
 The wires immersed in acidulated water cause its decom- 
 position. The pile has been compared to a Leyden jar, 
 capable of recharging itself indefinitely. This apparatus 
 
ELECTRICITY. &9 
 
 is interesting, as showing the identity of frictional and vol- 
 taic electricity. 
 
 (1) Single Fluid Batteries. —Various forms have been 
 employed; the principle being, however, the same in all. 
 Plates of zinc and copper are alternately connected, and to 
 the terminal plates wires are attached ; the plates are im- 
 mersed in dilute sulphuric acid, or other electrolyte. One 
 of the most convenient, where many plates are used, is 
 that of Dr. Hare, where two troughs are arranged at right 
 angles; in one are the plates, in the other the acid; by 
 turning a crank attached to a shaft supporting the troughs, 
 the liquid is thrown off or on the plates. They are not 
 now often employed. Smee's cell consists of two zinc 
 plates, and between them, but insulated by baked wood, is 
 a plate of silver coated with finely divided platinum, to 
 roughen it. Dilute sulphuric acid, 1 part to 10 of water, is 
 used as the electrolyte. The roughness of the negative plate 
 prevents to a great extent the adhesion of the hydrogen. 
 It is a convenient arrangement, much used in electro-plat- 
 ing, telegraphs, and for exciting the induction coils known 
 as electro-magnetic machines. In the sulphate of copper 
 cell a solution of blue vitriol is used as the exciting fluid. 
 No hydrogen escapes from the negative plate, as it is con- 
 sumed by the oxygen of the oxide of copper, sulphuric 
 acid being set free to act upon the zinc, and metallic cop- 
 per deposited on the negative plate. The reaction may be 
 thus expressed: Zn+CuO,S0 3 -f nHO=ZnO,S0 3 +nHO + 
 Cu. This form is rarely used, as the copper deposits on the 
 zinc on account of local action, and the sulphate of zinc 
 formed is decomposed by the current, and zinc is deposited 
 upon the copper. If employed, both plates should be well 
 scrubbed after each immersion. 
 
 (2) Double Fluid Batteries. — These have a different liquid 
 for the positive and for the negative plate, the two being 
 
TO MEDICAL CHEMISTRY. 
 
 separated by a porous cell, which allows of the transmis- 
 sion of the electrical effect, but prevents to any consider- 
 able extent the admixture of the liquids. DanieWs Constant 
 Battery consists of plates, generally concentric cylinders, of 
 zinc and copper. Next to the copper is a saturated solu- 
 tion of sulphate of copper, then a porous cell, and in con- 
 tact with the zinc, dilute sulphuric acid. The action is 
 essentially the same as in the cell last described, but the 
 porous cell prevents the contact of the copper solution 
 with the zinc, and thus avoids the deposition of that 
 metal on the positive plate, and vice versa. The reaction 
 may be expressed thus: CuO,S0 3 -f HO,S0 3 -f-Zn = ZnO, 
 S0 3 -fHO,S0 3 -f- Cu. The sulphuric acid set free during the 
 reaction, passes through the porous cell and maintains a 
 uniform chemical action on the zinc. This battery is con- 
 stant for days, and is largely used where great intensity 
 is not required. The liquids however will gradually mix 
 by osmose (132), rendering it necessary after a time to 
 clean the zinc plate. Grave's consists of a zinc and pla- 
 tinum plate separated by a porous cell ; the zinc is excited 
 by dilute sulphuric acid ; next to the platinum is concen- 
 trated nitric acid. The hydrogen is consumed by the 
 oxygen of the nitric acid at the surface of the negative 
 plate. The reaction may be given as Zn-f HO,S0 3 -f HO, 
 NO s =ZnO f SO s + 2HO-fN0 4 . The force of a Voltaic circuit 
 is cseteris paribus equal to the amount of chemical action 
 at the surface of the positive plate, less that necessary to 
 effect the decompositions. The last atom of oxygen of 
 nitric acid is loosely combined and readily unites with 
 the hydrogen of the electrolyte. Nitric acid batteries are 
 therefore the most intense known. 
 
 In Bunsen's cell dense carbon is substituted for platinum ; 
 these are much cheaper than the last, but more troublesome and 
 less intense. A solution of bichromate of potassa 1 lb., sulphuric 
 acid 2£ lbs., and water 1 gall., is advantageously substituted for 
 
ELECTRICITY. 71 
 
 nitric acid in Bunsen's battery, no fumes being given off. 
 Chromic acid is liberated and yields its oxygen to burn the hy- 
 drogen, depositing green sesquioxide of chromium Cr 2 3 . In 
 the Maynooth battery iron replaces platinum, becoming passive 
 in strong nitric acid. This is a cheap and intense combination, 
 but troublesome to manage. 
 
 99. Combination of Cells. Electro-motive Force.— Prop- 
 erly speaking, the term battery is applied to a collection 
 of cells or elements united. It is frequently used to sig- 
 nify a form of cell. It must be borne in mind that the 
 chemical and electrical effects in any voltaic circuit are 
 equivalent and mutually dependent ; whatever retards one 
 diminishes the other. The greater the resistance to the 
 passage of electricity, the less the amount of chemical 
 action, and the less the quantity of electricity developed. 
 Therefore by diminishing resistance, or by increasing in- 
 tensity, the quantity of electricity from a given positive 
 surface will be proportionately increased. To increase in- 
 tensity, a number of cells are employed, the zinc of one 
 connected with the copper of the next, as in Yolta's pile. 
 Here each cell gives a new impulse to the current; but 
 as the quantity developed depends upon the size of the 
 plate or the number of polar chains (95), increasing the 
 number of cells in this way only indirectly increases the 
 quantity developed by augmenting intensity, and thus 
 overcoming resistances. This combination of quantity and 
 intensity is termed electro-motive force. The maximum 
 effect is found to be produced (Ohm's law) when the resist- 
 ance in the closing arc and that in the battery are equal. 
 
 The product of quantity by intensity is a constant. If we had 
 a pair of plates of 100 square inches of surface, we might desig- 
 nate the quantity by 100 and the intensity by 1. If we cut this 
 into one hundred plates of 1 inch square, and connect them alter- 
 nately, copper and zinc, the quantity is but T ^ ff of its former 
 amount, or 1, while the intensity is 100. It is obvious that by 
 connecting all the zinc plates together, and similarly all the 
 coppers, we have the same effect as in the two original plates. 
 
T2 MEDICAL CHEMISTRY. 
 
 Again, suppose we had two large plates, say of 1000 square 
 inches each, if we had to pass the current around a piece of soft 
 iron by means of a short thick wire, we should probably attain 
 the maximum magnetic effect by using the two single large 
 plates, as here quantity, not intensity, is required. If we plunge 
 the wires of such a cell into acidulated water, no decomposition 
 will take place; there is not intensity enough to traverse the 
 electrolyte ; cut each plate into two of 500 square inches, and 
 join them consecutively, decomposition will begin, but by cut- 
 ting each into four of 250 square inches, we should probably 
 get the maximum effect. Although the amount of water decom- 
 posed depends upon the quantity of electricity passing, we have 
 gained by diminishing surface to one-fourth, in order to quad- 
 ruple intensity. 
 
 100. Effects of Voltaic Electricity. — 1. Physical; 2. 
 Chemical; 3. Physiological. — 1. Physical. Deflagration. 
 When electricity is resisted, it develops heat. The 
 amount of heat developed is directly as the resistance, 
 multiplied by the square of the intensity of the current. * 
 By passing a powerful current through thin metallic 
 wires, they are heated, fused, or burned. This fact is 
 applied to submarine blasting, etc. When the current 
 passes between carbon poles which are touched and then 
 separated, an arch of flame passes, the carbon becomes 
 white-hot, is softened, and carried over from the positive 
 to the negative pole. The light is intense (electric light), 
 and the heat the highest attainable by artificial means. 
 The phenomena are observed in vacuo or in a neutral 
 gas. 
 
 101. Electro-Magnetism. — If a current be transmitted 
 from north to south above a compass-needle, or from south 
 to north below it, the north pole will deflect to the east, 
 and remain in a position due to the combined deflecting 
 power of the current and directive tendency of the earth's 
 magnetism. If the direction of the current be reversed, 
 the deflection will also be reversed. By increasing the 
 
 * De la Rive, Traite d'Electricite, t. II., p. 177 
 
ELECTRICITY. T3 
 
 number of turns of the wire around the needle, the eifect 
 is correspondingly increased, less the retardation of the 
 current due to the increased length of wire. By using an 
 astatic needle (H), one bar being placed within the coil 
 and one above it, a very delicate index of the direction 
 and the force of currents is obtained. This is called the 
 Galvanometer. The poles of the magnet, moreover, tend 
 to revolve around the wire, but in opposite directions ; no 
 such rotation is seen, therefore, unless the current is al- 
 lowed to affect but one pole at a time. When the current 
 passes in the direction from the face to the back of a 
 watch, the north pole will rotate in the direction of the 
 hands (right-handed rotation), and vice versa. If the wire 
 be free to move and the magnet stationary, the wire will 
 revolve. 
 
 102. Ampere's Theory. — Ampere supposed that in a 
 permanent magnet each particle might be considered as 
 surrounded by a constantly circulating current of elec- 
 tricity ; the effect would be the same as of that of all these 
 currents united, and passing around the magnet ; the direc- 
 tion of the current is right-handed when we look at the south 
 pole. Wires carrying parallel currents in the same direc- 
 tions mutually attract; when the currents are in opposite 
 directions they repel. Wires carrying currents in the 
 same direction, but not parallel, tend to become so. These 
 facts may be shown by experiment. A consideration of the 
 foregoing will render clear the whole phenomena of elec- 
 tro-magnetism. 
 
 Fig. 15 represents a model devised by the author for rendering 
 clear these somewhat difficult points. N S represents a perma- 
 nent magnet; A, a disc of tin with an arrow cut out of it, re- 
 presents the direction of Ampere's supposed current, and will 
 serve to show the difference between the right- and left-handed 
 rotation and the opposite polarity of the front and back of a cur- 
 rent (103). A wire, B, supposed to carry a current, passes from 
 N to S above the needle, and S to N b'eloAv it; it will be seen 
 
74 MEDICAL CHEMISTRY. 
 
 at once that when the N. pole of the needle turns to the east, 
 the two currents are parallel. (Fig. 16.) 
 
 Fig. 15. Fig. 16. 
 
 103. Circular Currents Magnetic— If a piece of wire 
 be bent into a circle, or, better, coiled into a helix (like a 
 corkscrew), and have soldered to its ends a small plate 
 of zinc and one of copper, and be floated on the surface 
 of acidulated water, it will be found to arrange itself in 
 the magnetic meridian, and to be attracted and repelled 
 by the magnet (De la Hive's ring). In any case, if the 
 current be circulating in the direction of the hands of a 
 watch, the north pole will be towards the back of the 
 watch, and vice versa. Hence one side of the wire has 
 X., and the other S. polarity. 
 
 Rogefs Oscillating Helix shows this fact in a striking manner. 
 A helix of tolerably fine wire is fastened to a support, and con- 
 nected with one pole of a battery : the other pole is in contact 
 with a cup of mercury, into which the lower end of the helix 
 dips. This completes the circuit. As the upper and lower sides 
 of the coils of the helix have opposite polarity, they mutually 
 attract. This shortens the helix, and the point is raised out of 
 the mercury. The current is thus interrupted, the magnetic 
 polarity ceases, and the point of the wire falls again into the 
 mercury. A constant oscillation is thus maintained. The intro- 
 duction" of a permanent magnet causes a more rapid contraction. 
 
 104. Electro-Magnets. — By coiling wire around soft 
 iron, powerful temporary magnets may be produced. The 
 
ELECTRICITY. 75 
 
 magnetism continues so long as the current continues to 
 flow, and ceases when it is interrupted. Magnets on this 
 principle have been made to support a ton, and to show 
 that all bodies are more or less influenced by the mag- 
 net (11). 
 
 When the quantity of electricity is more than sufficient, the 
 magnetism of the bar does not cease upon its interruption, but 
 the armature adheres with a slight force. If, however, a thin 
 piece of brass or paper be placed between the magnet and arma- 
 ture, no such residual magnetism is noticed. It instantly ceases 
 when the keeper is forcibly removed, after breaking the circuit. 
 If a considerable length of wire be coiled so as to form a thick 
 helix, a bar of soft iron will be drawn up into its centre or core, 
 and there remain suspended without any apparent means of sup- 
 port. {Axial Magnetism.) 
 
 105. Applications of Electro-Magnets. — Engines have 
 been constructed to be moved by electricity. Apart from 
 other considerations, the cost of the zinc necessary to pro- 
 duce a certain mechanical effect, compared with ordinary 
 fuel, forbids the expectation of their useful employment. 
 
 Magnetic Telegraphs. — As there is no practical limit to 
 the distance to which electricity may be transmitted 
 through a good conductor, and as a current of electricity 
 will induce magnetism in a core of soft iron which may 
 be discharged at pleasure, it is obvious that we can, by 
 causing the armature of the magnet to make signals, com- 
 municate through indefinite distances. To make and 
 break the circuit with ease, a key is used by which two 
 ends of the wire are pressed together easily. As the cur- 
 rent becomes very feeble from the resistance of the long 
 conducting wire, a relay or receiving magnet is used. In 
 this the current from the distant station passes around a 
 delicate electro-magnet, the armature of which is allowed 
 the least possible quantity of play. This acts as the key 
 to a local battery close at hand, which works the recording 
 apparatus. The signals may be arbitrary, by strokes of a 
 
16 
 
 MEDICAL CHEMISTRY. 
 
 bell, or by a mural alphabet of dots, dashes, and spaces 
 
 (Morse), or by exceedingly ingenious arrangements the 
 
 message may be printed (House, Hughes), or even sent 
 
 autographically (Chemical Telegraph). It is impossible 
 
 to enter into details here. 
 
 The following sketch will serve to give the student a rough 
 idea of the arrangement of a line of Morse telegraph. In prac- 
 tice, the current is continually passing through the main line, 
 and is broken to make the signals : 
 
 Fig. 17. 
 
 A, main line battery ; B, signal key ; C, main line wire ; D, 
 ground wires ; E, ground plates ; F, relay ; G, its armature ; 
 H, one end of wire of local circuit, the other being attached to 
 the armature of the relay magnet ; — when the armature is drawn 
 to the magnet, these ends are brought in contact, and the local 
 circuit is completed ; — I, local battery ; X, recording magnet, 
 which, when the current passes, draws its armature, L, which 
 presses the point, P, against a fillet of paper passing over the 
 roller, R. The recording apparatus is not necessary. A good 
 operator will be able to read the Morse alphabet by the sound 
 of the clicking of the relay. A single wire only is employed, 
 the circuit being completed through the earth by means of the 
 ground plates. 
 
 Magnetometers. — As the quantity of magnetism de- 
 veloped is proportionate to that of the electricity passing 
 (up to the point of saturation), electro-magnets are used 
 
ELECTRICITY. ft 
 
 to measure currents of considerable power by noticing the 
 weight necessary to detach the armature. 
 
 106. Induced Currents. — If a tolerably long wire be 
 connected with a cell or battery, no spark will be seen on 
 making the connection ; but on breaking it, a vivid spark 
 will be visible, which will be greater in proportion to the 
 length of the wire and the power of the cell, up to a cer- 
 tain point ; at the same time a slight shock will be felt. 
 This is the extra current of Faraday, and probably de- 
 pends upon the disturbance of the normal electricity of the 
 wire by the current of low intensity passing through it. 
 Its direction is opposite to that of the battery or primary 
 current. The two may be separated by coiling the wire 
 from the battery (primary wire) and placing a second 
 similar coil (secondary coil) parallel to it, but insulated 
 from it ; (ribbands are better than wires.) On making con- 
 tact with the battery, a feeble shock is felt on grasping the 
 ends of the secondary wire, but on breaking it the shock is 
 marked and sparks may be obtained. In this case but 
 little extra current is noticed in the primary wire. By 
 continuing the experiment, currents of decreasing intensity 
 may be induced in a third, fourth, and as far as a ninth 
 coil or spiral ; in every case the current induced is mo- 
 mentary, and in a direction opposite t<5 that of the inducing 
 one. We have thus a means of obtaining electricity of 
 tension by means of the voltaic current. 
 
 lOt. Electro-Magnetic Machines. — Under this name in- 
 duction coils are sold and much used in medicine. Their 
 construction is simple. Around a spool is wound a short 
 coarse wire wrapped with silk, to insulate its turns. Out- 
 side of this is wound a long fine wire similarly wrapped. 
 The inner (primary) wire is connected with the cell; to 
 the outer one are attached convenient handles for commu- 
 nicating the shock. The circuit in the primary wire is 
 
78 
 
 MEDICAL CHEMISTRY. 
 
 broken by any suitable means, as by drawing it over a 
 rasp, or by the automatic break described below. On each 
 contact and break a current is induced in the secondary 
 wire ; that produced on the break being much more in- 
 tense. These to and fro currents are felt upon grasping 
 the handles. A bundle of soft iron wires introduced into 
 the primary coils increases the shock by becoming mag- 
 netic (electro-magnetism [111] ); by withdrawing them 
 gradually, the shocks may be reduced. 
 
 It may be well for the student clearly to understand the auto- 
 matic break-piece attached to the apparatus usually sold, as it 
 often requires adjustment. 
 
 &g. 18. 
 
 The wire, A, Fig. 18, from the battery is fastened to a binding 
 screw, H, whence a wire passes to the metallic post, B, which 
 has on it a point, C, tipped with platinum. This rests against a 
 platinum spring, D, which carries at its top a piece of soft iron. 
 From the lower part of the spring the primary wire passes around 
 the small electro-magnet, E, and thence to its coil and back to 
 the battery. On making connection, the current passes through 
 the post B, spring A, and around the electro-magnet E. This 
 then attracts its keeper, and draws the spring away from the 
 point C. The circuit is thus broken, the spring flies back and 
 instantly renews it. This takes place many times in a second, 
 producing a peculiar humming. The point C is adjustable by 
 means of a screw. 
 
ELECTRICITY. 19 
 
 108. The Ruhmkorff Coil is simply a large apparatus, 
 similar to the one described. The external wire in one 
 recently made by Ritchie is forty miles long. It is pro- 
 vided with a large surface of tin foil packed in the base, to 
 distribute and weaken the extra current (106). The elec- 
 tricity flows in but one direction, as the induced current 
 set up on making the primary connection is too feeble to 
 travel the whole length of the outer coil. By means of 
 this apparatus sparks of eighteen inches in length may 
 be obtained in rapid succession, and all the phenomena 
 of statical electricity shown with a splendour before un- 
 known. 
 
 Although the name of Ruhmkorff is attached to this appa- 
 ratus, the credit belongs mostly to others. Prof. Henry inves- 
 tigated the phenomena of induced currents. Faraday invented 
 the concentric coils ; De la Rive the automatic break-circuit ; 
 Fizeau the condenser. In Ruhmkorff's original coil he obtained 
 a spark of one inch. After Fizeau's improvement, Hearder, by 
 more careful insulation, reached three inches. Mr. E. S. Ritchie, 
 of Boston, by a new method of winding and insulation, arrived 
 at the eighteen-inch spark above mentioned. 
 
 109. Chemical Effects of the Voltaic Current. — These 
 will be considered under the head of Chemical Decom- 
 position (162). 
 
 110. Physiological Effects. — These vary with the 
 strength and direction of the current and the mode of its 
 application. A moderate current produces contractions, 
 when sent in the direction of the distribution of a nerve 
 of general sense, and pain, and sometimes paralysis when 
 reversed. The phenomena are noticed only upon making 
 and breaking the circuit, but it is by no means certain that 
 the influence of the current is not exerted during the whole 
 time of its flow. Nerves of special sense, except the olfac- 
 tory, are excited so as to give rise to the sensations 
 proper to them. The muscles ruajr be excited by passing 
 currents of considerable intensity across them, independent 
 
80 MEDICAL CHEMISTRY. 
 
 of the direction of the nerve fibres ; and when the nerves 
 are paralysed, the muscles sometimes still contract under 
 such influence. The secreting organs and absorbents are 
 stimulated by electricity ; the blood is coagulated around 
 the positive, and rendered more fluid around the negative 
 pole. Chemical substances can probably be introduced 
 into the system or removed from it by the same agent. 
 For the medical applications of electricity, see (117). 
 
 MAGNETO-ELECTRICITY. 
 
 111. As a current will induce magnetism; so, recipro- 
 cally, a magnet will induce an equivalent amount of elec- 
 tricity. If we introduce into a coil of wire the pole of a 
 permanent magnet, a galvanometer will show the presence 
 of a momentary current in the wire, the direction depend- 
 ing upon the name of the pole introduced. 
 
 112. Magneto-electric Machines. — Opposite the poles of 
 a powerful horse-shoe magnet are placed two soft iron 
 armatures, wrapped with insulated wire; they are so 
 arranged as to be rapidly rotated by means of a multiply- 
 ing wheel. The keepers become magnetic by induction, 
 the electricity induced by them in the wires is conveyed 
 to handles, and may give rise to sparks, shocks, and de- 
 compositions. The currents being to and fro, are thrown 
 into the same direction by means of a commutator or pole 
 changer. 
 
 As powerful magnets are produced by comparatively feeble 
 currents, so they are required to give satisfactory results in the 
 apparatus above named.* As no batteries are required, and the 
 
 * By using the magneto-electric current, as the primary, to excite a 
 powerful electro-magnet, and using this again as a source of electricity, 
 Mr. Wilde has obtained an electric arch having three times the actinic 
 power of the sun. It is manifest that the mechanical force required to 
 turn the machine is here converted into electricity. — Chem. News, Nos. 338, 
 339. 
 
ELECTRICITY. 81 
 
 rotation may be performed by machinery, attempts have been 
 made to use magneto-electricity in telegraphs, electro-plating, 
 and electric light, but with partial success. For medical use the 
 absence of an exciting cell certainly constitutes an advantage, 
 counterbalanced however by the comparatively feeble current, 
 and the labour required to produce the rotation. 
 
 THERMO-ELECTRICITY. 
 
 113. As any obstruction to the passage of electricity 
 develops heat, so an obstruction to the passage of heat in 
 a conducting circuit develops electricity. If an homoge- 
 neous, straight, short wire be connected with a sensitive 
 galvanometer, and heated, no evidence of electrical current 
 Avill be obtained. If, however, it be bent or twisted, its 
 molecular tension at that point is altered, and on heating 
 it the needle will be deflected. 
 
 If two dissimilar metals be joined, and the junction 
 heated, electricity will pass. This phenomenon is most 
 manifest in metals of a highly crystalline structure, and 
 which are poor conductors. The order of the metals in 
 the thermo-electric series bear no relation to their position 
 in the voltaic pile, nor can it be certainly connected with 
 their properties as regards heat or other force. The fol- 
 lowing is a list of some of the most important, beginning 
 with the most positive: Bismuth, platinum, lead, tin, cop- 
 per, gold, silver, zinc, iron, antimony. The alloy German 
 silver is highly positive. The thermo-electric position of 
 alloys is not a mean of that of their constituents. 
 
 114. Thermo-Multiplier. — By arranging a large number 
 of bars in a pile, heating one series of junctions, and keeping 
 the others cool, a battery may be formed capable of mag- 
 netising large bars; by connecting a similar arrangement 
 with a galvanometer (101), we have a means of measuring 
 temperature far more delicate than any thermometer. 
 
12 
 
 MEDICAL CHEMISTRY. 
 
 Fig. 19. 
 
 The method of arranging the bars can be understood from 
 
 the adjoining figure. The 
 bars are kept separate by 
 non-conducting material. 
 The instrument made by 
 Mr. Weygant for the Phila- 
 delphia High School, will 
 show the heat from the face 
 of an observer at the dis- 
 tance of eight feet,* and 
 distinctly that of a fly 
 crawling over the pile. 
 
 M. Marcusf has proposed 
 a pile of alloys, the posi- 
 tive being, copper 10, zinc 
 6, nickel 6; the negative, 
 antimony 12, zinc 5, bis- 
 muth 1. This will bear 
 a high temperature, and 
 all the effects of the ordi- 
 nary voltaic combination may be obtained. 
 
 115. Heat and Cold by Electricity.— By passing a current 
 of low intensity through the connecting wire, one end of the 
 pile becomes heated and the other cooled ; the amount 
 of difference of temperature being equivalent to that re- 
 quired to produce a corresponding current, making allow- 
 ance for the heat developed by the resistance of the con- 
 ductors. 
 
 Electricity of Crystals, etc. — Certain crystals when 
 heated develop electricity, one extremity becoming the 
 other. On clearing crystals of mica, breaking metals, as 
 zinc, or other bodies, as sugar, light is seen and electricity 
 manifested. In fact, it may be stated that no molecular 
 change can take place in matter unattended by electrical 
 disturbance. 
 
 116. Animal Electricity. — 1. Statical. — Certain fishes, 
 as the electrical ray and the Surinam eel, have the power 
 of giving electrical shocks at will. The electricity being 
 
 Journal Franklin Institute, Aug., 1855. f Chem. News, No. 286. 
 
ELECTRICITY. 83 
 
 collected by the condenser and Leyden jar, is found to 
 exhibit all the phenomena of that derived from ordinary 
 physical sources. The two extremities or sides of the 
 animal are of opposite polarity; the head of the eel and 
 the top of the torpedo being positive. The electricity of 
 the eel is more intense than that of the torpedo. After 
 repeated discharges, the fish becomes exhausted and harm- 
 less until allowed rest and food. The electrical organ 
 consists of a series of small membranous tubes, which in 
 the torpedo are arranged perpendicularly to the back, and 
 in the eel longitudinally. These tubes are packed regu- 
 larly together, forming hexagonal columns. Each of the 
 tubes is minutely subdivided by membranous diaphragms 
 forming cells which contain a mucous fluid ; these again 
 are traversed by a fringe of nerve filaments coming from 
 the 8th pair. If communication with the brain be cut off, 
 no electricity is developed. 
 
 2. Dynamical. — The existence of voltaic currents in the 
 animal body has been demonstrated by numerous experi- 
 ments. Matteucci constructed a pile of muscles of recently 
 killed frogs and pigeons by which he was enabled to 
 deflect the galvanometer as much as 40°, and to decom- 
 pose iodide of potassium.* The following are some of the 
 more important facts. 1. The poles of a galvanometer 
 applied to different surfaces give evidence of the passage 
 of a current, as between the skin and mucous membranes. 
 2. There are normal electrical currents existing in muscles 
 and nerves which are temporarily diminished upon the 
 contraction of the former or the sudden action of the 
 latter. 3. All the organs of the body exhibit electrical 
 currents when they have been divided and the normal 
 surface and the surface of the section are brought into 
 contact. The direction of the current in nerves and 
 
 * De la Rive, Tratti (VEIectricUe, tome III. p. 12. 
 
84 MEDICAL CHEMISTRY. 
 
 muscles is from without to within. The electro-mo- 
 tive power lasts after death as long as the excitability 
 of the nervous and muscular fibres. 
 
 117. Medical Applications of Electricity. — These are 
 becoming more numerous as the subject is better under- 
 stood. Among the cases in which it has been successfully 
 applied may be mentioned, paralysis, rheumatism, indura- 
 tions, certain tumours, constipation, eruptions of the skin, 
 amenorrhoea, aneurism, and suspended animation. There 
 is considerable diversity in the methods of application, 
 and some discordance in the testimony as to their relative 
 value. The following are the most important: 1. The 
 direct current, which may be continuous, as in the case of 
 aneurism ; or interrupted, as generally used. Complete 
 interruption is not necessary, as by altering the pressure 
 on the electrodes a variation in the intensity of the cur- 
 rent is produced — the wavy or labile current. Any of the 
 voltaic cells heretofore described may be used. Pulver- 
 macher's chain consists of a number of zinc and brass 
 wires, so arranged as to form, when dipped in vinegar, a 
 flexible voltaic pile of some intensity. It is rarely used. 
 The interruption may be by hand, by clock-work, or, as in 
 Smith's apparatus, automatic. 2. The extra current (106) 
 has more intensity than the primary current, and is defi- 
 nite in its direction. It is given by the machines of 
 Duchene, Kidder, Chester, Hall, etc. 3. The secondary 
 or induced current, obtained from the induction coil (127), 
 or magneto-electric machine. The former is to and fro, 
 the latter definite in direction. These are the most intense 
 currents, and those most generally used. They are some- 
 times termed faradaic currents, and their application 
 faradisation. For the details of the methods of apply- 
 ing these currents in various cases, the student is referred 
 to the works on medical electricitv. 
 
ELECTRICITY. 85 
 
 CORRELATION AND CONSERVATION OF FORCE. 
 
 118. As there is no destruction of matter, nor is it now 
 created, so force is never lost, nor does it now originate. 
 The universe gives us no example of rest, and there is 
 reason to believe that even the molecules of matter, when 
 apparently at rest, are in a constant state of motion or 
 vibration, and that these vibrations give us the various 
 phenomena of the physical forces. We may include the 
 modifications of force under the heads of gravitation, light, 
 heat, electricity, magnetism, chemical affinity, and vital 
 force. How these are connected will be evident from a 
 few examples. 
 
 Gravitation produces motion, as in falling bodies. Mo- 
 tion, when arrested, develops heat (friction, percussion), or 
 electricity (90). It also promotes chemical affinity, as in the 
 synthesis of alcohol (144); and decomposition, as in the 
 explosion of chloride of nitrogen. It may be produced by 
 heat (expansion, etc.), electricity (pith-balls), magnetism 
 (magnetic toys), chemical affinity (indirectly), and the 
 vital force. The fact that heat and motion are mathemati- 
 cally equivalent has been shown (35). 
 
 Light produces chemical change (the growth of trees), 
 and perhaps magnetism. 
 
 Heat produces motion, light, electricit} 7- , and it affects 
 magnetism. Magnetism is destroyed by a red heat, and 
 bars may be magnetised by heating to redness and sud- 
 denly cooling them while they are in the plane of the 
 magnetic meridian. Heat causes chemical combination 
 (mixed oxygen and hydrogen), and decomposition (gun- 
 powder). It is essential to animal and vegetable exist- 
 ence. 
 
 Electricity produces motion, light, heat, magnetism, 
 and causes various physiological phenomena. 
 
86 MEDICAL CHEMISTRY. 
 
 Magnetism develops motion and electricity (by the aid 
 of motion), and thus indirectly the other phenomena. 
 
 Chemical affinity develops electricity (galvanism), light, 
 heat (deflagrations), and indirectly motion. It is the 
 source of vital heat, and probably of all vital function. 
 
 The vital force (if it be a distinct force) develops 
 directly and indirectly the others named. It is due to 
 chemical change constantly going on in the organism. 
 In drawing a match, the vital force produces motion, 
 which, being resisted by friction, is converted into heat, 
 which develops the affinity between the combustible of 
 the match and the oxygen of the air. Combination en- 
 sues ; the match burns ; heat is developed by the combi- 
 nation, light by the heat, and electricity and magnetism 
 might be produced by the agency of a therm o-pile. 
 
PART II. 
 
 PRINCIPLES OF CHEMISTRY. 
 
 MOLECULAR FORCES 
 
 Are those which act only at insensible distances ; they 
 may be divided into : — 
 
 I. Cohesion, the attraction of the particles of the same 
 body. 
 
 II. Adhesion, the attraction of the particles of different 
 bodies without change of properties. 
 
 III. Chemical Affinity, the attraction of the particles 
 of different bodies with the loss of their specific identity. 
 
 I. COHESION 
 
 119. Is believed to be but a modification of the great 
 force of universal gravitation (9). It is strongest in solids, 
 and imperceptible in gases. It is opposed by heat (49), 
 and may be overcome by mechanical force. It may pro- 
 duce motion, as in the projection of an arrow from a bent 
 bow. To variations of cohesion are due the properties of 
 hardness, softness, malleability, ductility, tenacity, brittle- 
 ness, elasticity, etc. The nature of these variations, and 
 the causes of the differences of the above qualities in 
 various bodies, or in the same body under different con- 
 ditions, are wholly unknown to us. 
 
 (87) 
 
88 MEDICAL CHEMISTRY. 
 
 Hardness has no relation to density ; soft steel changes but 
 little, if any, in density, by being hardened. Steel is hardened 
 by being heated and then suddenly cooled ; it is tempered by 
 reheating and slow cooling ; the temper is drawn down, that is, 
 the steel is softened more, as the temperature of the reheating 
 is higher. Copper is hardened by slow cooling, and tempered 
 by a sudden chill. Elasticity is the tendency of a body to 
 resume its original form or volume ; there is no perfectly elastic 
 solid body ; air and permanent gases are absolutely elastic. 
 Tenacity is most marked in bodies that are not crystalline 
 (amorphous). Glass suddenly cooled will fly to pieces ex- 
 plosively on its surface being scratched or broken. (Bologna 
 phials; Prince Rupert's drops.) 
 
 120. Crystallisation (Gr. krystallos, ice). When the 
 force of cohesion causes the particles of bodies to arrange 
 themselves when solid in certain definite geometrical 
 forms, the process is termed crystallisation. Although 
 the varieties of crystals are apparently infinite, yet all 
 may be included in six systems, according to the number, 
 length, and inclination of their axes. The axes are imagi- 
 nary straight lines connecting opposite sides, edges, or 
 angles of the crystals. 
 
 In the first system, monometric 
 ^^^^^^ (Gr. monos, one, metron, measure), 
 the axes are all equal and at right 
 angles. The fundamental form is a 
 cube, Fig. 20, and from it may be 
 derived the regular octohedron (eight- 
 sided figure), which is bounded by 
 equilateral triangles; the rhombic 
 dodocahedron, having twelve equal 
 rhombic sides ; the tetrahedron, having four equilateral 
 triangles, one as a base, and three as sides; with many 
 others. The following bodies are found in this system: 
 most metals, diamond, galena, white iron pyrites, common 
 salt, sal-ammoniac. 
 
 In the second system, dimetric (dis, twofold, metron, 
 
MOLECULAR FORCES. 
 
 89 
 
 Fig. 21. 
 
 measure), the axes are at right angles, but only two arc 
 equal. The fundamental form is a 
 right square prism ; Fig. 21 ; that 
 is, a column having a square base, 
 a varying height, and standing up- 
 right. From it may be derived the 
 corresponding octohedron and other 
 forms. The following among others 
 crystallise in this system : calomel, 
 ferrocyanide of potassium, oxide of 
 tin, cyanide of mercury. 
 
 In the third system, trimetric (tris, threefold, 7netron, 
 measure), the axes are at right angles and all unequal. 
 The fundamental form is a right rectangular or right 
 rhombic prism, having a rectangle or rhombus for a base, 
 and standing upright; Figs. 22 and 23. The sulphates of 
 
 Fig. 22. 
 
 Fig. 23. 
 
 Fig. 24. 
 
 magnesia, zinc, lead, and baryta; nitre, sulphur (from 
 solution) crystallise in this system. 
 
 In the fourth system, monoclinic (monos, one, clino, I 
 incline), one of the axes is oblique to the other two. The 
 fundamental forms are a right rhomboidal or oblique 
 rhombic prism; Figs. 24 and 25. In the former, the base 
 is a rhomboid, in the latter a rhombus; the former is up- 
 right, the latter inclines. In the former the oblique axis 
 is in the base, in the latter in the elevation. Borax, sul- 
 
90 
 
 MEDICAL CHEMISTRY 
 
 phates of soda, lime, and iron and sulphur (from fusion) 
 are examples. 
 
 In the fifth system, triclinic (tris, threefold, clino, I 
 
 Fig. 25. 
 
 Fig. 
 
 26. 
 
 
 
 
 
 incline), none of the axes are at right angles. The funda- 
 mental form is a prism having a rhoinboidal base and in- 
 clined ; the oblique rhomboidal prism ; Fig. 26. Boracic 
 acid and sulphate of copper are examples. 
 
 The sixth system, Hexagonal (Gr. Hex, six, gonia, 
 angle), has four axes, one vertical and passing through 
 the intersection of the three equal horizontal axes, the 
 angle between which is 60°. The hexagonal prism, Fig. 
 21, and the rhomboJiedron, Fig. 28, belong to this system. 
 
 Fig. 27. 
 
 Fig. 28. 
 
 Familiar examples are seen in ice, iceland spar, quartz, 
 and cinnabar. 
 
 121. Formation of Crystals. — In order that crystals 
 may form, the particles should be free to move over each 
 other, hence the bodies should be fluid. Solid bodies 
 
MOLECULAR FORCES. 91 
 
 sometimes crystallise under the influence of long-continued 
 
 vibration, or without apparent cause. 
 
 "Wrought iron car-axles, couplings, etc., which are made up 
 of bundles of fibres, and have great tenacity, sometimes become 
 crystalline and break suddenly ; tough, transparent, amorphous 
 sugar (candy) will become after a time crystalline, opaque, and 
 brittle. 
 
 122. Methods of Procuring Crystals. — From solution 
 by slow evaporation. The larger the quantity of liquid, and 
 the more gradual the evaporation, the larger and more 
 perfect will be the crystals. A hot saturated solution 
 allowed to cool deposits the excess of dissolved matter in 
 crystals. Foreign bodies, as sticks, introduced, favour 
 crystallisation, the crystals depositing on them as a nucleus; 
 this is frequently seen in urinary calculi. Chemical and 
 electrical precipitation often give crystals. A liquid 
 obtained by fusing a solid will often crystallise. When a 
 solid is sublimed (57), crystals are obtained. 
 
 123. Useful Applications. — When two bodies of differ- 
 ent solubility are dissolved in the same liquid, as the 
 liquid is evaporated, the least soluble crystallises first. 
 Thus, in making salt from sea-water, the common salt first 
 crystallises, forming a crust which is scraped off, leaving 
 behind the mother liquor, w^hich contains the more soluble 
 sulphate of magnesia, chloride of potassium, etc. 
 
 Crystalline form is generally an index of purity, and 
 it is exceedingly difficult to determine the true chemical 
 constitution of an amorphous (Gr. a, not, morphe, form) 
 body. 
 
 As bodies generally crystallise in the same form, we 
 are often enabled thus to identify them. Some bodies 
 crystallise in two systems; these are termed dimorphous 
 (Gr. dis, twofold, morphe, form). The properties of di- 
 morphous bodies often differ remarkably with the crystal- 
 line form. 
 
92 MEDICAL CHEMISTRY. 
 
 Sulphur crystallised in the third system has a density of 
 2*04; in the fourth, of 1 # 98. Ked iodide of mercury is scarlet in 
 the fourth, and yellow in the second. It may be converted into 
 the latter form by heating, and returns to the former by friction. 
 
 H. ADHESION 
 
 May take place between solids (striction, cements); solids 
 and liquids (wetting, capillary attraction, solution, dialy- 
 sis); solids and gases (absorption) ; between liquids (solu- 
 tion, diffusion, osmose); liquids and gases (absorption); 
 between gases (diffusion). 
 
 124. Between Solids. — Pieces of flat glass may ad- 
 here so closely as to be inseparable, and show no sign of 
 the junction on being cut with the diamond. This is 
 termed striction, as distinguished from friction or passive 
 resistance to motion, which can only take place during 
 motion. Cements are fluid or semi-fluid bodies which ad- 
 here to solids and bind them together. 
 
 The line between cohesion and adhesion cannot be sharply 
 drawn ; iron and platinum may be welded at high temperatures, 
 and dough, putty, or soft clay, under ordinary circumstances. 
 
 125. Between Solids and Liquids. Wetting. — The 
 
 hand plunged into water is wetted ; into mercury, not. In 
 
 one case the liquid adheres to the surface ; why it does 
 
 not in the second cannot be explained. Mercury will wet 
 
 brass or gold or lead, but not glass or iron. 
 
 If a clean scale pan be put on the surface of water in a dish, 
 it will be found that a very considerable weight will be required 
 in the other pan to draw it away; it is not even then separated 
 from the water, a film of which adheres to the bottom of the pan ; 
 the weight is then the measure of the cohesion of the water, not 
 of the adhesion of the pan. The statement so often made in 
 text-books, that in liquids the cohesive and repulsive forces are 
 in equilibrium, is inaccurate, as is shown by the foregoing ex- 
 periment, as well as by the spheroidal form of drops of liquid 
 when not wetting a surface, as in the dew-drop, or water sprinkled 
 on a dusty floor or a hot plate. 
 
MOLECULAR FORCES. 93 
 
 126. Capillary Attraction — (Lat. capillus, a hair). 
 When tubes of fine bore are plunged into a liquid capable 
 of wetting them, the liquid rises within and without ; 
 within to a height much greater than without, and higher 
 as the diameter of the tube is less. If the liquid do not 
 wet the tube, a corresponding depression takes place. 
 The form of the surface is concave in the first case, and 
 convex in the second. The height varies with the nature 
 of the liquid, and is nearly inversely as the diameter of 
 the bore. 
 
 The cause of the rise of the liquid is readily understood ; the 
 attraction of the liquid for the sides of the tube causes it to draw 
 itself up, and as the weight of the column is comparatively 
 slight, it rises until that weight and the cohesive force of the 
 liquid balance its attraction for the tube. This also accounts for 
 the concave meniscus. The cause of the depression is not so easy 
 to understand without the aid of mathematical demonstration. 
 Any liquid under the influence of its cohesive force alone will 
 assume the form of a sphere, as in oil suspended in a mixture of 
 alcohol and water of the same specific gravity, (Plateau's ex- 
 periment). Gravity flattens this sphere into a spheroid, as in 
 a dew-drop. Adhesion spreads it out, as when water is sprinkled 
 on a clean table. , The liquid in a tube not being capable of 
 being wetted by it, is under the influence of the two former 
 forces only. It is hardly necessary to say that the phenomena 
 are not due to repulsion. 
 
 Phenomena due to Capillarity. — Fluids rise in the wick 
 of a lamp, and as they are burned or evaporated a new 
 supply is furnished. A capillary tube, if filled, will not 
 run over if broken off, but the liquid will remain at the 
 top. Water does not freeze at 32° F. in capillary tubes, 
 and if not allowed to reach the ends of the tube, liquids 
 evaporate very slowly. A small greased needle will float 
 on the surface of water. Floating bodies, when wetted, 
 collect in groups or apparently adhere to the sides of the 
 vessel. Ropes are contracted with immense force on 
 being wetted, and rocks may be split by the expansion of 
 wooden wedges driven into holes and wetted. In dry 
 
94 MEDICAL CHEMISTRY. 
 
 seasons the moisture of the subsoil is brought nearer- the 
 surface of the porous ground. Capillarity is diminished 
 by heat. 
 
 12?. Solution. — When the particles of a solid and liquid 
 mutually interpenetrate, the former disappears, and is said 
 to be dissolved. It still retains its general properties, as 
 smell, taste, colour, and, on evaporating the liquid, is 
 recovered unchanged. The dissolving liquid is called a 
 menstruum; the most universal solvent is water, next 
 glycerine, then alcohol. Why some bodies are soluble 
 and others insoluble in a given menstruum, cannot be ex- 
 plained. Solution is favoured by circumstances diminish- 
 ing cohesion, as powdering and heat; also by stirring, 
 which favours intermixture. When a menstruum refuses 
 to take up any more of a body, it is said to be saturated. 
 A liquid saturated with one substance may still take up 
 another, provided it be more soluble. Fine crystals that 
 have become soiled may be safely washed with a saturated 
 solution of the same ingredient. Although heat generally 
 favours solution, yet lime and some of its salts are most 
 soluble in cold water, and sulphate of soda at 92° F. 
 
 The term solution is also generally but inaccurately applied to 
 certain chemical operations. Thus, a piece of silver thrown into 
 nitric acid disappears with the evolution of orange-red fumes. 
 It is said to be dissolved in the nitric acid. This is not strictly 
 true, for, on evaporating, transparent crystals soluble in water 
 are obtained, but no metallic silver. The change is more com- 
 plex, the silver has been oxidised by the oxygen of the nitric 
 acid, and a base, oxide of silver, formed ; this again has combined 
 with another portion of acid and nitrate of (the oxide of) silver 
 formed. We have, however, at present no good substitute for 
 the word thus loosely used. 
 
 128. Dialysis (Gr. dia, through, lusis, separation). — 
 Bodies in solution may be divided into two classes : crys- 
 talloids, those which tend to crystallise; and colloids (Gr. 
 kolle, glue), those which do not, but form on evaporation 
 
MOLECULAR FORCES. 95 
 
 a jelly-like mass. On putting a mixture of a crystalloid 
 and a colloid into a vessel furnished with a bottom of 
 parchment or similar material, the crystalloid will pass 
 through while the colloid remains. Colloids exist in two 
 forms, — one a clear solution, as white of egg in water 
 (peptised, Gr. pepsis, coction), or opalescent, and as the 
 same white of egg coagulated (pectised, Gr. pektos, coagu- 
 lated). Many bodies pass readily from the first to the 
 second condition.* Dialysis must be constantly taking 
 place in the animal body. 
 
 Among the applications of this interesting discovery may be 
 mentioned the preparation, in a soluble state, of bodies hereto- 
 fore only known as insoluble. Among these are silica, sesqui- 
 oxide of iron, stannic acid, Prussian blue. Urea and salts are 
 separated from urine, and crystalline poisons from organic mix- 
 tures. It must be borne in mind, however, that the process of 
 separation cannot be complete. The nutritious juice of flesh has 
 been obtained from waste brine by dialysis, and it is proposed to 
 render salt meat fresher by the same process. f 
 
 129. Between Solids and Gases. Absorption. — On 
 plunging a bright knife-blade into water, the adherence of 
 bubbles of air will be noticed; this takes place to a less 
 degree when the surface is roughened. The absorbing 
 power of porous bodies is marked on account of the ex- 
 tensive surface they present. The retention of odours by 
 the hair and clothing is a familiar example. Freshly 
 burned charcoal will absorb 90 times its volume of am- 
 monia, 85 of hydrochloric acid, 65 of sulphurous acid, 55 
 of sulphuretted hydrogen, 40 of nitrous oxide, 35 of car- 
 bonic acid, 35 of olefiant gas, 9*42 of carbonic oxide, 9*25 
 of oxygen, T4 of nitrogen, 5 of marsh gas, 1 T5 of hy- 
 drogen. The five gases last named are permanently elas- 
 tic. Gases easily liquefied are most largely absorbed, and 
 
 * Graham, Phil. Trans., June, 1861. Odling, Chem. News, March, 1S62. 
 Brande & Taylor, 134. 
 
 f Whitelaw, Che m. News, March, 1S64. 
 
9b MEDICAL CHEMISTRY. 
 
 in some cases the pressure from their condensation is 
 enough to liquefy them. The deodourising powers of dry 
 charcoal (206) depend upon this absorption and condensa- 
 tion. Platinum, when finely divided, (platinum sponge 
 or black,) possesses similar properties. 
 
 130. Between Liquids. Solution. — As a general 
 rule, liquids are indefinitely soluble in each other. In 
 some cases a point of saturation may be reached. Ether 
 is soluble in ten parts of water, and water in ten of ether. 
 
 131. Diffusion. — Two liquids brought into contact 
 without stirring will gradually intermingle or diffuse. 
 The phenomena are best studied by placing in ajar of one 
 liquid a phial containing the second. The laws govern- 
 ing the rate of diffusion of liquids have been determined 
 by Mr. Graham, but they are too complex to be discussed 
 fully in an elementary work. In solutions, the quantity 
 of dissolved substance diffused in the same time is pro- 
 portioned to the strength of the solution. Common salt, 
 hydrochloric and sulphuric acids have great diffusive 
 power; albumen is very feeble in this respect. No di- 
 rect relation exists between the specific gravity of a solu- 
 tion and its rate of diffusion. 
 
 132. Osmose (Gr. osmos, impulsion). — The diffusion 
 of liquids through porous partitions. — If a piece of gut 
 be partially filled with milk, tied at both ends, and im- 
 mersed in water, it will after a time be found to be dis- 
 tended, while the water is slightly coloured by the milk. 
 If a bladder, filled with molasses and fitted with a tube, 
 be immersed in a jar of water, the molasses will rise in 
 the tube, while the water will slowly become sweetened. 
 In these cases, the water evidently passes through faster 
 than the other liquid. The same effect is seen when sa- 
 line solutions are used. It is to this action that the rise 
 of sap in trees is due, and it probably plays an important 
 part in animal physiology. Osmose is increased by heat. 
 
 
MOLECULAR FORCES. 9f 
 
 The cause of osmose are: 1. The diffusive tendency of the 
 liquids. 2. Capillary attraction. 3. The unequal absorption of 
 the liquids by the septum, the one most readily absorbed passing 
 the most rapidly. 4. Chemical action on the septum, the liquid 
 acting the most passing the most rapidly. It cannot be due to 
 capillary attraction alone, as is asserted by some physiologists, 
 for capillarity is diminished, but osmose increased, by heat. 
 
 133. Between Liquids and Gases. Absorption. — 
 
 The amount of gas which a liquid will take up is directly 
 
 as the pressure, and diminishes with the temperature. 
 
 Such solutions have a lower boiling-point than the liquids 
 
 themselves, and possess, generally, the properties of the 
 
 dissolved gases. When in water, they are known in the 
 
 Pharmacopoeia as Aquae, as Aqua Ghlarihii, Aqua Acidi Car- 
 
 bonici. Water at 59° F., and under atmospheric pressure, 
 
 dissolves T2T*2 vols, of ammonia, 458 of hydrochloric acid, 
 
 43*6 of sulphurous acid, 3*23 of sulphuretted hydrogen, 
 
 2-36 chlorine, 1 of carbonic acid, 0*030 of oxygen, 0*0147 
 
 of nitrogen, 0*019 of hydrogen.* These are all expelled 
 
 by prolonged boiling. 
 
 The greater solubility of oxygen, when compared with nitro- 
 gen, will account for its being found in larger proportion in the 
 air contained in natural waters. 
 
 134. Between Gases. Diffusion. — If we put into a 
 bottle liquids of different density, and insoluble in each 
 other, as water, oil, and mercury, they will arrange them- 
 selves in the order of their specific gravities. This is not 
 the case with gases. If we connect two globes, one filled 
 with oxygen and the other with hydrogen, by means of a 
 narrow tube, the one containing hydrogen being above that 
 filled with oxygen, they will be found to intermingle, and 
 form a permanent, homogeneous mixture, although the 
 oxygen is 16 times as heavy as the hydrogen, — a greater 
 difference of specific gravity than exists between mercury 
 and water. The law regulating this phenomenon is that 
 
 * Bunsen, Gasometry, p. 286. 
 
98 MEDICAL CHEMISTRY. 
 
 the rate of the diffusion is inversely as the square root of 
 
 the density of the gas. Thus, hydrogen will diffuse into 
 
 oxygen four times as fast as oxygen into hydrogen.* The 
 
 constant constitution of our atmosphere depends upon 
 
 this law. 
 
 The diffusion of hydrogen into air is strikingly shown by 
 holding a jar of hydrogen over an inverted porous cell, into 
 which has been fastened a glass tube, the lower end of which 
 dips into water ; the hydrogen rushing into the cell faster than 
 the air escapes, causes a condensation which forces the air in 
 bubbles from the lower end of the tube. The separation of gases 
 by means of their unequal diffusibility through porous parti- 
 tions is termed Atmolysis.f When gases pass through certain 
 membranes, they deviate from the above law, those most easily 
 liquefied passing most readily. This is owing to the condensing 
 power of the membrane, and does not really invalidate Mr. Gra- 
 ham's law given above. The effusion of gases, or their passage 
 through small openings in thin plates into a vacuum, obeys the 
 same law. 
 
 CHEMICAL AFFINITY 
 
 135. Causes the particles of different bodies to unite, 
 with the loss of specific identity. By specific identity we 
 mean the properties by which a body is recognised. The 
 term, derived from the Latin affinis, a liking, merely ex- 
 presses the fact that certain bodies tend thus to unite, 
 without attempting to explain this tendency. The strength 
 of affinity varies exceedingly, some bodies, as chlorine or 
 oxygen, uniting actively with nearly all the elements ; 
 others, as carbon, boron, and silicon, combining with but 
 few, to form compounds of comparatively feeble stability. 
 136. Admixture and Combination. — Adhesion produces 
 the admixture of bodies; affinity their combination. In 
 the first the properties of the constituents may be recog- 
 
 * Graham, Chemistry, Am. ed., p. 87. 
 
 ■j- Graham, Comptes Rendus, t. L VII., p. 181. 
 
MOLECULAR FORCES. 99 
 
 nised ; in the second they are lost. Bodies merely mixed 
 may be separated by mechanical means ; when combined, 
 only by chemical means. Bodies may be mixed in any 
 proportion ; they combine in definite and fixed proportions. 
 
 Thus, if we mix sulphur and iron filings, we may distinguish 
 the constituents by the eye, the iron may be withdrawn by the 
 magnet, or the sulphur dissolved out by bisulphide of carbon. 
 We may mix a grain of sulphur with a ton of iron, and vice 
 versa, or in any intermediate proportion. If we apply heat to 
 the mixture, the sulphur and iron combine to form a cinder- 
 like mass not possessing any properties of either sulphur or 
 iron. It cannot be decomposed except by some chemical agent, 
 and if the sulphur and iron are not in the proportion of 4 to 7, 
 the excess will remain out of combination. 
 
 In some cases of solution, as alcohol and water, there are phe- 
 nomena partaking of the character of those of combination. In 
 certain instances the properties of bodies are not entirely lost, 
 as in carbonate of ammonia, and rare examples of decomposi- 
 tion by mechanical means may be mentioned (161). 
 
 137. Circumstances Influencing Combination. — Chemi- 
 cal combination is opposed by cohesion ; it is favoured by 
 light, heat, electricity, catalysis, the nascent state, and me- 
 chanical force. 
 
 138. Cohesion opposes chemical affinity by retaining in 
 the respective masses the particles which tend to leave 
 them and combine. It is overcome by powdering-, fusion, 
 or solution. 
 
 Iron in mass requires an intense heat for its combustion, — that 
 is, its combination with the oxygen of the air. In the form of 
 filings it burns brilliantly in a spirit-flame ; in that of Que- 
 vennes iron (Ferrum Eedactum, U. S. P.) it ignites like tinder, 
 and in still finer powder will take fire spontaneously (pyrophy- 
 rus). Fusion and solution not only overcome cohesion, but facili- 
 tate the mixture of bodies. Seidlitz powders may be kept mixed 
 in a dry place for any length of time, but on water being added 
 combination at once takes place. Iodine and sulphur are fused 
 together in making iodide of sulphur. 
 
 139. Light favours combination. Mixed chlorine and 
 hydrogen maybe kept for an indefinite period in the dark; 
 in diffused daylight they combine slowly ; in the sunlight, 
 
100 MEDICAL CHEMISTRY. 
 
 explosively. The chemical or actinic power of light 
 resides chiefly in and beyond the violet ray. The subject 
 will be more fully discussed under Decomposition (156). 
 
 140. Heat is the most usual method of causing combi- 
 nation. Oxygen and hydrogen will not combine when 
 mixed until a flame is applied. The effect of heat in pro- 
 moting combustion is familiar in lighting a fire, candle, or 
 gas jet. 
 
 141. Electricity acts indirectly, by the development of 
 heat when resisted, as in the electrical cannon or powder 
 cup, and directly, as when nitrogen and oxygen are 
 caused to combine by passing through them a series of 
 electrical sparks. 
 
 In the electrical cannon an insulated wire, passing through 
 the vent, is furnished with a knob ; its inner end does not touch 
 the opposite side of the cannon. A spark passing to the knob 
 traverses the wire, and has to leap the space between its end 
 and the side of the gun. The resistance of the mixed gases pre- 
 viously introduced develops heat, and they are caused to com- 
 bine. In the powder cup, two stout wires are united by a fine 
 one, around which gunpowder is placed. A single voltaic cell 
 will cause explosion from the heat developed, owing to the re- 
 sistance of the fine wire to the passage of the current. Both 
 expedients are used in submarine blasting. 
 
 142. Catalysis — (Gr. kata, downwards, and luo, I loose). 
 This term merely serves to group together a series of 
 hitherto unexplained phenomena. Bodies appear to act 
 by their presence alone. The alloy of silver and platinum 
 will dissolve chemically in nitric acid ; platinum alone is 
 unaffected. The silver is said to act by catalysis or 
 presence. 
 
 143. The Nascent State— (Lat. nascens, being born). 
 Bodies which refuse to combine when in their ordinary or 
 free condition, will do so when in the act of being liber- 
 ated from combination. In this way large numbers of 
 compounds are formed which could not be obtained by 
 
MOLECULAR FORCES. 101 
 
 any other means. The compounds of sulphur and phos- 
 phorus with hydrogen are examples. 
 
 Sulphur and hydrogen cannot be combined when free, but by 
 uniting sulphur with iron, forming sulphide of iron, FeS, and 
 throwing this into acidulated water, HO, a mutual interchange 
 of atoms takes place, forming FeO, oxide of iron, and HS, sulphu- 
 retted hydrogen ; the former combines with the acid. 
 
 144. Mechanical Force. — Long continued agitation will 
 in rare cases determine combination. Olefiant gas, C 4 H 4 , 
 (existing in ordinary coal gas,) hydrated sulphuric acid, 
 and mercury, shaken for four days in a glass vessel, re- 
 sulted in the production of alcohol. 
 
 This interesting discovery by Berthelot* has been applied on 
 the large scale in France, f but without success in a commercial 
 point of view. The reaction may be thus expressed: C 4 [I 4 + 
 2HO=C 4 H 6 2 (alcohol). The reaction is indirect, and will be 
 more fully explained under Organic Chemistry. 
 
 LAWS OP CHEMICAL COMBINATION. 
 
 145. Analysis and Synthesis. — The laws which govern 
 the formation of chemical compounds have been ascer- 
 tained purely by experiment. The composition of a body 
 may be determined by taking it apart (analysis, Gr. ana, 
 lud, to separate), or in some cases by putting together its 
 constituents in their proper proportions (synthesis, Gr. 
 syn, tithemi, to put together). 
 
 146. Laws. — I. All chemical compounds are definite in 
 their constitution, the ratio of their constituents being 
 constant. Hence all bodies combine in certain definite 
 ratios (equivalents, combining weights, atomic weights). 
 See table (181). 
 
 II. Bodies combine either in their lowest ratio or a 
 multiple of the same by a whole number. 
 
 III. The combining weight of a compound is the sum 
 of those of its constituents. 
 
 * Cfiimie organiqne, etc., t. I., p. 104. f CJiem. Neivs, Jan., 1803. 
 
 9* 
 
102 MEDICAL CHEMISTRY. 
 
 147. Illustrations of these Laws.— I. Pure water is 
 
 found by analysis, no matter what its source, to consist 
 of oxygen and hydrogen in the ratio of 8 of the former to 
 1 of the latter. If we mix the gases in this ratio and 
 combine them, pure water results; if either be taken in 
 excess, that excess will remain uncombined. Iron and 
 oxygen combine in the ratio of 8 of oxygen to 28 of iron, 
 and so by analysis of all known bodies the ratios in which 
 their elements unite are ascertained and in many cases 
 verified by synthesis. In order to render these ratios 
 absolute, one body is fixed upon as a standard ; hydrogen 
 is generally taken as unity, having the smallest combining 
 weight, and thus avoiding the inconvenience of large 
 and fractional numbers. The proportions in which bodies 
 unite are termed their combining weights, because they 
 express the quantities which will exactly combine ; atomic 
 weights, because they are supposed to represent relative 
 weights of their atoms or molecules ; and equivalents, 
 because one body taken in its ratio is equal in chemical 
 effect to any other body taken in its ratio. 
 
 The use of a standard is merely a matter of convenience. It 
 is obvious that we may take 1 of hydrogen to 8 of oxygen, or 10 
 of hydrogen to 80 of oxygen, and so on. When in practice we 
 have a given quantity of a body, we ascertain the quantity of 
 any other, necessary to combine with it by rule of three. Thus 
 the combining weight of sulphur being 16, that of iron 28, to 
 find how much sulphur is required to exactly combine with 100 
 lbs. of iron, we have 28 : 16 : : 100 : 57*14 lbs. of sulphur re- 
 quired. The meaning of the term equivalent will be better un- 
 derstood by an example. If in 9 grains of water, HO, we remove 
 1 grain of hydrogen and supply its place by iron, forming FeO 
 oxide of iron, we must use 28 grains of iron which thus exactly 
 unites with the oxygen and performs the same chemical part as 
 1 grain of hydrogen. 
 
 148. II. Water being composed of 1 part of hydrogen 
 and 8 of oxygen, the next combination is hydrogen 1 part, 
 and oxygen 16 or twice 8. We may have 14 of nitrogen 
 (its combining weight) united with 8, 16, 24, 32, or 40 of 
 
MOLECULAR FORCES. 103 
 
 oxygen, but in no case does less than 8 of oxygen combine. 
 
 This is true of all elements and compounds. It should be 
 
 clearly borne in mind that the compounds formed by the 
 
 second, third, fourth, etc., multiple of an element, differ as 
 
 much from each other as the first compound did from its 
 
 constituents, and the same is true of most compound 
 
 bodies when united. The apparent exceptions to the 
 
 second law in the case of sesquioxides will be noticed 
 
 hereafter. 
 
 Calomel and corrosive sublimate differ only in the quantity of 
 chlorine being double in the latter. The difference of the prop- 
 erties of various combinations of the same elements in com- 
 pounds will be obvious when We come to the description of the 
 bodies themselves. 
 
 149. III. Besides the elements, we have frequently to 
 combine compound bodies. The most important of these 
 are known as acids and bases. Any body which has a 
 sour taste, will redden vegetable blues, and will combine 
 with a second compound body to form a new third sub- 
 stance, is termed an acid; a base is any body capable of 
 combining with an acid and neutralising it. An acid and 
 a base united form a salt. 
 
 The above definitions are necessarily imperfect, as nature 
 never defines. They will, however, do provisionally. We have 
 a large class of salts (the haloid group, 224), of which common 
 salt is an example, which are not formed by the union of an 
 acid and a base. 
 
 To determine the combining weight of an acid or a base, 
 it is only necessary to add up its constituents. Thus, hy- 
 drated sulphuric acid, HO,S0 3 =l + 8-fl6-f 24=49; po- 
 tassa, KO=39-f-8, = 4t. These numbers are as invariable 
 as those given in the table of elements (181), and might 
 form a separate table, though the arithmetical process is 
 so simple that this is not often done. When a known 
 quantity of an acid or base is given, the amount necessary 
 to saturate is determined as before by proportion. 
 
104 MEDICAL CHEMISTRY. 
 
 Thus to neutralise 100 lbs. of hydrated sulphuric acid, H0,S0 3 , 
 with lime, CaO=28, we have 49 : 28 : : 100 : 57*1 lbs. lime. In 
 practice, test papers are used to determine when saturation has 
 taken place. The most common is litmus-paper, which is red- 
 dened by acids and has its colour restored by certain bases 
 which neutralise the acid. By having a blue and a feebly red- 
 dened paper, and mixing gradually the acid and base, we can 
 determine the proper quantity without the necessity of weighing. 
 
 150. The Atomic Theory of Dalton supposes that the 
 relative weights of the atoms of bodies are those indicated 
 by their combining weights. Of the absolute weight of 
 the atoms we cannot even conjecture. Hydrogen being 
 the lightest atom, that of oxygen would be eight times as 
 heavy, iron 28 times, and so on. The atoms being sup- 
 posed to have the same density, their relative bulk would 
 correspond with their respective weights. Upon this 
 theory, the laws of combination are easily explained. 
 
 Suppose a trillion of atoms to constitute an appreciable quan- 
 tity; call this quantity n. As each atom of oxygen is eight 
 times as heavy as one of hydrogen, the quantity n of oxygen 
 will be eight times as heavy as the quantity n of hydrogen. 
 When they combine, each atom of oxygen unites with one of 
 hydrogen, and there being the same number of each, one trillion 
 or n molecules of water, HO, will be formed. If, however, we 
 take more atoms of hydrogen, n-\-a, where a represents the ex- 
 cess, than there are of oxygen, those in excess will be left un- 
 combined, and we shall have the same n molecules of water and 
 a of hydrogen will remain. This illustrates the first law. 
 
 An atom is indivisible. Hence, if we add more than one 
 atom, we must take two, three, or more, and the weight of the 
 added body will be in the ratio of its atomic weight multiplied 
 by the number of atoms taken. Calling the weight of oxygen 
 eight, if we add to an atom of nitrogen two of oxygen, they will 
 weigh twice eight, and so on; what is true of a single atom is 
 true of n atoms, or our supposed appreciable quantity. (Second 
 law.) 
 
 A molecule is composed of two or more atoms; its weight, 
 therefore, is the weight of its constituent atoms, and what is true 
 of one molecule is true of n molecules, or our supposed appre- 
 ciable quantity. (Third law.) 
 
 151. Combination by Volume. — It is easier to measure 
 gases than to weigh them. By filling a vessel of known 
 
MOLECULAR FORCES. 105 
 
 capacity with water or mercury, arid displacing this by an 
 equal bulk of gas, its volume is at once determined. Know- 
 ing its specific gravity, the weight of this volume is found 
 by multiplying the weight of an equal bulk of air by this 
 specific gravity (193.) 
 
 151. Gay-Lussac's Law. — It is found that a very 
 simple law governs combination by volume. Equal vol- 
 umes (with certain exceptions) contain equal numbers of 
 atoms, and hence are equivalent. If we take a given bulk 
 of hydrogen, and call its weight unity, the weight of equal 
 bulks of the following gases and vapours will be : nitrogen 
 14, chlorine 35*5, iodine (vapour) 127, water vapour 9, 
 etc. ; these numbers, it will be seen, are those of the com- 
 bining weights of those bodies. 
 
 The most important exceptions to this law are oxygen, which 
 with a combining weight of 8 has a density of 16, compared 
 with hydrogen as 1 ; its volume is therefore but one-half that of 
 hydrogen. The same is true of sulphur (at 1600° F., at which 
 temperature its volume becomes constant), phosphorus, and ar- 
 senic; while ammonia, hydrochloric acid, alcohol, and some 
 other compound vapours have a volume double that of hydrogen 
 for an equivalent weight. The volume of oxygen being assumed 
 as unity, that of hydrogen and its group is 2, that of the com- 
 pound vapours above noticed 4. It will be seen that these bear 
 a simple arithmetical relation to each other. In all cases where 
 the term equivalent is used in this volume, it will refer to com- 
 bining weight, unless otherwise specified. 
 
 152. Symbols; Notation. — The object of chemical sym- 
 bols is to express to the eye the elements existing in any 
 body, with their exact proportions; also their supposed 
 arrangement and the theoretical changes taking place 
 during reactions. They are algebraic in their character, 
 but not strictly so. 
 
 The initial letter of the Latin or English name repre- 
 sents one equivalent, or atom of the element. Thus 
 represents not only oxygen, but 8 parts by weight on the 
 hydrogen scale. Where several elements begin with the 
 
106 MEDICAL CHEMISTRY. 
 
 same letter, a second small letter is added. Thus P 
 stands for Phosphorus, Pt for Platinum, Pb for Plumbum 
 (Lead), etc. When it is desired to express more than one 
 equivalent of an element, the number expressing the 
 quantity (coefficient) is placed at the right hand and 
 below the line. Thus 3 , three atoms of oxygen ; Pb 2 , 
 two atoms of lead. 
 
 Two elements combined together form a binary com- 
 pound (Lat. bis, twice). This combination is indicated by 
 simply joining the two symbols. Thus HO, water, is a 
 combination of an atom of hydrogen with one of oxygen. 
 The coefficient is placed to the left and on the line. Thus 
 2HO means two molecules of water, and is equal to H 2 C>2. 
 
 In algebra, ab would signify a X b ; but in chemical notation 
 no confusion can result, as a symbol represents a substance as 
 well as a quantity. To speak of multiplying hydrogen by oxy- 
 gen is manifestly absurd. A very common error with beginners 
 is to multiply the combining weight instead of the coefficient of 
 the elements by the coefficient of the compound. Thus, instead 
 of 2HO=H 2 2 , or 2Fe 2 3 =Fe 4 6 , we have H 2 16 , or FenAs ', this 
 blunder is most transparent, and yet it is exceedingly common 
 with students. 
 
 A ternary compound is one containing three elements 
 (Lat. ter, three times). In inorganic chemistry they are 
 always made up of two pairs of elements, one element 
 being common to both sides. Thus the two binaries KO, 
 potassa, and S0 3 , sulphuric acid, unite to form KO,S0 3 , a 
 ternary compound (sulphate of potassa). Binaries thus 
 united have simply a comma placed between them. A 
 coefficient placed as for binaries only affects as far as the 
 comma, unless a parenthesis or vinculum is used. Thus, 
 6(KO,S0 3 ), or 6KO,S0 3 , will represent six equivalents of 
 sulphate of potassa. 
 
 The importance of the parenthesis may be seen by reducing 
 the following formulae to their elements. 3(AgO,P0 6 )=Ag 3 3 , 
 P 3 15 ; 3AgO,PO.=Ag,0 I ,PO a . 
 
MOLECULAR FORCES. 107 
 
 A quarternary compound (Lat. quarto, four times) in 
 inorganic chemistry consists of two ternaries. The sign -f 
 is placed between them. They require the same use of 
 the parenthesis as binaries. Thus, KO,S0 3 +MgO,S0 3 , 
 double sulphate of potassa and magnesia. A» a general 
 rule, when a compound breaks up, it is first at the -j-niark, 
 secondly at the comma, and lastly the elements separate. 
 
 Symbols are also used to explain the theoretical changes 
 taking place during reaction. If we throw potassium, K, 
 on water, HO, it unites with the oxygen, 0, of the water, 
 and sets free the hydrogen, H. This may be expressed 
 thus, HO-fK=KO-fH. In this case the sign -J- merely 
 has the algebraical significance of addition, and does not 
 mean combination. 
 
 In writing symbols, the electro-positive element of a compound 
 (164) is written first. For the present it will suffice to say that 
 in binary compounds the metallic element is written first, and 
 in ternaries the base. 
 
 153. Nomenclature. — The object of chemical nomen- 
 clature is to indicate the composition of a body by its 
 name. It is yet quite imperfect. 
 
 Before the time of Lavoisier the names given to compounds 
 were empirical ; many of these are retained as synonyms, and 
 it is important for the student to learn both the systematic and 
 the empirical names ; a list will be found in the Appendix. The 
 following are some examples : Sacchamm Saturni, sugar of lead, 
 acetate of lead; Crocus Martis, saffron of Mars, Oolcothar, 
 anhydrous sesquioxide of iron; lapis infernalis, lunar caustic, 
 nitrate of (oxide of) silver. 
 
 All binary compounds terminate in ide, which is affixed 
 to the abbreviated name of the electro-negative (164) con- 
 stituent. Thus, FeO oxide of iron, HgS sulphide of mer- 
 cury, NaCl chloride of sodium. The termination uret is 
 synonymous, as sulphuret for sulphide, but is now disused 
 in scientific works. 
 
 It is to be regretted that it has been retained for the sulphides 
 in the last edition of the U. S. Pharmacopoeia, while the other 
 urets have been properly changed to ides. 
 
108 MEDICAL CHEMISTRY. 
 
 The termination ide gives no indication of the propor- 
 tions in which the elements are combined ; this is done 
 by prefixes. Sub (Lat. under), an excess of electro-posi- 
 tive element; proto (Gr. protos, first), one atom of each 
 element; sesqui (Lat., half as much), two of positive to 
 three of negative ; Deut (Gr. deuteros, second), or Bin 
 (Lat. Bis, twice), two of negative to one of positive; ter 
 (Lat. ter, three times), three of negative. The following 
 table will be useful in aiding the memory of the student, 
 the signs -f and — indicating the proportion of the elements 
 first and last written. 
 
 Example. 
 Cu 2 0, Suboxide of copper. 
 FeS, Protosulphide of iron. 
 Fe 2 Cl 3 , Sesqui-chloride of iron. 
 Mn0 2 , Deut or Binoxide of Man- 
 ganese 
 1 3 Ter Sb 3 , Tersulphide of antimony. 
 
 These prefixes are also used with the same meaning for 
 ternary compounds. Thus, 2PbO,C 4 H 3 03, s?/&-acetate of lead; 
 FeO,C0 2 , £> r °fo-carbonate of iron; 2NH 4 0,3C0 2 , sesqui-eaxhon- 
 ate of ammonia ; KO,2Cr0 3 , 5i-chromate of potassa; Fe203_3SO a , 
 tfer-sulphate of (the sesquioxide of) iron (inaccurate). 
 
 Confusion has arisen from putting the prefix of the base before 
 that of the salt in which it occurs. Thus protosulphate and 
 protocarbonate of iron are used to express either the proportions 
 of acid and base, or the constitution of that base, generally the 
 latter. The prefix per is used to signify any higher compound, 
 and is often used for sesqui, as perchloride of iron for sesqui- 
 chloride. It is indefinite, and should never be employed in 
 this way. 
 
 154. Oxygen Acids and Bases. — When the name of a 
 metal ends in turn, and it becomes oxidised, so as to form 
 a base, the last syllable changes to a. Thus : potassium, 
 potassa; sodium, soda; magnesium, magnesia. This 
 rule is of limited application ; where not applied, the name 
 
 + - 
 
 Prefix. 
 
 2 or more 1 
 
 Sub 
 
 1 1 
 
 Proto 
 
 2 3 
 
 Sesqui 
 
 1 2 
 
 Deut, or Bin 
 
MOLECULAR FORCES. 109 
 
 of the metal in the base is used, the oxygen being 
 understood. Thus, nitrate of silver for nitrate of the 
 oxide of silver. 
 
 The most usual termination of an acid is in ic, the rarer 
 termination ous being used to signify a lower degree of 
 oxidation; thus, S0 3 sulphuric acid, S0 2 sulphurous. 
 The prefix hyper (Gr. huper, above) is used to indicate a 
 higher degree of oxidation, and hypo (Gr. hupo, under) a 
 lower one ; the former is generally abbreviated to per, 
 as chlonc acid, C10 5 ; hyper or per-chloric, C10 7 ; hypo- 
 chloric, C10 4 . When an acid combines with a base to form 
 a salt, the termination ic changes to ate, ous to ite, the 
 prefixes being unaltered. These rules are illustrated in 
 the following series. 
 
 Compounds of Chlorine with Oxygen, and their Salts. 
 
 C10 7 Hyper (per) chloric acid KO,C10 7 Perchlorale of potassa. 
 
 CIO5 chloric " KO,C10 5 chlorate 
 
 C10 4 Hypo " " KO,C10 4 Hypo " 
 
 C10 3 chlorous " KO,C10 3 chlorite 
 
 CIO Hypo " " KO,C10 Hypo " 
 
 Care must be taken not to confound ite with ide. The 
 former contains the letter t, which stands for ternary • the 
 latter d, for dual or binary ; this will aid the memory. 
 
 There is no systematic nomenclature for acid, bases and 
 salts not containing oxygen. 
 
 The name of an acid only indicates its elements, and not their 
 proportions. These must be retained by memory. The number 
 of important oxygen acids in inorganic chemistry is not great, 
 and they are arranged in the table below in a manner calculated 
 to enable the student easily to commit them to memory. The 
 symbols represent the acids when dry or in combination; in the 
 free state they are practically (except C0 2 and Cr0 3 ) combined 
 with water. 
 
 PO Hypo-phosphorous. 
 CIO Hypo-chlorous. 
 S 2 2 Hypo-sulphurous. 
 10 
 
 Combined Oxygen Acids. 
 
 C0 2 Carbonic. 
 S0 2 Sulphurous. 
 SnOo Stannic. 
 
110 MEDICAL CHEMISTRY. 
 
 N0 3 Nitrous. 
 S0 3 Sulphuric. 
 P0 3 Phosphorous. 
 Si0 3 Silicic. 
 B0 3 Boracic. 
 Mn0 3 Manganic. 
 Fe0 3 Ferric. 
 Cr0 3 Chromic. 
 As0 3 Arsenious. 
 Au0 3 Auric. 
 
 N0 4 Hyponitric. 
 CIO4 Hypochlorie. 
 
 N0 5 Nitric. 
 
 P0 6 Phosphoric. 
 
 C10 5 Chloric. 
 
 Br0 6 Bromic. 
 
 I0 5 Iodic. 
 
 Sb0 5 Antimonic. 
 
 As0 5 Arsenic. 
 
 Bi0 6 Bismuthic. 
 
 Cr 2 7 Perchromic. 
 Mn 2 7 Permanganic. 
 
 DECOMPOSITION 
 
 155. Is the breaking up of a compound body into sim- 
 pler forms. It may be considered under two heads. 
 (1) Where the constituents of a body separate and remain 
 so, or form new compounds among themselves, — decompo- 
 sition proper (spontaneous [?] decomposition). (2) Where 
 decomposition is effected by the agency of some other 
 body, with which an interchange of constituents takes 
 place, — decomposition by superior affi7iily. 
 
 I. DECOMPOSITION PROPER. 
 
 This is seen in all organic bodies after death, under 
 favourable conditions as to temperature and moisture. It 
 is improperly termed spontaneous, as no change can take 
 place in matter without the agency of force. It is favoured 
 by light, heat, electricity, catalysis, example and mechani- 
 cal force. 
 
 15G. Light. — The chemical or actinic power of light 
 resides chiefly in the violet ray, and beyond this where 
 light is invisible, unless concentrated by a lens, when 
 it is lavender-coloured. The effect of light in caus- 
 ing decomposition is seen in the fading of colours, the 
 
MOLECULAR FORCES. Ill 
 
 growth of vegetation, and it is applied in the art of pho- 
 tography. 
 
 Carbonic acid, C0 2 , is exhaled by animals, and is a product 
 of ordinary combustion. It is absorbed by vegetables and, 
 under the influence of sunlight, decomposed, the oxygen being 
 exhaled and the carbon assimilated. This beautiful balance of 
 animal and vegetable existence is applied in the well-known 
 aquarium. 
 
 The principle of the art of photography is easiest understood 
 by a description of the daguerreotype. In all cases the steps are 
 four : 1. To render the plate sensitive to light ; 2. To expose it ; 
 3. To develop the image ; 4. To fix it. 
 
 1. A polished silver surface is exposed to the vapour of iodine 
 in a chemically dark room. Iodide of silver, Agl, is formed. 
 This undergoes a change (more probably molecular than strictly 
 chemical) on exposure to light. An image of the object is re- 
 ceived at the focus of a convex lens, in a dark box (camera), on 
 a plate of ground glass. 2. This is removed, and the sensitive 
 plate inserted. Objects are visible by the light which they 
 irregularly reflect, white bodies reflecting the most and black the 
 least. The iodide of silver is most changed when there is most 
 light, and thus gives a picture. 3. In order to render this visi- 
 ble, the plate is exposed to the vapour of mercury, which adheres 
 most where there has been most change. 4. To prevent further 
 change, the unaltered iodide of silver is removed by a solution 
 of cyanide of potassium. All photographic processes are more 
 or less alike in general principle. 
 
 157. Heat. — Limestone, CaO,C0 2 , when heated, is de- 
 composed, the fixed lime, CaO, remaining, and the volatile, 
 C0 2 passing off. Gunpowder consists of charcoal, nitre, 
 and sulphur. When fire is applied, it is converted into 
 heated gases, occupying an enormously increased bulk. 
 In symbols the change taking place, when the powder is 
 not confined, maybe expressed thus: C 3 -f KO,N0 5 -f-S= 
 3C0 2 -f-N-f KS, the latter forming the smoke. 
 
 158. Electricity may act indirectly by developing heat 
 when resisted (141), and directly in the case of voltaic 
 decomposition. The latter will be considered under a dis- 
 tinct head, Electro-Ciiemistry (162). 
 
 159. Catalysis (142). — Chlorate of potassa, when heated 
 
112 MEDICAL CHEMISTRY. 
 
 to redness, fuses and gives off all its oxygen rapidly, KO, 
 C10 5 =KCl-f 6 . If mixed with powdered sand or black 
 oxide of manganese, the gas comes off quietly, and at a 
 much lower temperature. The black oxide is unchanged, 
 and may be used over and over again. 
 
 160. Example. — A solution of pure sugar will not fer- 
 ment ; upon the addition of a small quantity of any fer- 
 menting matter, as yeast, decomposition begins, and con- 
 tinues until the sugar is broken up. The ferment is said 
 to act by example. We do not really know how it acts. 
 
 161. Mechanical Force. — Although, as before stated 
 (135), it is generally true that a chemical compound may 
 be decomposed only by chemical means, yet there are im- 
 portant exceptions. In some cases the action is indirect, 
 as when heat is developed by friction or percussion; in 
 other cases it is direct. The two salts, sulphate of alu- 
 mina and sulphate of potassa, which united constitute 
 alum, may be separated by their different rates of diffu- 
 sion (131). Neutral metallic salts, such as those of gold, 
 silver, platinum, and copper, are decomposed by filtering 
 through charcoal, the metal being deposited on the char- 
 coal. This is due to the enormous surface which the 
 porous charcoal exposes (206). 
 
 ELECTRO-CHEMISTRY. 
 
 162. When a voltaic current is passed through an elec- 
 trolyte (94), decomposition takes place. If the liquid to 
 be studied be put into a separate vessel (decomposing 
 cell), and the conducting wires be tipped with platinum or 
 carbon, its constituents may be separated and examined. 
 
 163. Essential Phenomena. — The amount of chemical 
 action in the battery cells, of electricity developed, and of 
 chemical decomposition in the decomposing cell, are equiv- 
 
MOLECULAR FORCES. 113 
 
 alent With the same electrolyte the same constituent 
 appears invariably at the same pole. 
 
 Thus for 32 m 5 grains of zinc, Zn, dissolved in the battery, 9 
 grains of water, HO, are decomposed, 40*5 grains of oxide of 
 zinc, ZnO, formed, and 1 grain of hydrogen, H, liberated. The 
 electricity thus generated will, if passed through water, decom- 
 pose 9 grains (H=1.0=8), but if through iodide of potassium, KI, 
 (K=39. 1=127), 166 grains, or one equivalent will be broken up. 
 The oxygen in the first case, and the iodine in the second, appear 
 at the end of the wire attached to the -f- or platinum pole. 
 By measuring the amount of gas liberated in a given time, the 
 relative quantity of the current may be determined. An instru- 
 ment for this purpose is called a voltameter. 
 
 164. Electro-Positive and Negative Bodies. — We 
 have thus a means of arranging simple and compound 
 bodies according to their relative electrical characters. 
 These may be determined: 1. By the decomposing cell, the 
 — body going to the -f pole (95). 2. By a simple cell, 
 the direction of the current being indicated by a galva- 
 nometer. 3. Of two metals immersed in an electrolyte and 
 joined, the + alone is corroded. Of all the elements, 
 oxygen is the most negative, caesium the most positive. 
 The metals generally are positive to the non-metallic 
 bodies. Acids, and all corrosive agents, are negative, 
 bases positive. 
 
 No absolutely accurate scale of the relative electrical position 
 of the elements can be made. The direction of the current in a 
 single cell varies with the electrolyte, and the compounds of 
 some of the elements, as nitrogen, have not as yet been decom- 
 
 The following list is approximate only ; each element is posi- 
 tive to all below it, and negative to all above ; the less important 
 elements have been omitted. 
 
 Electro-Chemical Order of the Principal Elements. 
 
 Electro-negative. Bromine. 
 
 Oxygen. Iodine. 
 
 Fluorine. Nitrogen. 
 
 Chlorine. Sulphur. 
 10 * 
 
114 
 
 MEDICAL CHEMISTRY. 
 
 Phosphorus. 
 
 Arsenic. 
 
 Chromium. 
 
 Tungsten. 
 
 Boron. 
 
 Carbon. 
 
 Antimony. 
 
 Silicon. 
 
 Hydrogen. 
 
 Gold. 
 
 Platinum. 
 
 Mercury. 
 
 Silver. 
 
 Copper. 
 
 Bismuth. 
 
 Tin. 
 
 Lead. 
 
 Cadmium. 
 
 Cobalt. 
 
 Nickel. 
 
 Iron. 
 
 Zinc. 
 
 Manganese. 
 
 Aluminum. 
 
 Magnesium. 
 
 Calcium. 
 
 Strontium. 
 
 Barium. 
 
 Lithium. 
 
 Sodium. 
 
 Potassium. 
 
 Electro-positive. 
 
 The two newly-discovered metals, coesium and rubidium, are 
 more electro-positive than potassium. 
 
 These Terms Relative. — As we know of no absolutely 
 
 positive or negative state, we speak only of a body in 
 
 reference to some other combined with it. Thus, zinc is 
 
 negative to potassium but positive to tin, which again is 
 
 positive to gold. Chlorine is positive to oxygen in hypo- 
 
 + — 
 chlorous acid, CIO, but negative to hydrogen in hydro- 
 
 + — 
 chloric acid, HC1. 
 
 165. Voltaic Protection of Metals. — If a plate of zinc 
 and one of copper be exposed to a moist atmosphere, they 
 will both, after a time, rust; if joined together, the copper 
 remains bright. In the second case a simple voltaic cir- 
 cuit is formed, the electrolyte is polarised, the non-corro- 
 sive hydrogen atoms face the — copper, and vice versa. 
 This principle is applied in Dr. Hare's lightning-rod (93). 
 
 Other illustrations may be mentioned. A tinned basin rapidly 
 corrodes when the coating is scratched through, because iron is 
 positive to tin ; if coated with zinc, which is positive to iron, the 
 latter metal is preserved (galvanised iron). Iron-clad vessels 
 speedily foul and corrode in salt water, because of impurities in 
 the iron causing local action (97), and still more rapidly when 
 they are coppered below the water-line only, or when copper 
 pipes pass through them. 
 
 
MOLECULAR FORCES. 115 
 
 166. Electrotype. — This is the name given to the art of 
 cold casting of metals by electricity. As the metals are 
 electro-positive, they will deposit from solution upon a 
 conductor attached to the negative (zinc) pole. By 
 proper management they may be obtained of any desired 
 thickness, amorphous and bright, or dead. A gentle 
 current, not enough to evolve hydrogen at the — pole, is 
 required. The process is largely employed in the arts, 
 not only for plating and gilding, but for copying maps, 
 engravings, and medals, facing type, etc. 
 
 In silver plating, a solution of cyanide or oxide of silver is 
 made in cyanide of potassium. To the + pole is attached a 
 plate of silver, to the negative the object to be plated. A feeble 
 current is passed, the cyanide of silver is decomposed, the — 
 cyanogen* combining with the silver pole, and a corresponding 
 quantity of silver being deposited upon the object at the nega- 
 tive pole. Suppose the object to be plated to be of copper, the 
 change may be represented as follows : 
 
 + - + — + — 
 — Cu | Ag Cy Ag Cy Ag Cy | Ag -f before decomposition. 
 
 ij " + if+ ^+ ^T 
 
 Cu Ag | Cy Ag Cy Ag Cy Ag | after decomposition. 
 
 II. DECOMPOSITION BY SUPERIOR AFFINITY 
 
 16T. This may be divided into single and double de- 
 composition. 
 
 Single decomposition takes place between three bodies, 
 
 two of which are united, the third by combining with one 
 
 of these liberates the other. The general expression of 
 
 the change is : 
 
 +- ± +- + +- + 
 AB4-C=AC + B or CB-f A. 
 
 * Cyanogen is a compound body acting as an element and resembling 
 chlorine in its chemical relations (224). 
 
116 MEDICAL CHEMISTRY. 
 
 Thus when potassium is thrown upon water (152), 
 
 + -++- + 
 HO+K=KO+H; 
 
 or when sulphuric acid is added to carbonate of soda, 
 
 + - - + — -- 
 
 NaO,C0 2 + S0 3 =NaO, S0 3 + CO a . 
 
 The water of the sulphuric acid is omitted for the sake of sim- 
 plicity ; it does not enter into the reaction. 
 
 168. Double Decomposition takes place between two 
 pairs of elements or binaries (152). These mutually in- 
 terchange constituents. The general formula is: 
 
 +- -f— +- -f- 
 AB4-CD=AD+CB. 
 
 Thus, when solutions of sulphate of potassa and nitrate of 
 baryta are mixed, a white cloud (precipitate) falls. This is 
 sulphate of baryta, nitrate of potassa remaining in solution, 
 
 + -+- +- +~ 
 BaO,N0 5 +KO,S0 3 =BaO,S0 3 -f KO,N0 5 -> * 
 I 
 It is obvious that both acids and bases at the time of the inter- 
 change are in a nascent state (143), hence we get many com- 
 pounds by double decomposition exclusively. 
 
 169. The circumstances most prominently affecting 
 these forms of decomposition are insolubility, volatility, 
 and mass. 
 
 170. Insolubility. — Where the compound of any two of 
 the constituents of two given soluble compounds is insol- 
 uble, that compound will be formed on mixing them. 
 Hence it is not possible to give lists of the relative strength 
 (so called) of the various acids and bases, for an acid or a 
 base may be driven out of combination by one much more 
 feeble in the ordinary sense of the term, provided the cir- 
 cumstances modifying decomposition come into play. 
 
 Thus potassa will displace baryta in soluble combination. If 
 we add solution of potassa to nitrate of baryta, we will have 
 
 * An arrow pointing downwards indicates that the body is precipitated; 
 when horizontal, that it remains in solution ; when pointing upwards, that 
 it is liberated as gas. The signs + and — refer to the electro-positive 
 and electro-negative constituents. 
 
 
MOLECULAR FORCES. 117 
 
 BaO,N0 5 -f KO,HO=BaO,HO+KO,N(C But if sulphuric acid 
 be combined with potassa, the baryta will form an insoluble 
 compound with it and displace the potassa, KO,S0 3 -f-BaO,HO= 
 BaO, S0 3 +KO,HO->. This fact is applied in testing in the 
 
 humid way (174). 
 
 111. Volatility. — At the same temperature where 
 affinities are nearly balanced, the more fixed body will dis- 
 place that which is the more volatile. Hence, compounds 
 of gaseous acids and bases, as carbonic acid and ammonia, 
 are easily decomposed. And at high temperature, com- 
 paratively feeble fixed acids, as boracic, silicic, and phos- 
 phoric, will displace the strongest. 
 
 Carbonic acid, which is a gas at ordinary temperature, is 
 driven out of combination by all other acids, except the hydro- 
 cyanic ; under favorable circumstances, as when in solution 
 under pressure, it shows the properties of a powerful acid, dis- 
 solving rocks which are unaffected by all other acids except the 
 hydrofluoric. Boracic acid has no sour taste, and barely red- 
 dens litmus ; it is, perhaps, at ordinary temperature, the feeblest 
 of acids, but at a red heat, above which it volatilises, it will 
 drive sulphuric acid, which boils at 640°, from its combinations. 
 
 112. Mass. — The quantity of material will sometimes 
 determine the direction of chemical change. If we pass 
 steam over red-hot iron filings, the oxygen of the vapour 
 of water will unite with the iron, and hydrogen will pass 
 over. If this be collected and the steam generator de- 
 tached, upon passing the hydrogen back over the red-hot 
 oxide of iron, it will take up its oxygen, reform steam, 
 and leave metallic iron. 
 
 ANALYSIS 
 
 May be divided, according to its object, into Qualitative 
 and Quantitative, and, according to the method pursued, 
 into wet or humid, dry, by the balance and volumetric. 
 
 173. Qualitative Analysis seeks only to determine 
 the nature of a body. Often a body may be recognised 
 
118 MEDICAL CHEMISTRY. 
 
 by its physical properties, such as colour, lustre, taste, 
 
 smell, solubility, hardness, crystalline form, and specific 
 
 gravity. 
 
 Thus the mineralogist can distinguish most of his specimens, 
 and even their localities. In the dry way we are assisted by the 
 blowpipe (212). The behaviour of a body in the outer (oxydis- 
 ing) or inner (reducing) flame, the colour given to fluxes, enables 
 us to decide on its character in a rapid and satisfactory manner. 
 
 114. Liquid Tests. Reagents. — To determine the pres- 
 ence of a body in solution, we have only to add an- 
 other which contains a substance capable of forming an 
 insoluble compound with one of the constituents of the 
 former, ^precipitate falls (168), and by its colour, solubility 
 or insolubility in excess of the reagent, or in other re- 
 agents, the nature of the body may be determined. This 
 method is applicable where we are seeking to determine 
 simply the presence or absence of a body without regard 
 to the nature of those with which it may be associated. 
 When all the constituents of a body are to be determined, 
 we have to proceed in a more complex manner. A diag- 
 nosis by exclusion is a preliminary step, adding a reagent, 
 as sulphuretted hydrogen, which precipitates a very large 
 number of substances. The absence of a precipitate at 
 once excludes these and narrows the inquiry to that ex- 
 tent. In case of a precipitate, the colour, etc. are noted, 
 and by successively applying other reagents a final con- 
 clusion is arrived at. 
 
 Examples. — If to a solution suspected to contain copper we 
 add ferrocyanide of potassium (340), the absence of a precipi- 
 tate or the presence of a brown one would be decisive. If to 
 water supposed to be impure we add sulphydrate of ammonia 
 (380), the appearance of a black precipitate indicates the pres- 
 ence of either lead, tin, bismuth, mercury, cobalt, nickel, silver, 
 gold, platinum, iron, copper, or uranium. To determine which 
 of these is present, other reagents must be used. The tests will 
 be given with the various elements and compounds. 
 
 Ho. Delicacy of Tests. — The delicacy of a liquid test 
 
MOLECULAR FORCES. 119 
 
 depends (1) upon the insolubility of the precipitate ; (2) 
 upon its opacity. If we add sulphuric acid to a soluble 
 salt of lime in strong solution, we get a precipitate of sul- 
 phate of lime ; but if the quantity of water be greater than 
 400 times the weight of the sulphate of lime formed, it 
 will dissolve as fast as formed. Magnesia and alumina 
 are very insoluble, but form gelatinous opalescent precipi- 
 tates which may escape the eye, while those formed by 
 sulphuretted hydrogen or ferrocyanide of potassium with 
 the heavy metals are very opaque, and will be visible even 
 when in very small quantity. In comparing the delicacy 
 of tests, we always suppose the same quantity of solvent 
 to be used. In certain cases, (sulphocyanide of potassium 
 with salts of the sesquioxide of iron, for instance,) no pre- 
 cipitate is formed, but a distinct colour which forms some- 
 times a very delicate test. 
 
 176. Spectral Analysis. — By passing the light of a flame 
 through a prism or series of prisms, a spectrum is obtained 
 (30). That of the sun is intersected with numerous lines 
 (Fraunhofer's lines). If into the flame we introduce a 
 loop of wire containing a small portion of a combustible 
 or volatile body, a line or lines make their appearance. 
 These lines are constant in their position and colour for 
 the same body. Where the light from one substance 
 placed in the flame is caused to pass through its own 
 flame, the two neutralise, and a black line is seen. All 
 bodies do not yield satisfactory spectra. 
 
 The delicacy of this test is very great. Bunsen and Kirchoff, 
 to whom we principally owe its discovery, calculated that they 
 had detected the i, 37775^(7^ of a grain of sodium. The new 
 metals Ccesium, Rubidium, Thallium, and Indium were discov- 
 ered by its means, and observers are now making investigations 
 into the probable constitution of the sun and stars by its aid. 
 It is stated that the position and colour of the lines vary, in 
 some cases, with the temperature. 
 
 177. Quantitative Analysis seeks to determine not 
 
120 MEDICAL CHEMISTRY. 
 
 only the nature of a body, but the exact amount or quantity 
 
 of its constituents. It requires considerable experience 
 
 and the most conscientious and scrupulous care to obtain 
 
 reliable results. Of the wet way, by weight, the general 
 
 steps may be thus stated : 1. Weigh the body ; 2. Dissolve 
 
 it chemically ; 3. Precipitate and wash ; 4. Dry, weigh, 
 
 and calculate. 
 
 To take a simple example. A weighed portion of silver coin is 
 acted on by nitric acid by the aid of heat as long as red fumes 
 are given off. To the filtered solution is added pure hydro- 
 chloric acid as long as any precipitate falls. This is put on a filter 
 and thoroughly washed with distilled water ; the precipitate is 
 then dried and weighed. It consists of chloride of silver, AgCl. 
 As the equivalent of chlorine is 35*5 and of silver 108, we can 
 readily calculate the amount of the latter present. Thus, if the 
 precipitate weigh 100 grains, 143*5=108 : : 100 : 82-28 grains 
 of silver. 
 
 178. Volumetric Analysis. — This is a rapid method, but 
 
 of comparatively limited application. It depends upon 
 
 noting the quantity of a solution of a reagent of known 
 
 strength required entirely to precipitate or neutralise the 
 
 substance under investigation. 
 
 This method will be best understood by the example of the 
 assay of silver coins. The solution used is of common salt, of 
 which 542*74 parts are required to precipitate 1000 parts of 
 silver. The strength of the solution is such that a given meas- 
 ure (French decilitre=3*381 f 3) shall contain 542*74 thousandths 
 of a gramme (15.433 grs.). A second solution of one-tenth of 
 the strength of the first is also prepared. The coin is acted on 
 Dy nitric acid, which dissolves both the silver and copper. One 
 measure of the solution, of course, precipitates 1000 parts by 
 weight of silver, the copper being unaffected. If any silver 
 remain, an equal measure of the decimal solution is added, 
 which precipitates the T ^<jo part additionally of silver, and it is 
 thus added as long as any precipitate is observed. As a large 
 quantity of the solution may be prepared at once, the only 
 weighing required is that of the coin, of which so much is taken 
 that it should be almost entirely precipitated by the first addi- 
 tion, if at the lowest allowable standard. 
 
 179. Cupellation is used only in the separation or 
 assay of gold and silver. A small cup (cupel) of bone 
 
MOLECULAR FORCES. 121 
 
 ash is prepared ; the alloy is enclosed in lead and placed 
 in the cupel, which is exposed to a draught of air at a 
 high temperature. The whole melts, the lead oxydises 
 and soaks into the porous cupel, carrying with it the other 
 metallic oxides, leaving a bright button of silver, or of its 
 alloy with gold, as the case may be. In the latter case, 
 the silver, which must be at least three times the weight 
 of the gold, is afterwards removed by warm nitric acid. 
 When too little silver is added, a portion escapes the 
 action of the acid. 
 
 11 
 
PART III. 
 
 CHEMISTRY OF THE ELEMENTS. 
 
 TABLE OF THE ELEMENTS. 
 
 180. Note. — Those in capitals are important; those in italics, less so; 
 and those in ordinary type, unimportant in Medical Chemistry. 
 
 ELEMENT. 
 
 SYMBOL. 
 
 EQUIVALENT. 
 
 Oxygen, 
 
 o, 
 
 8- 
 
 Hydrogen, 
 
 H, 
 
 I" 
 
 Nitrogen, 
 
 N, 
 
 H- 
 
 Carbon, 
 
 c, 
 
 6- 
 
 Sulphur, 
 
 s, 
 
 16- 
 
 Selenium, 
 
 Se, 
 
 40- 
 
 Phosphorus, 
 
 P, 
 
 31- 
 
 Chlorine, 
 
 CI, 
 
 35-5 
 
 Iodine, 
 
 I, 
 
 12Y- 
 
 Bromine, 
 
 Br, 
 
 80- 
 
 Fluorine, 
 
 E, 
 
 19- 
 
 Boron, 
 
 B, 
 
 11- 
 
 Silicon, 
 
 Si, 
 
 21- 
 
 Potassium (Kalium), 
 
 K, 
 
 39-00 
 
 Sodium (Natrium), 
 
 Na, 
 
 23- 
 
 Lithium, 
 
 L, 
 
 7- 
 
 Ccesium, 
 
 Cs, 
 
 133- 
 
 Rubidium, 
 
 Rb, 
 
 85 36 
 
 (122) 
 
 
 
TABLE OF THE ELEMENTS. 123 
 
 ELEMENT. 
 
 SYMBOL. 
 
 EQUIVALENT 
 
 Thallium, 
 
 T, 
 
 204- 
 
 Indium, 
 
 In, 
 
 3592 
 
 Barium, 
 
 Ba, 
 
 68-5 
 
 Strontium, 
 
 Sr, 
 
 437 
 
 Calcium, 
 
 Ca, 
 
 20- 
 
 Magnesium, 
 
 Mg, 
 
 12- 
 
 Aluminum, 
 
 Al, 
 
 1369 
 
 Glucinum, 
 
 Gl, 
 
 26-50 
 
 Zirconium, 
 
 Zr, 
 
 33-62 
 
 Yttrium, 
 
 Y, 
 
 32-20 
 
 Erbium, 
 
 E, 
 
 ? 
 
 Terbium, 
 
 Tb, 
 
 ? 
 
 Thorium, 
 
 Th, 
 
 59-59 
 
 Manganese, 
 
 Mn, 
 
 27-5 
 
 Iron (Ferrum), 
 
 Fe, 
 
 28' 
 
 Chromium, 
 
 Cr, 
 
 26* 
 
 Nickel, 
 
 Ni, 
 
 29-5 
 
 Cobalt, 
 
 Co, 
 
 29-5 
 
 Copper (Cuprum), 
 
 Cu, 
 
 31-66 
 
 Zinc, 
 
 Zn, 
 
 32-52 
 
 Cadmium, 
 
 Cd, 
 
 56- 
 
 Lead (Plumbum), 
 
 Pb, 
 
 103-56 
 
 Tin (Stannum), 
 
 Sn, 
 
 59- 
 
 Yanadium, 
 
 Y, 
 
 68-4 
 
 Tungsten (Wolfram), 
 
 w, 
 
 92- 
 
 Molybdenum, 
 
 Mo, 
 
 48- 
 
 Tellurium, 
 
 Te, 
 
 64-5 
 
 Bismuth, 
 
 Bi, 
 
 210- 
 
 Arsenic, 
 
 As, 
 
 T5- 
 
 Antimony (Stibium), 
 
 Sb, 
 
 122- 
 
 Uranium, 
 
 u, 
 
 60- 
 
 Cerium, 
 
 Ce, 
 
 46- 
 
 Lantanum, 
 
 Ln, 
 
 46 
 
124 
 
 MEDICAL CHEMISTRY. 
 
 ELEMENT. 
 
 
 SYMBOL. 
 
 EQUIVALENT. 
 
 Didymium, 
 
 
 D, 
 
 48- 
 
 Titanium, 
 
 
 Ti, 
 
 25- 
 
 Tantalum, 
 
 
 Ta, 
 
 68- 
 
 Niobium, 
 
 
 Nb, 
 
 48- 
 
 Mercury (Hydrargyrum), 
 
 Hg, 
 
 100- 
 
 Silver (Argentum), 
 
 Ag, 
 
 108- 
 
 Gold (Aurnm), 
 
 
 Ah, 
 
 98* 
 
 Platinum, 
 
 
 Pt, 
 
 98-5 
 
 Palladium, 
 
 
 Pd, 
 
 53-2 
 
 Iridium, 
 
 
 Ir, 
 
 98-5 
 
 Osmium, 
 
 
 Os, 
 
 99-5 
 
 Rhodium, 
 
 
 R, 
 
 52- 
 
 Ruthenium, 
 
 
 Ru, 
 
 52- 
 
 
 OXYGEN, 0=8. 
 
 
 181. Natural Sources. — It forms about one-fifth of the 
 atmosphere, eight-ninths (by weight) of water; exists in 
 all rocks, most ores, and in all animal and vegetable sub- 
 stances. It is estimated to constitute three-fourths of the 
 matter of the earth. 
 
 Preparation. — Heat chlorate of potassato redness; is 
 given off and chloride of potassium remains. KO,C10 3 = 
 
 KCl-f-06. The addition of one-fourth, by weight, of black 
 
 oxide of manganese, Mn0 2 , or of one-tenth of anhydrous 
 sesquioxide of iron, Fe 2 3 ( Colcothar), causes the gas to 
 be evolved more regularly, and at a lower temperature 
 (159) ; it is then not so pure. 
 
 Many other processes have been suggested ; the above is almost 
 universally employed. The " oxygenesis" of Messrs. Bobbins, a 
 mixture of binoxide of barium, Ba0 2 , and bichromate of potassa, 
 KO,2Cr0 8 , evolves 0, at ordinary temperature, on the addition 
 
CHEMISTRY OP THE ELEMENTS. 125 
 
 of a dilute acid. If the compound could be sold at a moderate 
 price, it would do much towards the introduction of this element 
 into medical use. 
 
 182. Manipulation of Gases. — The pneumatic trough 
 consists of a cistern provided with tanks, which are closed 
 above and open below, and are furnished with suitable 
 stopcocks ; in these considerable amounts of gases may be 
 stored. To collect smaller quantities, the receiving vessel 
 is filled with water by immersing it so as to allow the air 
 to escape ; if its lower edge be kept under water, it will 
 remain filled. It is then placed on a submerged shelf, 
 which may be perforated to admit of the delivery tube 
 of the generating apparatus, or the edge of the jar may 
 project slightly with the same object. The water is sus- 
 tained in the jar by atmospheric pressure (193); as gases 
 are lighter than water, a bubble admitted into the jar rises 
 to the top, and allows an equal volume of water to fall out, 
 and thus the gas will gradually fill the jar. To transfer 
 gases, it is only necessary to put the mouth of the jar filled 
 with gas slightly below that of one filled with water, be- 
 neath the surface of the cistern, and incline the former. 
 The gas will pass up and displace its volume of water from 
 the second jar. Gases soluble in water may be collected 
 over mercury. When very light or very heavy, they may 
 be conveyed to the top or bottom of the jar, and thus 
 displace the air, as in the case of hydrogen and carbonic 
 acid. 
 
 In the absence of a pneumatic trough, a gas may be collected 
 in a large tumbler over a soup-plate. The tumbler being filled 
 to the brim, a piece of card or thick paper is slid over the mouth ; 
 it may then be inverted into the plate filled with water, without 
 the liquid falling out. A bit of wood at the bottom of the plate 
 will serve to keep the edge of the tumbler sufficiently elevated to 
 allow of the introduction of the delivery tube. The plate will be 
 apt to overflow when the water of the tumbler passes out ; this 
 can be easily provided against. Where jars are too large to be 
 dipped into the pneumatic trough, they may be filled by suction. 
 11* 
 
126 MEDICAL CHEMISTRY. 
 
 Apiece of gum tube is carried to the top of the jar, or floated 
 on the surface of the water by a cork or bit of wood ; the air is 
 then drawn out by the lungs or a pump. Where a slight admix- 
 ture of air is not objectionable, nearly all gases may be collected 
 by simple displacement of the air of the receiving vessel. Large 
 globes of oxygen for the lecture-table are thus filled. 
 
 183. Properties of Oxygen. — A permanently elastic, in- 
 odourous, tasteless, transparent gas; s. g. 1106; water at 
 60° dissolves 3 p. c. ; the most magnetic of gases ; combus- 
 tibles burn in it with increased brilliancy ; it is the only 
 supporter of animal life. 
 
 Physiological Effects. — It acts as a stimulant, quicken- 
 ing the pulse and respiration, causing after a time fever 
 and death. It converts the venous into arterial blood. 
 Its therapeutic uses have not been satisfactorily deter- 
 mined, except in anaemia, in which Trousseau* recom- 
 mends highly its inhalation to the extent of six to ten 
 quarts a day. As air contains but one-fifth of its bulk 
 of this vital agent, it is obvious that its inhalation in cases 
 of suspended animation might insure a favourable result in 
 an otherwise hopeless subject. 
 
 184. General Chemical Relations. — It combines with all 
 the elements except fluorine, and with many of them forms 
 more than one compound (oxide). When the process is 
 unattended by the evolution of light, it is termed oxida- 
 tion ; (rusting, fermentation, respiration and decay are in- 
 cluded under this head ;) when light and heat are feebly 
 evolved, it is known as slow combustion, as the glow of a 
 stick of phosphorus or a damp match in air ; when with 
 vivid light and heat, we have ordinary combustion. 
 
 These actions differ only in degree ; the heat in oxidation and 
 slow combustion passes off as rapidly as it is formed, and is not 
 sensible to ordinary observation, but may accumulate and pass 
 into ordinary combustion, as in the cases of masses of rusting 
 iron or oiled rags. Oxygen is not essential to combustion, which 
 may take place in chlorine, etc. In the broadest sense, all 
 
 * Cliniqiie Medicate, t. III., p. 63. 
 
 
CHEMISTRY OF THE ELEMENTS. 127 
 
 chemical combination where an element unites on one side, is 
 combustion, although it is generally defined as chemical union 
 attended by light and heat. 
 
 Characters of Oxides. — The lower oxides {protoxides, 
 sesquioxides) of the metals are bases ; the higher oxides 
 of the elements generally are acids; the lower oxides 
 of the non-metallic elements are acid or neuter. The ses- 
 quioxides sometimes combine with protoxides, acting as 
 quasi acids. 
 
 Thus MnO, protoxide of manganese, is a well marked base, 
 Mn 2 3 a feeble base, Mn0 2 neuter ; Mn0 3 and Mn 2 O r are acids. 
 Sulphur, selenium, and tellurium, have also the property when 
 acting as electro-negative constituents of forming both acids and 
 bases. The name amphigen (Gr. amphi, both, and gennao, I 
 produce) has been applied to this group. Thus we may have 
 KO,As0 3 , arsenite of potassa, an oxygen salt; KS,AsS 3 , sul- 
 phur salt; KSe,AsSe 3 , selenium salt; KTe,AsTe 3 , tellurium salt. 
 The same amphigen exists in the acid and base ; an oxygen acid 
 will not unite with a sulphur base. The selenium and tellurium 
 salts are unimportant. 
 
 185. Ozone. — When electrical sparks are passed through 
 dry oxygen, a small portion, not more than two per cent., 
 is converted into an allotropic form (that is, an identical 
 body, but having different properties), called ozone. This 
 change is also produced during the slow combustion of 
 phosphorus in air, or 0, and during many chemical changes. 
 Nascent (143) O contains a large proportion of ozone. 
 — Properties. It has a peculiar odour resembling fresh- 
 boiled lobster (Houzeaux), is four times as dense as ordi- 
 nary O (Andrews), and is the most powerful oxidising 
 agent known. At ordinary temperatures it oxidises silver, 
 consumes organic matter, bleaches, and decomposes iodide 
 of potassium. It is concerted into ordinary O, at tem- 
 peratures above 212°. It is present in the atmosphere in 
 varying amounts, being absent in foul localities. — Tests. 
 Paper moistened with a mixture of starch and pure 
 iodide of potassium becomes bine by its action, and 
 
128 MEDICAL CHEMISTRY. 
 
 sulphate of manganese is decomposed by it, causing paper 
 immersed in a dilute solution of the salt to become brown. 
 These tests are not entirely satisfactory. 
 
 Schonbein believes that exists in two polar conditions, ozone 
 and antozone, which, when united, form ordinary 0. The for- 
 mer is evolved from the higher oxides of chromium, manganese, 
 and lead, the latter from binoxides of hydrogen and barium. 
 These views are strengthened by the recent experiments of 
 Meissner * and Baudrimont,f but cannot be considered as con- 
 firmed. Schonbein, the discoverer of ozone, and who has spent 
 years in its investigation, himself admits that as yet neither ozone 
 nor antozone have been obtained separate from ordinary oxygen. 
 Permanganate of potassa, KO,Mn 2 7 , in solution either alone or 
 with the addition of sulphuric acid, is a convenient source of 
 ozonised air. 
 
 HYDROGEN, H=l. 
 
 186. Natural Sources. — Water, animal and vegetable 
 substances. 
 
 Preparation. — By removing from water, HO ; practi- 
 cally by the action of dilute sulphuric acid upon commer- 
 cial zinc, Zn+H0,S0 3 =Zn0,S0"+H4 Being thirteen 
 times lighter than air, it may be collected by displace- 
 ment, the delivery tube passing to the top of a jar held 
 with the mouth downward. 
 
 The self-regulating generator of Dr. Hare is useful in all cases 
 where gases are evolved without the aid of heat. A cylinder 
 has within it a bell-glass, mouth downwards, furnished with a 
 stopcock, and supported on a frame. The zinc in the case of H 
 is suspended or supported within the inner jar ; acid water is 
 poured into the outer one ; the stopcock being open, it fills both 
 to the same level, and acts upon the zinc. When the air is ex- 
 pelled from the inner jar, the stopcock is closed ; the accumulat- 
 ing gas drives the liquid out of the inner jar, and the zinc being 
 no longer acted upon, all action ceases. When the stopcock is 
 
 * Chemical News, No. 239. f Ibid., No. 334. 
 
 X In giving reactions, the essential changes only will be represented. 
 In almost all eases the quantity of water present is considerable, but as 
 it appears on both sides of the equation, may be safely omitted. The re- 
 action above expressed would be more accurately Zn+II0,S03+»H0= 
 ZnO,S03 + )*HO + H, in which ?<H0 represents any fixed quantity of water. 
 
CHEMISTRY OF THE ELEMENTS. 129 
 
 opened, gas escapes, the liquid rises by the weight of that in the 
 outer cylinder, and action recommences. 
 
 Properties. — A colourless, inodourous, tasteless, trans- 
 parent, permanently elastic gas ; s. g. *0069 (the lightest 
 of known bodies); inflammable, respirable when diluted 
 with air, but not a supporter of life ; water dissolves 25 
 per cent. "When mixed with in nearly atomic propoi** 
 tions and ignited, violent explosion ensues ; when the two 
 are burned gradually at a jet, an intense heat is produced 
 (the compound blowpipe). Its physiological effects are 
 unimportant. 
 
 Chemical Relations. — Is the most electro-positive of the 
 non-metallic bodies, and resembles the metals in many 
 respects. It is replaced by them in combination. When 
 acting as an electro-negative body, it forms hydrides. 
 With O, it forms water, HO, and H0 2 , binoxide of H. 
 
 WATER, HO=9. 
 18?. Natural Sources.— The sea, rivers, wells, springs, 
 the atmosphere, organic bodies ; is formed during the com- 
 bustion of hydrogen, and of all bodies containing it. 
 
 Water is universally diffused through nature. Even rocks of 
 considerable hardness, as limestone and sandstone, lose a large 
 percentage on drying. The body of man consists of from two- 
 thirds to three-fourths of water; the medusae or jelly-fish eon- 
 tain over 99 per cent. Potatoes contain 75 per cent.; turnips 
 90, water-melons 94, and cucumbers 97 per cent, of water. A 
 cubic foot of air at 60°, saturated with moisture, contains 5.756 
 grains. 
 
 Properties. — A transparent, inodourous, colourless, 
 tasteless liquid, solid below 32° F., and boiling at 212° 
 F., at 30 in. Bar. Is compressed -%-$. -q-Jq, ■$-$-$ in bulk by the 
 pressure of one atmosphere, 15 pounds. Is taken as the 
 standard of specific gravity of all solids and liquids. One 
 cubic inch weighs, at 60° F., 252*5 grains ; is 815 times 
 heavier than air. It is the most universal of all solvents. 
 
130 MEDICAL CHEMISTRY. 
 
 188. Impurities. — Water always contains air, and fre- 
 quently carbonic acid in solution. As is more soluble 
 than N, dissolved air is richer than the atmosphere in the 
 former. It is found exceedingly difficult to obtain water 
 free from air ; when it is removed by boiling or the air- 
 pump, it is almost instantly reabsorbed. Rain-water, 
 which is distilled from natural reservoirs, as rivers, lakes, 
 and the sea, is the purest natural form of water, when 
 collected at a distance from habitations. It usually con- 
 tains nitrates, probably formed during evaporation from 
 the nitrogen and oxygen of the air, or from the combina- 
 tion of these elements under the influence of atmospheric 
 electricity. When collected near habitations, it may con- 
 tain ammonia and organic matter. When rain falls upon 
 the surface of the earth, a portion runs off, and the re- 
 mainder penetrates. Owing to the inclined position of 
 the strata, or layers of the earth's crust, it may sink to 
 considerable depths, and be exposed to great pressure and 
 increased temperature. It thus, by the aid of dissolved 
 carbonic acid, C0 2 , exercises considerable solvent power 
 upon the constituents of the rocks,* and when it issues 
 through natural or artificial openings (springs, wells, etc.), 
 is more or less charged with mineral matter. On expo- 
 sure to the air and surface drainage, it is further contami- 
 nated by organic matter. Hard water contains lime in 
 solution, as sulphate, CaO,S0 3 , or carbonate, CaO,C0 2 . 
 Sulphur waters contain sulphuretted hydrogen, HS, prob- 
 ably derived from the decomposition of pyrites ; and min- 
 eral waters various salts, generally with an excess of car- 
 bonic acid. Sea-water contains 2*T per cent, of common 
 salt, NaCl ; '04 per cent, of chloride of magnesium, MgCl ; 
 •03 of sulphate of magnesia, MgO,S0 3 ; -02 of sulphate of 
 
 * The term rock is used in its geological sense, to indicate any constitu- 
 ent of the earth's crust, whether hard as granite, or soft as clay. 
 
CHEMISTRY OF THE ELEMENTS. 181 
 
 lime, CaO,S0 3 ; with smaller proportions of chloride of po- 
 tassium, KC1 ; bromide of magnesium, MgBr ; carbonate of 
 lime, CaO,C0 2 ; with traces of iodine, ammonia, and silver. 
 
 Tests. — Dr. Clark's soap test indicates approximately the hard- 
 ness of water. An alcoholic solution of soap is prepared and 
 tested by a solution containing a known quantity of lime. This 
 is added by degrees to the water to be tested until the bubbles 
 formed become persistent. From the quantity of soap solution 
 used the amount of lime in the water is found. Permanganate 
 qfpotassa, KO,Mn 2 7 , indicates the presence of organic matter by 
 the loss of its colour, and according to Dr. Wood,* one grain of 
 crystallised permanganate is decolourised by 5 grains of organic 
 matter. This result can only be considered as an approxima- 
 tion. The presence of infusoria does not indicate a high degree 
 of impurity ; they are absent in very foul water. 
 
 189. Purification. — Water, to a certain extent, is purified 
 by natural agencies; on escaping into the atmosphere, 
 carbonic acid, C0 2 , escapes, and the earthy and metallic car- 
 bonates held in solution by that gas are deposited. In 
 certain cases the soluble salts in different streams which 
 meet mutually decompose each other, forming nearly insol- 
 uble compounds. (Example: Carbonate of lime and sul- 
 phate of iron in the tributaries of the Schuylkill, FeO,S0 3 
 + CaO,C0 2 =FeO,C0 2 -f CaO,S0 3 .) 
 
 Thus, river water is freer, on the average, from saline 
 ingredients than that of springs. Organic matters par- 
 tially subside and are consumed by aquatic plants and 
 animals and destroyed by the ozone given off by the former 
 under the influence of sunlight. The small quantity of 
 mineral ingredients in ordinary river water cannot be con- 
 sidered as injurious to health. When water freezes, dis- 
 solved matters separate, and the water obtained from melted 
 ice (even that formed from sea-water) is pure enough for 
 ordinary purposes. Water is purified artificially, (1) By 
 filtration or subsidence which remove suspended matters, 
 as fine particles of sand, mud, etc. Charcoal filters will 
 
 * Journal Chemical Society, March, 1863. 
 
132 MEDICAL CHEMISTRY. 
 
 also remove certain dissolved organic matters (206). (2) 
 By distillation, which gives, when carefully conducted, 
 pure water. 3. By boiling, which disengages carbonic 
 acid, C0 2 , and thus forms the deposit of the less soluble 
 carbonates. 4. By the addition of substances which act 
 chemically or mechanically. 
 
 Solution of permanganate of potassa, KO,Mn 2 7 , added to 
 ■water containing organic matter, will purify it rapidly and 
 harmlessly ; a very slight pink tinge indicates that all organic 
 matter has disappeared. This may be removed by inserting a 
 clean stick for a few moments. Finings, such as gelatine, 
 white of egg, etc., act mechanically by sinking and carrying 
 down fine suspended matter. Alum, in small quantity, com- 
 bines with organic matter, and, as the compound sinks, carries 
 down suspended particles. Carbonate of soda, NaO,00 2 , chloride 
 of ammonium, NH 4 C1, vegetable astringents and molasses act 
 chemically in decomposing salts of lime, and are used to prevent 
 incrustations in steam-boilers. Citric acid or lemon-juice added 
 to hard water will correct its purgative tendency. 
 
 190. Chemical Relations. — Although neutral to test 
 paper, water combines energetically. With acids, it acts 
 as a base, HO,S0 3 , and with bases as an acid, KO^HO, 
 with this important difference, that it does not neutralise 
 but rather enhances the chemical power of the body. It 
 is indeed the essential medium in chemical combination at 
 ordinary temperatures. It also combines with salts. Its 
 combination is usually attended with evolution of heat, 
 and when combined it cannot be driven out at 212° F. 
 The combinations of water are called hydrates (Gr. hudor, 
 water). 
 
 The anhydrous acids are mostly destitute of chemical action ; 
 the same is true of bases, though both greedily take up water 
 (with certain exceptions) and become hydrates. The water of 
 an hydrated acid or base does not usually enter into combina- 
 tion, KO,HO+HO,S0 3 ==KO,S0 3 +2HO. While the combination 
 of water is attended with an elevation of temperature, a depres- 
 sion is observed during solution. Thus, when lime is slaked, 
 heat is evolved ; when Epsom salt is dissolved, the liquid is 
 cooled. 
 
CHEMISTRY OF THE ELEMENTS. 133 
 
 Water of Crystallisation is not chemically combined ; it 
 may be driven off, in which case the body loses its crys- 
 tallised form, but is not chemically changed ; water chemi- 
 cally combined, constituent water, cannot be removed 
 without decomposition. 
 
 Crystallised oxalic acid, HO,C 2 3 -}-2HO, may have the two 
 equivalents of water of crystallisation driven off, and will recrys- 
 tallise unchanged; if the basic water be removed and not re- 
 placed by a base, it is decomposed into carbonic oxide, CO, and 
 carbonic acid, C0 2 . 
 
 191. Officinal Forms. — (a) Aqua. Natural water, 
 in its purest attainable state; (b) Aqua destillata. Take 
 80 pints of water, distil 2 pints and reject ; then distil 64 
 pints. 
 
 The term. Aqua, U. S. P., signifies a gaseous or volatile 
 body dissolved in water, as Aqua chlorini, Aqua cinna- 
 momi. Liquor, a solution of a fixed body, as Liquor po- 
 tass &. 
 
 Definitions. — Maceration, the long-continued soaking 
 
 of a body in water at from 60° to 90°. Digestion, the 
 
 same in hot water. Infusion, subjecting a body for a 
 
 short time to the action of hot or cold water, or the result 
 
 of the process, Infusum, TJ. S. P. Decoction, boiling a 
 
 body in water, or the result of the process, Decoctum, U. 
 
 S. P. Filtration, separating an insoluble body from a 
 
 liquid by means of a porous medium ; the liquid which 
 
 passes through is called the filtrate. Edulcoration or 
 
 displacement pouring upon the solid matter left on the 
 
 filter a supply of menstruum whereby that remaining in 
 
 the solid is displaced. Lixiviation or leaching, pouring 
 
 water upon a porous solid mass, whereby any soluble 
 
 matter is washed out, as in making lye from ashes. 
 
 Levigation, rubbing a body to fine powder. Elutriation, 
 
 throwing a powder into water ; the coarser particles settle 
 
 first, the finer ones remain suspended, and may be sepa- 
 12 
 
134 MEDICAL CHEMISTRY. 
 
 rately collected. Decantation, pouring off a liquid from 
 a precipitated solid, or drawing it off with a syphon or 
 pipette (195). 
 
 NITROGEN, N=14. 
 
 192. Natural Sources. — The atmosphere, native nitrates, 
 most animal and many vegetable substances. 
 
 Preparation. — By burning Phosphorus in confined air, 
 over water, the oxygen of the air is consumed. Phosphoric 
 acid, P0 5 , is formed and dissolved by the water. 
 
 Properties. — Generally negative. Is without colour, 
 taste, smell, or poisonous effects. Is permanently elastic, 
 does not support combustion or animal life. S. G. 972. 
 Water dissolves T47 p. c. 
 
 General Chemical Relations. — Has feeble affinities, and 
 unites directly with but few bodies ; indirectly with many, 
 forming compounds of the highest importance. With 
 forms five compounds : Nitrous oxide, NO ,; Nitric oxide, 
 N0 2 ; Nitrous acid, N0 3 ; Hyponitric acid, N0 4 ; Nitric 
 acid, N0 5 ; — with H, Ammonia, NH 3 . We have also the 
 Atmosphere, a mixture of N and with other gases and 
 vapours. 
 
 THE ATMOSPHERE. 
 
 193. Extent, Density, and Weight. — Is supposed to ex- 
 tend about 50 miles above the surface of the earth ; its 
 density is inversely as the square of the distance from that 
 surface; at 2'1 miles one-half, and 5*4 miles one-fourth, 
 etc. One hundred cubic inches at 30 in. Bar. and 60° F., 
 weigh 30-829 grs. Thirteen cubic feet of air weigh a 
 pound avoirdupois nearly. Air is assumed as the 
 standard of s. g. of all gases and vapours, and is taken as 
 1000. The weight of 100 cubic inches of any gas may be 
 obtained by multiplying its s. g, by 30*829, the weight of 
 
CHEMISTRY OP THE ELEMENTS. 135 
 
 an equal bulk of air. Thus, 100 c. i. of nitrogen = 972 x 
 30*829=29-966 grs. 
 
 Pressure. The Barometer. — The pressure of the atmo- 
 sphere is due to its weight, and is, on the average, at the 
 level of the sea, 15 lbs. to the square inch,= to a column 
 of water 34 feet, or of mercury 30 in. high. The mercu- 
 rial barometer is a tube about 34 inches long, sealed at its 
 upper end, containing a column of mercury ; its lower end 
 is immersed in an open cistern of the same. The mercury 
 is introduced in small portions, and boiled so that all air 
 and moisture are expelled from the tube. When it is in- 
 verted, the mercury falls to the point where its weight is 
 balanced by that of the atmosphere, and leaves a vacuum 
 space above it (the Torricellian vacuum). As atmospheric 
 pressure increases, the column is forced up; when it 
 diminishes, the weight of the mercury causes it to fall. 
 These fluctuations are measured by a scale attached to the 
 side of the tube near the upper end of the column. 
 
 In accurate observations, corrections must be made for tem- 
 perature, capillarity, and the varying level of the mercury in the 
 cistern. The aneroid barometer consists of a brass box, partially 
 exhausted, with an elastic metallic lid, which latter is connected 
 with an index, and rises or falls with the varying pressure. It 
 is more sensitive and convenient than the mercurial barometer, 
 and sufficiently accurate for ordinary purposes. 
 
 194. Mariotte's Law. — The volumes of all gases, at the 
 
 same temperature, are inversely as the pressure ; their 
 
 density and elastic force are directly as the pressure and 
 
 inversely as the volume. 
 
 Thus, a quart of air reduced to a pint has the pressure on its 
 surface doubled ; its volume is one-half, and its density twice 
 that of the original. This law, although not absolutely true, is 
 nearly enough so for all practical purposes. 
 
 195. Among the instruments which depend upon the 
 physical properties of fluids, may be mentioned the fol- 
 lowing : 
 
136 
 
 MEDICAL CHEMISTRY. 
 
 The syphon, Fig. 29, used in decantation, is in its simplest 
 form a bent tube, having one leg longer than the other, the 
 length being calculated from the surface of the liquid. When 
 filled, and the shorter leg immersed, the liquid in the longer leg 
 drops out, and the pressure of the atmosphere forces up that in 
 the vessel to take its place. When both ends are bent upwards 
 (the Wlirtemberg syphon), it may be kept constantly filled, and 
 will act as soon as one is immersed a short distance, as that leg 
 then becomes practically shorter than the other, a b, Fig. 30. 
 
 Fig. 29. Fig. 30. Fig. 31. 
 
 _ The pipette, Fig. 31, in its 
 simplest form is a glass tube, 
 which is filled by dipping it into 
 the liquid or by suction. When 
 the finger, placed on top, closes 
 the tube, the liquid is held up 
 by atmospheric pressure ; on 
 removing the finger, the liquid 
 drops out. They are often made 
 with bulbs, so as to hold a lar- 
 ger quantity of liquid, and some- 
 times graduated. 
 
 The continuous was7i-bottIe,Yig. 
 32, has its cork pierced by two 
 tubes, one running to the bottom. 
 When filled with water and in 
 verted, the liquid will flow out 
 of the tube C D, on to the pre- 
 cipitate in the funnel, until it 
 rises so as to close the lower 
 
CHEMISTRY OF THE ELEMENTS. 
 
 137 
 
 opening of the tube a b. It will then cease until the fall of the 
 liquid in the funnel reopens the tube. 
 
 Safety tubes are much used in distilling. The simplest con- 
 sists of a tube, A B, Fig. 33, reaching to the bottom of the 
 vessel, and sealed at its lower end by the contained liquid. 
 Should the delivery tube become obstructed, the pressure of the 
 accumulated gas or vapour in the retort would force the liquid 
 out of the tube and prevent explosion. On the other hand, 
 should sudden condensation occur, causing a partial vacuum in 
 the flask, air will descend the safety tube, and bubbling through 
 the liquid, prevent the regurgitation of that into which the de- 
 livery tube dips. 
 
 Fig. 34. 
 Fig. 33. 
 
 Welter's Safety tube, Fig. 34, is used where the contents of the 
 retort are solid, or where, for other reasons, the former cannot 
 be used. Its principle is the same. 
 
 The Atomiser 
 is an instrument 
 for diffusing the 
 spray of liquids. 
 A vertical tube, 
 A B, dips into 
 the liquid ; at 
 right angles to 
 its upper end, 
 and close to it, 
 is a second tube, 
 12 * 
 
138 MEDICAL CHEMISTRY. 
 
 CD. When air is blown through the horizontal tube, 
 the liquid rises in the vertical tube, overflows and be- 
 comes mingled with the blast of air. This is because the 
 pressure on the surface of the column of liquid is less 
 when the current of air is passing over the top of the tube 
 than that of the atmosphere when at rest. The latter, 
 pressing on the surface of the liquid in the containing ves- 
 sel, forces it up into the tube, where, coming into contact 
 with the blast, it is converted into mist. This instrument 
 is variously constructed. It is used to perfume or deo- 
 dourise the air of rooms, to apply remedies to the air 
 passages, and to. produce local anaesthesia by cold (67). 
 
 196. Composition of the Atmosphere. — It contains in 
 100 parts by volume, when dry, 79-10 of X, 20*90 of O, 
 with about -0004 of carbonic acid, C0 2 . There are also 
 constantly present moisture, ammonia, NH 3 (probably as 
 carbonate), marsh gas, C 2 H 4 , and organic matter. The pro- 
 portions of the first-named elements are nearly invariable 
 (134). The quantity of ozone (allotropic oxygen, 185) varies. 
 It appears to be greatest in spring and least in winter, 
 to be absent in foul localities and during certain epi- 
 demics, as cholera. Our information on this subject is yet 
 far from reliable. Carbonic acid, owing to its low diffu- 
 sive power (134), sometimes accumulates in undisturbed 
 places, as wells, caverns, etc. The amount of moisture 
 constantly varies ; is on the average one-half of the 
 amount necessary to saturation. Ammonia and marsh 
 gas are present in exceedingly small proportion, the for- 
 mer not exceeding 42 parts in the million. Organic mat- 
 ter is most prevalent near inhabited localities and in close 
 rooms. Other gases and vapours may be accidentally 
 present. 
 
 197. Physical Changes.— The temperature of the at- 
 mosphere diminishes with the height, about 1° for every 
 
 
CHEMISTRY OF THE ELEMENTS. 139 
 
 300 feet, although this is subject to considerable variation 
 The snow line is highest near the equator. The causes 
 of this fall of temperature are the increased capacity for 
 heat of rarer air, and the more rapid radiation and evapo- 
 ration at greater elevations. The capacity of the air for 
 moisture increases in a geometrical ratio, while the tem- 
 perature rises in arithmetical ratio. Hence, cooling the 
 air increases its relative humidity or dampness. When 
 the aqueous vapour arrives at its temperature of maxi- 
 mum tension (58), it is deposited as fog, rain, snow, etc. 
 The temperature at which moisture is deposited on a cold 
 body is termed the dew point, and is lower as the air is 
 drier. Instruments for determining the amount of abso- 
 lute or relative moisture in air are termed hygrometers or 
 psychrometers. 
 
 Air at 32° can absorb T £ „th of its weight of watery vapour, at 
 59° ^th, at 86° T ' ff th, and so on, so that for every 27° above 32° 
 its capacity is doubled. The absolute humidity of air is the 
 amount of moisture it contains ; the relative humidity, or damp- 
 ness, the relation of the former to temperature, or the approach 
 of moisture to condensation. Air when damp conducts better 
 than when dry, and thus produces a sensation of chilliness in 
 cool weather ; it also retards evaporation from the surface of the 
 body, and causes oppression and languor in warmer seasons. 
 
 Winds are currents of air produced by convection (48). 
 They mostly arise from the unequal heating of the earth's 
 surface, owing to changes of season, of day and night, 
 the obliquity of the sun's rays, and the different absorb- 
 ing power and specific heat of the materials of the earth's 
 crust (?2). 
 
 198. Chemical Changes. — Combustion and respiration 
 consume the oxygen, and replace it with an equivalent 
 amount of carbonic acid, C0 2 ; also watery vapour, HO. 
 There is constantly given off from the lungs, skins, and 
 emunctories of animals various excreta, and from decom- 
 posing offal a notable proportion of organic matter. When 
 
140 MEDICAL CHEMISTRY. 
 
 the processes of nature are not restricted, these are rap- 
 idly diffused (134), assimilated, and rendered harmless by 
 the vegetable kingdom (156) and atmospheric ozone. 
 Accumulated, effete, and decomposing organic matter is 
 the most fertile source of disease, and favours the spread 
 of epidemics and contagious disorders. Typhus and 
 cholera are striking examples. 
 
 The prevalence of fevers and the exanthemata during the 
 winter, when dwellings are kept closed, and water less freely 
 used, and their comparative rarity during the summer, can be 
 seen by inspecting the bills of mortality of any large city. We 
 have not any satisfactory and convenient test for the amount of 
 organic impurity in the air. The sense of smell is sufficient, 
 when it is considerable in quantity, to warn us of its presence, 
 and hence the uselessness of mere deodourisers or disguisers of 
 filth. Dr. Angus Smith's air-test consists of a standard solution 
 of permanganate of potassa, KO,Mn 2 7 , through which the air 
 is drawn. The greater its impurity, the less bulk required to 
 remove the pink colour of the permanganate. The ratio of the 
 quantities of air required was, in one series of experiments, as 
 follows : High ground, 30 miles from Manchester, 176 ; open 
 street in the town, 72-76 ; near dirty houses, 44 ; closely-packed 
 railroad-car, 8.* The permanganate solution is decolourised by 
 other reducing agents, as sulphurous acid, S0 2 , and sulphuretted 
 hydrogen, HS. These should be intercepted before drawing the 
 air through the permanganate. 
 
 The microscope detects in the dust of rooms various excre- 
 mentatious matter, as exuviae of animals, portions of clothing, 
 food, and in hospitals epithelial cells and lint charged with 
 organic corpuscles.f If the air of a crowded apartment be 
 passed through water, the solution acquires a disgusting smell, 
 and rapidly putrefies. 
 
 199. Antiseptics, Deodourisers, Disinfectants. — These 
 terms are loosely used and often confounded. Antiseptics 
 are processes or bodies which prevent or retard putre- 
 faction or decay, such as drying and the use of common 
 salt, which act by removing moisture ; various chemical 
 compounds, as creosote, carbolic acid, chloride of zinc, 
 
 * Athenxnm, June 12, 1858, Brande & Taylok, Am. ed., p. 151. 
 ■j" Condy on Air and Water, p. 75. 
 
CHEMISTRY OF THE ELEMENTS. 141 
 
 corrosive sublimate, etc., which coagulate the putrescible 
 matters ; sulphurous acid, and the sulphites, which check 
 fermentation and putrefaction; and act as oxidisers. 
 Deodourisers remove offensive odours, generally by abstract- 
 ing h}'drogen. Fumigations with tar, vinegar, camphor, 
 aromatic weeds and herbs, and the like, only disguise the 
 offensive matter. Disinfectants are supposed to prevent 
 the propagation of disease. The most efficient are a high 
 temperature, say 240°, and thorough cleansing. Anti- 
 septics and deodourisers may act indirectly by preventing 
 fermentation in organic matter, or by chemically destroy- 
 ing it. The malarious miasm is destroyed or suspended 
 at 32°. 
 
 It should be remembered that while offensive odours 
 warn us of the presence of injurious organic matter, they 
 may not themselves be the cause, or aids of the spread 
 of disease. Sulphuretted hydrogen, HS, phosphoretted 
 hydrogen, PH 3 , and ammonia, NH 3 , are, when evolved in 
 the laboratory and largely diluted, nearly innocuous, and 
 when accompanying the complex organic substances 
 resulting from decay, only warn us of their presence. 
 Chlorine and ozone will remove their hydrogen, and thus 
 the smell; but unless they be in considerable quantity, 
 the organic matter may remain. The miasm of cholera, 
 malarious fevers, etc., is imperceptible to the senses. It 
 is probable that, after temperature and cleanliness (includ- 
 ing ventilation), ozone is the best disinfectant. It is 
 given off indirectly during the action of chlorine, and 
 from the permanganates. Sulphurous acid, S0 2 , from 
 burning sulphur, will check fermentation, and is therefore 
 recommended by high authority.* Carbolic acid is more 
 manageable, and perhaps equally efficient, f 
 
 * Graham, Elements of Chemistry, Am. ed., p. 253. 
 
 f Crook KS, Report on the Cattle Plague. Chem, News, No. 339. 
 
142 MEDICAL CHEMISTRY. 
 
 200. Ventilation. — The products of combustion, respi- 
 ration, organic decomposition, etc., being of higher tem- 
 perature than that of the atmosphere, will rise, be diffused, 
 and eventually rendered innoxious. From desire of com- 
 fort in cold climates and seasons, and from inattention to 
 cleanliness, this is often prevented. Habitations are 
 closed, clothing but seldom changed, and personal and 
 other impurities allowed to accumulate. Hence results a 
 large increase of disease and mortality. The problem of 
 supplying a proper quantity of fresh air of a proper tem- 
 perature and moisture to buildings is one difficult of 
 solution. The most simple method of ventilation is to 
 admit fresh air by numerous openings near the floor of the 
 apartment, and allow the heated, foul atmosphere to pass 
 off above. The cooling effect of walls and windows inter- 
 feres seriously with this plan; the foul air in contact with 
 these colder bodies becomes reduced in temperature below 
 that of the room, and falls to be again supplied to the 
 inmates. If the openings of exit be large, the external 
 air will descend and cool the foul air, besides causing un- 
 pleasant draughts. The external air in winter contains 
 so little moisture (196), that on heating it, unless water 
 be artificially supplied, the air of the apartment is rendered 
 injuriously dry. In large buildings artificially heated, the 
 downward system of ventilation in which fresh air is ad- 
 mitted above and the foul air drawn off below by means 
 of forced ventilation, is to be preferred. Forced venti- 
 lation is brought about by injecting fresh air by cowls, 
 fans, etc., (plenum method,) or by aiding its withdrawal 
 by artificial heat in the ventilating shafts, by exhausting 
 cowls, the steam-jet, etc. The limits of this work will not 
 allow of a full discussion of the subject; in each case 
 much must depend upon a knowledge of the laws of heat, 
 and on the part of the adviser, his judgment in their ap- 
 
CHEMISTRY OF THE ELEMENTS. J4$ 
 
 plication. In private houses the open Franklin stove 
 affords an excellent means of ventilation, but care is re- 
 quired to supply pure fresh air in place of that constantly 
 withdrawn, in such a way as not to cause unpleasant or 
 hurtful draughts. 
 
 COMPOUNDS OF NITROGEN WITH OXYGEN. 
 
 201. Nitric Acid, N0 5 =54,H0,NO 5 =63. 
 
 Prep. — The anhydrous acid is obtained by passing 
 dry chlorine over dry nitrate of silver ; it is a white solid, 
 crystallising in the third system and decomposing spon- 
 taneously. The hydrated acid is made by the action of 
 sulphuric acid upon nitrate of potassa (or soda), two 
 equivalents of the former being employed for convenience, 
 
 KO,N0 5 -f 2(HO,S0 3 ) = HO,n4+KO,S0 3 +HO,S0 3 .-> 
 The latter salt, the bisulphate of potassa, remains in the 
 retort. 
 
 Prop. — When pure, a colourless, fuming liquid, S. G. 
 1-522, boiling at 184°, and solid at — 40°. Is highly 
 corrosive. It ordinarily contains hyponitrio acid, N0 4 , 
 which gives to it a reddish colour. The ordinary acid, 
 4HO,N0 5 , has a S. G. of 142, and distils at 250 p . The 
 latter is the officinal acid, and that usually employed in 
 the arts. 
 
 Chem. Bel. — Is a powerful oxydising agent, capable of 
 causing combustion ; it generally yields 3 eq. of O, leaving 
 N0 2 , which passing into the air gives orange-coloured 
 fumes of N0 4 . The monohydrated acid, HO,N0 5 , or a 
 mixture of the commercial acid, 4HO,N0 5 , with an equal 
 bulk of HO,S0 3 , which latter abstracts a portion of water 
 from the former, has a peculiar action on certain organic 
 bodies, as cotton, starch, and glycerine. It removes a 
 
144 MEDICAL CHEMISTRY. 
 
 part of their hydrogen, replacing it with N0 4 , forming 
 explosive compounds. The ordinary or dilute acid con- 
 verts starch and sugar into oxalic acid. These changes 
 will be further considered under Organic Chemistry. 
 
 Nitric acid acts on the metals in three ways: (1) 
 When concentrated, is itself in part decomposed, Cu 3 
 
 + 4(HO,N0 5 )=3(CuO,N0 5 )+N0 2 +4HO.-> (2) When 
 
 -> 
 dilute, the metal takes oxygen from the water, Zn+HO, 
 
 -> t 
 ISr0 5 =ZnO,N0 5 +H. Only the more easily oxydised 
 
 metals are affected in the latter case, and ammonia is 
 
 formed as a secondary product. (3) When the metal does 
 
 not form a basic oxide, as tin or antimony, it raises it to 
 
 its highest oxide (Sn0 2 ,Sb0 5 ), and generally converts 
 
 the lower oxides of the metals into the higher. The 
 
 slightly diluted commercial acid acts more readily on the 
 
 metals than when concentrated. It forms nitrates, all of 
 
 which are soluble and deflagrate with combustibles. Those 
 
 of potassa, KO,N0 5 , sesquioxide of iron, Fe 2 3 ,3N0 5 , 
 
 teroxide of bismuth, Bi0 3 ,3N0 5 , and protoxide of mercury, 
 
 HgO,N0 5 , are omcinal. It may contain sulphuric or 
 
 hydrochloric acids, iron, or, when made from nitrate 
 
 of soda, iodine. It may be purified by distillation over 
 
 nitrate of silver. 
 
 Tests. — (1) It bleaches a boiling solution of sulphate 
 of indigo ; the absence of chlorine or ozone must first be 
 ascertained. (2) Mixed with strong sulphuric acid and a 
 solution of ferrous sulphate, FeO,S0 3 , added, a rose or 
 purple tint results. (3) When free, it will, on the addition 
 of hydrochloric acid, dissolve gold leaf. (4) When acting 
 on copper, etc., orange-coloured fumes are evolved. (5) 
 If converted into nitrate of potassa, the characteristics of 
 that salt will be made evident. 
 
 Therapeutical and other Effects. — In large doses, an 
 irritant poison. Antidotes : alkalies, soap, chalk, magnesia, 
 
CHEMISTRY OF THE ELEMENTS. 145 
 
 etc., mucilaginous and oily drinks and enemeta. Ex- 
 ternally, concentrated, a caustic; stains the skin of a per- 
 manent yellow; when diluted, stimulant and astringent. 
 Internally, diluted, is tonic, astringent, and is supposed to 
 promote the secretion of bile. Is largely employed in the 
 arts in the preparation of various metallic compounds, 
 analysis, etc. 
 
 Incompatibles. — All the nitrates being soluble, the acid 
 is not liable to form precipitates. Hence it only acts 
 when free to decompose the weaker salts, as acetates and 
 carbonates, and will neutralise the basic oxides generally, 
 (potassa, magnesia, oxide of zinc, etc.) 
 . Officinal Forms. (1) Acidum Nitricum, s. g. 142,4HO, 
 N0 5 . (2) Acidum nitricum dilutum, R Acid : Nitric ^iii, 
 Aquae destillatse q. s. ad Oj. s. g. T068. Dose, gtt xx to 
 xlt.d. 
 
 202. Hypunitric Acid (Nitrous Acid), N0 4 =46. 
 Prep. — By mixing two volumes of N0 2 and one of O 
 
 in an exhausted glass vessel, or by the distillation of dry 
 
 nitrate of lead, PbO,N0 5 =N0 4 +PbO+0. Is formed 
 when N0 2 escapes into the air. 
 
 Prop. — At 0°, a colourless liquid; at — 40°, solid; at 
 ordinary temperatures, a ruddy vapour; S. Gr. 1591, pos- 
 sessing powerful oxydising properties. Supports combus- 
 tion, but imperfectly ; has a suffocating odour. The liquid 
 possesses no acid properties and does not directly combine 
 with bases, but indirectly forms a lead salt, and compounds 
 with certain organic bodies. 
 
 203. Nitrons Acid, N0 3 =38. 
 
 May be formed by passing through a tube cooled 
 to 0, a mixture of 4 volumes of N0 2 and one of O. It is 
 a greenish liquid, readily decomposed ; it does not combine 
 directly with bases, but indirectly forms nitrites, which 
 are soluble in alcohol. 
 13 
 
146 MEDICAL CHEMISTRY. 
 
 Nitric Oxide, NO 2 =30, is formed during the deoxidatiou 
 of nitric aeid (201). It is a permanently elastic, colour- 
 less, irrespirable gas, s. g. 1038, sparingly soluble in 
 water, supporting the combustion of phosphorus, but not 
 of most ordinary combustible^; it has a strong affinity 
 for 0, with which it unites to form NO*. Is neutral. 
 
 204. Nitrous Oxide, (Laughing Gas,) NO=22, 
 Prep. — By heating gently nitrate of ammonia, 
 
 NH 4 0,N0 5 =2NO-f 4H(X The gas should be allowed to 
 stand over water until transparent. 
 
 Prop. — A colourless, inodourous, transparent gas, of a 
 sweetish taste ; S. G. 1525 ; water dissolves its own volume. 
 Is liquefied by a pressure of 50 atmospheres at 60°. 
 Supports combustion nearly as well as O ; is distinguished 
 from the latter by its sweetish taste and greater solubility. 
 Is neutral. 
 
 Physiological Effects. — Causes, when inhaled in moder- 
 ate quantity, exhilaration, hence the name laughing-gas; 
 in larger quantity, is anaesthetic. 
 
 205. Ammonia, NH 3 , or NH 4 0, will be considered under 
 the metals. 
 
 CARBON, 0=6. 
 
 206. Natural Sources. — Native as the diamond, graphite, 
 and impure, as coal ; combined in atmospheric carbonic acid, 
 marsh gas, and in the native carbonates. Is the essential 
 constituent of organic matter. 
 
 Properties. — Yary with the form. (1) Diamond, the 
 hardest known body, crystallises in the first system ; s. g. 
 3.5 ; a good conductor of heat but not of electricity. (2) 
 Graphite, plumbago or black lead, soft, crystallises in the 
 6th system; s. g. 1-8 to 21; conducts electricity and has a 
 metallic lustre. (3) Graphine, or plumbagine, the deposit 
 in coal-gas retorts ; hard and difficult to work ; mammillated 
 
 
CHEMISTRY OF THE ELEMENTS. 14T 
 
 structure; somewhat metallic lustre; s. g. 1*76; a good con- 
 ductor of electricity, (used in Bunsen cells.) (4) Charcoal, 
 an amorphous body, the properties of which vary with the 
 source, (a) Wood charcoal, Carbo ligni, U. S. P., is best 
 obtained from the shoots of the willow, previously dried 
 and distilled at a moderate heat. Is a shining, black, 
 hygroscopic powder, without taste or smell; has from its 
 extent of surface great powers of absorbing and condensing 
 gases, thus promoting their combination ; hence its power 
 as a deodouriser. 
 
 Dr. Stenhouse has shown that small animals imbedded in 
 powdered charcoal rapidly decay without offensive odours being 
 evident. The offensive matters from sewers are easily intercepted 
 and consumed by dry charcoal filters. Charcoal poultices absorb 
 and render inoffensive purulent discharges. This action is due 
 to the condensation of the oxygen of the air in the pores of the 
 charcoal at the same time with that of the efiluviae. By boiling 
 charcoal with ^-th of its weight of bichloride of platinum, PtCl 2 , 
 its power of condensation is much increased. Wood thoroughly 
 dried yields 25 per cent, of charcoal ; green wood much less, its 
 carbon passing off as tar, acetic acid, and wood spirit. 
 
 (b) Animal Charcoal. — Obtained by charring bones, 
 Carbo animalis, the best by charring blood with pearlash. 
 It is more dense than the last variety, and possesses re- 
 markable powers of absorbing vegetable colouring and 
 bitter principles. By digesting Carbo animalis with muri- 
 atic acid, IT. S. P., each ^xii previously diluted with ^xii 
 of water for two days and then washing the residue, the 
 phosphate of lime of the bones is removed and the Carbo 
 animalis purificatus, IT. S. P., is obtained. 
 
 Animal charcoal will remove the colour from most organio 
 solutions. It also absorbs all vegetable bitters except picric acid ; 
 but yields most of them again to boiling alcohol. It is an anti- 
 dote to all vegetable and animal poisons, but requires to be given 
 in large quantity and care taken that excess of acid is not 
 present. 
 
 (c) Lampblack is the soot of combustibles containing 
 10* 
 
148 MEDICAL CHEMISTRY. 
 
 an excess of carbon; is usually made from coal-tar. It 
 has less lustre than the other varieties of charcoal, is much 
 less dense, and has but little antiseptic or decolourising 
 power. 
 
 (d) Coal is fossil wood ; peat and lignite are transition 
 forms. Coke is carbon obtained by driving off the volatile 
 matters from bituminous coal, as in gas-making. 
 
 207. General Properties of Carbon. — It is dimorphous, 
 insoluble in all menstrua, fused and volatilised only in the 
 voltaic arc ; is not affected by chemical agents as ordinary 
 temperatures. (Animal charcoal in chlorine water is 
 slowly consumed by the nascent oxygen.) Its combusti- 
 bility varies with the variety; wood charred at a moder- 
 ate temperature sometimes ignites spontaneously, while 
 graphite and the diamond are difficult to burn. 
 
 Gen. Ghem. Relations. — At high temperatures it is the 
 most powerful of reducing agents, owing to its affinity for 
 O. It forms with the metals carbides, as cast-iron, and 
 unites, as a general rule indirectly, with other elements. 
 It forms with Carbonic Acid, C0 2 , Carbonic oxide, CO, 
 Oxalic acid, HO,C 2 3 , and croconic, metallic, and rhodizonic 
 acids. Its compounds with H are considered under Or- 
 ganic Chemistry, except those named below. With N it 
 forms the important quasi element Cyanogen, C 2 N. 
 
 CARBON AND OXYGEN. 
 
 208. Carbonic Acid, {fixed air, choke damp,) C0 2 =22. 
 Natural Sources. — The atmosphere, the native carbon- 
 ates. Is formed during respiration and combustion. 
 
 Prep. — On the large scale, by adding Sulphuric acid, 
 HO ; S0 3 , to powdered chalk or marble, CaO,C0 2 +HO,S0 3 
 
 = CaO,S0 3 -f H04-C0 2 . In the laboratory, by replacing 
 
 the sulphuric by muriatic acid, which leaves no insoluble 
 
 residue. CaO,C0 2 -f HCl=CaCl-f HO-f-C0 2 . It maybe 
 
 collected by displacement (183). 
 
CHEMISTRY OP THE ELEMENTS. 149 
 
 Prop. — A colourless, inodourous, transparent gas, s. g. 
 1529, liquid under 28 atmospheres at 32°, and solid at — 12°; 
 is incombustible, extinguishes flame, does not support life, 
 but is not poisonous when diluted. It constitutes the after 
 or choke damp of the miner, and frequently accumulates in 
 old wells and in depressed spots in volcanic districts (Upas 
 Valley). Water dissolves its own volume, and when 
 charged under pressure of 5 atmospheres acquires a pun- 
 gent taste, reddens litmus and forms an agreeable drink 
 useful in erethism of the stomach — Aqua acidi carbonict, 
 Mineral water. Fermented drinks owe their sparkling 
 and pungent qualities to this gas. It is also the agent in 
 the raising of bread. 
 
 General Chemical Relations. — It reddens litmus and 
 combines with bases to form the carbonates, most of 
 which are insoluble ; those of potassa, soda, lithia, lime, 
 magnesia, iron, lead, and zinc are officinal. Owing to its 
 volatile character, it is readily displaced, being driven out 
 of combination by all acids except the Hydrocyanic, HCy. 
 Under favourable circumstances it shows great power as 
 an acid, decomposing rocks and playing an important 
 part in the economy of nature. The carbonates and 
 bicarbonates of the alkalies have an alkaline reaction. 
 A carbonate is known by its effervescing when treated 
 with hydrochloric acid, the gas evolved being inodourous. 
 Medical Effects. — Has been applied locally as a seda- 
 tive ; swallowed in solution, it forms a grateful drink in 
 fevers, and allays thirst and checks vomiting. Inhaled, 
 it rapidly causes insensibility, the treatment being expo- 
 sure to the fresh air, dashing with cold water, frictions, 
 and in extreme cases artificial respiration. Its presence 
 in wells is made evident by lowering a candle into the 
 suspected locality ; the presence of an irrespirable gas will 
 extinguish it. It may be removed by causing draughts 
 13 * 
 
150 MEDICAL CHEMISTRY. 
 
 of air, by burning straw, or by throwing down water, or 
 better, mixed lime and water. Recent experiments seem 
 to show that when inhaled largely diluted, it is innoxious, 
 an air containing twenty-five per cent, having been sup- 
 plied to a bird without injuring it.* 
 
 209. Carbonic Oxide, CO =14. 
 
 Preparation. — Is formed when C is burned with 
 an insufficient supply of 0, the C0 2 formed at first being 
 deoxidised by incandescent carbon above. It is best made 
 by pouring an excess of HO,S0 3 on powdered Ferrocy- 
 
 ANIDE OF POTASSIUM, K 2 Cv 3 Fe.-|- 
 
 Properties. — A transparent, colourless, inodourous, 
 permanently elastic gas, burning with a feeble blue flame, 
 producing C0 2 ; S. Gr. 968; water absorbs 2*5 per cent. It 
 is a narcotic poison. It frequently escapes from stoves , 
 the treatment, that indicated under C0 2 . It is chemically 
 neutral and unimportant. 
 
 210. Oxalic Acid, HO,C 2 3 +2HO=63. 
 Preparation. — By the action of nitric acid upon starch 
 
 or cane sugar, or of alkalies upon sawdust, f It exists in 
 combination in certain plants (Oxalis, Eumex, Rheum). 
 
 Properties. — Long, four-sided, oblique prisms, (third 
 system ;) of an acid taste and reaction ; is soluble in eight 
 parts of water at 60° and its weight of boiling water. Is 
 used for taking out ink-spots and iron-moulds ; resembles 
 in appearance Epsom salt, and is sometimes swallowed 
 by mistake. It is an irritant poison; the antidote is 
 chalk or whitewash. The 2 eq. of water of crystallisation 
 may be removed without its decomposition, but it cannot 
 exist except in combination with its constituent water 
 (190) or a base. It forms salts containing one, two, or 
 four equivalents of acid. 
 
 * Hammond, Hygiene, p. 153. 
 
 f The reactions involved are omitted, being complex and comparatively 
 unimportant. 
 
CHEMISTRY OP THE ELEMENTS. 151 
 
 Test — With a lime salt, or lime-water, gives a white pre- 
 cipitate; with nitrate of silver, also a white precipitate 
 which explodes slightly when dried and heated. Many 
 of the oxalates become carbonates when heated to redness. 
 
 211. HYDRO-CARBONS. — The compounds of C and 
 
 H are exceedingly numerous ; the following are generally 
 
 considered under the head of Inorganic Chemistry. (1) 
 
 Light carburetted hydrogen, C 2 H 4 , marsh gas, fire damp, 
 
 a constant product of decomposing vegetable matter, and 
 
 obtained artificially by the dry distillation of the acetates. 
 
 It is always present in the atmosphere. It is a colourless, 
 
 transparent, inodourous, inflammable, permanently elastic 
 
 gas, not very poisonous; Si g. 522. Water dissolves 0*039 
 
 per cent. (2) Olefiant gas, Ethylene, C 4 ,H 4 , obtained by 
 
 the action of HO,S0 3 upon alcohol, resembles the former, 
 
 but is liquefied by cold and pressure ; has a faint ethereal 
 
 odour, and is a narcotic poison; has a s. g. 96?, and 
 
 burns with a brilliant white flame. Water dissolves 0*161 
 
 per cent. Coal gas is a mixture of the above with the 
 
 vapours of other hydrocarbons. 
 
 In making illuminating gas, the coal is distilled in iron or 
 clay retorts; the tar and ammonia which accompany the gas are 
 condensed and absorbed in the hydraulic main, jet washers, and 
 condensers ; the cyanogen, C 2 N, carbonic acid, and sulphur com- 
 pounds are removed by lime or moist oxide of iron. Wood, resin, 
 wax, oil, etc., yield illuminating gas when distilled. 
 
 212. Nature and Structure of Flame. — By flame is 
 understood volatile matter burning ; pure flame gives but 
 a feeble light. Solid matter, heated until it becomes 
 luminous, is said to be incandescent, and if not easily 
 oxidised, as platinum, it may remain so for an indefinite 
 period without chemical change. Ordinary flame is 
 hollow because the jet or column of volatile matter can 
 only come in contact with the O of the air on its outer 
 surface. A solid flame is produced by introducing into 
 
152 MEDICAL CHEMISTRY. 
 
 the centre of the burning gas. In a luminous flame, three 
 cones may be distinguished. (1) An inner blue or dark 
 one which consists of gases derived, in the case of an 
 ordinary lamp or candle, from the destructive distillation 
 of the oily matter (cone of generation). (2) A luminous 
 cone (cone of decomposition). In this the compounds of 
 C and H receive a limited supply of 0, which having a 
 greater affinity for the H, unites with it ; the carbon thus 
 precipitated in the solid form, is rendered incandescent by 
 the intense heat generated by the combination of the O 
 and H, making the flame luminous. (3) An outer cone 
 (cone of complete combustion) of a feeble yellow col- 
 our, in which the C, meeting with an abundant supply 
 of 0, is burned up. In the middle flame we have a high 
 temperature, deficient supply of O, and abundance of the 
 reducing agents C and H. Hence, many metallic oxides 
 placed in it are deoxidised (reducing flame). At the 
 extremity of the outer flame we have also a high tempera- 
 ture, but an abundance of O, and the reverse effect takes 
 place (oxydising flame). When urged by a jet of air — 
 the blowpipe — the flame is elongated and the intensity of 
 the heat increased. When the gas is mixed with air or 
 O before ignition, no decomposition takes place, no solid 
 matter is deposited, and the flame is blue and feebly 
 luminous. The introduction of a fixed solid body, as lime 
 in the compound blowpipe flame, at once produces a bright 
 light by incandescence. A mixture of air or O with an 
 inflammable gas or vapour is liable to explode, owing to 
 the sudden combination of the whole. The contact of a 
 cold, conducting body may reduce the temperature of the 
 gases below the point of ignitiGn. Hence an explosive 
 mixture may be safely burned at the end of a long, fine, 
 metallic tube. Wire gauze, which may be considered as a 
 number of short tubes of small diameter, acts in this way 
 
CHEMISTRY OP THE ELEMENTS. 153 
 
 and a lamp surrounded by it may be safely carried into an 
 atmosphere containing an inflammable gaseous mixture — 
 the safety lamp. A jet of mixed gases issuing under press- 
 ure is less likely to allow the flame to travel backwards, 
 as the gases move forward rapidly to supply the combus- 
 tion. When a cold body is introduced into an ordinary 
 flame, the carbon, instead of being burned in the third 
 cone, is deposited ; hence, for heating purposes, gas should 
 be previously mixed with air, so as to burn without de- 
 composition. 
 
 213. Carbon and Nitrogen. Cyanogen, C 2 N, resembles 
 in its chemical relations the Halogens (223), and will be 
 considered hereafter (235). 
 
 SULPHUR, S=16 
 
 214. Natural Sources. — Occurs native in volcanic dis- 
 tricts. Exists in combination in the native sulphides, as 
 iron (FeS 2 ) and copper pyrites, CuS,Fe 2 S 3 ; galena, PbS, 
 cinnabar, HgS, the native sulphates, as gypsum, CaO,S0 3 
 -f 2HO, and heavy spar, BaO,S0 3 '; in organic bodies, in 
 the hair, nails, and horns, the protein bodies, and certain 
 volatile oils. 
 
 Preparation. — Is obtained by sublimation from its earthy 
 impurities. When the vapour is collected in a cooled 
 vessel, fine crystals are deposited, — Flowers of sulphur, 
 Sulphur sublimatum, U. S. P. If the vapour is con- 
 densed into the liquid state, and cast into moulds, it forms 
 roll sulphur, or brimstone. It is obtained less pure from 
 pyrites, and the milk of sulphur, Lac sulphuris, Sulphur 
 pr^ecipitatum, U. S. P., is procured by chemical precipi- 
 tation. 
 
 Properties. — In its ordinary form is a lemon-yellow, 
 volatile, inflammable, solid ; brittle, tasteless, of a peculiar 
 
154 MEDICAL CHEMISTRY. 
 
 odour when rubbed. Is a non-conductor of heat and 
 electricity, and gives negative electricity when rubbed. 
 It is dimorphous, crystallising from solution in right 
 rhombic octohedra (3d system), s. g. 2*05, and from 
 fusion in oblique rhombic prisms (4th system), s. g. 1*97. 
 It is insoluble in water, almost so in alcohol ; is soluble 
 in bisulphide of carbon, CS 2 , benzine, C^He, and di- 
 chloride of sulphur, S 2 C1. Also in alkaline solutions, but 
 with some chemical change. It melts at 234°, forming a 
 limpid amber-coloured liquid ; as the temperature rises, this 
 becomes darker and more viscid; at about 480° is so 
 tenacious as to be poured with difficulty ; from 500° to its 
 boiling-point, 788°, becomes thinner, and if allowed to 
 cool, passes through the same conditions. Its vapour is 
 of an orange colour, s. g. 6636. In the state of vapour 
 it combines with finely divided metals, with evolution of 
 light and heat. 
 
 Allotropic Modifications. — By the sudden cooling of 
 sulphur heated to about 500°, a dark, plastic, amber- 
 coloured mass is obtained, which gradually assumes the 
 form of ordinary sulphur ; it is in great part insoluble in 
 CS 2 . Black sulphur is obtained by repeating frequently 
 the same process ; it probably always contains foreign 
 matter. 
 
 Four allotropic modifications of sulphur are now admitted: 
 1. Common or prismatic sulphur, soluble in CS 2 ; 2. Octohedral 
 sulphur, partially soluble in CS 2 ; 3. Crummy sulphur, ex- 
 tracted by CS 2 , but afterwards insoluble in it; 4. Insoluble 
 sulphur, insoluble in CS 2 , and forming the bulk of the soft 
 sulphur prepared as above stated. 
 
 General Chemical Relations. — Is an electro-negative 
 body, closely resembling oxygen, forming sulphur bases 
 and acids and neutral sulphides; also compounds with 
 hydrogen resembling HO and H0 2 . It combines with 
 oxygen to form seven compounds, only three of which 
 
 
CHEMISTRY OP THE ELEMENTS. 155 
 
 will be considered, namely, Sulphuric acid, S0 3 , Sul- 
 phurous acid, S0 2 , and Hyposulphurous acid, S 2 2 . 
 
 Medical Effects. — Is innoxious; is given internally in 
 skin diseases, gout, and rheumatism ; externally is used 
 in vapour or ointment in the same. Dose, sj to ^iij. Is 
 used in the arts for the manufacture of sulphuric acid, and 
 from its ready inflammability in that of matches and gun- 
 powder. 
 
 Officinal Forms. — 1. Sulphur sublimatum — Com- 
 mercial flowers of sulphur. 2. Sulphur lotum, Washed 
 sulphur, hot water being used to remove traces of acid 
 from the former. 3. Sulphur pr-sbcipitatum, Lao sul- 
 phuris, Milk of sulphur. Is made by boiling together 
 for two hours ifxii of sublimed sulphur with ^xviii 
 of lime previously slaked, and Oxv of water, adding 
 enough of the latter to compensate for evaporation. 
 Bisulphide of calcium and hyposulphite of lime are 
 formed (3CaO+S 6 =2CaS 2 -H-CaO,S 2 2 ->). The solution 
 is diluted with an equal bulk of water, and decomposed 
 by muriatic acid, added gradually so long as a precipitate 
 falls (2CaS 2 + CaO,S 2 2 + 3HCl = 3CaCl->+3HO+S 6 ). 
 
 The chloride of calcium is removed by washing. It is a 
 milky white powder, having a peculiar odour. Is more 
 easily suspended in water than the other officinal forms, 
 hence used in the preparation of hair-washes. All the 
 forms of sulphur should be entirely volatilised by heat, 
 and the two last-named devoid of acid reaction. The 
 Unguentum sulphuris, U. S. P., contains one part of S to 
 two of lard. 
 
 SULPHUR AND OXYGEK 
 215. Sulphuric Acid, SO 3 =40— HO,S0 3 =49. 
 Prep. — (1) Anhydrous, is obtained by distilling the 
 Nordhausen acid ; is in white, silky prisms, melting at 65°, 
 boiling at 110° ; attracts water greedily. (2) Nordhausen 
 
156 MEDICAL CHEMISTRY. 
 
 or fuming oil of vitriol, HO,2S0 3 , is made by distilling 
 dried green vitriol (4(FeO,S0 3 +HO)==2Fe 2 3 +2S0 2 -f 
 HO,2S0 3 -f3HO). Is a dark, fuming, corrosive liquid, s g. 
 1-9; hissing when dropped into water; is too impure for 
 internal administration. 
 
 3. Sulphuric acid, oil of vitriol, Actbum sulphuricum, 
 U. S. P. Into a leaden chamber are introduced sulphurous 
 acid, S0 2 , obtained by burning S, nitric acid, and steam ; 
 or the floor of the chamber is covered with a stratum of 
 water. When the water becomes sufficiently charged with 
 acid, it is drawn off, concentrated in leaden pans, and 
 afterwards in a platinum still. The following reaction is 
 approximate: (1) S0 2 + HO,N0 5 = S0 3 + HO+M) 4 ; (2) 
 2S0 2 +N0 4 = 2S0 3 +N0 2 ; (3) N0 2 +0 2 =:N T 4 , and so con- 
 tinuously, the N0 2 receiving 2 from the air of the cham- 
 ber to form N0 4 , which again parts with it to the S0 2 , 
 becoming reduced to N0 2 . Commercial oil of vitriol, HO, 
 S0 3 , is a heavy, corrosive oily liquid, s. g. 1-845. It is the 
 most powerful of the acids, chars and destroys organic 
 matter. Attracts moisture ; hence is used as a desiccating 
 agent, and must be kept in tight glass-stopped bottles. 
 When mixed with excess of water, the elevation of tem- 
 perature is enough to boil the latter. 
 
 A straw or small bit of stick will render a whole carboy of acid 
 black ; the carbon is merely diffused, and may be separated by 
 filtration through gun-cotton. By mixing 2 vols, of HO,S0 3 and 
 1 of HO, and allowing the mixture to cool, a terhydrate, 3HO,S0 3 , 
 is obtained, which will convert paper into a parchment-like body, 
 contracting it in all its dimensions, and increasing its strength 
 sixfold. 
 
 Medical Effects. — Concentrated or in large doses, an 
 irritant poison ; antidote : magnesia or other neutralising 
 bodies, given in milk; water is inadmissible on account 
 of the heat developed by its admixture. Externally a 
 caustic ; internally, diluted, tonic, astringent and refrige- 
 rant. It is incompatible, when free, with all alkalies and 
 
CHEMISTRY OF THE ELEMENTS. 157 
 
 alkaline earths, and the salts of the weaker acids ; when 
 combined, with the soluble salts of baryta, strontia, and 
 lead. 
 
 Officinal Forms. — Acidtjm sulphuricum; S. Gr. 1-843. 
 Should be entirely volatilised by strong heat, and when 
 diluted with distilled water should not be coloured by 
 
 SULPHYDRIC ACID, HS (21 f). AdDUM SULPHURICUM 
 
 dilutum, S. G. 1-082, contains gij to the Oj. Acidum 
 sulphuricum aromaticum — Elixir of vitriol, is made by 
 preparing a pint of tincture of ginger gj, cinnamon ^iss, 
 both coarsely powdered, with alcohol, q. s., and adding to 
 this a cooled mixture of ^vj of acid, sulphuric, and Oj 
 
 ALCOHOL. 
 
 General Chemical Relations. — Forms an extensive series 
 of well-marked salts, — the sulphates. Those of Potassa 
 KO, Soda NaO, Magnesia MgO, Ferrous and ferric oxides 
 FeO,Fe 2 3 , Oxide of manganese MnO, Zinc ZnO, Copper 
 CuO, and Mercury HgO, are officinal. It acts on the 
 metals in two ways. (1) When the metal is not easily 
 oxidised, and the acid is concentrated, one equivalent of 
 acid is decomposed, furnishing oxygen to the metal ; with 
 the oxide thus formed a second equivalent combines — 
 Cu + 2(HO,S0 3 ) = CuO,S0 3 + S0 2 . (2) When dilute, the 
 metal, if easily oxidised, decomposes the water present — 
 Zn-fHO,S0 3 =ZnO,S0 3 + H. The test for sulphuric acid 
 is a soluble salt of baryta, which gives a dense, white pre- 
 cipitate, insoluble in boiling HO,N0 5 . 
 
 216. Sulphurous Acid, S0 2 =32. 
 
 Prep. — Is formed when sulphur is burned. Is made 
 by reducing HO,S0 3 . 
 
 HO,S0 3 may be reduced by copper, mercury, etc. A cheaper 
 plan is to use \, by weight, of solid sulphur ; 2(HO,S0 3 )+S=2SO a 
 -J-2HO. Powdered charcoal will answer, but the gas is contami- 
 nated by C0 2 — 2(HO,S0 3 )4-C=2S0 3 -f C0 2 +2HO. 
 14 
 
158 MEDICAL CHEMISTRY. 
 
 Prop. — A colourless gas of a suffocating odour, acid 
 taste and reaction s. g. 2211 ; it extinguishes flame and is 
 poisonous; it bleaches, and by its affinity for oxygen 
 arrests fermentation and putrefaction; below 14° is a colour- 
 less, limpid liquid, and at — 105° solid. Water dissolves 50 
 vols., and acquires the odour and bleaching properties of 
 the gas. A crystalline hydrate is formed at low tempera- 
 ture. Colours removed by S0 2 may be restored by an 
 alkali. 
 
 Medical Effects. — Is used internally in solution, and as 
 the sulphites, in zymotic diseases and blood poisoning; 
 also externally in skin diseases. 
 
 Officinal Form. — Acidum stjlphurosum. Is made by 
 passing the gas evolved by the action of powdered char- 
 coal upon HO,S0 3 through distilled water kept cool, nearly 
 to saturation, s. g. about 1-035. It should be kept cool, 
 and is liable to absorb and become partially converted 
 into HO,S0 3 . Dose for internal use, f^j, largely diluted. 
 
 General Chemical Relations. — Forms sulphites, of 
 which those of the alkalies are powerful antizymotic and 
 reducing agents. That of soda is officinal. Hyposulphu- 
 rous acid, S 2 2 =48, is not isolable. The hyposulphite 
 of soda, made by digesting sulphur with sulphite of soda, 
 is used to dissolve the salts of silver in photography and 
 electro-plating. It has been used for the same purposes 
 as the sulphite. 
 
 SULPHUR AND HYDROGEN. 
 
 21 1. Sulphuretted Hydrogen — Eydrosulphuric or sul- 
 phydric acid, HS=1T. 
 
 Prep. — Is formed by the union of its elements when in 
 the nascent state (143); they do not combine when free. 
 It is found in native sulphur waters, resulting from the 
 decomposition of iron pyrites, FeS 2 , and in sewers and 
 other foul localities, where organic matter containing sul- 
 
CHEMISTRY OP THE ELEMENTS. 159 
 
 phur is decomposing. Under the latter circumstances it 
 is generally combined with ammonia, and accompanied by 
 other volatile products of putrefaction. It is made by the 
 action of dilute HO,S0 3 upon sulphide of iron. FeS-f 
 HO,S0 3 =FeO,S0 3 _^+HS t , or when required pure by the 
 reaction of HC1 on SbS 3 . SbS 8 +3HCl=SbCl S H.+ 3HS.i l 
 
 Prop. — A colourless, inflammable gas, of a character- 
 istic odour and acid reaction; s. g. 1T4T ; is liquefied by 
 a pressure of IT atmospheres at 60°, and is a white solid at 
 — 122°. Water absorbs 3 volumes, the solution slowly 
 decomposes, sulphur being deposited. It does not sup- 
 port combustion, and is a narcotic poison. 
 
 Medical Effects. — Concentrated, is rapidly fatal; diluted, 
 causes headache, nausea, and prostration. Is instantly 
 decomposed by chlorine or ozone, which latter may be 
 evolved from a solution of permanganate of potassa. 
 Taken internally in the form of native sulphur water, is 
 popular in the treatment of chronic rheumatism, gout, and 
 skin diseases. 
 
 Chemical Relations. — Is a sulphur acid, combining 
 with sulphur bases to form salts, as KS,HS; NH 4 S,HS. 
 It precipitates many of the metals from their solutions, 
 and is one of our most valuable tests. HS 2 is unimportant. 
 
 SULPHUR AND CARBOK 
 
 218. Bisulphide of Carbon (sulpho-carbonic acid), CS 2 , 
 made by passing the vapour of sulphur over red-hot carbon, 
 is a volatile, mobile, inflammable liquid, of high refractive 
 power, insoluble in water, s. g. 1-2*12. It is used in the 
 construction of prisms, and in vulcanising india-rubber. 
 It freely dissolves fatty matters, and ordinary sulphur and 
 phosphorus. Workmen exposed to its vapours are affected 
 with headache, vertigo, hyperesthesia, and eventually be- 
 come cachectic, with dimness of sight and hearing, impair- 
 ment of memory, and loss of sexual power. It has been 
 
160 MEDICAL CHEMISTRY. 
 
 used in skin diseases, rheumatism, and enlarged glands. 
 It is a sulphur acid. A protosulphide and sesquisulphide 
 are known. 
 
 PHOSPHORUS, P=31. 
 
 219. Natural Sources. — Organic substances; the na- 
 tive phosphates. 
 
 Prep. — On the large scale from bones, in which it 
 exists as. phosphate of lime, 3CaO,P0 5 , which are: 1. Cal- 
 cined, to remove animal matter; 2. Digested with HO,S0 3 , 
 which combines with most of the lime, liberating the 
 greater part of the phosphoric acid, P0 5 . This is heated 
 in a close iron retort with charcoal, which combines with 
 the O of the phosphoric acid, forming CO, leaving the 
 phosphorus to distil over.* 
 
 Prop. — A soft, translucent solid, of a waxy appear- 
 ance ; is tasteless ; has an alliaceous odour. When per- 
 fectly pure, is colourless ; ordinarily has a reddish tint, 
 which increases with exposure to light ; specific gravity, 
 1-83. It melts at 111-5°, boils at 550°, giving a colour- 
 less vapour. May be distilled unchanged. Emits fumes 
 in the air, (chiefly phosphorous acid, P0 3 ,) which in the 
 dark are luminous ; this slow combustion is accompanied 
 by the formation of ozone, and may be prevented by the 
 presence of certain vapours, as ether, turpentine, and 
 naphtha. Yery inflammable, taking fire at 114° ; burns 
 with the evolution of copious white fumes of phosphoric 
 acid (P0 5 ). It is insoluble in water and alcohol ; soluble 
 in the fixed and volatile oils, in ether, glycerine, and bisul- 
 phide of carbon. 
 
 Allotropic Modification. — By exposing phosphorus for 
 a long time to light, or for a shorter time to a tempera- 
 
 * The true process and theory are a little more complicated, owing to 
 the existence of superphosphate of lime. The ahove gives the essential 
 steps of the process and changes. 
 
CHEMISTRY OF THE ELEMENTS. 161 
 
 ture between 464°-482°, it assumes a red colour, thickens, 
 and; becomes opaque. This amorphous phosphorus is un- 
 altered in the air, not poisonous ; specific gravity 214 ; 
 insoluble in all menstrua ; melts and takes fire at 500°. 
 Heated to the boiling-point, in an indifferent gas, becomes 
 again common phosphorus. Three other varieties of phos- 
 phorus have been described: the white, the black, and the 
 viscous. According to Hittorf,* phosphorus may be ob- 
 tained in rhombohedral (6th system) metallic-looking 
 crystals, resembling arsenic, and conducting heat and elec- 
 tricity ; s. g. 2'34. 
 
 Medical Effects. — In large dose, an irritant poison of 
 great energy. No direct antidote is known. Evacuate 
 the stomach ; give large draughts of cold water contain- 
 ing magnesia in suspension, or one part magnesia and eight 
 of chlorine water. — (Duflos.) 
 
 Workmen exposed to its vapours are liable to necrosis, 
 particularly of the lower jaw-bone. In medicinal doses, 
 stimulant, diuretic, and aphrodisiac. Is given in solution 
 in oil or glycerine ; dose, ^ to -^ E of a grain. Is ofiicinal 
 in the U. S. P. 
 
 Tests. — P may be recognised by its odour and luminous 
 appearance in the dark. When very small portions are 
 present, they may be taken up by digestion with CS 2 , 
 which, on evaporation, will leave the phosphorus finely 
 divided and luminous. A mere trace of P communicates 
 a green colour to the flame of burning H, and gives a 
 characteristic series of green lines in the spectroscope.")* 
 
 Ghem. Relations. — Forms a natural group with N,As and 
 Sb. It combines with seme of the metals, as iron, and is 
 not removed by the highest heat of the furnace. With 
 oxygen it forms P 2 0, oxyde of P; PO, hypophosphorous 
 
 * Chemical News, March 23, 1866. 
 
 f Woehlkr, D us art, Ciiristophle, etc. Chan. News, June 6, 1S63. 
 14* 
 
162 MEDICAL CHEMISTRY. 
 
 acid ; P0 3 , phosphorous acid ; and P0 5 , Phosphoric acid. 
 With H, solid P 2 H, liquid PH 2 , and gaseous PH 3 , phos- 
 phides of H. With jN" and S, unimportant compounds ; 
 the latter are five in number, four corresponding to the O 
 compounds, and one PS 12 unique ; they are highly in- 
 flammable. 
 
 220. Phosphoric Acid, P0 5 =71. 
 
 Prep. — Is formed anhydrous when P is burned in 
 dry air or 0. Is then an amorphous white powder, deli- 
 quescent and hissing on the contact of water, becoming 
 hydrated. The terhydrate, 3HO,P0 5 , is made by the 
 action of diluted HO,X0 5 on P. It is very sour, not cor- 
 rosive, does not act on copper or silver, and is not poi- 
 sonous. 
 
 Ghem. Relations. — Phosphoric acid possesses the remark- 
 able property of uniting with either one, two, or three 
 equivalents of water or a base, giving rise to three classes 
 of salts of different physical and chemical properties, 
 which however are mutually convertible. The monobasic 
 acid, HO,P0 5 , gives rise to the metaphosphates ; 2HO,P0 5 
 to the bibasic, ^rophosphates ; 3HO,P0 5 to the tribasic 
 or common phosphates. Three additional varieties have 
 been described. 
 
 The series of phosphates of soda, so ably investigated by 
 Graham,* show in a remarkable manner the peculiar flexibility 
 of this. acid. Thus we have the following list: 
 
 Monobasic, NaO,P0 5 , Metaphosphate of soda. 
 
 -p., . f NaO,HO,P0 5 , Bipyrophosphate. 
 
 Bibasic, { 2Na0 ,P0 5 , Pyrophosphate. 
 
 f NaO,2HO,P0 5 , Acid phosphate (exists in the urine). 
 
 Tribasic, < 2NaO,HO,P0 5 , Common phosphate (officinal). 
 (3NaO,P0 5 , Subphosphate. 
 Each variety, in case of double decomposition, continues with 
 the same amount of the new base as it previously possessed. 
 Thus AgO,N0 5 +NaO,P0 5 =AgO,P0 5 +NaO,NCU; 2(AgO,N0 6 ) 
 
 * Elements of Chemistry, Am. ed., p. 321. 
 
 
CHEMISTRY OF THE ELEMENTS. 163 
 
 +2NaO,P0 6 = 2AgO,P0 6 +2(NaO,N0 6 ) - ; 3( AgO,N0 5 )+2NaO, 
 
 HO,P0 5 = 3AgO,P0 6 4-2(NaO,N0 5 )^4-HO,N0 6 ->. The tribasic 
 
 variety may be converted into bibasic and this into monobasic by 
 the application of heat, or the process may be reversed by long 
 boiling with water. 
 
 Officinal Forms. — Acidum phosphoricum glaciale, 
 glacial phosphoric acid, is HO,P0 5 ; the Acidum phos- 
 phoricum dilutum, s. g. 1056, contains 3HO,P0 5 . The 
 acid is tonic and refrigerant. The phosphates are admin- 
 istered in certain cases of defective nutrition. 
 
 Phosphoric acid should give no precipitate with nitrate of 
 silver or chloride of barium (absence of HO,S0 3 , or HC1) ; should 
 not be coloured by HS, or NH 4 S,HS, (absence of metallic im- 
 purity) ; should not corrode a strip of silver, (absence of HO, 
 N0 5 ) ; should not affect HgCl, (absence of P0 3 ). 
 
 Phosphorous acid, P0 3 , formed during the slow com- 
 bustion of P, is unimportant in medical chemistry. 
 
 221. Hypophosp"horous Acid, not isolable, HO,PO -f 
 2HO=66. — Is formed when P is boiled with an alkali or 
 alkaline earth, phosphuretted hydrogen being given off. 
 3(CaO,HO)+P 4 = 3(CaO,PO)_ + PH 3 * (approximately). 
 The hydrated acid is a syrupy liquid, easily decomposed, 
 a powerful reducing agent. The Hype-phosphites have 
 been used in tuberculous cachexia, impotence, etc. Oxide 
 of P (P 2 is unimportant) is supposed by some to be 
 merely allotropic P. 
 
 222. Phosphuretted Hydrogen, which results from the 
 union of its elements when in the nascent state, is given 
 off during the manufacture of the hypophosphites, or when 
 CaP is thrown into water. It is a mixture of the solid 
 P 2 H, liquid PH 2 , and gaseous PH 3 ; it is spontaneously 
 inflammable, a property which it loses when mixed with 
 a small quantity of ether or turpentine, and which is due 
 to the presence of PII 2 . It has a garlicky odour, and is 
 poisonous m j it is decomposed by CI and ozone. 
 
164 MEDICAL CHEMISTRY. 
 
 CHLORINE, 01=35-5. 
 
 223. Nat. Sources. — Common salt ; the native chlorides. 
 
 Prep. — (1) By gently heating 4 parts of hydrochloric 
 acid, HC1, with one of binoxide of manganese, Mn0 2 - 
 Mn0 2 +2HCl=MnCU+2HO t + Cl- > . (2) By the action of 
 dilute acids onchloride of lime (bleaching salt), CaO,C10+ 
 CaCi+2(HO,S0 3 )=2(CaO l SO,)+2HO-*+ClJ. The gas 
 
 may be collected by displacement 
 
 Prop. — A heavy greenish yellow gas, of a suffocating 
 odour, s. g. 2470 ; water absorbs two vols. (Aqua Chlo- 
 rinii, TJ. S. P.) It supports combustion, but is fatal to 
 animal life. By cold and a pressure of 4 atmospheres, 
 becomes a bright, yellow, limpid liquid, s. g. 1*33; has 
 not been obtained solid. It is a powerful deodouriser and 
 bleacher of organic colours (except carbon). Colours re- 
 moved by chlorine cannot be restored. 
 
 Med. Effects. — Even when diluted, chlorine causes 
 spasm of the glottis, and, if inhaled, great irritation of 
 the air passages and congestion of the lungs. Some relief 
 is afforded by the inhalation of alcohol or ether. Much 
 diluted, has been inhaled in aphonia and chronic bron- 
 chitis, and might be useful in the case of metallic foreign 
 bodies in the air passages, which resist ordinary surgical 
 measures for extraction, causing their gradual conversion 
 into soluble chlorides. It is given internally in solution 
 in scarlatina, diphtheria, and other anginose affections. 
 
 Its solution in water is officinal as Aqua Chlorinii, 
 and is prepared by passing a current of washed chlorine 
 into distilled water, in a large bottle loosely plugged with 
 cotton, agitating the liquid from time to time until satu- 
 rated. Chlorine water has a yellowish colour and the 
 odour of the gas; is apt to decompose, forming HC1 and 
 
CHEMISTRY OP THE ELEMENTS. 165 
 
 O ; it should be kept in a cool place excluded from the 
 light ; it contains CIO and C10 7 . 
 
 224. Gen. Chem. Relations. — Chlorine is the type of the 
 Halogens (salt-generators), a group of highly electro-neg- 
 ative bodies, having a feeble affinity for 0, but an energetic 
 one for H and the metals; so much so that these bodies 
 are never found uncombined in nature. The other Halogens 
 are Bromine Br, Iodine I, and Fluorine F. The members 
 of the Cyanogen group, although compound bodies, act as 
 halogens, and are conveniently studied in connection with 
 them. Their compounds, except those of F, are mostly 
 soluble, and are obtained directly or indirectly from the 
 sea. The compounds of the halogens with H are acids 
 (hydrogen acids, hydracids) ; with the metals they com- 
 bine directly to form salts (Ex., NaCl — common salt), 
 which are simpler in constitution than the amphide salts 
 (184), being binary compounds. When a hydracid is 
 added to an oxygen base, water and a haloid salt result. 
 AgO-f HCl=AgCl-f HO^.; an oxygen acid, added to a 
 haloid salt, gives an oxy-salt and hydracid, NaCl-f HO, 
 S0 3 =NaO,SO ;r ->-f-HCl t ; an oxy-salt, reacting with a 
 haloid salt, yields new compounds of the same type, AgO, 
 N0 5 +NaCl=AgCl+NaO,N0 5 ->. The deodourising and 
 
 bleaching powers of CI are due to its affinity for H ; ozone 
 is probably set free as a secondary product in some cases. 
 The combustion of a taper or other hydrocarbon in CI 
 is due to the combination of the latter with the H of 
 the former. 
 
 So energetic are the affinities of CI for H and the metals, that 
 a paper dipped in oil of turpentine will give rise to a spontane- 
 ous flash of light, HC1 being formed and the carbon deposited 
 in a dense, black cloud. Most of the metals in leaf or powder 
 burn spontaneously, forming chlorides. P also combines at or- 
 dinary temperatures, forming PC1 6 , but the flame is feeble, owing 
 to the absence of solid matter (212). 
 
166 MEDICAL CHEMISTRY. 
 
 Tests. — When free, its odour and bleaching properties; 
 either combined or free, gives, with AgO,N0 5 , a white, 
 curdy precipitate of AgCl, insoluble in cold or boiling HO, 
 N0 5 , soluble in ammonia, and blackening on exposure to 
 light. 
 
 225. Chlorine and Oxygen. — These elements do not com- 
 bine directly, and their compounds are unstable. They 
 are Perchloric acid, HO,C10 7 , not isolable; Chloric acid, 
 HO,C10 5 ; Hypochloric acid, C10 4 ; Chlorous acid, C10 3 ; 
 and Hypochlorous acid, CIO. 
 
 226. Chloric Acid, HO,C10 5 =85. 
 
 Prep. — By passing a current of CI into hot caustic po- 
 tassa, KO,HO, — chlorate of potassa, KO,C10 5 , and chloride 
 of potassium are formed. 6(KO,HO) + Cl 6 =KO,C10^ + 
 5KCU. The hydrated acid is obtained by decomposing 
 chlorate of baryta, BaO,C10 5 ; by diluted HO,S0 3 , BaO,S0 3 
 
 -J-nHO, C10 5 ^ result. The solution is concentrated by 
 evaporation in vacuo. It is a sour liquid, a powerful oxy- 
 dising agent, and easily decomposed. The chlorates are 
 all soluble and deflagrate with combustibles, even more 
 violently than the nitrates ; hence their use in pyrotechny. 
 The Chlorate op potassa, KO,C10 5 , is officinal. By add- 
 ing strong sulphuric acid to KO,C10 5 , explosive, yellowish 
 vapours of C10 4 arise. This gas may be liquefied by cold 
 and pressure, and is readily soluble in water. It does not 
 form salts. 
 
 22*7. Hypochlorous Acid, C10=43-5. — Is a gas resem- 
 bling chlorine somewhat in colour, odour, and exceeding it 
 in bleaching properties, s. g. 3040; water dissolves 200 
 vols. It readily decomposes with explosion. The acid 
 itself is unimportant. The hypochlorites are largely used 
 as deodourisers and internally in cases where CI is indi- 
 cated, and as a convenient extemporaneous source of that 
 element. The chloride of lime, so called, contains hypo- 
 
CHEMISTRY OP THE ELEMENTS. 161 
 
 chlorite of lime and chloride of calcium ; it is made by- 
 passing CI gradually over hydrate of lime, 2(Ca0,H0) 
 + Cl 2 = CaO,C10 + CaCl+ 2H0 ; from this the other hypo- 
 chlorites may be obtained by double decomposition. 
 
 228. Chlorine and Hydrogen; Hydrochloric, or Muriatic 
 Acid, HC1=36'5. 
 
 Prep. — By decomposing common salt by HO,S0 3 . 
 
 ]STaCl+HO,S0 3 =NaO,S0^4-HGl. The gas is passed into 
 a succession of bottles containing water, in which state of 
 solution it is used in practice, ActduM muriaticum, 
 U. S. P. To obtain it pure, it should be diluted with an 
 equal bulk of water and distilled over chloride of barium, 
 BaCl. 
 
 For making a small quantity, the following proportions will be 
 found convenient: 3 of NaCl, 5 of HO,S0 3 , and 5 of HO; three 
 of HO are mixed with the HO,S0 3 , and when cool poured upon 
 the NaCl in a large retort which is gently heated ; the remain- 
 ing two parts of HO are placed in the receiver to absorb the 
 gas. The gaseous HOI is conveniently obtained on the small 
 scale by boiling an ounce or two of the commercial acid. - 
 
 Prop. — The gaseous acid is colourless, irrespirable, s. g. 
 1247 ; extinguishes flame, and is incombustible. It has a 
 pungent acid odour, and fumes in the air, from its attrac- 
 tion for moisture. By a pressure of 40 atmospheres it con- 
 denses into a limpid liquid, s. g. 1-2T. Water absorbs 480 
 vols, and increases in bulk §i The strongest solution still 
 contains 6 eq. of water ; its s. g. is 1-21. The Commercial 
 acid contains 8 eq. of HO, s. g. 1-16. It is, when pure, a 
 colourless liquid fuming in the air, sharply acid and cor- 
 rosive ; the commercial acid has a yellowish colour due to 
 iron or sometimes to organic matter. It may be purified 
 by diluting with an equal bulk of water and distilling over 
 chloride of barium. 
 
 Ghem. Relations. — It is the type of the hydracips. It 
 
168 MEDICAL CHEMISTRY. 
 
 acts on easily oxidised metals, as zinc, with the evolution 
 
 of H, and formation of the chloride ;Zn + HCl=ZnCU +H. 
 With bases it forms a chloride and water, AgO-f-HCl= 
 AgCl-f HO->; F 2 3 ,3HO + 3HCl=F 2 Cl 3 ^+6HO. Two 
 
 measures of HC1 to one of HO,N0 5 , form Nitromuriatio 
 acid, Aqua regia, which will dissolve gold and platinum. 
 It contains free chlorine and chloronitric acid, N0 2 C1 2 , 
 chloronitrous acid, N0 2 C1, and does not keep well. 
 
 Med, Effects. — In large doses, HC1 is an irritant poison; 
 antidotes, chalk, soap, etc. In moderate doses, gtt x to xx, 
 is used in low fevers, scarlatina, phthisis, dyspepsia, and 
 diphtheria. Is usefully added to gargles, as infusion of 
 cinchona, in the proportion of f^ss or f^ij to fjvi. 
 
 Officinal Forms. — Acidum muriaticum, s. g. 1-160. 
 Acidum muriaticum dilutum, made by adding aquae des- 
 tillatae, q. s. to ^iv. of the acid to make Oj; s. g. 1-038. 
 
 Muriatic acid should be colourless, wholly volatilised by heat; 
 when diluted with aq. destillat. should yield no precipitate with 
 HS (absence of metals generally), BaCl (absence of HO,S0 3 ), 
 ammonia in excess (absence of iron), should not dissolve gold- 
 leaf (absence of HO,N0 5 ). 
 
 229. Acidum Nitromuriaticum.— R. Acid, nitric fiij; 
 acid, muriatic, ^vss; after effervescence has ceased, keep 
 in a glass-stoppered bottle, protected from the light. Aci- 
 dum nitromuriaticum dilutum is made by adding to the 
 former aq. destillat. q. s. ad Ojj. Is supposed to act speci- 
 fically on the liver. Is used internally in the same doses 
 as acid, murial., and externally in baths. 
 
 230. Other Compounds of CI. — With N it indirectly 
 forms a highly explosive oily liquid, NC1 3 (?); with S, by 
 direct combination, SCI and S 2 C1, both reddish liquids of 
 offensive odour; the latter is used in the vulcanisation of 
 India-rubber. With P, directly, PC1 5 , a solid; and indi- 
 rectly, PC1 3 , a liquid. 
 
CHEMISTRY OF THE ELEMENTS. 169 
 
 BROMINE, Br= 18-26. 
 
 231. Nat. Sources. — Sea-water, saline springs, etc., from 
 which it is obtained by a process analogous to that for 
 procuring chlorine. Is officinal as Brominium. 
 
 Prop. — Opaque, brownish-red liquid. The only ele- 
 ment besides mercury existing in the liquid form at ordi- 
 nary temperatures ; s. g. 2-966; at 19° freezes. 
 
 Is volatile at ordinary temperature ; has a peculiar odour 
 resembling chlorine, but quite distinct; caustic taste ; boils 
 at 145-4°, giving a vapour resembling N0 4 ; s. g. 5390. 
 Slightly soluble (3 p. c.) in water, more so in alcohol and 
 ether. Is caustic, and stains the skin yellow. 
 
 Gen. Ghem. Bel. — Resembles Chlorine; it does not 
 support combustion, but bleaches. Forms with 0, Bromic 
 Acid, HO, Br0 5 (not isolable), and with H, Hydrobromic 
 Acid. Forms compounds (bromides) with N, S, P, CI, I, and 
 most of the metals, of which the Bromide of Potassium 
 is officinal. The Bromides are decomposed by CI, but Br 
 decomposes the Iodides. 
 
 Test. — Chlorine water produces an orange-yellow tint 
 in a solution, if bromine be present. 
 
 Med. Effects. — In overdose, an irritant poison ; antidote, 
 ammonia (Smee). Is used externally, concentrated or in 
 watery solution, as a caustic. Internally is rarely given 
 free, generally as Bromide of Potassium. 
 
 IODINE, i=m. 
 
 232. Natural Sources. — Is widely diffused in nature, 
 being found in sea-water, sea-weeds, sponge, salt-water 
 mollusca, cod-liver oil, mineral springs, in many vegeta- 
 bles, and the native iodides, as iodide of lead. It is ob- 
 tained commercially from kelp, the ashes of sea-weeds, in 
 15 
 
170 MEDICAL CHEMISTRY. 
 
 which it exists as iodide of sodium. The process is analo- 
 gous to that for obtaining CI and Br. 
 
 Properties. — Soft bluish-black scales of a metallic 
 lustre. It may be obtained by sublimation in oblique 
 rhomboidal crystals (5th system). It evaporates at com- 
 mon temperatures, having an odour somewhat resembling 
 that of CI and Br ; its taste is hot and acrid ; it is irri- 
 tant when inhaled, and stains the skin of an evanescent 
 yellow; when continually applied, it causes thickening and 
 desquamation of the cuticle. The s. g. of iodine is 4-948 ; 
 it fuses at 225°, boils at 347°, giving a vapour of a beau- 
 tiful violet colour, and having a s. g. 8716. It requires 
 7000 parts of water for solution, which is of a brownish 
 colour. The addition of iodide of potassium renders it 
 freely soluble. It is soluble in 12 parts of alcohol, and 
 freely in ether, glycerine, and benzole. 
 
 General Chemical Relations. — Has the general charac- 
 ter of the halogens (244). Its affinities are more feeble 
 than those of CI and Br. It does not bleach, but is a de- 
 odouriser. Indirectly, it forms iodic acid, HO,I0 5 , the 
 periodic acid, HO,I0 7 , the hydriodic acid, HI; also com- 
 pounds with ~N, S, P, CI, Br, and the metals. Iodine, 
 hydriodic acid, the iodides of sulphur, potassium, iron, 
 lead, arsenic, and mercury are officinal. The iodide of 
 nitrogen, IS"HI 2 , made by adding ammonia to a strong 
 tincture of iodine, is when dry a black solid, exploding 
 when touched. 
 
 Impurities. — Fixed adulterations, as charcoal, plum- 
 bago, and black oxide of manganese, remain when the 
 iodine is sublimed. Water, which sometimes exists to the 
 extent of 15 or 20 per cent., may be detected by the scales 
 of iodine adhering to the sides of the bottle, and removed 
 by quicklime. Iodide of cyanogen being more volatile 
 than iodine, rises at the beginning of the sublimation, 
 
CHEMISTRY OF THE ELEMENTS. lfl 
 
 and condenses on a cold surface in colourless, pungent 
 crystals. Test. — Boiled starch yields a deep blue colour; 
 the solutions must be cold, and the iodine free. If com- 
 bined, it may be liberated by HO,N0 5 . 
 
 Medical Effects. — Is used externally as a counter-irri- 
 tant and discutient ; internally as an alterative. In over- 
 dose, is an irritant poison ; antidote, boiled starch. The 
 contact of metals in any form should be carefully avoided 
 in administering it. 
 
 233. Officinal Forms : — 
 
 (1) Iodinium. 
 
 (2) Tinctura Iodinii contains gj in Oj alcohol, or gr j to 
 gtt xxxv. When first made it is decomposed by admix- 
 ture with water ; after a time, hydriodic acid, HI, and 
 other compounds are formed which prevent this. It is 
 generally used externally. Dose, gtt x to xx. The so- 
 called colourless tincture of iodine is made by adding an 
 equal bulk of solution of ammonia (276). It contains 
 iodide of ammonium ; explosive iodide of nitrogen might 
 be formed from it (232). 
 
 (3) Tinctura Iodinii Composita contains ^ss Iodinii, ^j 
 Potassii Iodidi, to Oj Alcohol. It may be diluted without 
 change. Dose, gtt x to xxx. 
 
 LiQtJOR Iodinii Compositus — LugoVs solutiori, contains 
 gr ccclx of Iodine, ^iss Potass. Iodid., in Oj Aquce. The 
 iodine is rendered soluble by the KI. This solution keeps 
 well, and is the best form for internal use. Dose, gtt v 
 to x. 
 
 Unguent um Iodinii is made by rubbing gr xx Iodinii, 
 gr iv Potass. Iodid. with Ttyvj Aquce, until dissolved ; then 
 mixing thoroughly with gj Adipis. It is a powerful 
 stimulant and discutient, but does not keep well. 
 
 Ungtjentum Iodinii Compositum is prepared in the 
 same way, using gr xv Iodinii, gr xxx Potass. Iodid., 
 
172 MEDICAL CHEMISTRY. 
 
 lt[ xxx Aquce, and 3j Adipis. Is somewhat stronger than 
 the former, and keeps better. 
 
 Acidum Hydriodicum Dilutum is made by passing a 
 current of HS through I, suspended in distilled water, 
 until the color of the I disappears; sulphur is deposited. 
 3j Iodinii, with q. s. Aquce destillatos to make ^vj, are the 
 proportions used. I+HO-f HS==HI_ > +HO_ > -f S. Thes.g. 
 
 of the preparation is 1*112; it contains 10 grs. of I to f^j. 
 Dose, gtt iv, gradually increased. Effects, those of I. 
 
 Sulphuris Iodidum, Iodide of Sulphur, S 2 I ; is made 
 by melting together in a glass flask a mixture of %iv 
 Iodinii and ^j Sulphur, sublimat. It is insoluble in 
 water, soluble in 60 parts of glycerine ; entirely volatilised 
 by heat, and decomposed by long boiling in water. Is 
 used externally in chronic skin diseases. The Ung. Sul- 
 phuris Iodidi contains gr xxx to 3j Adipis. It should not 
 be perfumed, as S 2 I is decomposed by many volatile oils. 
 
 FLUORINE, F=19. 
 
 234. Nat. Sources. — Fluor spar, CaF, Cryolite, A1 2 F 3 , 
 3XaF; it exists in recent bones and the enamel of teeth. 
 Owing to its energetic affinities, has never been satisfac- 
 torily isolated. Its only compounds with the non-metallic 
 elements are Hydrofluoric Acid, HF, and fluoride of sili- 
 con, SiF 3 , and fluoride of boron, BF 3 . 
 
 Hydrofluoric Acid, HF=20. — Is prepared by the action 
 of HO,S0 3 upon powdered fluor spar in a leaden vessel, 
 
 CaF+HO,S0 3 =CaO,SO^+HF. Is a colourless, highly 
 corrosive gas, s. g. 689 ; below 60°, is a colourless liquid, 
 s. g. 1*06; it has not been frozen. A hydrate, 4HO,HF, s. g. 
 11 6, is made by gradually adding water to this liquid; it 
 boils at 284°, and may be preserved in gutta-percha bot- 
 tles. It is chiefly used for etching upon glass, which it 
 accomplishes by attacking the silica of that substance. 
 
CHEMISTRY OF THE ELEMENTS. 173 
 
 In etching upon glass, the plate is first covered with wax, con- 
 veniently by pouring over it a solution of wax in benzine, and 
 allowing the latter to evaporate. The design is then traced 
 through the wax with the point of a needle, and the plate laid, 
 face downwards, upon a leaden trough containing the powdered 
 CaF and HO,S0 3 . The gas rises upon the application of a gentle 
 heat, and speedily corrodes the glass where not protected by the 
 wax ; the latter may be removed by benzine or oil of turpentine. 
 The liquid acid may be used, but the lines while eaten into the 
 glass are transparent and not easily seen ; when the gaseous acid 
 is used, they are rough and translucent. 
 
 CYANOGEN, C 2 NCy=26. 
 
 235. Prep. — C and N unite at a high temperature in 
 the presence of a strong base. When a current of N or air 
 is passed over a mixture of charcoal and pearlash heated to 
 redness, cyanide of potassium, KCy, is formed, KO,C0 2 + 
 C 4 +N = KC 2 N_>+3e t O. It is also formed during the de- 
 structive distillation of coal and animal matters, the ammo- 
 nia formed at the same time acting as the base. It may 
 be obtained free by heating to redness well dried cyanide 
 of mercury, HgCy ; a portion of the Cy passes over, the 
 mercury volatilises, but is condensed in the cooler part of 
 the retort, and a black body, paracyanogen, C 4 N 2 , remains. 
 The gas must be collected over mercury. 
 
 Prop. — A colourless, neutral gas, of a pungent odour, 
 irritating to the eyes, highly poisonous, inflammable, burn- 
 ing with a peachblossom-coloured flame, s. g. 1806. Water 
 dissolves 4.5 volumes, alcohol 23 volumes. The watery 
 solution rapidly decomposes on exposure to light; is con- 
 densed by cold and a pressure of three atmospheres into 
 a colourless, limpid liquid, s. g. 0.9; at — 30° is solid. 
 
 Chemical Relations. — Although a compound, cyanogen 
 
 acts as an element. It belongs to the halogens, forming a 
 
 hydrogen acid, HCy, and cyanides. Its affinities are less 
 
 energetic than those of CI, Br, and I ; it does not combine 
 
 15* 
 
174 MEDICAL CHEMISTRY. 
 
 directly with H, bleach, nor support combustion, except 
 of the alkali metals, which, when ignited and introduced 
 into it, combine directly, producing their cyanides. It 
 forms a curious and important series of conjugate com- 
 pounds* with S and certain metals, which are not isolable, 
 but have the same chemical relations as Cy. The most 
 important of these are, Ferrocyanogen, ~FeCy 3 ,ferricyan- 
 ogen, Fe 2 Cy 6 , and sulpho cyanogen, S 2 Cy. 
 
 With 0, it forms a series of acids which exist (except cyanuric 
 Cy 3 3 ) only in combination with water or a base ; they are poly- 
 meric — that is, have the same constituents in multiple propor- 
 tions. HO,CyO, Cyanic acid ; the cyanate of ammonia is identical 
 or isomeric with urea. 2HO,Cy 2 2 , fulminic acid; the fulmi- 
 nates are highly explosive ; that of mercury is used in percussion- 
 caps and friction-primers. 3HO,Cy 3 3 , cyanuric acid, and HO, 
 Cy 3 3 , -f- 2H0, fulminuric acid. 
 
 236. Hydrocyanic Acid {Prussic Acid), HC 2 N, or HCy 
 
 Prep. — Anhydrous by passing dry HS over dry cyanide 
 
 of silver, AgCy-f HS=AgS_ + +HCy ; diluted by the reac- 
 tion of AgCy and HCl+nHO=AgCl-f HCy+nHO,-> or 
 
 by the action of dilute sulphuric acid upon ferrocyanide 
 of potassium, K 2 FeCy 3 . This reaction is complex. 
 
 Prop. — Anhydrous, a colourless liquid, s. g. 7058 ; 
 powerful characteristic odour ; solid at 3°, boils at 79° ; 
 s. g. vapour 696. Is fearfully poisonous, whether applied 
 to the tongue, the skin, or when inhaled ; a single drop 
 placed upon the tongue produces almost instant death. 
 It is feebly acid, and prone to decomposition. The dilute 
 acid possesses the same properties in a less degree ; it has 
 a warm, acrid taste, and inhaled produces irritation of the 
 nose and fauces. 
 
 * Conjugate compounds are those in which the properties differ from 
 those of their constituents in degree rather than in kind. 
 
CHEMISTRY OF THE ELEMENTS. 1^5 
 
 Medical Effects. — In medicinal doses, is sedative and 
 antispasmodic ; externally, is applied to allay the itching 
 of prurigo. Dose of the medicinal acid, gtt ij to vj, diluted. 
 
 In poisonous doses, the effects are, sudden loss of con- 
 sciousness, difficult and rattling respiration, immobility, 
 and sometimes contraction of the pupils, swelling and 
 stiffness of the neck, and convulsions. In many cases 
 death is almost instantaneous. Where time is allowed 
 for the use of antidotes, chlorine, which may be liberated 
 by moistening chloride of lime on a towel with vinegar, 
 is the most efficient. It may be inhaled cautiously, or 
 given internally as chlorine water. Next to chlorine ranks 
 ammonia; a mixture of ferrous sulphate, FeO,S0 3 , with 
 ferric sulphate, Fe 2 3 ,3S0 3 , and carbonate of potassa, 
 KO,C0 2 , has been used successfully. It converts the 
 poison into inert Prussian blue, Fe 4 Cfy 3 . Gold affusion 
 to the spine, and frictions, are also to be employed. 
 
 Tests. — When not overpowered by other strong odours, 
 that of HCy is characteristic. 1. Nitrate of silver gives 
 a dense white precipitate, insoluble in cold, HO,N0 5 , solu- 
 ble in boiling, HO,N0 5 , not blackened on exposure to the 
 light (distinction from AgCl). When well dried it may 
 be decomposed by heat in a tube of hard glass, and the 
 characteristic flame of Cy obtained. 2. Scheele's. Add to 
 the suspected solution a few drops of a solution of fer- 
 rous sulphate, FeO,S0 3 , followed by solution of potassa, 
 KO,HO, a greenish colour will be produced, which darkens 
 on agitation, from the absorption of 0. Then add diluted 
 HC1; Prussian blue, Fe 4 Cfy 3 , will remain behind, and may 
 be recognised by its colour and insolubility in dilute acids. 
 3. Liebig's. Add to the suspected solution a few drops of 
 sulphydrate of ammonia, NH 4 S,HS, sulphocyanide of 
 ammonium will be formed (NH 4 S,HS-f HCy-f 2 (air)= 
 NH 4 S 2 Cy-f 2H0). This gives a blood-red tinge with the 
 
U6 MEDICAL CHEMISTRY. 
 
 salts of the sesquioxide of iron (ferric salts). Sulphocya- 
 
 nide of potassium, KS 2 Cy, exists in the saliva of man, the 
 
 dog, horse, and sheep ; * this fact should be borne in mind 
 
 in using this test. 
 
 These tests may be conveniently applied to the vapour of the 
 acid, as it issues from a complex liquid, by putting the latter in 
 a small jar over which is inverted a watch-glass. Into the latter 
 the test solutions are to be placed. (Taylor. )f The tests should 
 be applied early on account of the volatile and unstable charac- 
 ter of the poison. After putrefaction it is found as sulphocyanide 
 of ammonium, which may be dissolved out by alcohol. In order 
 to separate the acid from the complex contents of the stomach, 
 the latter should be acidulated with tartaric acid, and distilled at 
 a temperature not exceeding 178°, the receiver being kept cool 
 by ice. 
 
 Officinal Form. — Acidum Hydrocyanicum dilutum. 
 Prepared (1) by the action of dilute sulphuric acid upon 
 ferrocyanide of potassium, (K 2 Cfy). (2) Extempora- 
 neously, by mixing 50^ grs. of cyanide of silver, AgCy, 
 with ^i of distilled water, and adding 41 grs. of muriatic 
 acid. When the chloride of silver has subsided, pour off 
 for use; it should be kept in well-stopped bottles, away 
 from the light. It contains two per cent, of real acid. 
 Dose, gtt i to v. Scheele's acid contains 5 per cent, and 
 should never be employed. Incompatibles, the alkalies, 
 salts of silver, iron, copper, and mercury ; paregoric. 
 
 23?. Ferrucyanogen, FeCy 3 ,Cfy, Ferricyanogen, Fe 2 Cy 6 
 Cfdy, and Sulphocyanogen, S 2 Cy. When cyanide of po- 
 tassium is digested with iron filings, oxygen is absorbed, 
 the iron disappears, and lemon-yellow crystals of ferro- 
 cyanide of potassium, K 2 FeCy 3 -f-3HO or K 2 Cfy, may 
 be obtained on evaporation. By passing through a cold 
 dilute solution of K 2 Cfy a current of chlorine, the liquid 
 acquires a reddish colour, and on evaporation yields ruby 
 crystals of ferricyanide of potassium, K 3 Fe 2 Cy 6 , or K 3 
 
 * Lehmann's Physiological Chemistry, i. 421. 
 f Braxde and Taylor, Am. ed., 2G9. 
 
CHEMISTRY OF THE ELEMENTS. l?t 
 
 Cfy; 2K 2 Cfy-f Cl=K 3 Cfdy->-|-K:Cl->. Sulphocyanide of 
 potassium, KS 2 Cy or KCsy, is prepared by fusing S with 
 KCy. 
 
 Chemical Relations. -—These remarkable bodies are 
 members of a group of bodies (argento-cyanogen, pla- 
 tino-cyanogen, cobalto-cyanogen, nitro-prussides) none of 
 which are isolable. They are all electro-negative, and 
 act as halogens, forming H acids (hydroferrocyanic 
 H 2 Cfy, hydroferricyanic H 3 Cfdy, hydro sulphocyanic HCsy) 
 and salts. The ferrocyanides of potassium and iron are 
 officinal. 
 
 The iron in the ferro and ferricyanides has its chemical and 
 to a certain extent its physical properties suspended. It has 
 become electro-negative. It cannot be detected by the usual 
 chemical tests, and the crystals are diamagnetic, that is, are 
 repelled by the magnet, whereas all bodies in which iron exists 
 in its ordinary, or basic, or electro-positive form, are powerfully 
 magnetic. 
 
 BORON, B=10-9. 
 
 Is an unimportant element belonging to a natural group 
 with carbon and silicon. It exists in boracic acid, B0 3 , 
 which is found in certain lagoons in Tuscany, and as 
 Borax, biborate of soda, NaO,2B0 3 -f 10HO, found native 
 in India and California. B0 3 fuses to a transparent glass, 
 its crystalline hydrate, HO,B0 3 -f 2HO, is in transparent 
 pearly scales (5th system), soluble in 25 parts of cold and 
 3 of boiling water, and in alcohol, to the flame of which it 
 communicates a green colour; it is volatilised at a white 
 heat. It is nearly tasteless, and feebly reddens litmus ; at 
 ordinary temperature is the feeblest of the acids, but from 
 its fixed character will decompose the sulphates at a red 
 heat (171). 
 
It8 MEDICAL CHEMISTRY. 
 
 SILICON, Si=21. 
 
 238. Exists combined in nature as Silica, Si0 3 . In this 
 form it is abundantly distributed, silica being found nearly- 
 pure as quartz and sand, and combined in clay, granite, 
 feldspar, and many crystallised minerals. It exists also 
 in the stalks and husks of grain, in the ashes of plants, in 
 the hair, and forms the skeletons of infusoria, which, when 
 fossil, constitute polishing slates and powders. The ele- 
 ment has been, like boron, obtained in three forms, resem- 
 bling carbon in its modifications of the diamond, graphite, 
 and lampblack. 
 
 Silica, Silicic Acid, Si0 3 . — Quartz, flint, agate, chal- 
 cedony, etc., are nearly pure varieties of this substance. 
 From its insolubility it possesses no acid reaction, but at 
 a high temperature combines with bases to form the sili- 
 cates, as glass. Mr. Graham has obtained it in the soluble 
 form by dialysis (128). It has then an acrid taste, and 
 reddens vegetable blues; it speedily assumes the insoluble 
 or pectised condition. It may be precipitated from an 
 alkaline silicate as a gelatinous hydrate containing a vari- 
 able proportion of water; it is then soluble in the mineral 
 acids and combines with caustic alkalies. The latter 
 attack the softer forms of glass, abstracting the silica. 
 With F it forms a gaseous fluoride of silicon, SiF 3 , which 
 is decomposed by water, yielding silica and hydrofluosilicic 
 acid, 2HF,3SiF 3 . The latter is used in analysis. 
 
 THE METALS. 
 
 239. Nat. Sources. — The less easily oxidised metals, as 
 silver, gold, platinum, copper, and bismuth, are found na- 
 tive, that is in the metallic state. Lead, copper, mercury, 
 arsenic, antimony, and iron, zinc and others, occur as sul- 
 
CHEMISTRY OP THE ELEMENTS. 179 
 
 phides. Iron and tin usually occur as oxides. The fol- 
 lowing occur as oxy-salts: the metals of the alkalies and 
 alkaline earths, as carbonates, sulphates, and silicates; iron 
 as carbonate, zinc as carbonate and silicate; lead as car- 
 bonate, sulphate, phosphate, etc. The native chlorides 
 and iodides, except of sodium, are rare. 
 
 240. Extraction. — Native metals are separated from 
 the surrounding rock or gangue by crushing, the metal 
 being tougher resists, while the rock is powdered ; the two 
 are then thrown into water; the metal, by its greater 
 specific gravity, sinks, while the powdered rock remains 
 temporarily suspended and is poured off with the water. 
 When the metal occurs in large masses, these are picked 
 out by hand ; when the particles are very fine, they cannot 
 be separated by difference of specific gravity, and are then, 
 in the case of the precious metals, extracted by amalgama- 
 tion, the action of chlorine or the alkalies, which latter 
 dissolve the quartzy gangue. Oxides and oxy-salts are 
 reduced by carbon at a high heat. Sulphides are roasted, 
 that is, heated with exposure to air ; the S is burned off, 
 and the metal generally remains as oxide. 
 
 241. Properties. — The metals are all opaque; gold in 
 very thin film transmits a greenish light. They are all 
 insoluble in menstrua. When attacked by acids, it is not 
 true solution, but chemical compounds are formed. They 
 have a brilliant lustre; this is also possessed by C 
 (graphite), I, and some sulphides (galena, pyrites, etc.). 
 They are the best conductors of heat and electricity, silver 
 standing first, and bismuth last on the list. Some, as gold, 
 iron, lead, and tin, are highly malleable; gold may be 
 beaten into leaves the 3^0 otf °f an mcn m thickness ; bis- 
 muth, antimony, and arsenic may be powdered; zinc is 
 malleable or brittle according to the temperature. Their 
 ductility or tenacity varies. Iron and platinum bear draw- 
 
180 MEDICAL CHEMISTRY. 
 
 ing into very fine wire ; lead has only ^ the tenacity of 
 the former. Their specific gravity varies from lithium, 
 0-593, the lightest solid body known, to platinum, 21530, 
 the heaviest. Their fusing points vary from — 39° mercury 
 to the heat of the compound blowpipe. They are proba- 
 bly all volatile, but the following may be distilled : mer- 
 cury, zinc, cadmium, arsenic, potassium and sodium. 
 
 242. Chem. Relations. — With each other they form al- 
 loys; those with mercury are termed amalgams. They 
 all unite with 0, but with varying affinity. Some, as po- 
 tassium, decompose water at ordinary temperature ; others, 
 as iron, at a red heat ; others, as silver, gold; and plati- 
 num, will only unite by indirect methods. The protoxides 
 are strong bases, the sesquioxides feeble ones, sometimes 
 acting as acids ; the higher oxides are generally neuter or 
 acid. The sulphides, chlorides, and iodides generally cor- 
 respond in their number and the proportion of their con- 
 stituents to the oxides Ex. : FeO,Fe 2 3 , FeS,Fe 2 S 3 , FeCl, 
 Fe 2 Cl 3 , etc. As exceptions to this law, we find generally 
 more sulphides than oxides, and fewer chlorides and iodides. 
 
 Constitution of Salts. — A salt is the union of an acid 
 with a base, or of a halogen body with a metal (224). 
 Oxygen, sulphur, selenium, and tellurium are the only 
 electro-negative bodies capable of forming both acids and 
 bases. Ex. : KO,As0 3 ; KS,AS 3 , KSe,AsSe 3 ; KTe,AsTe 3 j 
 they are termed the amphigen bodies (184). The amphi- 
 gen must be the same in the acid and base. 
 
 Thus, an oxygen acid will not unite with a sulphur base, but 
 decomposes it. KS+HO,S0 3 =KO,S0 3 ->+HS.t Sometimes we 
 have a union of an oxide and a sulphide or chloride, forming an 
 oxy sulphide ; Ex. : Sb0 3 ,2SbS 3 ; or oxychloride, as 5Sb0 3 ,SbCl 3 ; but 
 these are not salts. The only important amphide salts are those 
 of and S. It has been proposed to bring all salts under the 
 same constitution, as haloid salts, by assuming the H as the acidi- 
 fying principle in all acids. Under this binary theory of salts, 
 sulphuric acid is H,SO t , sulphate of potassa K,S0 4 , etc., the metals 
 
CHEMISTRY OF THE ELEMENTS. 181 
 
 merely replacing the hydrogen of the acid. This theory, although 
 attractive, is incompatible with many well-established chemical 
 facts. 
 
 243. Normal Salts. — The rule in regard to the constitu- 
 tion of oxy-salts is, that they must contain as many 
 equivalents of acid as there are of oxygen in the base. 
 Thus, for & protoxide one, FeO,S0 3 ; a sesqui- or fer-oxide 
 three, Fe 2 3 ,3S0 3 , Bi0 3 ,3N0 5 . Such salts have been termed 
 neutral, but normal is preferable, as the salts of the ses- 
 quioxides are acid to test-paper. Where a body is chemi- 
 cally indifferent as Mn0 2 , the term neuter is suggested. 
 Where the proportion of acid is not so great as that indi- 
 cated, a su&-salt is formed which generally crystallises 
 imperfectly or not at all, and is in many cases insoluble ; 
 3PbO,C 4 H 3 3 , tris-acetate of lead; 2Fe 2 3 ,5S0 3 , sub-sul- 
 phate of sesquioxide of iron. 
 
 The student is generally confused, in studying the sesqui com- 
 pounds, by overlooking the fact that the equivalent is doubled. 
 The proportion of iron in Fe 2 3 is Fe01£; but to avoid the half 
 equivalent, the formula is doubled; hence, two eq. of a protoxide 
 yield but one of a sesquioxide. In all cases of reactions of 
 sesqui compounds, three equivalents of the reacting body are 
 required. The student will find the study of the reactions given 
 below very useful in overcoming the difficulties of those met 
 with in the chemistry of the metals. They are the types of 
 changes constantly recurring. 
 
 1. Protoxide with HC1; ZnCU+HCl^ZnCU-f-HCU. 
 
 2. Sesquioxide with HC1; Fe 9 3 ,3HO+ 3HCl=Fe 2 CU -{- 6HCU 
 
 3. Protosalt with alkali; FeO,S0 3 + KO,HO = FeO,HO + KO, 
 
 SCU, or FeCl-f KO,HO=FeO,HO+KCU. 
 
 4. The same with an alkaline carbonate; FeO,SCM-KO,COo= 
 FeO,C0 8 +KO,SCU or FeCl+KO,C0 2 ==FeO,C0 2 -f KG1-*. 
 
 5. Sesqui-salt with an alkali; Fe 2 3 ,3S0 3 -f 3(KO,HO)=Fe 2 3 , 
 3IIO+3(KO,S0 3 )h.,* or Fe 2 Cl 3 +3(KO,HO)=Fe 2 3 ,3HO-f 3KCL>. 
 
 For other important typical reactions, see Chemistry of Chlo- 
 rine. 
 
 * The sesqui-salts usually react with alkaline carbonates, as with the 
 caustic alkalies, CO2 being given off. 
 16 
 
182 MEDICAL CHEMISTRY. 
 
 General Methods of Preparing Compounds of the Metals. 
 
 244. 1. Oxides are made by (a) direct combination, as 
 in burning zinc ; (b) by precipitation of a salt by caustic 
 alkali, as in making ferric hydrate, FeaO^HO (314); 
 in this case the oxide is generally hydrated. (c) By 
 decomposing an oxy-salt, as in making lime from its car- 
 bonate or red precipitate from the nitrate of mercury. 2. 
 Sulphides are usually found native or formed by direct 
 combination. 3. Chlorides, (a) By direct combination of 
 the gas or the free chlorine of Aqua regia (228). (6) By 
 the action of HC1 on an easily oxidised metal, Zn-f-HCl= 
 ZnCl^+H. (c) By dissolving an oxide or carbonate in 
 HC1; ZnO+HCl=ZnCl+HO. 4. Iodides and bromides, 
 by direct union, as in iodide of iron, or by double decom- 
 position, as iodide of mercury, HgCl+KI=rHgI-f KCl->. 
 
 5. Sulphates and nitrates, by the action of the acid on 
 the metal, or its oxide or carbonate. (b) Carbonates are 
 found native or obtained by double decomposition, as in 
 Vallet's mass, FeO,C0 2 (320). The other salts of the 
 oxy-acids are made by direct action of the acid on the 
 oxide of the metal, or its carbonate, or by double decom- 
 position. 
 
 245. Isomorphism. — Certain bodies of similar chemical 
 constitution have the property of replacing each other in 
 crystalline compounds without altering their crystalline 
 form. In many cases these similar compounds have the 
 same color, and even taste. These bodies are said to be 
 isomorphous (Gr. isos, equal, and morphe, form). 
 
 Strictly speaking, any bodies crystallising in the same system 
 are isomorphous, as the diamond and alum; but the term is 
 restricted to those -which have also similar chemical relations. 
 The law of Mitscherlich, that "the same number of atoms simi- 
 larly combined produce the same crystalline form," although 
 
CHEMISTRY OP THE ELEMENTS. 183 
 
 generally correct, cannot be considered as universally true. 
 Examples of isomorphism are found in the alums (301), in which 
 the sesquioxides of aluminum, iron, manganese, and chromium, 
 and potassa, soda, and ammonia replace each other, without 
 change in form, amount of water of crystallisation, &c, and in 
 some cases the compounds are only distinguishable by chemical 
 tests. In double salts the two bases are never taken from the 
 same isomorphous family. Isomorphous salts are separated with 
 great difficulty by crystallisation, unless the difference of their 
 solubility is considerable. 
 
 The following more important metals are classified in iso- 
 morphous groups: (1) Mg, Ca, Mn, Fe, Co, Ni, Zn, Cd, Cu, Cr, 
 Al; (2) Ba, Sr, Pb, K, NH 4 , Na, Ag, Au; (4) Sb, As, Bi. 
 
 246. Classification. — The more important metals (in 
 Medical Chemistry) may be thus classified: — 
 
 1. Metals of the Alkalies : K, Na, Li, NH 4 . Their oxides 
 and carbonates are all soluble ; they have a powerful alka- 
 line reaction and are caustic. Their oxides are soluble in 
 alcohol. 
 
 2. Metals of the Alkaline Earths: Ca, Mg, Ba, Sr. Their 
 oxides have a more feebly alkaline reaction, are less solu- 
 ble in water ; MgO is quite insoluble. Their carbonates 
 and phosphates are insoluble ; they form soluble bicarbo- 
 nates. 
 
 3. Metals of the Earths. Aluminum is the only impor- 
 tant member. Their oxides are insoluble, without alkaline 
 reaction, and combine with both acids and bases. 
 
 4. Metals Proper; Heavy Metals; Calcigenous Metals: 
 Mn, Fe, Cr, Zn, Cd, Sn, Bi, As, Sb, Cu, Pb, Hg, Au, Ag, 
 Pt. Their oxides are precipitated by IIS or NII 4 S,HS. 
 Hg, Au, Ag, Pt are termed noble metals; their oxides are 
 reduced by heat alone, and they do not decompose water 
 at any temperature. 
 
 The following enter into compounds which arc officinal, 
 U.S. P.: K, Na, Li, NII U Ca, 13a, Mg, Al, Fe, Cr, Cu, Cd, 
 Pb, As, Sb, Bi, Ug,Ag. 
 
184 MEDICAL CHEMISTRY. 
 
 POTASSIUM, K=39.* 
 Syllabus of Compounds.^ 
 
 Oxide (hydrated), KO,HO: (a) Liquor Potassse; (b) 
 Potassa. 
 
 Sulphide, Potassii Sulphuretum, Liver of Sulphur, 
 2KS 3 +KO,S 2 2 , variable. 
 
 Iodide, KI, Potassii Iodidum. 
 
 Bromide, KBr, Potassii Bromidum. 
 
 Cyanide, KCy, Potassii Cyanidum. 
 
 Ferrocyanide, K 2 Cy 3 Fe-f 3HO; Potassii Ferrocyani- 
 dum- Ferricyanide, K 3 Cy 6 Fe 2 ; Sulphocyanide, KCyS 2 . 
 
 Nitrate, KO,N0 5 , Potassse Nitras, Nitre, Saltpetre. 
 
 Carbonates: {a) Potassse Carbonas impura, Pearlash; 
 (b) Potassse Carbonas, KO,C0 2 ; (c) Potassse Carbonas 
 pura, Salt of Tartar; (d) Potassse Bicarbonas, KO,HO, 
 2C0 2 , Sal Aeratus. 
 
 Oxalates, KO,C 2 3 +HO; KO,2C 2 3 +HO,KO,4C 2 3 
 -fTHO; Salt of Sorrel, Salt of Lemon. 
 
 Sulphate, KO,S0 3 , Potassse Sulphas; Bisulphate, KO, 
 S0 3 +HO,S0 3 . 
 
 Chlorate, KO,C10 5 , Potassse Chloras; Hypochlorite, 
 KO,C10 + KCl, Eau de Javelle. 
 
 Acetate, Potassse Acetas, KO,C 4 H 3 3 , or KO,A. 
 
 Tartrates: (a) Potassse Bitartras, KO,HO,C 8 H 4 O 10 , 
 Cream of Tartar; (b) Potassse Tartras, 2KO,C 8 H 4 O 10 , 
 Soluble Tartar; (c) Potassse et Sodse Tartras, KO,NaO, 
 C 8 H 4 O 10 , Rochelle Salt. 
 
 Citrate, KO,C 12 H 5 1 2 : (a) Potassse Citras ; (b) Liquor 
 
 * Officinal compounds have their names in Latin, also in Italics ; the 
 symbols indicate their chemical character. 
 
 f The hydrates of oxides of metals, although ternary compounds, are 
 considered with the anhydrous oxides and other binary compounds for the 
 sake of convenience. 
 
CHEMISTRY OP THE ELEMENTS. 185 
 
 Pota,ssse Gitratis; (c) Mistura Potassse Citratis, Neutral 
 Mixture. Potassa cum calce, Alumen , Ferri et Potassse Tar- 
 traSj Potassse Permanganas, Potassse Bichromas, Liquor 
 Potassse Arsenitis, and Antimonii et Potassse Tartras will 
 be considered under the Leads of Ca, Al, Fe, Mn, Cr, As, 
 and Sb. 
 
 247. Nat. Sources. — Exists in many rocks and minerals, 
 as clay, feldspar, mica, etc. These gradually disintegrate 
 and decompose under atmospheric influences ; the potassa 
 is taken up from the soil thus formed, and assimilated by 
 plants from the ashes of which it is obtained by lixiviation 
 as impure carbonate (potash, pearlash). The leaves and 
 young shoots are richest in potassa. 
 
 Prep. — By heating the carbonate to whiteness with C; 
 K distils over. 
 
 Prop. — Potassium is a brilliant white metal, silvery 
 lustre, soft at common temperatures ; brittle and crystal- 
 line at 32° ; melts at 144'5° ; distils at a low red heat, 
 giving a vapour of a green colour. S. g. 0*865. It has a 
 strong affinity for 0, its cut surface instantly tarnishes ; 
 it soon oxidises in the air, and must be kept under naph- 
 tha or petroleum. It forms with oxygen KO and K0 3 , 
 the latter unimportant. Potassa, KO, is formed by burn- 
 ing K in dry air ; it is a white, fusible, volatile body, com- 
 bining eagerly with HO, with the evolution of heat. It 
 is a powerful base, forming a series of salts most of which 
 are colourless and soluble. The best test is bichloride of 
 platinum, PtCl 2 , which forms a yellow, sparingly soluble 
 double chloride, KCl + PtCL,. With Sulphur it forms 
 five compounds, KS, KS 3 , and KS 5 being the most im- 
 portant. The other compounds of K and KO will be 
 considered in detail hereafter. 
 
 248. (1) Hydrate, KO, HO ; Liquor Potassse. — Is made 
 as follows: Take of Potassa Bicarb, fxv, Calcis six, 
 
 10* 
 
186 MEDICAL CHEMISTRY. 
 
 Aquse Destillatee q. s. Dissolve the bicarbonate in Oiv 
 of the water, and boil until effervescence ceases ; add 
 enough to make up the loss by evaporation ; then mix the 
 lime with Oiv water, heat to the boiling-point in a metal- 
 lic vessel, add to the potassa solution, and boil for 10 
 minutes ; strain through a muslin strainer, and add to the 
 residue on the strainer enough distilled water to make 
 Ovij. Keep in well-stoppered green glass bottles. It 
 may also be made by dissolving Potassa, U. S. P., %i, in 
 Oj of distilled water, pouring off the solution from any 
 sediment that may deposit. 
 
 The bicarbonate is selected on account of its purity ; it loses 
 CO a during the boiling, becoming sesqui-carbonate. The lime 
 forms an insoluble compound with C0 2 . and therefore acts as 
 the stronger base (170). "With KO,C0 2 , the reaction would be, 
 KO,C0 2 -fCaO,HO=CaO,C|0 2 +KO,HO^. Green glass bottles 
 are less liable to be attacked by alkaline solutions than those of 
 ordinary glass. 
 
 Prop, and Med. Effects. — A corrosive, colourless liquid, 
 s. g. 1-065, containing 5 T 8 o per cent, of KO,HO. Has a 
 powerful affinity for C0 2 . In large doses, a corrosive 
 poison ; antidotes : weak acids and oily matters. In medi- 
 cinal doses, gtt xx t. d. is given as an antacid and alter- 
 ative. Used in gout, rheumatism, chronic skin diseases, 
 obesity, etc. Should be given diluted in milk. Is incom- 
 patible with all acids, acid salts, and those of the metals 
 generally, except sodium. 
 
 Potassa, Caustic potash, Potassa fusa, KO,HO, is made 
 by evaporating Liquor potassae in an iron vessel until boil- 
 ing ceases and the potassa melts ; it is then poured into 
 moulds. It is a white, deliquescent solid, producing a 
 soapy feel when rubbed between the fingers, from the de- 
 struction of the cuticle. The commercial article is impure 
 and of a grayish colour ; it may be purified by alcohol, 
 which dissolves the KO,HO, and leaves most of the im- 
 
 
CHEMISTRY OP THE ELEMENTS. 181 
 
 purities. It is used externally as an escharotic ; from its 
 deliquescent character is apt to spread. It may be neu- 
 tralised by weak vinegar. 
 
 249. (2) Sulphide, Potassii sulphuretum, Hepar sulphu- 
 ris, Liver of sulphur. Prep. — By heating ^j Sulphur 
 Sublimat. mixed with ^ij Potass se carb. until effervescence 
 ceases and the mass melts ; it is then poured upon a 
 slab, and when cool broken into pieces; 3(KO,C0 2 )-f-S 8 = 
 2KS 3 -f KO,S 2 2 +3C0 2 . Is a mixture of tersulphide of 
 K with hyposulphite of KO ; on exposure to the air, it 
 gradually absorbs O, and becomes converted into sul- 
 phate. 
 
 Prop. — A liver-coloured, uncrystalline mass, smelling 
 of HS, which is freely evolved by the addition of dilute 
 acids. It is freely soluble in water. Med. Effects. — In 
 overdose, a poison irritating the stomach, depressing the 
 nervous system and the action of the heart. Antidote : 
 Sulphate of zinc, ZnO,S0 3 . Is rarely used internally ; ex- 
 ternally is applied as a lotion, gr. xv to xxx to 3j Aquae 
 in chronic skin diseases. Its odour may be disguised by 
 oil of Anise (Ruschenberger). Is incompatible with acids, 
 acidulous salts, and those of the metals generally. 
 
 250. Bromide, KBr ; Potassii Br omidum. 
 
 Prep. — Is generally made on the large scale; ^ij of bro- 
 mine are added to ^j of iron filings in Oiss of distilled 
 water. They combine, by the aid of a gentle heat, to form 
 a greenish solution of FeBr; to this is added £ij, gr. lx, 
 of pure carbonate of potassa, dissolved in Oiss of distilled 
 water, until no further precipitate is produced. The pre- 
 cipitate is washed and the filtrate crystallised, FeBr-f KO, 
 
 C0 2 =FeO,C0 2 +KBr.^ 
 
 i 
 Prop. — In cubic crystals resembling KI; is sparingly 
 
 soluble in alcohol ; should not lose weight on being heated. 
 
 Its taste resembles that of NaCl. 
 
188 MEDICAL CHEMISTRY. 
 
 Med. Effects. — Has a marked sedative action on the 
 nervous system ; causes anaesthesia of the fauces ; is ad- 
 ministered before operations or examinations of the throat; 
 used in epilepsy, sleeplessness, and other nervous disor- 
 ders, in engorgement of the uterus and prostate, sperma- 
 torrhoea, etc. Dose, gr. v to xxx, t. d. Incompatibles, those 
 of the iodide. 
 
 251. Iodide, KI; Potassii Iodidum. 
 
 Prep. — Is generally prepared on the large scale. Iodine 
 %xvi is boiled with potassa ^vi in Oiij of distilled water. 
 The solution is evaporated to dryness, mixed with pow- 
 dered charcoal ^ij and heated for 15 minutes to redness 
 in an iron crucible. The mass is lixiviated and the salt 
 crystallised out. (l)6KO+I 6 =KO,I0 3 -f 5KI; (2)KO,I0 5 
 -fC 6 =KI+6CO. 
 
 Prop. — Anhydrous, cubic crystals (1st system), opaque 
 white, or transparent; of a saline, cooling, disagreeable 
 taste ; soluble in two-thirds its weight of cold water and 
 6 or 8 parts of cold alcohol. 
 
 Impurities and Adulterations. — Bromide of potassium, 
 sometimes sold for the iodide, does not precipitate with cor- 
 rosive sublimate. The most common impurities are : 1. 
 Chlorides, which, with nitrate of silver, throw down a 
 white precipitate, AgCl, freely soluble in ammonia. KI 
 throws down iodide of silver, Agl, which is scarcely solu- 
 ble in ammonia. 2. Bromides, which may be detected by 
 removing all the I from the liquid by sulphate of copper 
 and S0 2 , and testing for bromine. Iodate and carbonate 
 of potassa may be detected by their insolubility in alcohol. 
 If the iodide should be very deliquescent, KO,C0 2 may be 
 suspected. 
 
 Med. Effects. — Those of iodine generally. Used in slow 
 poisoning by mercury and lead ; which it is supposed to 
 convert in the tissues into iodides, which it afterwards 
 
CHEMISTRY OP THE ELEMENTS. 189 
 
 dissolves. May thus render mercury active, and produce 
 salivation. Dose, gr. v to xxx; has been given in ^ss 
 doses. 
 
 Incompatible s. — Mineral acids, salts of copper, lead, 
 silver, iron, manganese ; all the preparations of mercury, 
 except the red iodide — tartaric acid. 
 
 TTnguentum Potassii Iodidi, is made by rubbing up 
 gr. lx Potass. Iodid., dissolved in f^j Aquae, with 3j Adi- 
 pis. 
 
 252. Cyanide — Potassii Gyanidum — KCy. Is prepared 
 by melting together a mixture of ^viii dried ferrocyanide 
 of potassium, K 2 Cfy, and ^iij of pure carbonate of po- 
 tassa, KO,C0 2 ; iron is precipitated, and the fused mass is 
 poured off, and, when cool, broken into pieces, which must 
 be kept in well-stopped bottles. The product is a mixture 
 of KCy with cyanate of potassa, KO,CyO, and other im- 
 purities. It contains on the average not more than 50 p. 
 c. of KCy. Pure KCy in crystals may be obtained by 
 passing a current of HCy into a solution of KO,HO in 
 alcohol. 
 
 Prop. — Is a white, amorphous, deliquescent mass, of 
 an acrid taste, a smell of HCy, and irritating to the skin ; 
 it is very soluble in water, and sparingly so in alcohol. It 
 slowly evolves HCy on exposure to the air, and rapidly by 
 the action of dilute acids. Is much used as a solvent of 
 silver in photography and electro-plating. It will remove 
 nitrate of silver stains from the hands or clothing. 
 
 Med. Effects. — Those of HCy ; is uncertain, and rarely 
 administered internally. Cases of poisoning by it are not 
 unfrequent. The stomach should be evacuated, and the 
 antidotes for HCy administered. 
 
 253. Ferrocyanide, K 2 Cfy-f 3HO ; Potassii Ferrocyani- 
 dum ; yellow prussiate of potash. 
 
 Prep. — On the large scale by heating refuse animal 
 
190 MEDICAL CHEMISTRY. 
 
 matter containing N, with pearlash and scrap iron in an 
 iron vessel. May be made by digesting iron filings with 
 KCy. 
 
 Prop. — Large, transparent, lemon-yellow crystals, square 
 octohedra (2d system) ; inodourous, of a sweetish saline 
 taste ; soluble in about 4 parts of cold and one of boiling 
 water ; insoluble in alcohol. Loses its water of crystalli- 
 sation at 126°, and becomes white. Is valuable as a test; 
 used as a source of HCy and KCy ; also in the manufac- 
 ture of Prussian blue, Fe 4 Cfy 3 , and in dyeing. Is not poi- 
 sonous, and is rarely used in medicine. 
 
 Ferricyanide of potassium, K 3 Cfdy, red prussiate of 
 potash (237), occurs in ruby red, inflammable crystals (2d 
 system), soluble in 4 parts water. Is used as a test and 
 in dyeing, but not in medicine. Sulphocyanide of potas- 
 sium, KC 2 NS 2 , made by digesting the cyanide with sul- 
 phur, is used as a test. It exists in the saliva of man 
 (236). 
 
 254. Nitrate, KO,N0 5 , Potassae Nitras, Nitre, Saltpetre. 
 
 Prep. — May be made by adding HO,N0 5 to KO,HO 
 or KO,C0 2 . Exists in many caves in the southwest por- 
 tion of the United States, also in India, Egypt, Peru, and 
 many parts of Europe. Is formed artificially on the large 
 scale in nitre beds. 
 
 N and combine directly under the influence of the electric 
 spark; indirectly, when in the nascent state (143), especially 
 when in the presence of a powerful base, or when absorbed by 
 porous bodies (121). Thus charcoal exposed to the effluviae of 
 sewers contains nitrates from the combustion of ammonia. The 
 researches of Kuhlmann on the influence of platinum sponge 
 have shown that any gaseous compound of N, in excess of 0, 
 will produce nitric acid. 
 
 Prop. — Exists in colourless, anhydrous, hexagonal 
 prisms (6th system) ; of a sharp, cooling taste ; soluble in 
 T parts cold and its weight of boiling water ; insoluble in 
 
CHEMISTRY OF THE ELEMENTS. 191 
 
 alcohol. When fused below a red heat and cast into 
 moulds, forms sal prunelle; at a higher temperature yields 
 a part or all of its O. Is used in the manufacture of nitric 
 acid and gunpowder, also in pyrotechny. 
 
 Med. Effects. — In large doses, an irritant poison; no 
 direct antidote is known. In small doses, gr. i to x, is sup- 
 posed to be refrigerant, diuretic, and diaphoretic. Has 
 been employed in fevers, croup, asthma, rheumatism, etc. 
 Is not now much administered. Paper, soaked in a strong 
 solution, dried and lighted, burns slowly giving off fumes, 
 which when inhaled afford much relief in some cases of 
 spasmodic asthma. 
 
 255. Carbonates. 
 
 Potassse Garbonas impura, Pearlash, is obtained by 
 lixiviating the ashes of plants ; it contains many impu- 
 rities. When mixed with its weight of cold water, it dis- 
 solves, leaving most of these behind, and on evaporation 
 gives : — 
 
 Potassse Garbonas, KO,C0 2 . A white granular deli- 
 quescent body of nauseous taste and alkaline reaction. 
 Is not quite pure. 
 
 Potassse Garbonas pur a, Salt of tartar. Is made by 
 heating and then igniting the bicarbonate. Was formerly 
 prepared by heating cream of tartar, whence its popular 
 name. In its properties it resembles the last-named salt. 
 
 Potassse Bicarbonas, KO,C0 2 -f-HO,C0 2 , or KO,HO, 
 2C0 2 . 
 
 Prep. — Is made by passing a current of C0 2 through 
 a solution of ^xlviii of Potass. Garb, dissolved in Aq. Des- 
 tillat. Ox until no more is absorbed. The solution is fil- 
 tered and evaporated at a temperature not exceeding 160°. 
 
 Prop. — Transparent crystals (3d system), soluble in 4 
 parts of cold water ; when the solution is boiled, a portion 
 of C0 2 is given off. It is free from impurities which are 
 
192 MEDICAL CHEMISTRY. 
 
 left behind during nitration and crystallisation. It may 
 contain a portion of unsaturated carbonate, in which case 
 it will give a brick-red precipitate with a solution of cor- 
 rosive sublimate. Sal aeratus is the older name for the 
 bicarbonate, but is now usually applied commercially to a 
 powder containing a portion of unsaturated carbonate. 
 The bicarbonate is less disagreeable, irritating, and alka- 
 line than the carbonates, and being pure is used in making 
 many of the other preparations of KO. At a red heat it 
 loses HO and C0 2 and becomes KO,C0 2 . 
 
 Med. Effects. — The carbonates of potassa, dose gr. x 
 to xxx, are antacid, used in gout, rheumatism, lithiasis, etc. 
 They are incompatible with all acids, acidulous salts, and 
 those of the metals generally. 
 
 256. Oxalates. — Oxalic acid forms with KO: (1) Neutral 
 oxalate of potassa, KO,C 2 3 -f HO ; (2) Binoxalate, KO, 
 2C 2 3 +HO, found in certain plants, as Rumex, oxalis ace- 
 tosella, and garden rhubarb; (3) Quadroxalate, KO,4C 2 3 -f 
 7HO. The two latter are sold as Salts of sorrel, or Salt 
 of lemons, and are used for removing iron mould and ink 
 stains. They possess the poisonous properties of oxalic 
 acid (210). 
 
 257. Sulphate, KO,S0 3 , Potassae sulphas. — May be made 
 by the action of HO,S0 3 on those salts of KO which it de- 
 composes. Is a residue from making nitric acid on the large 
 scale. Is in hard anhydrous crystals (6th system), soluble 
 in 10 parts water. Is purgative, but rarely used in medi- 
 cine ; from their hardness the crystals are employed in 
 making Dover's powder, serving to comminute and inter- 
 mingle the Ipecac, and Opium ; from the same property 
 when undissolved they may act as an irritant poison. Bi- 
 sulphate of potassa, KO,S0 3 +HO,S0 3 , or KO,HO,2S0 3 , 
 is a residue after making HO,N0 5 on the small scale, has 
 an acid reaction, is soluble in two parts water ; is used to 
 
CHEMISTRY OF THE ELEMENTS. 193 
 
 adulterate cream of tartar. By dissolving Jj each of this 
 salt and Potass, carb. pura separately in water, and then 
 mixing them, a cheap, effervescent, purgative draught is 
 obtained. 
 
 258. Chlorate, KO,C10 5 ; Potassa Chloras. 
 
 Prep. — (1) By passing a current of CI through a weak 
 solution of KO,HO; 6KO + Cl 6 =KO,C10 5 -f 5KC1. (2) By 
 the reaction of KC1 and 3(CaO,C10)=KO,C10 5 +3CaCl. 
 The chlorate is separated by crystallisation. 
 
 Prop. — In flat, pearly, tabular anhydrous crystals (5th 
 system), having but little taste, soluble in 20 parts cold 
 and 2 boiling water. Gives up all its at a red heat, 
 and deflagrates even more violently than the nitrate. 
 Strong acids liberate C10 4 , which is yellowish and explo- 
 sive. Rubbed with powdered sulphur, explosion ensues ; 
 this should be borne in mind in dispensing it. 
 
 Med. Effects. — Passes unchanged into the urine ; has 
 been successfully employed internally and locally in various 
 throat affections, cancrum oris, ptyalism, aphthae, scarla- 
 tina, diphtheria, etc. Dose, gr. x to xxx. Is only decom- 
 posed by strong acids. Should give no precipitate with 
 AgO,N0 5 (absence of chloride). 
 
 259. Acetate, KO,C 4 H 3 3 , Potassse Acetas, Sal diureticus. 
 Prep.— By saturating acetic acid with bicarbonate of 
 
 potassa, and evaporating gently to dryness. In all cases 
 of union of an acid and alkaline base, the point of satu- 
 ration may be determined approximately by the taste and 
 accurately by litmus-paper. 
 
 Prop. — A deliquescent white foliated mass, soluble in 
 one-half its weight of water and 2 parts of alcohol. It 
 should not affect test-paper; if it has been heated too 
 highly, will be alkaline from the loss of the volatile acetic 
 acid. It should be entirely soluble in water and alcohol ; 
 this test shows the absence of ordinary impurities. 
 17 
 
194 MEDICAL CHEMISTRY. 
 
 Med. Effects. — Is a powerful diuretic gr. x to xxx, and 
 cathartic 3] to ^iij. Used in dropsy, skin diseases, and 
 rheumatism. It renders the urine alkaline. As it is 
 easily decomposed, should be given alone in solution in 
 water. May be made extemporaneously by saturating 
 weak vinegar with sal aeratus or salt of tartar ; 3j to ^ij 
 of the latter being used for a dose as a cathartic. 
 
 TARTRATES. 
 
 260. Potassse Bitartras, KO,HO,C 8 HAo, or KO,HO,T.* 
 Cream of tartar, acid tartrate of potassa. 
 
 Prep. — Occurs impure as Argols, a reddish or dirty 
 white deposit in wine-casks. This is purified by solution 
 in boiling water and recrystallisation. 
 
 Prop. — Hard gritty crystals (3d system), soluble in 
 184 parts cold and 18 of boiling water, of a slight agree- 
 able acid taste. Is entirely decomposed by heat, leaving 
 charcoal and pure KO,C0 2 . Its slight solubility should be 
 borne in mind in prescribing. The addition of 4 part by 
 weight of borax will render cream of tartar soluble in 16 
 parts of boiling water, and it will not deposit on cooling. 
 When sold in powder, is very apt to be adulterated ; should 
 be bought in crystals. 
 
 Chem. and Med. Effects. — Tartaric acid is bibasic ; in 
 cream of tartar but one equivalent of the basic water is re- 
 placed by a base, it has therefore acid properties. By re- 
 placing the second eq. of water with KO, we get neutral 
 tartrate, Soluble tartar; with NaO, Eochelle salt, with 
 Fe 2 3 , Ferri et Potassse Tartras, and with Sb0 3 tartar 
 emetic. Cream of tartar is cathartic, diuretic, and re- 
 frigerant. Used in dropsy, sj to ^iij t. d., as a hydragogue 
 
 * Compounds of the acids generally regarded as organic with the inor- 
 ganic bases will be considered with the latter, as more convenient. The 
 organic acids are conventionally represented by their initial letter with a 
 dash over it. 
 
CHEMISTRY OF THE ELEMENTS. 195 
 
 and diuretic. Its solution, made with boiling water- and 
 allowed to cool, forms a laxative and cooling drink. Is 
 incompatible with alkalies, alkaline earths, and their car- 
 bonates ; sulphides, acetate of lead. 
 
 Potassse Tartras, 2KO,C 8 H 4 O 10 ; Soluble tartar. 
 
 Prep. — By boiling ^xvi Potass, carb. with ^xxvi pow- 
 dered Potass. Bitart. in Oj Aquae bullient., the cream of 
 tartar being gradually added to saturation. The solution 
 is evaporated and crystallised, KO,HO,T-f KO,C0 3 = 
 2KO,T_ > +C0 2 t. 
 
 Prop. — White, neutral, slightly deliquescent crystals 
 (4th system), soluble in one part cold and one-half of boil- 
 ing water j insoluble in alcohol. Is decomposed by heat 
 like the bitartrate. Its taste is saline and bitter. Is pur- 
 gative ; dose, 3j to gj ; but little used ; is incompatible 
 with the mineral acids and the salts of lime, baryta, and 
 lead. 
 
 Potassse et Sodse Tartras, KO,NaO,C 8 H 4 O 10 , Rochelle 
 or Seignette salt. Made as the last preparation, using 
 ^xii Sodse Carbonatis instead of Potass. Carb., KO,HO, 
 T+NaO,C0 2 =KO,NaO,T_^+C0 2 t . 
 
 Prop. — Large, transparent, prismatic, slightly efferves- 
 cent crystals (3d system) ; soluble in 2 J parts of cold 
 water ; taste saline and slightly bitter ; is among the least 
 offensive of the salines. Should be neutral to test-paper, 
 and give no precipitate with BaCl (absence of sulphates), 
 or AgO,N0 5 (absence of chlorides). 
 
 Med. Effects. — Laxative gj; purgative ^ss to § j ; may 
 be administered with tartar emetic ; renders the urine 
 alkaline when absorbed. Incompatibles, those of the tar- 
 trate. Is largely employed in the form of: — 
 
 Pulveres Effervescentes Aperientes — Seidlitz powders. 
 (1) R Sodas Bicarb, pulv. aj, Potassse et Sodas Tartrat. 
 ^iij, TT[ et ft. chart. No. xii; wrap in blue paper. (2) R. 
 
196 MEDICAL CHEMISTRY. 
 
 Acid. Tartaric, pulv. gr. ccccxx, ft. chart. No. xii ; wrap 
 in white paper. The blue and white papers are dissolved 
 separately in water, mixed, and the draught swallowed in 
 a state of effervescence. Much less water is required for 
 the white than for the blue packet. For a cheap substi- 
 tute, see bisulphate of potassa. 
 
 Remarks. — The blue paper contains gij Rochelle salt 
 with gr. xl of sodde bicarb.) the white paper, gr. xxxv 
 acid, tartaric. When mixed, the free acid unites with the 
 soda of the bicarbonate, liberating C0 2 , and forming tar- 
 trate of soda. They should be kept dry. 
 
 261. Citrate, 3KO,C 12 H 5 O ]0 ; Potassae Citras. 
 
 Prep. — By dissolving acid, citric. %x in Oij aquae des- 
 iillat., and adding gradually %xiv potassae bicarb. When 
 effervescence has ceased, filter and evaporate to dryness 
 with constant stirring. 
 
 Prop, and Med. Effects. — A granular white powder, of 
 a saline, slightly bitter taste, deliquescent and very soluble 
 in water ; insoluble in alcohol. By heat yields C and KO, 
 C0 2 . As above prepared, is quite pure. Is esteemed re- 
 frigerant and diaphoretic ; much used in fevers. 
 
 Liquor Potassae Citratis. R. Acid. Citric, ^ss, Potassae 
 Bicarb, gr. cccxxx, Aquae Oss, solve et cola.* A conven- 
 ient extemporaneous form. Dose, a tablespoonful. 
 
 Mistura Potassae Citratis, neutral mixture. R. Succ. 
 Limonis recentis Oss ; Potass. Bicarb, q. s. ad saturitat. ; 
 cola. This is a more agreeable preparation than the last, 
 having the flavour of the fresh lemon-juice, and retaining 
 some of the liberated carbonic acid. In practice the juice 
 of one lemon is allowed to a f ^yj mixture, and is not quite 
 neutralised. Dose, a tablespoonful. 
 
 * Cola, strain; in this case through muslin. 
 
CHEMISTRY OP THE ELEMENTS. 197 
 
 SODIUM, Na=23. 
 
 Syllabus op Preparations. 
 
 Hydrate, NaO,HO ; Liquor Sodae. 
 
 Chloride, NaCl ; Sodii Chloridum. 
 
 Nitrate, NaO,N0 5 ; Cubic nitre. 
 
 Carbonates: (a) Sodae Carbonas, Sal Soda, NaO,C0 2 
 -f-lOHO; (6) Sodae Carbonas Exsiccata, NaO,C0 2 ; (c) 
 Sodae Bicarbonas, NaO,C0 2 +HO,C0 2 , or NaO,HO,2C0 2 , 
 Pulveres Effervescentes. 
 
 Sulphate, NaO,SO 3 +10HO; Sodae Sulphas, Glauber's 
 salt. 
 
 Sulphite, NaO,S0 2 +3HO, Sodae Sulphis; Bisulphite, 
 NaO,HO,2S0 2 ; Hyposulphite, NaO,S 2 2 +5HO. 
 
 Phosphates ; Sodae Phosphas, 2NaO,HO,P0 5 +24HO ; 
 Sal perlatum. 
 
 Hypochlorite, NaO,C10-f NaCl; Liquor Sodae Chlo- 
 rinates, Labarraque's solution. 
 
 Borate, NaO,2B0 3 ; Sodae Boras, Borax. 
 
 Silicates. 
 
 Acetate; Sodae Acetas, NaO,C 4 ,H 3 3 -f 6HO. 
 
 Valerianate, NaO,C 10 H 9 O 3 ; Sodae Valerianas. 
 
 262. Nat. Sources. — Common salt, certain plants and 
 minerals ; see Carbonate of Soda. Abundant in animal 
 forms. 
 
 Prep. — From carbonate of soda by reduction with C. 
 
 Prop. — Resembles K, but is less easily oxidised; in 
 dry air forms a crust which preserves the metal within ; 
 does not take fire on water unless the latter be warm or 
 the metal prevented from moving about. Is soft, silvery, 
 s. g. 0.97; melts at 20*7°, and gives a colourless vapour at 
 a white heat. It burns with a characteristic yellow flame. 
 17* 
 
198 MEDICAL CHEMISTRY. 
 
 Chem. Bel. — With forms soda, NaO, and Na0 2 ; its 
 compounds correspond with those of K in most respects, 
 are generally more soluble. Its salts are colourless and 
 all soluble. Its presence is determined by exclusion (174), 
 by the yellow colour communicated to flame, by its salts, 
 and by its characteristic yellow line in the spectroscope. 
 
 263. Hydrate, NaO,HO. 
 
 Liquor Sodee, solution of caustic soda, is made in the 
 same manner as Liq. Potassae ; the proportions of (crystal- 
 lised) carbonate of soda and of lime are %xxvi of the former 
 to ^viii of the latter; s. g. of the solution 1*0T1, and it 
 contains 5 - 7 p. c of KO,HO. The solid hydrate is largely 
 sold as concentrated lye; is used as a powerful detergent 
 and in soap-making. 
 
 264. Chloride, NaCl, Sodii Ghloridum, Chloride of So- 
 dium, Common Salt, NaCl. 
 
 Prep. — Is obtained from sea-water, salt springs, or salt 
 mines (rock-salt) in which it exists native. Sea-water 
 (188) or that of salt springs is evaporated, until the 
 greater part of the NaCl crystallises out; the mother 
 liquor, holding in solution the more soluble salts, as the 
 Chloride of Magnesium, MgCl, the Sulphate of Soda, 
 NaO,S0 3 , etc., is drawn off, constituting bittern. 
 
 Prop, and Med. Effedfe. — Anhydrous cubes (first sys- 
 tem) ; of a well-known, agreeable taste ; when pure, does 
 not alter in the air; soluble in about 3 parts water; the 
 solubility is not increased by heat. In small doses, is 
 tonic and anthelmintic; in large ones, emetic and purga- 
 tive; used in haemoptysis. Is the antidote to Nitrate of 
 Silver. 
 
 Impurities. — Insoluble matters, Chlorides of Calcium 
 and Magnesium, Sulphates of Soda and Lime. 
 
 Incompat. — Strong Sulphuric Acid, NO,S0 3 , Nitrate of 
 Silver, AgO,N0 5 , Nitrate of Mercury, HgO,N0 5 , soluble 
 lead salts. 
 
CHEMISTRY OP THE ELEMENTS. 199 
 
 265. Carbonates. 
 
 Sodce Carbonas, NaO,CO 2 +10HO, Sal Soda, Washing 
 Soda. 
 
 Sources. — (1) Native carbonate natron is found in Hun- 
 gary, Egypt, South America, and California. It is irregu- 
 lar in composition. (2) Barilla, the ashes of the salsola 
 soda and other plants growing near the sea. (3) Kelp, 
 the ashes of sea-weed. (4) Artificially from common 
 salt, NaCl, or cryolite, 3NaF+Al 2 F 3 . 
 
 Prep. — (1) From common salt (Le Blanc's process). 
 The salt is first converted into sulphate (salt-cake), NaCl+ 
 HO,S0 3 =NaO,S0 3 +HCl. This is mixed with powdered 
 limestone and coal made into balls and heated in a rever- 
 beratory furnace. The black mass resulting is lixiviated 
 with hot water, the solution evaporated to dryness and 
 again calcined with sawdust. The mass is again lixivi- 
 ated and crystallised. 
 
 The reaction is complex and variable. It is essentially NaO, 
 SOg+^ + CaO^O^NaO^Oa+CaS-J^CO. An excess of lime 
 is used, and there is formed in addition some oxy-sulphide of 
 calcium, CaO,3CaS. 
 
 (2) From cryolite, 3NaF-fAl 2 F 3 . This mineral is 
 found abundantly in Greenland. It is mixed thoroughly 
 with powdered chalk and calcined, 3NaF-f Al 2 F 3 -f 6(CaO, 
 C0 2 )=6CaF-f 3NaO-f A1 2 3 . The soda remaining in so- 
 lution is converted into carbonate by a stream of C0 2 , the 
 liquid drawn off and crystallised. 
 
 Prop. — In colourless, efflorescent, oblique rhombic 
 prisms (4th system) ; of an alkaline reaction and harsh, 
 disagreeable taste ; soluble in half its weight of cold water 
 and gi 3d at 9T0; its solubility decreases above this point; 
 is insoluble in alcohol. When heated, the crystals melt 
 in their water of crystallisation; this is driven off, and 
 finally the salt melts. The crystals contain about 60 p. c. 
 of water. 
 
200 MEDICAL CHEMISTRY. 
 
 Med. Effects. — In large doses, an irritant poison; anti- 
 dotes : weak acids and oily matters. In medicinal doses, 
 gr. x to xx, those of Potass, carb. Is used externally as a 
 detergent in skin diseases. Is incompatible with acids, 
 acidulous salts, those of the metals generally, lime water, 
 CaO,HO, and muriate of ammonia, NH 4 C1. 
 
 Sodae Carbonas Exsiccata is made by heating Sodae 
 carb., stirring constantly until dried. It is used for 
 making into pills and as a blowpipe reagent. Dose, gr. v 
 to XV. 
 
 Sodae Bicarbonas, XaO,HO,2C0 2 , Supercarbonate of 
 soda, Soda sal aeratus. 
 
 Prep. — Bypassing C0 2 over Sodas Carbonas conven- 
 iently placed on perforated wooden shelves. The water of 
 crystallisation runs off, and the crystals become opaque 
 and powdery. 
 
 Prop, and Med. Effects. — A white powder of an alka- 
 line taste and reaction; soluble in 13 parts cold water; is 
 converted by boiling water into sesquiearbonate, 2XaO, 
 3C0 2 . It is used in the same cases as the Potass. Bicarb, 
 in the preparation of Seidlitz powder (260), and of the 
 Pulveres effervescentes, soda powders. These form a 
 convenient, extemporaneous substitute for soda water, 
 Aqua acidi carbonici (208). The blue papers contain gvj 
 of Sodae Bicarb, in fine powder, and the white, £v of 
 Acid. Tartaric, each divided into 12 packets. These are 
 dissolved separately in water, mixed and swallowed in a 
 state of effervescence. One or two constitute a dose. 
 Tartrate of soda is formed. 
 
 266. Sulphate, XaO,SO 3 +10HO; Sodae Sulphas, Glau- 
 ber's salt, Sal mirabile, Salt cake. 
 
 Prep. — By the action of sulphuric acid upon common 
 salt (265). Is a residue in the manufacture of HC1, and 
 other chemical processes. 
 
CHEMISTRY OF THE ELEMENTS. 201 
 
 Prep. — Long colourless, efflorescent, hexagonal prisms, 
 (6th system), of a saline, bitter taste. Soluble in 5 parts 
 cold water and 2 at 91°, which is its temperature of maxi- 
 mum solubility. The crystals contain T5 p. c. water in 
 which they readily melt by heat and lose entirely in dry 
 air at common temperatures. Is purgative, but is rarely 
 used in medicine. 
 
 26 t Sulphite, Sodse Sulphis, NaO,S0 2 + 3HO. 
 
 Prep. — By passing a current of S0 2 through a solution 
 of NaO,C0 2 until all the C0 2 is given off, evaporating the 
 solution and crystallising. 
 
 Prop. — White prismatic crystals (3d system) having a 
 slightly alkaline reaction; soluble in 4 parts of cold and 
 their weight of boiling water. The solution has a char- 
 acteristic odour. The salt on exposure to the air gradually 
 absorbs 0, becoming sulphate ; on the addition of acids, S0 2 
 is evolved. By passing S0 2 through the solution of NaO, 
 C0 2 to saturation, a bisulphite, NaO,HO,2S0 2 , is formed, 
 which has an acid reaction and the smell and taste of S0 2 , 
 which it evolves on exposure to the air. 
 
 Med. Effects. — Those generally of S0 2 . Is used ex- 
 ternally in skin diseases, and internally in zymotic affec- 
 tions. Dose, 3j t. d. The hyposulphite, NaO,S 2 2 -f-5HO, 
 is officinal in the British Pharmacopoeia. It is in large, 
 colourless, prismatic crystals (3d system), soluble in rather 
 more than half its weight of water at 60°, and insoluble 
 in alcohol. It is used in the arts as a solvent of silver 
 compounds. It is given in the same cases as the sulphite. 
 Dose, gr x to xx t. d. 
 
 268. Phosphates. 
 
 Bern. — The peculiarities of P0 5 in combining with one, 
 two, or three eq. of water or a base, and the numerous salts 
 thus formed, have already been discussed (220). Of the 
 phosphates of soda there named but one is officinal : — 
 
202 MEDICAL CHEMISTRY. 
 
 Sodas Phosphas, 2NaO,HO,P0 5 +24HO, Sal perlatum, 
 tasteless purging salt, rhombic phosphate of soda. 
 
 Prep. — By saturating the excess of P0 5 in superphos- 
 phate of lime (obtained by treating calcined bones with 
 HO,S0 3 ) with NaO,C0 2 ; 2NaO,HO,P0 5 is formed and 
 crystallised out. 
 
 Prep, and Med. Effects. — Large, colourless, efflorescent, 
 oblique rhombic (4th system) crystals ; they have a taste 
 resembling NaCl, are soluble in 4 parts cold and 2 of 
 boiling water ; insoluble in alcohol. When gently heated, 
 the salt loses its water of crystallisation, and at a red heat 
 its basic water, becoming pyrophosphate, 2NaO,P0 5 . The 
 tribasic salt gives a yellow, the bibasic a white, and the 
 monobasic, metaphosphate NaO,P0 5 , also a white precipi- 
 tate with AgO,N0 5 . Is purgative. Dose, 3j to 3jj. Prom 
 the similarity of its taste to common salt may be given in 
 broth or soup. 
 
 269. Hypochlorite,NaO,C10+NaCl; Liquor Sodas Chlo- 
 rinates; Labarraque's solution. 
 
 Prep. — Dissolve ^xxiv Sodas Carb. in Oiij Aquas; to 
 this add %x\i Calcis Chlorinates (291) mixed smoothly 
 with water ; then add enough water to make Oxii. Shake 
 well and set aside for 24 hours ; decant the clear liquid 
 and drain the precipitate on a muslin strainer, adding 
 water if necessary, until the whole amount of liquid is 
 Oxiss. Keep in a well-stoppered bottle excluded from the 
 
 light. CaO,C10+ CaCl f 2(NaO,COO=Na0^10+NaC"C 
 -f-2(CaO,C0 2 ). In the proportions of the U. S. P. given 
 
 above, there is an excess of NaO,C0 2 , which renders the 
 solution more permanent. 
 
 Prep, and Med. Effects. — A transparent solution having 
 slightly the colour and smell of CI, which it evolves with a 
 little C0 2 , on the addition of HC1; it bleaches and deodour- 
 ises. Is one of the most elegant, permanent, and manage- 
 
CHEMISTRY OP THE ELEMENTS. 203 
 
 able of the chlorine solutions. Used in scarlatina and 
 other anginose affections. Dose, gtt x to xxx; externally, 
 is largely used in gargles and lotions to ulcerated and 
 offensive parts, also in chronic skin diseases and as a gen- 
 eral deodouriser. 
 
 270. Borate, NaO,2BO 3 +10HO, Sodse Boras, Borax. 
 
 Prep. — Occurs native and is made by the addition of 
 native boracic acid, B0 3 , to soda. 
 
 Prop. — A white, crystalline salt (3d system), soluble 
 in 12 parts cold and 2 of boiling water; taste, sweetish 
 alkaline ; reaction, alkaline ; exposed to the air, effloresces ; 
 contains ordinarily 10 eqs. water of crystallisation, in 
 which it fuses at a moderate heat ; at a higher heat, loses 
 its water of crystallisation and fuses, forming, when cool, 
 glass of Borax -j glass of borax dissolves most metallic 
 oxides, which colour it ; hence its use in blowpipe analysis. 
 Is a biborate of soda. 
 
 Med. Effects. — Refrigerant and diuretic; has the pro- 
 perty of rendering cream of tartar freely soluble in water. 
 Dose, gr x to xxx. Generally used, rubbed up with sugar 
 and honey, as a mild astringent in aphthous sore mouth 
 of children. (Mel Sodce boratis, U. S. P.) 
 
 The silicates of soda will be considered under Glass. 
 
 2U. Acetate, NaO,C 4 H 3 3 +6HO; SodseAcetas. Prep.— 
 By saturating Sodce bicarb, with Acid, acetic. Prop. — 
 Long, white, efflorescent, striated prisms (4th system), solu- 
 ble in 3 parts of cold water and 40 of alcohol. When heated, 
 the salt melts in its water of crystallisation and is finally 
 decomposed into C and JSFaO,C0 2 . It resembles acetate of 
 potassa in medical properties ; dose, gr xx to gr cxx. 
 
 272. Valerianate, NaO,C 10 H 9 O 3 ; Sodse Valerianas.— 
 Prep. — Is made by saturating Yalerianic acid, HO,C, 
 H 9 3 , obtained by tne action of bichromate of potassa, 
 KO,2Cr0 3 , on Fusel oil, C 10 H n O,HO(414). Is not admin- 
 
204 MEDICAL CHEMISTRY. 
 
 istered in medicine, but is used for the preparation of 
 the valerianates of zinc, morphia, and quinia. 
 
 273. Lithium, Li=T. — Is a rare metal found in combina- 
 tion in Spodumene, Petalite, and in certain mineral waters. 
 Is obtained by the electrolysis of its fused chloride. Is 
 the lightest solid body known, s. g. - 594. Its carbonate, 
 officinal as Lithiae Carbonas, is a white powder soluble in 
 100 parts of cold water and communicating a red tinge to 
 flame. It is antacid, used in lithic diathesis, gout, etc. ; 
 may be given in solution in Aquae Acid. Carbonic. It is 
 distinguished from strontia by the solubility of its salts 
 in HO,S0 3 . 
 
 AMMONIUM, NH 4 =18. (Hypothetical.) 
 
 Syllabus. 
 
 Oxide, NH 4 0, Ammonia ; (a) Aqua Ammonias fortior ; 
 (6) Aqua Ammonias; (c) Linimentum Ammonias; (d) 
 Bpiritus Ammonias; (e) Spiritus Ammonias aromaticus 
 (contains carbonate also). 
 
 Chloride, NH 4 C1, Ammonias Murias, Sal Ammoniac. 
 
 Carbonates, Ammonias Carbonas, 2NH 4 0,3C0 2 ; Bicar- 
 bonate. 
 
 Nitrate, ]S T H 4 0,lSr0 5 . 
 
 Sulphate, NH 4 0,S0 3 , Ammonias Sulphas. 
 
 Sulphur Salt, NH 4 S,HS, Sulphydrate of Ammonia. 
 
 Acetate, NH 4 0,C 4 H 3 3 , Liquor Ammonias Acetatis, 
 Spirit of Mindererus. 
 
 Valerianate, NH 4 O,C 10 H 9 O 3 , Ammonias Valerianas. 
 
 214. Remarks. — N and H combine in the nascent state, 
 especially when the latter is in excess, to form a gaseous 
 body, Ammonia, which when dry yields, on analysis, NH 3 . 
 This body combines with hydrated acids to form well- 
 marked saline compounds, which however always contain 
 
CHEMISTRY OF THE ELEMENTS. 205 
 
 an equivalent of water. Thus NH 3 -fHO,S0 3 =NH 3 HO, 
 S0 3 . It is assumed from analogy with other bases that 
 this water is essential, and that ammonia as a base has 
 the formula NH 4 0==NH 3 ,HO ; the sulphate would then 
 be, NH 4 0,S0 3 , analogous to that of KO or JSaO. NH 4 
 has never been isolated. Chemists also suppose the ex- 
 istence of NH imidogen, and NH 2 amidogen, hypothetical 
 bodies. The fact of the formation of an amalgam in 
 which NH 4 may be supposed to exist lends support to 
 the above view which is adopted as convenient and prob- 
 ably correct. 
 
 Ammonium Amalgam. — (1) When mercury is connected 
 with the negative (zinc) pole of a voltaic battery in a 
 solution of ammonia, it swells, becomes pasty, and assumes 
 the characters of an amalgam. O is given off at the -f 
 pole, but there is no corresponding evolution of H at the 
 — pole until the current is interrupted ; the amalgam then 
 speedily decomposes, yielding mercury, ammonia, and H 
 (2) When an amalgam of sodium and mercury is thrown 
 into a saturated solution of sal ammoniac, N H 4 C1, it in- 
 creases to several hundred times its original bulk and has 
 the characters and undergoes the changes mentioned above 
 The following reaction is supposed to take place : NaHg-f- 
 NH 4 Cl==NH 4 Hg + NaCl. This hypothetical metal NH„ 
 ammonium, resembles in its chemical relations KO and 
 NaO. Its salts are all volatile or decomposed by heat ; 
 they may be recognised by the evolution of gaseous am- 
 monia, NH 4 0, upon the addition of lime or caustic alkali. 
 
 2?5. Ammonia, NH 4 0. 
 
 Sources. — Is formed during the destructive distillation 
 of orgajiie matters containing or in the presence of N; 
 also during putrefaction, the decomposition of the cyanides, 
 the rusting of iron, and the action of dilute HO,N0 5 upon 
 certain metals. Is prepared upon the large scale from the 
 18 
 
206 MEDICAL CHEMISTRY. 
 
 liquor obtained from the hydraulic main, washers, and con- 
 densers of gas-works. This is neutralised with HO,S0 3 , 
 which fixes the ammonia, and on evaporation NH 4 0,S0 3 
 is crystallised out. From this the other compounds may 
 be obtained. By using HC1, NH 4 C1 is obtained directly. 
 
 Prep. — On the large scale by heating the crude sulphate 
 with milk of lime, NH 4 0,S0 3 +CaO,HO==NH 4 0,HO+ 
 CaO,S0 3 . The gas is absorbed by water kept cold. It 
 may be prepared on, the small scale by heating its solu- 
 tion Aqua Ammoniae. It must be collected over mercury 
 or by displacement, in the latter case the delivery tube 
 passing to the top of the receiver. 
 
 Prop. — A colourless, irrespirable gas, s.g. 59T ; liquid 
 at — 40°, or by a pressure of 6 atmospheres at 40° ; solid 
 at — 103°. It will burn in air if a light be held in a jet 
 of the gas, and in CI. Has a powerful alkaline reaction, 
 hence termed volalile alkali. Water at 32° absorbs 1000 
 vols. (Bunsen); at 50°, 610 vols., increasing in bulk about 
 two-thirds. It is also soluble in alcohol. The strongest 
 solution in water has a s.g. 0*815, and contains 325 p. c. 
 of liquid ammonia. This boils at 130°, giving up the gas, 
 and gelatinises at — 40°. 
 
 216. Officinal Forms. 
 
 (a) Aqua Ammoniae Fortior, s.g. '900, contains 26 p. c. 
 of the gas ; it gradually becomes weaker from the escape 
 of the gas, and should be kept in a cool place in well-stop- 
 pered bottles. Is too strong for medical use. Vesicates 
 rapidly when held in contact with the skin; is an irritant 
 poison ; antidotes, weak acids and oils. When its vapour 
 is inhaled it produces much irritation, which may be re- 
 lieved by the steam of vinegar. Its incompatibles are 
 those generally of potassa and soda. 
 
 (b) Aqua Ammonias. Prep. — By heating a mixture of 
 sal ammoniac and lime in excess ; the gas is absorbed by 
 
CHEMISTRY OF THE ELEMENTS. 201 
 
 distilled water, NH 4 Cl+CaO=NH 4 6+CaCl_ > . In the 
 officinal process the lime is slaked and made into a paste 
 with water, which is further diluted before the addition of 
 the NH4CI ; the process on the moderate scale is thus much 
 facilitated. It contains about 10 p. c. of ammonia. 
 
 Prop. — A colourless liquid, s. g. 0*959, having the smell 
 and properties of ammonia. When neutralised with acetic 
 acid, should not precipitate with carbonate of ammonia, 
 2NH 4 0,3C0 2 (absence of lime, etc.), nitrate of silver, AgO, 
 N0 5 (absence of chlorides), or chloride of barium, BaCl 
 (absence of sulphates). 
 
 Med. Effects. — In large doses an irritant poison. In 
 medicinal doses, gtt x to xxx, stimulant and antacid. Is 
 administered and applied externally in snake-bites and 
 stings of insects. Its vapour is inhaled in syncope and 
 suspended animation. Is applied externally in burns and 
 scalds, and as a rubefacient and vesicant. 
 
 (c) Linimentum Ammonias, volatile liniment, is made 
 by mixing f^j Aquae Ammonias with ^ij Olei Olivae. 
 
 (d) Spiritus Ammonias. Prep. — By passing ammonia 
 into alcohol; the strength is that of aqua ammonias. Is 
 rarely used internally ; it may be added to alcoholic lini- 
 ments without decomposing them. 
 
 Spiritus Ammonias Aromaticus. Prep. — By dissolving 
 3j Ammonias Carbonatis in f^iij Aquas Ammonias, pre- 
 viously mixed with f ^iv Aquas; to this is added a solution 
 in Alcohol Oiss, of 01. Limonis f^iiss, 01. myristicas tyxl, 
 01. Lavandulae ^xv, and Aquas q. s. ad Oij. 
 
 Prop. — An agreeable stimulant, aromatic antacid ; 
 dose, gtt xxx to f^j, diluted. Incompatible with acids, 
 acidulous and metallic salts. It probably contains neutral 
 carbonate of ammonia, NH 4 0,C0 2 . 
 
 211. Chloride, NH 4 C1 5 ; Ammonia Murias, Sal ammo- 
 niac. 
 
208 MEDICAL CHEMISTRY. 
 
 Prep. — By subliming a mixture of common salt, NaCl, 
 and sulphate of ammonia, NaCl+NH 4 0,S0 3 =NaO,S0 3 _ > 
 +NH 4 Cl f . It may also be made by direct combination 
 of gaseous HC1 and NH 4 0, and by the action of HC1 on 
 the carbonate or on gas liquor. 
 
 Prop. — White, inodourous, translucent, fibrous salt; 
 taste pungent, saline. Soluble in three parts cold and one 
 of boiling water ; less so in ordinary alcohol. Sublimes 
 unchanged at a red heat ; very difficult to powder, unless 
 in a hot iron mortar with a hot pestle. It may be granu- 
 lated by evaporating its solution, and constantly stirring 
 as the mass thickens. Reaction slightly acid. 
 
 Med. Effects. — Alterative ; useful in hoarseness and 
 sore throat, and is in these cases usefully combined with 
 chlorate of potassa. Is given also in croup, bronchitis, 
 neuralgia, intermittents, rheumatism, and enlarged pros- 
 tate. Is applied externally to bruises. Dose, gr v to xxx. 
 
 2T8. Carbonates; Ammonise Carbonas, Carbonate of Am- 
 monia, 2NH 4 0,3C0 2 . 
 
 Prep. — Is made by subliming a mixture of NH 4 C1 and 
 chalk, 3NH 4 Cl+3(CaO,C0 2 ) = 2NH 4 0,3CO|, + 3CaCl -f 
 NH 4 0. 
 
 Prop. — White, moderately hard, translucent masses; 
 soluble in four parts cold water, and in diluted alcohol ; it 
 is decomposed by boiling water. Smell pungent, ammo- 
 niacal ; taste sharp, alkaline. Exposed to the air, it dis- 
 engages neutral carbonate of ammonia (NH 4 0,C0 2 ), and 
 becomes Bicarbonate (2NH 4 0,3C0 2 _NH 4 0,C0 2 ==NH 4 0, 
 2C0 2 ). The bicarbonate is inodourous and fixed; its crys- 
 tals resemble those of bicarbonate of potassa. A neutral 
 carbonate, NH 4 0,C0 2 , is known; it probably exists in 
 Spiritus Ammonise Aromat. 
 
 Med. Effects. — A mild preparation, possessing the thera- 
 peutical properties of ammonia. Dose, gr v. 
 
CHEMISTRY OF THE ELEMENTS. 209 
 
 Incompatibles. — Those of the soluble carbonates and of 
 ammonia. 
 
 219. The Nitrate of Ammonia is made by saturating 
 HO,N0 5 with Carbonate of Ammonia ; its crystals are 
 isomorphous with those of KO,N0 5 , which they much 
 resemble in taste and appearance. Is used as a source of 
 nitrous oxide (204). 
 
 280. Sulphate, NH 4 0,S0 3 ; Ammoniae Sulphas. Is ob- 
 tained on the large scale from gas liquor ; is not used in 
 medicine, but largely employed in the manufacture of the 
 preparations of Ammonia and in Ammonia Alum (302). 
 
 281. Sulphur Salt, NH 4 S,HS, Sulphydrate of ammonia, 
 hydrosulphuret of ammonia, bisulphide of ammonium, is 
 made by passing a current of well-washed HS through 
 Aqua Ammoniae fortior, to saturation. The solution, 
 nearly colourless at first, becomes yellow by keeping, and 
 deposits sulphur. It exists in gas liquor, sewers, privies, 
 etc. It has a foetid odour. Is of the highest importance 
 as a test, but is seldom used in medicine. It is properly 
 termed sulphydrate of sulphide of ammonium ; the sul- 
 phide of ammonium, NH 4 S, a sulphur base being united to 
 HS, a sulphur acid. 
 
 282. Phosphate. — None of the phosphates of ammonia are 
 important ; the tribasic phosphate of soda and ammonia, 
 NaO,NH 4 0,HO,P0 5 , is used as a test for magnesia and in 
 blowpipe analysis. Was formerly employed in medicine. 
 It is known as Microcosmic Salt, or Salt of phosphorus. 
 
 283. Acetate, NH 4 0,C 4 H 3 3 , Liquor Ammonice Acetatis, 
 Spirit of Mindererus. 
 
 Prep. — By saturating Acid. Acetic, dilut, (412); by 
 Carbonate of Ammonia. 
 
 Prop. — Is a colourless inodorous liquid of a saline taste, 
 and prone to change. 
 
 Med. Effects. — Is diaphoretic and diuretic; used in fevers, 
 18* 
 
210 MEDICAL CHEMISTRY. 
 
 and externally as a cooling lotion ; also as an antidote to 
 alcohol. Dose, f^ss to f^iss. Is incompatible with the 
 alkalies and alkaline earths, and the soluble salts of iron, 
 copper, zinc, mercury, and silver. 
 
 284. Valerianate, NH 4 O,Ci H 9 O 3 , Ammonise Valerianae. 
 
 Prep. — By saturating valerianic acid (414), HO,Ci 
 H 9 3 , by gaseous ammonia. 
 
 Prop. — Snow-white, pearly, flat, four-sided crystals (2d 
 system), volatilised, nearly unchanged by heat. Yery 
 soluble in water and alcohol. 
 
 Prop. — Is not poisonous; a powerful antispasmodic; 
 used in hysteria, neuralgia, etc. May be given in pill or 
 alcoholic solution ; the watery solution rapidly decomposes. 
 Dose, gr ij to viij. An elixir made by adding to the 
 watery solution, cologne water, aromatics, and syrup, is 
 much used. 
 
 CALCIUM, Ca=20. 
 Syllabus. 
 
 Oxide, CaO: (a) Calx-, Hydrate, CaO,HO. (b) Liquor 
 Calcis. (c) Linimentum Calcis. (d) Potassa cum Calce. 
 
 Chloride, CaCl: (a) Calcii Chloridum; (b) Liquor Cal- 
 cii Ghloridi. 
 
 Sulphides, CaS, CaS 2 , CaS 5 . 
 
 Fluoride, CaF, Fluor Spar. 
 
 Carbonates, CaO,C0 2 ; (a) Calcis Carbonas Prsecipi- 
 tata; (b) Greta Pr separata; (c) Testa Pr separata. 
 
 Sulphate, CaO,S0 3 +2HO, Gypsum, Selenite, Alabas- 
 ter. 
 
 Phosphate, 3CaO,P0 5 , Calcis Phosphas Prsecipitata. 
 
 Hypophosphites, CaO,2HO,PO. 
 
 Hypochlorite, CaO,C10-fCaCl-f 2B.O,Calx chlorinata, 
 Bleaching Salt, Chloride of lime. 
 
CHEMISTRY OF THE ELEMENTS. 211 
 
 285. Sources. — Abundantly, in combination, in nature 
 as carbonate in marble, Marmor, Chalk, Creta, Oyster- 
 shell, Testa, etc. ; as sulphate in Gypsum, as phosphate 
 in bones, as silicate in many minerals, as chloride in cer- 
 tain mineral springs and sea-water, and as fluoride in 
 fluor-spar. 
 
 Prep. — By electrolysis of its fused chloride. 
 
 Prop. — Resembles lead, but harder; has a yellowish 
 colour ; does not oxidise in dry air ; fusible, but not vola- 
 tile, at a red heat. Readily burns in the air with a bril- 
 liant light forming CaO. It also forms a binoxide, Ca0 2 , 
 which is not a base ; three sulphides, CaS, CaS 2 , and CaS 5 , 
 and compounds with the halogens. The Phosphide, made 
 by passing the vapour of P over red-hot lime, is brownish, 
 and when thrown into water gives spontaneously inflam- 
 mable phosphuretted hydrogen; it quietly crumbles to 
 powder in moist air. 
 
 286. Oxide, CaO, (a) Calx, Lime. 
 
 Prep. — By heating the carbonate in a current of air; if 
 heated in a close vessel, is fused and but slightly decom- 
 posed. 
 
 Prop. — A grayish- white solid; taste caustic, alkaline. 
 S. g. 2*3 ; is very refractory. Absorbs on exposure to 
 the air, water and C0 2 , and falls to powder (air-slaked 
 lime); combines with water, to form a hydrate (slaked 
 lime). When mixed in excess with water, forms milk of 
 lime (whitewash). Is sparingly soluble in water, and more 
 so in cold than in hot water. Reaction, alkaline, is caustic ; 
 a strong base. Mortar is a mixture of sand or gravel with 
 lime ; the theory of its hardening is not well understood. 
 Hydraulic mortars, which have the property of harden- 
 ing under water, contain silicate of alumina (clay). Lime 
 is much used in agriculture. It acts by neutralising acids, 
 by decomposing organic matter, by liberating potassa from 
 
212 MEDICAL CHEMISTRY. 
 
 its combination with silica in clays and other rocks, and 
 by furnishing the supply of lime compounds found in the 
 plant. 
 
 Incompatibles. — Acids, acidulous salts, soluble sulphates, 
 tartrates, carbonates; the metallic salts generally; the 
 vegetable astringents. Is the antidote to Oxalic Acid. 
 
 Test. — Oxalic acid gives a white precipitate in neutral 
 or alkaline solutions ; sulphuric acid only in concentrated 
 solutions. 
 
 (b) Liquor Calcis; Lime Water. 
 
 R. Calcis giv; Aq. Destill. Oviii. Slake the lime with 
 a little of the water, then pour on the rest. Keep in well- 
 stopped bottles over the insoluble excess of lime. Ordinary 
 soft water will answer. 
 
 Rem. — "Water at 60° dissolves about T 4 5 of lime; one 
 pint contains, at 60°, about 9-J grs. ; when heated, a por- 
 tion of the lime precipitates; the solution absorbs car- 
 bonic acid readily, and an insoluble carbonate precipi- 
 tates. 
 
 Med. Effects. — Antacid, and the compounds formed by 
 its union with the gastric acids, are astringent. Used in 
 diarrhoea, vomiting, dyspepsia, etc. ; externally as an astrin- 
 gent lotion. Dose, f^ss to f^iv. 
 
 (c) Linimentum Calcis. R. Liq. Calcis f^viii, Olei 
 Lini ^vij. M. Used in burns and scalds. 
 
 (d) Potassa cum Calce, Yienna Paste. 
 
 Prep. — Is made by rubbing together equal parts of 
 lime and caustic potassa ; is deliquescent, but less so than 
 the latter; is employed in the same cases, and is a milder 
 application. 
 
 28T. Chlorides, Calcii Chloridum, Chloride of Calcium, 
 CaCl. 
 
 Prep. — Is made by dissolving carbonate of lime in 
 hydrochloric acid. CaO,C0 2 +HCl=CaCl-f HO and C0 2 *. 
 
CHEMISTRY OP THE ELEMENTS. 213 
 
 Prop. — When anhydrous is a whitish, hard, translu- 
 cent substance, having a great attraction for moisture ; is 
 used largely as a desiccating agent, and when crystallised 
 in frigorific mixtures; taste acrid, bitter; reaction slightly 
 alkaline; soluble in about Jg its weight of water, at 60° ; 
 also in 10 parts anhydrous alcohol. The crystals contain 
 6 equivalents of water of crystallisation. 
 
 Incompat. — Those of the salts of lime, and of the 
 soluble chlorides. 
 
 Med. Effects. — Tonic and alterative ; used in solution. 
 
 Liquor Galcii Ghloridi, Solution of Chloride of Cal- 
 cium, is made by 'dissolving chloride of calcium in its 
 weight and a half of water, and filtering. Dose, gtt xxx 
 to 5j; in overdose, may produce symptoms of irritant 
 poisoning; antidotes, the carbonates or sulphates. 
 
 Carbonates. 
 
 (a) Calcis Carbonas Praecipitata. R. Liq. Galcii 
 Chlorid. Ovss; Sodse Garb, ^lxxii (ft)vi); Aq. Destill. q. s. 
 Dissolve the Sodse Garb, in Ovi Aquae; heat this solution, 
 and that of Galcii Chlorid., to the boiling-point, and mix 
 them ; allow the carbonate to subside, wash it well, and dry 
 on bibulous paper. (CaCl-f NaO,C0 2 =CaO,C0 2 -f NaCl->.) 
 
 Prop. — An insoluble white powder, smooth, and en- 
 tirely dissolved with copious effervescence in Muriatic 
 acid. May be adulterated with CaO,S0 3 , which is de- 
 tected by thus treating it. 
 
 (6) Greta Preeparata. 
 
 Prep. — Is made by the levigation and elutriation (191) 
 of ordinary chalk, by which the grosser and gritty par- 
 ticles are gotten rid of. 
 
 Prop. — Found in conical masses, smooth, and entirely 
 free from grit. 
 
 Med. Effects. — Internally, antacid and astringent; ex- 
 
214 MEDICAL CHEMISTRY. 
 
 ternally, a desiccating and soothing application. Dose, gr 
 x to xxx. 
 
 (c) Testa Preeparata. 
 
 Prep. — Is made by treating well-washed oyster-shells 
 in the same manner as chalk; does not differ from Greta 
 Preeparata, except in containing a little animal matter. 
 
 288. Sulphate, CaO,S0 3 +2HO. 
 
 Is found native, crystallised in right rhomboidal prisms 
 (4th system) as selenite, which has the power of doubly re- 
 fracting light ; fibrous as gypsum and massive as alabaster. 
 When heated it loses 20 p. c. of water, (calcined plaster, 
 plaster of Paris) with which it will again unite, forming 
 a plastic mass which soon solidifies; hence is used for 
 making casts. At a red heat becomes anhydrous and will 
 not again combine with water ; it forms the greater part 
 of the incrustations (scale) of steam-boilers. Is soluble 
 in 500 parts of cold water ; the addition of the chlorides 
 of ammonium or tin increases its solubility. Is so soft 
 as to be scratched with the nail ; s. g. 292 ; gives to water 
 permanent hardness (188). Is used in agriculture ; being 
 decomposed by the carbonates of the alkalies, it fixes the 
 ammonia which arises as carbonate from manures and 
 forms carbonate of lime, CaO,S0 3 -f NH 4 0,C0 2 =CaO, 
 C0 2 -f-NH 4 0,S0 3 . It is not employed in medicine. 
 
 289. Phosphate, 3CaO,P0 5 . 
 
 Galcis Phosphas Praecipitata. — Prep. — Dissolving cal- 
 cined bone in HC1, diluted with its bulk of water, and 
 filtering, precipitating the solution with Liq. Ammonias and 
 washing the precipitate thoroughly with boiling water. 
 
 Prop. — A white powder without taste or smell, insolu- 
 ble in water, but dissolved in HO,N0 5 , HCl,HO,P0 5 , and 
 HO,C 4 H 3 3 (acetic acid), from which it may be precipi- 
 tated unchanged by caustic alkalies. 
 
 Med, Effects. — Used in scrofula, phthisis, rachitis, and 
 
 
CHEMISTRY OP THE ELEMENTS. 215 
 
 other diseases supposed to be dependent upon a deficiency 
 of phosphates or of phosphorus in the system ; dose, gr 
 x to xxx ; is probably rendered soluble by the gastric acids, 
 or may be dissolved by the addition of the acids above 
 named. Is the basis of the so-called chemical food. 
 
 290. Hypophosphite, CaO,2HO,PO. Is prepared by 
 boiling milk of lime and P together ; inflammable phos- 
 phuretted hydrogen is evolved ; the clear liquid is decanted, 
 filtered, and crystallised. 3(CaO,HO)+P 4 +6HO=(3CaO, 
 2HO,PO,) + PH 3 (approximately). Is a pearly, white salt, 
 soluble in 6 parts cold water. Has been employed in 
 phthisis, scrofula, impotence, and other affections in which 
 phosphorus is supposed to be indicated. Dose, gr v to x 
 t. d. in water with syrup. Is not officinal. 
 
 291. Hypochlorite, Calx Ghlorinata, Bleaching Pow- 
 der, Chloride of Lime, CaO,C10+ CaCl+2HO. 
 
 Prep. — Made by the action of CI on CaO,HO; (2CaO, 
 HO)-f Cl 2 -f CaO,C10-f CaCl+2HO j should contain at 
 least 25 per cent, of chlorine. 
 
 Prop. — Grayish-white powder ; taste hot, acrid, bitter, 
 and astringent ; smell characteristic ; bleaches powerfully ; 
 speedily loses its chlorine when kept ; is decomposed on 
 exposure to the air, absorbing C0 2 , which liberates CI ; 
 the same effect is produced by acids generally ; soluble in 
 10 parts water ; when heated it gives off 0. 
 
 Med. Effects. — Not much used internally, the Liq. Sod& 
 chlorinatse being preferred ; used largely as a deodouriser, 
 and as a stimulant wash. It acts chiefly by the liberation 
 of its chlorine. 
 
216 MEDICAL CHEMISTRY. 
 
 MAGNESIUM, Mg=12. 
 
 Syllabus. 
 
 Oxide, MgO, Magnesia. 
 
 Carbonate, Magnesias Carbonas, 4(MgO,C0 2 ),-f MgO, 
 HO+6HO (variable). 
 
 Sulphate, MgO,S0 3 -f 6HO, Magnesias Sulphas, Epsom 
 salt. 
 
 Citrate, 3MgO,C 12 H 5 O n , Liquor Magnesias Citratis. 
 
 Sources. — In sea-water as MgCl and MgO,S0 3 ; in Dolo- 
 mite, MgO,C0 2 -fCaO,C0 2 , Magnesite, MgO,CO,; in the 
 native silicates as serpentine, hornblende, asbestus, steatite, 
 (talc, soapstone,) etc. 
 
 Prep. — By the reaction of sodium and MgCl at a high 
 temperature. 
 
 Prop. — A silvery, white, ductile, malleable metal, s. g. 
 1T4, fusible and volatile at a red heat, does not readily 
 oxidise in dry air nor decompose water ; burns with a 
 brilliant bluish-white flame forming MgO, its only oxide. 
 It resembles zinc, with which its salts are isomorphous. 
 The light of burning Mg wire has been employed for 
 taking photographs, and in some cases to aid in speculum 
 examinations. 
 
 292. Magnesia, MgO, Calcined Magnesia. 
 
 Prep. — Made by heating Carbonate of Magnesia to a 
 full red heat, in an open crucible ; the carbonate loses its 
 carbonic acid and water, and anhydrous magnesia remains ; 
 may be precipitated as hydrate by the action of caustic 
 alkali on its sulphate. 
 
 Prop. — An insoluble, light, white bulky powder, nearly 
 insipid, fused only by the compound blowpipe ; it should 
 not effervesce with acids (absence of C0 2 ), nor precipitate- 
 with BaCl (absence of sulphates). It forms a hydrate 
 
CHEMISTRY OF THE ELEMENTS. 21 T 
 
 with water without perceptible elevation of temperature. 
 Its reaction is feebly alkaline ; it slowly attracts moisture 
 and C0 2 from the air. Dense Magnesia (Henry's, Hus- 
 band's, etc.) is from ± to \ the bulk of ordinary magnesia, 
 and is less rough to the taste ; it may be produced, 1. By 
 trituration ; 2. By using a high heat during calcination ; 
 3. By packing the carbonate closely in the crucible before 
 heating ; 4. By heating just below redness the carbonate 
 prepared by mixing hot concentrated solutions of sulphate 
 of magnesia and carbonate of soda (Barr) ; 5. By heating 
 chloride of magnesium. The fourth method is the best. 
 
 Tests. — Is precipitated from its salts as hydrate by the 
 caustic alkalies, and as carbonate by their carbonates, but 
 not by carbonate of ammonia, or the bicarbonates ; a white 
 crystalline precipitate is formed with the soluble phos- 
 phates on the addition of a little ammonia (ammonio-mag- 
 nesian phosphate). 
 
 Med. Effects. — Antacid; the salts formed are laxative; 
 from its low equivalent has a high neutralising power. 
 The freshly prepared hydrate is an antidote to arsenious 
 acid. 
 
 Incompatible s. — All acids and acidulous salts; neutral 
 salts of the heavy metals. 
 
 293. Carbonate, Magnesias Carbonas, Magnesia Alba. 
 
 Prep. — On the large scale by double decomposition of 
 sulphate of magnesia and carbonate of soda, carbonate of 
 magnesia and sulphate of soda resulting, MgO,S0 3 -(-NaO 
 C0 2 =MgO,CO,-fNaO,S0 3 _>. Its composition is not con- 
 stant, being a mixture of carbonate and hydrate of mag- 
 nesia, 4(MgO,C0 2 )+MgO,HO + 6HO. The native carbon- 
 ate, MgO,C0 2 , magnesite, and the double carbonate of lime 
 and magnesia, MgO,C0 2 -J-CaO,C0 2 , dolomite, are not em- 
 ployed directly in medicine. 
 
 Prop. — A white, insoluble, smooth, nearly insipid, in- 
 19 
 
218 MEDICAL CHEMISTRY. 
 
 odorous solid; generally found in small cubes; it is solu- 
 ble to a certain extent in Aqua Acidi carbonici, forming 
 the so-called fluid magnesia. It is decomposed by heat. 
 Impurities. May contain carbonate or sulphate of soda; 
 chloride of sodium, lime, alumina, iron; which may be 
 detected by their respective tests. 
 
 Med. Effects. — Those of magnesia. The carbonic acid 
 is liberated in the stomach. 
 
 Incompatibjes. — Those of MgO and of the carbonates. 
 
 294. Sulphate, Magnesias Sulphas, MgO,S0 3 -f HO, Ep- 
 som Salt. 
 
 Prep. — Occurs native in certain caverns in the United 
 States, and as an efflorescence in the soil; also in certain 
 springs, and in sea-water (bittern), from which it is pre- 
 pared by evaporation and careful crystallisation. Made 
 also from dolomite, m,agnesite, and from the native sili- 
 cious hydrates. 
 
 Prop. — Transparent, inodorous, bitter, nauseous, neu- 
 tral, oblique rhombic prisms (4th system, sometimes in the 
 3d) ; soluble in an equal weight of water at 60° ; they melt 
 in their own water of crystallisation, which they lose at a 
 high heat, and then fuse into an enamel. 
 
 Impurities. — Iron and chloride of magnesium. 
 
 Med. Effects. — Mild cathartic. Dose, 3SS to ^i. In- 
 compatibles. Those of the soluble sulphates; the alkalies 
 and their carbonates. 
 
 295. Citrate, 3MgO,C 12 H 5 O n , Liquor Magnesias Citratis. 
 Prep. — Dissolve gr. cccl (^vij, gr. xxx) acidi citrici 
 
 in f^iv Aquas, and add Magnesias gr. cxx (^ij), and stir 
 until dissolved. Filter the solution into a strong fjxii 
 bottle, and add Syrupi Acid, citric f% ij ; then add Potassas 
 bicarb, gr. xl, and Aquas q. s. The bottle must be imme- 
 diately corked, and the cork secured by twine. This is a 
 solution of citrate of magnesia with excess of citric acid, 
 
CHEMISTRY OF THE ELEMENTS. 219 
 
 which renders it more permanent. The Potass, bicarb, re- 
 acts with a portion of this excess to develop C0 2 , which 
 charges the liquid and renders it effervescent when 
 opened. Is a most excellent, prompt, and agreeable saline 
 cathartic. 
 
 BAE1JJM, Ba=68-5. 
 
 296. Sources. — Native carbonate (witherite), and sul- 
 phate (heavy spar). 
 
 Bern. — Is prepared like Mg. Is unimportant as a 
 metal; s. g. 1*5; decomposes water at ordinary tempera- 
 tures. It forms two oxides, BaO, baryta, and Ba0 2 , bin- 
 oxide of Ba; the latter yields the second eq. of 0, readily in 
 the form of ozone (antozone?). The protoxide forms a hy- 
 drate, BaO,HO, with evolution of heat; this dissolves in 20 
 parts cold or 3 of boiling water, and forms a very deli- 
 cate test for C0 2 . The nitrate BaO,N0 5 is used in pyro- 
 techny to communicate a green colour to flame ; also as a 
 test for sulphuric acid. The salts of baryta are poisonous ; 
 antidotes, the soluble sulphates (Epsom or Glauber's salt). 
 The chloride may be obtained by the action of HC1 upon 
 BaO,C0 2 =BaCl_„-f COJ 1 ; it is used, like the nitrate, as a 
 test, and is officinal in the Liquor Barii Ghloridi : R. Ba- 
 rii chlorid. %j, Aquae destillatse f^iij, M. et filtra. Dose, gtt 
 v t. d. Is considered alterative and anthelmintic. Incom- 
 patibles, the soluble sulphates, tartrates and oxalates, 
 nitrate of silver, salts of lead and mercury. 
 
 STRONTIUM, 8r=43-T. 
 
 29*7. Prep. — In same manner as Ba, which it closely 
 resembles. 
 
 Rem. — Forms strontia, SrO, and binoxide of strontium, 
 SrO.,. Its salts give a red tinge to flame. They precipi- 
 
220 MEDICAL CHEMISTRY. 
 
 tate with the soluble sulphates, but less completely than 
 those of Ba. May be distinguished by hydrofluo silicic acid, 
 which precipitates BaO, but forms a salt with SrO, soluble 
 in excess of acid. The preparations are not poisonous, 
 and have been used in medicine with the same objects as 
 those of Ba. 
 
 ALUMINUM, Al = 13-7. 
 
 298. Sources. — In combination in clays, granitic rocks, 
 and various minerals. 
 
 Prep. — By passing the vapour of chloride of aluminum 
 over sodium at a red heat, Al 2 Cl 3 -{-3Na=3]N"aCl-}-Al 2 , or 
 by heating cryolite with sodium, Al 2 F 3 ,3]S'aF+ 3^=6 NaF 
 + A1 2 . 
 
 Prop. — A white, tenacious, malleable, ductile metal of 
 the hardness of silver, s. g. 2*56; fuses above a red heat; 
 tarnishes in moist air; is not blackened by HS. Is not 
 acted on by cold HO,S0 3 , or HO,N0 5 , but readily dis- 
 solves in HC1, forming A1 2 C1 3 . Is acted upon also by alka- 
 line solutions. Its alloys are remarkable for strength, 
 lightness, and sonorousness ; that with copper, aluminum 
 bronze, has a permanent golden colour. The metal forms 
 but one oxide, A1 2 3 , and its binary compounds are all of 
 the same type. 
 
 299. Oxide, A1 2 3 , Alumina. 
 
 Prep. — Exists native in the sapphire, ruby, oriental 
 topaz, and corundum. These bodies are not attacked by 
 acids, and are inferior in hardness only to the diamond. 
 It may be obtained by igniting ammonia alum, or the 
 hydrate of alumina, Al 2 3 ,3HO. This hydrate is obtained 
 by precipitating its salts by- caustic alkali. It occurs native 
 in Gibbsite Al 2 3 ,3HO, and Diaspore Al 2 3 ,2HO. 
 
 Prop. — Anhydrous, a soft, white, tasteless, inodourous 
 
 
CHEMISTRY OF THE ELEMENTS. 221 
 
 powder, without action on vegetable blues. The precipi- 
 tated hydrate is a soft, gummy mass, like boiled starch, 
 combining readily with acids and bases. 
 
 Chem. Bel. — Is like all sesquioxides a feeble base, its 
 salts having an acid reaction; it combines also with bases 
 acting as an acid (NaO,Al 2 3 ). Its salts have a sweetish 
 astringent taste, and are generally soluble in water. Alu- 
 mina has a remarkable attraction for organic matter, it pre- 
 cipitates colouring matters from their solutions as lakes; 
 is a powerful detergent and deodouriser. Is used largely 
 in dyeing as a mordant (binder mittel, binding-medium, of 
 the Germans). Test. Alkalies throw down a gelatinous 
 hydrate freely soluble in acids. 
 
 Cotton impregnated with most organic colouring matters 
 readily parts with them on washing. By using first a compound 
 of aluminum, it adheres strongly to the fibre, also to the colour- 
 ing matter, thus binding them firmly together. Binoxide of tin 
 Sn0 2 , sesquioxide of iron Fe 2 3 , are also used as mordants. 
 
 300. Sulphate, Al 2 3 ,3S0 3 +18HO; Aluminse Sulphas. 
 Is obtained by dissolving freshly precipitated alumina in 
 sulphuric acid. Is used as a detergent, deodouriser, and 
 styptic. 
 
 301. Alums. 
 
 Alumina forms a series of double salts containing its sulphate 
 with that of an alkali. They are types of a large class of com- 
 pounds which have received the generic title of alums. Com- 
 mon potash alum is a double sulphate of alumina and potassa 
 with 24 parts of water, Al 2 q 3 ,3S0 3 -4-KO,S0 3 -f 24HO. We may 
 replace the potassa by the oxides of sodium, ammonium, lithium, 
 caesium, and rubidium, and obtain salts hardly distinguishable 
 from the potash alums. The alumina may be replaced by the 
 isomorphous sesquioxides of iron, manganese, and chromium : 
 in the latter case the alums are coloured, but otherwise resemble 
 in every respect common alum. The following list will give an 
 idea of the composition of these isomorphous double salts: 
 
 Al 2 3 ,3S0 3 -f- KO, S0 3 -f 24IIO, 
 
 Cr 2 3 NaO, 
 
 MnoO, NII 4 0, 
 
 FeA CsO. 
 
 19* 
 
222 MEDICAL CHEMISTRY. 
 
 We have also a series of minerals of the same type, in which 
 Si0 3 replaces S0 3 , but not isomorphous with the foregoing, as 
 they are anhydrous ; thus: 
 
 Alo0 3 ,3Si0 3 +KO,SiOs, Feldspar. 
 AL0 3 ,3Si0 3 + NaO,Si0 3 , Albite. 
 Alo0 3 ,3Si0 3 +LO,Si0 3 , Petalite. 
 Al 2 3 ,3Si0 3 +CaO,Si0 3 , Labradorite. 
 Many others are known in which the proportions of the two 
 salts vary, but the general type remains. 
 
 302. Alumen, Alum, Al 2 3 ,3S0 3 -f-KO,S0 3 +24HO. 
 
 Prep, — Is made in various ways on the large scale, the 
 
 principle of the process being to procure the sulphates of 
 
 alumina and potassa, and crystallise them together. 
 
 In this neighbourhood alum is made at the oil of vitriol works 
 by acting upon a pure white clay (silicate) with unconcentrated 
 sulphuric acid, mixing with the sulphate of alumina thus ob- 
 tained the sulphate of potassa remaining after the manufacture 
 of nitric acid, and crystallising. By replacing the KO,SO, by 
 NH 4 0,S0 3 , obtained from gas-liquor, ammonia alum is obtained. 
 
 Prop. — A colourless, slightly efflorescent salt, of a 
 sweetish, astringent taste, crystallising in regular octo- 
 hedra (1st system). It is soluble in 15 parts of cold and 
 |ths its weight of boiling water. When heated, it fuses 
 in its water of crystallisation, which is finally in great 
 part driven off, the mass froths, swells, and forms a white 
 porous mass, — dried alum, alumen exsiccatum. 
 
 Med. Effects. — Astringent, tonic, and antispasmodic; 
 in large doses, emetic and purgative. Given internally in 
 croup, as an emetic, in colica pictonum, etc. The alumen 
 exsiccatum is a favourite mild escharotic. Incompatible*. 
 The vegetable astringents, alkalies, and alkaline earths, 
 tartrates, and those of the soluble sulphates. 
 
 Alum is largely used in dyeing, the preparation of skins, 
 clarifying liquors (189), rendering wood and paper incom- 
 bustible, and as a filling for iron safes. 
 
 Aluminse et Ammonize Sulphas, Ammonia alum. Prep. 
 Given above; it is used as a substitute for ordinary alum. 
 
CHEMISTRY OF THE ELEMENTS. 223 
 
 from which it is distinguished by the ammonia evolved 
 upon treating it with a caustic alkali. The ammonio-fer- 
 ric alum, Fe 2 3 ,3S0 3 -f NH 4 0,S0 3 -f 24HO, contains no alu- 
 mina; it will be considered under Iron. 
 
 303. Silicates; Clay. 
 
 Clay is formed by the decomposition of rocks contain- 
 ing silicate of alumina ; it is very variable in its compo- 
 sition, the red varieties containing iron, and most clays 
 magnesia, lime, potassa, soda, etc. Pure clay — fire clay — 
 is a normal silicate of alumina, Al 2 3 ,3Si0 3 . Kaolin, a 
 white clay, used in making porcelain, contains Al 2 3 ,SiO^ 
 -f- 2HO ; marls contain phosphates and lime; Fuller's earth 
 is a porous clay used for extracting grease. 
 
 Prop. — When moist, exhales a peculiar odour; is plas- 
 tic, hence its value in the manufacture of porcelain, earth- 
 enware, etc. When dried it becomes hard and adheres to 
 the tongue. In soils it possesses the property of absorb- 
 ing large quantities of ammonia, and of decomposing the 
 compounds of that base. 
 
 GLASS AND PORCELAIN. 
 
 304. Glass is a mixture of the silicates of potassa and 
 soda with those of alumina, lime, and the metallic oxides. 
 The silicates of the alkalies alone are soft, acted upon by 
 water and chemical agents, and in some cases freely soluble 
 in water; those of the other bases named will crystallise 
 and thus lose their transparency ; by admixture the faults 
 of both are corrected. The composition of glass varies 
 exceedingly; the following are the most important varie- 
 ties. 
 
 Bohemian Glass. — Much prized for its hardness and 
 resistance to chemical agents; contains 66 p. c. silica, 12 
 potassa, 9 lime, and 10 alumina. It is used in the labora- 
 
224 MEDICAL CHEMISTRY. 
 
 tory as flasks and tubes, and in many ornamental and use- 
 ful forms. 
 
 Grown Glass. — Resembles the Bohemian; is used in the 
 plates of mirrors, large windows, lenses, etc. 
 
 Window Glass. — Used for common glazing, druggists' 
 bottles, etc. ; contains soda in place of potassa. It has a 
 greenish tinge when in thick plates. 
 
 Flint Glass, used in lenses, prisms, and fine cut glass- 
 ware; contains, in addition to potassa, oxide of lead (43 
 p. c). It is dense, soft, easily fusible, and of a high refrac- 
 tive power. 
 
 Paste, or strass, used for imitating gems, is a flint glass 
 containing a still larger proportion of lead. 
 
 Bottle Glass. — Contains oxide of iron, to which it owes 
 its green colour. Is made of the cheapest materials; it 
 contains but little alkali. Is not easily acted upon by acids 
 or alkalies. 
 
 Soluble Glass. — Is a silicate of potassa or soda contain- 
 ing an excess of base. When powdered, it is freely solu- 
 ble in boiling water. It is used as a detergent, as a fire- 
 proof varnish for wood, and as a cement. 
 
 Colours of Glass. — Soda glass has always a greenish 
 tinge ; the various metallic oxides communicate colours to 
 glass ; they may be incorporated with the glass in the melt- 
 ing-pot, or applied to its surface in the form of enamel or 
 glaze (stained glass). Green is produced by protoxide of 
 iron, FeO, or protoxide of copper, CuO ; blue, protoxide of 
 cobalt, CoO ; yellow, by oxide of silver, AgO, and teroxide 
 of antimony, Sb0 3 . The fluorescent canary glass is coloured 
 by the sesquioxide of uranium, U 2 3 ; ruby red, by oxide 
 of gold, AuO, and suboxide of copper, Cu 2 ; amethystine, 
 purplish-pink, by binoxide of manganese, Mn0 2 ; the same 
 in large quantity, mixed with oxide of cobalt, CoO, a black. 
 White enamel, used for watch-dials, is glass with oxide of 
 
CHEMISTRY OF THE ELEMENTS. 225 
 
 tin, SnO ; and an opalescent white glass, used for lamp- 
 shades, contains arsenic. Black oxide of manganese is 
 added in the manufacture of glass to take away its green- 
 ish tinge ; this is done by oxidising any FeO present to 
 Fe;,0 3 , which does not colour; the manganese itself com- 
 municates a pinkish tint to the glass, which being com- 
 plementary to the green neutralises it. It is hence called 
 glass-maker' ] s soap, or pyrolusite (Gr. pur, fire, and lud, I 
 wash). 
 
 305. Porcelain. — The various grades of earthenware 
 from the finest porcelain to the commonest red pottery are 
 all formed by baking clay; the difference being in the 
 quality of the clay and the methods of manufacture. For 
 porcelain the finest Kaolin free from all iron is used ; for 
 common pottery, ordinary clay, the iron of which gives the 
 well-known red colour. The articles, after being shaped 
 while the clay is in a plastic condition, are baked, when 
 they become hard but are porous, as in an ordinary brick 
 or flower-pot ; they are afterwards glazed. For porcelain 
 a fine glazing of powdered feldspar and quartz is used; 
 for stoneware, common salt, which at a high heat is decom- 
 posed and the soda formed unites with the silica of the 
 stoneware. Common black glazing contains lead, and 
 accidents may occur if acid liquids kept in dishes so 
 glazed are afterwards used in food. The colours used in 
 porcelain are the same as for glass. Fire bricks are made 
 from a pure clay, free from all metallic oxides. Hessian 
 crucibles are made of a mixture of clay and sand ; they 
 bear a high heat, but are apt to crack. Black-lead crucibles 
 are made of a mixture of plumbago and clay; they will 
 stand heat better than the former. In delicate chemical 
 operations porcelain and platinum crucibles are used. 
 
226 MEDICAL CHEMISTRY. 
 
 MANGANESE, Mn=2T8. 
 
 306. Sources. — The native black oxide, Mn0 2 , and car- 
 bonate. It is stated to exist in small quantity in the blood. 
 
 Prep. — By reducing Mn0 2 at a high heat by means of 
 carbon. 
 
 Prop. — A steel-gray metal, brittle, s. g. 8*00 ; on expo- 
 sure to the air oxidises and crumbles to powder. It ap- 
 pears to possess feeble magnetic properties at low tem- 
 peratures. 
 
 Ghem. Bel. — Forms with O, MnO, a base, Mn 2 3 , a 
 feeble base, Mn0 2 , a neuter body, Mn0 3 manganic acid, 
 and Mn 2 7 permanganic acid. Its other binary com- 
 pounds are of slight importance ; the iodide has been em- 
 ployed in medicine ; it may be made by the double de- 
 composition of MnO,S0 3 -fKI=MnI_>-f KO,S0 3 ; it is made 
 into a syrup like the Syrup. Ferri. lodid. The salts of 
 manganese have a delicate rose-colour. Test. Sulphydrate 
 of ammonia gives a flesh-coloured characteristic precipi- 
 tate ; the salts communicate an amethystine tint to borax 
 in the outer blowpipe flame. 
 
 307. Oxides. 
 
 The protoxide is obtained hydrated by the addition of 
 KO,HO to MnO,S0 3 =KO,S03l-f MnO,HO. It is white, 
 
 rapidly absorbing oxygen, and becoming sesquioxide. 
 The anhydrous protoxide is of a dirty green colour; it 
 rapidly absorbs 0, and at 600° takes fire. 
 
 The sesquioxide, Mn 2 3 , is isomorphous with A1 2 3 ; not 
 important. 
 
 The binoxide, Mn0 2 , pyrolusite, Manganesii Oxidum 
 nigrum, is found native. It readily yields a portion of 
 its O when heated. It does not unite with acids or bases; 
 an acid added to it forms a salt of the protoxide with evo- 
 lution of O, Mn0 2 +HO,S0 3 =MnO,SO.^+HO + O*. Is 
 
 
CHEMISTRY OP THE ELEMENTS. 227 
 
 extensively used in the manufacture of chlorine, of glass, 
 and the permanganates. It is officinal as Manganesii 
 Oxidum nigrum, but is rarely used in medicine. Man- 
 ganic acid, Mn0 3 , is not isolable. By heating Mn0 2 with 
 KO,N0 5 and KO,HO, KO,Mn0 3 is formed. This is an 
 uncrystallisable mass of a greenish colour {chameleon min- 
 eral) ; when thrown into water, it becomes purple and 
 finally red from the formation of permanganate, KO, 
 Mn 2 7 . 
 
 Permanganic Acid is known only in combination with 
 water or a base ; it is rapidly decomposed by organic mat- 
 ters and other deoxidising bodies, becoming reduced to 
 Mn 2 3 . See Potassse Permanganas (309). 
 
 The compound oxides, red oxide Mn 3 4 , or MnO,Mn 2 3 , 
 and varvicite Mn 4 7 =2MnO,Mn 2 3 , are unimportant. 
 
 308. Manganesii Sulphas, MnO,SO s -f 5HO (at 60°). 
 Prep. — By gently heating Mn0 2 with HO,S0 3 =MnO, 
 
 S0 3 -fHO-|-0, evaporating and crystallising. The quan- 
 tity of water of crystallisation will depend upon the tem- 
 perature of the latter operation. 
 
 Prop. — Rose-coloured rhombic crystals (3d system), 
 very soluble in water, insoluble in alcohol; of a bitter, as- 
 tringent taste. It may contain copper, iron, and arsenic. 
 Should give no precipitate with infusion of galls, a flesh- 
 coloured one with NH 4 S,HS, and a white one with K 2 Cfy. 
 
 Med. Effects. — In doses of z] to ^ij a cholagogue ca- 
 thartic; in smaller doses, gr x to xx, has been used in con- 
 junction with iron in anaemia. 
 
 309. Potassse Permanganas, KO,Mn 2 7 . 
 
 Prep. — Is always made on the large scale ; an outline 
 of the method is given in § 307. 
 
 Prop. — In brilliant purplish-red, right rhombic crystals 
 (3d system), soluble in 16 parts water at 60° ; they ex- 
 plode when heated. They communicate an amethystine 
 
228 MEDICAL CHEMISTRY. 
 
 tinge to water when in very small quantity ; the concen- 
 trated solution is of a deep red colour, permanent, and of 
 a peculiar taste. When necessary, it maybe filtered through 
 gun-cotton ; most other organic matters decompose it rap- 
 idly. 
 
 Med. Effects. — An excellent deodouriser. It probably 
 acts by eliminating ozone, and thus destroying organic 
 effluvia and compounds containing hydrogen. If exposed 
 in solution (Condy's solution) in shallow vessels, it speedily 
 purifies the air of a room, and will continue to act for a long 
 time. Added to foul water, it renders it sweet, becoming 
 at the same time reduced to Mn0 2 , which subsides, and 
 KO, which remains in solution. Has been used externally 
 in the treatment of various foul ulcers and offensive dis- 
 charges, gangrene, diphtheria, etc. Also to remove the 
 offensive odour of the armpits and feet, and that adhering 
 to the hands after certain operations, post-mortem exami- 
 nations, etc. Internally has been administered in cases 
 where an oxidising agent is supposed to be indicated, and 
 in zymotic diseases. It must be applied with a brush of 
 asbestus, as it is decomposed by organic matter. A liquid 
 containing one-tenth of a saturated solution is a convenient 
 strength for ordinary uses. In large doses would prove 
 an irritant poison, the antidote being albumen, milk, or 
 similar organic matters. It is used in the laboratory as 
 a reagent in volumetric analysis. 
 
 IRON, Fe=28. 
 
 Syllabus. 
 As Metal: (a) Ferrum; (b) Ferrum Bedactum, Que- 
 vennes iron. 
 
 Oxide : Ferri Oxidum Hydratum, Fe 2 3 ,3HO. 
 
CHEMISTRY OF THE ELEMENTS 229 
 
 Sulphide, FeS y Ferri Sulphuretum. 
 
 Chloride, Fe 2 Cl 3 : (a) Ferri Chloridum; (6) Tinctura 
 Ferri Chloridi, — gr xxix to f^j. 
 
 Iodide, Fel: (a) Syrupus Ferri Iodidi, — gr xlviii to 
 f gj ; (b) Pilulse Ferri Iodidi. 
 
 Ferrocyanide, Fe 4 Cfy 3 , Ferri Ferrocyanidum, Prussian 
 Blue. ! , 
 
 Nitrate, Fe 2 3 ,3N0 5 ; Liquor Ferri Nitratis. 
 
 Carbonates : (a) Pilulse Ferri Carbonatis (FeO,C0 2 ), 
 Vallet's Mass ; (bJMistura Ferri Composita, and (c) Pilulse 
 Ferri Compositse (contain FeO,C0 2 ) ■; (d) Ferri Subcarbo- 
 nas (Fe 2 3 ,C0 2 ?); (e) Trochisci Ferri Subcarbonatis. 
 
 Sulphates: (a) Ferri Sulphas, FeO,S0 3 -}-1HO, Cop- 
 peras, Green vitriol; (b) Ferri Sulphas Exsiccata, FeO,S0 3 
 -fHO; (c) Liquor Ferri Tersulphatis, Fe 2 3 ,3S0 3 ; (d) 
 Liquor Ferri Subsulphatis, 2Fe 2 3 ,5S0 3 , Monsel's solution; 
 (e) Ferri et Ammonise Sulphas (Fe 2 3 ,3S0 3 +NH 4 O,S0 3 + 
 24HO), Ammonio-ferric alum. 
 
 Phosphates : (a) Ferri Phosphas, 2FeO,HO,P0 5 ; (b) 
 Ferri Pyrophosphas (contains 2Fe 2 3 ,3P0 5 +9HO). 
 
 Lactate; Ferri Lactas, FeO,C 6 H 5 5 +3HO. 
 
 Tartrates: (a) Ferri et Potassse Tartras, Fe 2 3 ,KO, 
 C 8 H 4 O 10 -f HO ; (b) Ferri et Ammonise Tartras, Fe 2 3 , 
 NH 4 O,C 8 H 4 O 10 . 
 
 Citrates: (a) Ferri Gitras, Fe20 3 C 12 H 5 0„ ; (6) Liquo? 
 Ferri Citratis — -gss to f^j ; (c) Ferri et Ammonise Gitras, 
 Fe 2 3 ,NH 4 0,C 22 H 5 O n +2HO, (d) Ferri et Quinise Citras> 
 Fe 2 O 3 ,C 40 H 2<t N 2 O 4 ,C 12 H 5 O u -f 4?HO. 
 
 310. Sources. — The most important ores of iron are 
 the Magnetic oxide, Fe 3 4 , Specular iron or red haematite* 
 F 2 3 , Brown haematite, Fe 2 3 ,3HO, Sparry carbonate, FeO, 
 C0 2 , and Clay iron stone, which also contains the carbon- 
 ate. It exists abundantly as iron pyrites, FeS 2 , which is 
 not used as an ore ; in soils, rocks, mineral springs, the 
 20 
 
230 MEDICAL CHEMISTRY. 
 
 hseruatine of the blood, etc. Is the most abundant and 
 widely diffused of the heavy metals. Is found very rarely 
 native ; occurs combined with nickel in meteoric stones. 
 
 Prep. — Iron ores are reduced in the blast furnace by 
 means of carbon ; lime-stone is added to act as a flux — 
 that is, to combine with the silica of the ores, which would 
 otherwise unite with the iron ; the slag formed by the sili- 
 cate of lime floats on the surface of the reduced iron, and 
 is taken from the lower part of the furnace by a separate 
 opening. Cast iron, the product of the blast furnace, is a 
 carbide containing as high, in some cases, as 5 p. c, which 
 would give Fe 4 C. It also contains graphite, uncombined 
 carbon, silica, and often sulphur and phosphorus ; the lat- 
 ter are exceedingly difficult to remove and injurious to its 
 quality, sulphur rendering iron brittle when hot (red short) 
 and phosphorus when cold (cold short). Wrought iron is 
 made by burning the carbon out of cast iron by a current 
 of air (puddling). It may be obtained pure by reducing 
 pure Fe 2 3 by a current of- H at a red heat (Ferrum re- 
 dactum). Malleable iron, so called, is manufactured by 
 keeping plates or articles made of cast iron imbedded in 
 haematite or oxide of zinc, at a red heat, for a long time. 
 The iron loses a part of its carbon, and resembles in many 
 respects wrought iron. Steel contains from 1*3 to 1*75 p. c. 
 of carbon. It is prepared (1) by partially decarbonising 
 cast iron (puddled steel) ; (2) by exposing bars immersed 
 in charcoal powder to an intense heat for 48 hours or more 
 (blistered steel). The latter process is termed cementa- 
 tion. 
 
 Prop. — Cast iron is of a grayish-white appearance, s. 
 g. 1'20^J, melts at a white heat, and in small masses burns. 
 It expands on cooling. Wrought iron is infusible, but at 
 a white heat becomes pasty and may be welded ; it is mal- 
 leable, and one of the most ductile and tenacious of metals, 
 
CHEMISTRY OF THE ELEMENTS. 231 
 
 s. g. 1-780. It has a silvery, metallic lustre, which soon 
 tarnishes. Steel has a s. g. of 7'850, is more tenacious 
 than iron, and has the remarkable property of becoming 
 hardened when heated to redness and suddenly cooled ; 
 by reheating and slowly cooling, this hardness is dimin- 
 ished {drawn down), and the steel is said to be tempered. 
 It is then highly elastic, malleable and ductile. Iron and 
 steel possess magnetic properties, which they lose when 
 heated to redness. All the forms of iron rust when ex- 
 posed to moist air or when immersed in ordinary water. 
 The presence of a small portion of acid, or of certain salts, 
 increases greatly this change, and the presence of alkalies 
 and lime in water retards it. Iron does not rust in water 
 deprived of air. Cast iron long immersed in sea-water 
 has the iron entirely removed, leaving a mass of carbon. 
 Rust consists of hydrated sesquioxide, Fe 2 3 ,3HO, and 
 always contains NH 4 0, from the union of atmospheric N 
 with the nascent H given off during oxidation. When 
 iron is burned, the magnetic or black oxide Fe 3 4 is formed. 
 
 311. Passive Condition of Iron. — Iron is usually readily attacked 
 by acids, but may be rendered passive, in which state it is not 
 affected by concentrated nitric acid. This condition may be 
 brought about (1) by heating the iron and plunging into HO, 
 N0 5 ; (2) by dipping it in HO,N0 5 and washing with water ; (3) 
 by putting it in contact with a platinum wire or piece of passive 
 iron immersed in the acid; (4) by making it the positive pole of 
 a voltaic circuit, introducing it after the negative. These curious 
 results appear to depend upon the formation of a film of oxide. 
 Passive iron is employed as a cheap substitute for platinum in 
 the nitric acid battery (98). 
 
 312. Ghem. Bel. — Iron unites with most of the metals, 
 and with all the non-metallic elements, except H ? and B. 
 It forms with 0, 1. Protoxide, ferrous oxide, FeO, which 
 may be obtained by precipitating a salt of the protoxide 
 with a caustic alkali ; it forms a whitish hydrate, losing 
 its water, and becoming black, when boiled ; is attracted 
 
232 MEDICAL CHEMISTRY. 
 
 by the magnet ; exposed to the air, turns green, and ulti- 
 mately brown, absorbing O and becoming sesquioxide ; 
 when dry, it sometimes absorbs with such avidity as to 
 take fire ; is powerfully basic. Its salts are generally of a 
 delicate green colour, and nauseous, metallic taste ; they 
 absorb oxygen readily, except the native carbonate, be- 
 coming brown, from the formation of sesquioxide. 2. Ses- 
 quioxide, Ferric oxide, Colcothar, Crocus Martis, jewel- 
 lers' rouge, Fe 2 3 , prepared by precipitating a salt of the 
 sesquioxide by caustic alkali, and igniting the hydrate thus 
 formed, is of a red colour, not attracted by the magnet, 
 unaltered by heat, reduced by a current of hydrogen at a 
 red heat, or by C at a higher heat ; is feebly basic when 
 hydrated, inert when anhydrous. Its salts, formed gen- 
 erally by oxidising those of the protoxide, have a reddish 
 or brown colour, a styptic, astringent taste, and an acid 
 reaction. It is reduced by vegetable matter, the prot- 
 oxide formed again absorbing from the air and carry- 
 ing it to the fabric Thus the corrosive effect of rust or 
 iron mould is accounted for. Like alumina, it acts as a 
 mordant, and it renders the colours darker. 3. Black Ox- 
 ide, Magnetic Oxide, Fe 3 4 , most probably a combination 
 of FeO,Fe 2 3 , does not form salts. Ferric Acid, Fe0 3 , has 
 not been isolated ; its potassa salt forms a deep amethys- 
 tine-red solution, which soon decomposes ; it forms with 
 baryta a deep crimson, insoluble, permanent salt; with 
 S, FeS (Ferri Sulphur etum), Fe 2 S 3 , FeS 2 , iron pyrites, and 
 Fe 7 S 8 , magnetic pyrites. Iron pyrites, FeS 2 , occurs in 
 cubes or octohedra (1st system) of a brassy appearance, 
 and so hard as to strike fire, hence its name (Gr. pur, fire). 
 It is easily distinguished from gold by its hardness and 
 its lower s. g. 4'7, and the S0 2 evolved when it is heated. 
 Exposed to moist air, when mixed with protosulphide, as 
 in various shales, the latter absorbs O, developing consid- 
 
CHEMISTRY OF THE ELEMENTS. 233 
 
 erable heat, and becoming FeO,S0 3 , which is thus some- 
 times manufactured. 
 
 There are two varieties of common pyrites generally described ; 
 the hepatic, which is of a liver-colour, appears to be only common 
 pyrites partially oxidised. We have also two varieties of arseni- 
 cal pyrites. 
 
 The other important compounds of iron will be consid- 
 ered under their officinal preparations. 
 
 Tests. — For the protoxide : Ferricyanide of potassium, 
 K 3 Cfdy, throws down a blue precipitate (Fe 3 Cfdy, Turn- 
 bull's blue). For the sesquioxide : (1) Infusion of galls, a 
 black precipitate (ink) ; (2) Ferrocyanide of potassium, 
 K 2 Cfy, a blue one (Prussian blue, Fe 4 Cfy s ) ; (3) Sulpho- 
 cyanide of potassium, KCsy, strikes a blood-red colour ; 
 (4) HS gives a white precipitate of S ; and (5) NH 4 S,HS, 
 a black one of FeS. 
 
 Med. Effects. — The salts of iron are tonic and astrin- 
 gent, the former property being possessed more decidedly 
 by the £>rofo*compounds convenientl} r termed ferrous salts, 
 and the latter by the sesqui, or ferric salts. It is deficient 
 in the blood in anaemia. The blackening of the stools ob- 
 served during the internal use of iron is due to the for- 
 mation of sulphide. 
 
 Incompatible s. — The vegetable astringents, the alka- 
 lies, alkaline earths, and their soluble carbonates. The 
 members of the cyanogen group generally. 
 
 313. As Metal. — Ferrum Bedactum, Quevennes iron. 
 
 Prep. — By passing a current of H at a red heat over 
 Ferri subcarb., which may be regarded in many cases as 
 merely a sesquioxide, Fe 2 3 -f H 3 =Fe-f-3HO. 
 
 Prop. — A light tasteless iron-gray powder, having the 
 properties otherwise of iron. It readily absorbs moisture 
 from the air and oxidises ; hence it should be kept in well- 
 stopped bottles. Dose, gr j to iij ; is readily administered 
 20 * 
 
234 MEDICAL CHEMISTRY. 
 
 in lozenges, etc. It causes eructations of H. Is incom- 
 patible with acids and acid salts. 
 
 314. Oxide, Ferri Oxidum Hydratum, Fe 2 3 ,3HO. 
 
 Prep. — By adding to Oj Liq. Ferri Tersulphatis, pre- 
 viously mixed with Oiij Aquae, Aqua Ammonias, until in 
 slight excess ; the precipitate is separated by a wet muslin 
 strainer and washed, Fe 2 3 ,3S0 3 +3(NH 4 0,HO)=Fe 2 3 , 
 3H0-f 3(NH 4 0,S0 3 )->. In the absence of the Liq. Ferri 
 
 TersulphaL, the Tinct. Ferri Chlorid. may be used, Fe 2 Cl 3 
 -f 3(NH 4 0,HO)=Fe 2 3 ,3HO + 3NH 4 Cl->. Monsel's solu- 
 tion (321), or any soluble ferric salt, will yield the ferric 
 hydrate on the addition of alkali. 
 
 Prop. — A brownish pulpy mass, freely soluble in acids ; 
 when long kept, undergoes a change, becoming crystalline, 
 and losing one-half of its water ; its virtues as an antidote 
 are then impaired; it also quickly becomes crystalline 
 when frozen ; immediately, at 21° (Limberger) ; does not, 
 however, then lose its water, as when long kept, and 
 although less soluble than the amorphous, is more so than 
 that which has become crystalline, and less hydrated by 
 long keeping (Wittstein). 
 
 Med. Uses. — Used sometimes as a tonic; most valued 
 as an antidote to Arseniotjs Acid. 
 
 315. Sulphide, Ferri Sulphuretum, FeS, or (5FeS+ 
 Fe 2 S 3 ). 
 
 Prep. — By heating together Fe and S. 1. A mixture 
 of two parts of S and one of Fe by weight. 2. By rubbing 
 roll sulphur upon the end of an iron rod heated to redness 
 and allowing the fused mass to fall into water. It gener- 
 ally contains an excess of S, but when heated to expel this, 
 is a protosulphide (ferrous sulphide), FeS. Has a brown- 
 ish-black colour ; evolves HS on exposure to moist air. Is 
 used only for making sulphydric acid. HS (217). 
 
CHEMISTRY OP THE ELEMENTS. 235 
 
 316. Chloride, Ferri Chloridum, Tinctura Ferri Chlo- 
 ridi. 
 
 Prep. — Take of pieces of iron wire (card-teeth are con- 
 venient) gij, Acid. Muriatic %x\\, Add, Nitric. 3j or q. s. 
 Add the iron to 3 viij of the Acid. Muriat. in a large flask, 
 and heat gently until effervescence ceases ; filter, add the 
 remainder of the Acid. Muriat., heat nearly to boiling, and 
 add the Add. Nitric, by degrees until red fumes are no 
 longer evolved and the liquid does not afford a precipitate 
 with ferricyanide of potassium, K^Gfdy (absence of ferrous 
 chloride). Evaporate and crystallise. 
 
 Remark. — Iron forms a ferrous chloride, when acted 
 upon by HC1 ; Fe + HCl=FeCl-f H. It is a greenish 
 liquid, prone to change. By the action of the HO,N0 5 
 and HC1 this is converted into the ferric chloride, 6FeCl 
 +HO,N0 5 +3HCl=3Fe 2 Cl 3 +N0 2 +4HO. 
 
 Prop. — In orange-yellow grains of a crystalline struc- 
 ture which varies with the amount of water of crystallisa- 
 tion. Is rarely used in the solid form. In solution is 
 employed as a styptic and deodouriser. 
 
 Tinctura Ferri Chloridi; Muriated Tincture of Iron. 
 R. Ferri, ^iij ; Acid. Muriat., ^xviiss ; Alcohol, Oiij ; Acid. 
 Nitric, Aquse Destillatae, aa q. s. Proceed as in the last 
 preparation, but instead of crystallising add the aqueous 
 solution, which should measure Oj, to the alcohol. It was 
 formerly prepared by the action of HC1 on Ferri subcarb., 
 Fe 2 3 ,3HO + 3HCl=Fe 2 Cl 3 -f6HO. 
 
 Prop. — A transparent, reddish-brown liquid of a styptic, 
 sour taste and agreeable fruity odour, s. g. 0-990, contains 
 29 grs to f % j. Is used as a specific in erysipelas and spas- 
 modic stricture. Is incompatible with gum arabic. Dose, 
 gtt x to xxx gradually increased ; should be diluted with 
 water and sucked through a tube to avoid action on the 
 teeth. 
 
236 MEDICAL CHEMISTRY. 
 
 317. Iodide, Fel; Syrupus Ferri Iodidi. 
 
 Prep. — Introduce into a thin glass flask £ij Iodinii, 
 Ferri Jlli* gr ccc, Aquas destillatas f^iij; agitate until the 
 liquid acquires a green colour and loses the smell of 
 iodine. Then filter into it Oj Syrupi previously heated to 
 212°; shake thoroughly, and when cool add Syrupi q. s. 
 ad f^xxii. The iron is in excess; the sugar protects the 
 iodide from change ; without it the iron becomes oxidised 
 and the iodine set free, giving a brownish tinge to the 
 liquid; iron wire in the liquid will again combine with 
 this. It should be kept in the dark. 
 
 Prop. — A transparent, greenish liquid, which should 
 not affect starch (absence of free iodine). Has the medi- 
 cal properties of its constituents. Dose, gtt xx to xl, 
 dropped into water in a glass or porcelain vessel. Like the 
 Tinct. Ferri Chlorid., should be taken through a glass 
 tube, or quill. 
 
 Pilulse Ferri Iodidi, Blancard's Pills. 
 
 Prep. — ^ss Iodinii, gr ccxx Ferri fili and fjj Aquas, 
 are mixed as above, and filtered upon a mixture of Al- 
 ike as pulv. ^ss, Acacias pulv. et Ferri Redacli aa gr lx; 
 f^ij Aquas destillat. being poured upon the filter to wash it. 
 Evaporate with stirring to a pilular consistence, and make 
 300 pills. These are coated by shaking in a solution of 
 Balsam. Tolutani gr lxj in f^j JEtheris, and drying. Each 
 pill contains about gr j Ferri Iodid. and A gr Ferri Redacli. 
 They are quite permanent. 
 
 318. Ferrocyailide, Ferri Ferrocyanidum, Prussian Blue, 
 Fe 4 Cfy 3 . 
 
 Prep. — By adding gradually with stirring to a solution 
 of Potass. Ferrocyanid. %ix in Oij Aquas, Oj Liq. Ferri 
 Tersulphatis diluted with Oj Aquas, and washing the pre- 
 cipitate with boiling water; 3K 2 Cfy+2(Fe 2 3 ,3S0 3 )=Fe, 
 Cfy 3 + GCKCSOs)^. Soluble Prussian Blue (not officinal) 
 
 * Iron wire, card teeth. 
 
CHEMISTRY OP THE ELEMENTS. 237 
 
 is made, (1) by exposing the white precipitate obtained from 
 a ferrous salt by K 2 Cfy to the air, (Fe 4 Cfy 3 -t-Fe 2 3 ); (2) 
 by adding Fe 2 3 ,3N0 5 to an excess of K 2 Cfy, and washing, 
 (Fe 4 Cfy 3 -f2K 2 Cfy). Both of these dissolve in pure water. 
 Prop. — The officinal ferrocyanide is a deep blue, taste- 
 less, inodorous powder, insoluble in water and alcohol. 
 Is used in dyeing, painting, and when dissolved by the 
 aid of oxalic acid, HO,C 2 3 , forms blue ink. Has been 
 used as an antiperiodic and in neuralgia. Dose, gr v to x, 
 gradually increased. 
 
 319. Nitrates, Liquor Ferri Nitratis, Fe 2 3 ,3N0 5 . 
 Prep. — By the action of dilute HO,N0 5 in excess upon 
 
 iron.* At first & ferrous nitrate is formed, which has a pale 
 colour and is prone to decomposition, Fe-f-HO,N0 5 =FeO, 
 N.0 5 -f-H. This is employed in medicine when protected 
 by syrup, but is not officinal. The ferrous nitrate, heated 
 to 130° with the gradual addition of HO,N0 5 , becomes 
 ferric nitrate, 6(FeO,N0 5 )-f 4(HO,N0 5 )=3(Fe 2 3 ,3N0 5 ) 
 -f N0 2 +4HO; s. g. 1-060 to 1-070. It contains |j Ferri 
 to f^xxxvi of solution. 
 
 Prop. — An amber-coloured liquid of an acid, astringent 
 taste. Used especially in chronic diarrhoea, unattended 
 by ulceration. 
 
 320. Carbonates. 
 
 Bern. — An alkaline carbonate added to a ferrous salt 
 throws down a white hydrated ferrous carbonate, FeO,C0 2 ; 
 on exposure to the air this absorbs O, and loses C0 2 , be- 
 coming F 2 3 with a varying proportion of C0 2 . 
 
 Pilulse Ferri Carbonatis, Vallet's Mass. 
 
 Prep. — R. Ferri Sulph. ^viii; Sodse Garb. |ix; Mel. 
 Despum. ^iij ; Sacch. pulv. ^ii; Aq. Bull. Oij ; Syrup, q. s. 
 Dissolve the sulphate of iron and carbonate of soda, each 
 in Oj of water, to which has been previously added f 5 j 
 syrup; mix the two solutions, pour into a bottle, closely 
 
 * Excess of water is omitted in the reactions. See p. 128. 
 
238 MEDICAL CHEMISTRY. 
 
 stopped, just large enough to hold them, and allow the 
 precipitate to subside, (FeO,S0 3 + ]N'aO,C0 2 =FeO,C0 2 + 
 NaO,S0 3 ->); pour off the supernatant liquor; wash the 
 precipitate with water recently boiled and sweetened with 
 syrup (f^j to Oj), until the washings have no longer a 
 saline taste; place it upon a flannel cloth to drain, and 
 afterwards express as much water as possible; then im- 
 mediately mix with the honey and sugar ; by means of a 
 water-bath evaporate with constant stirring to a pilular 
 consistence. 
 
 Rem. — The use of the sugar is to protect the ferrous 
 carbonate, FeO,C0 2 , from change. An efficient and easily 
 administered chalybeate. Dose, gr v to x. The Mistura 
 Ferri Composita and Pilulde Ferri Composite contain 
 FeO,C0 2 ; they are liable to change, and but rarely pre- 
 scribed. 
 
 Ferri Subcarbonas, Precipitated carbonate of iron. 
 
 Prep. — As above, but without the use of syrup, the 
 precipitate is washed with water and dried on unsized 
 paper, without heat. The FeO,C0 2 at first precipitated 
 absorbs 0, turns reddish-brown, and loses a great part of 
 its C0 2 . The preparation is a hydrated sesquioxide con- 
 taining some C0 2 . 
 
 Prop. — A reddish-brown powder, soluble freely with 
 effervescence in HC1, with difficulty in other acids. When 
 heated, it loses water, becomes of a brighter red, and is 
 injured; by high heat it becomes anhydrous Fe 2 3 which 
 is not attacked by acids or alkalies, and is inert, (colcothar, 
 jeweller's rouge). When prepared as directed, may be 
 used, in the absence of the Ferri Oxid. Hydrat., in cases 
 of poisoning by As0 3 . Is given in doses of gr x to xx as 
 a tonic, and in large doses up to ^j as an antispasmodic. 
 The Trochisci Ferri Subcarbonatis contain each about 
 gr v. 
 
CHEMISTRY OF THE ELEMENTS. 239 
 
 321. Sulphates. 
 
 Ferri Sulphas, Ferrous sulphate, Copperas, Green vitriol, 
 FeO,S0 3 -f THO. Is made by acting on iron by dilute HO, 
 S0 3 , evaporating and crystallising; Fe-fHO,S0 3 =FeO, 
 SO3+H. On the large scale, from the refuse HO,S0 3 of 
 the refineries of petroleum, chloroform, etc., and old iron 
 scraps; also by the oxidation of iron pyrites; the latter is 
 too impure for medical use. 
 
 Prop. — When pure, is in bluish-green, transparent crys- 
 tals of a styptic taste and acid reaction ; soluble in 2 parts 
 cold and f boiling water; the crystals contain 7 eq. water 
 of crystallisation, 6 of which they lose by a moderate heat 
 (Ferri Sulphas Exsiccata) ; exposed to the air, becomes 
 green and finally covered with a brownish efflorescence 
 of subsulphate of sesquioxide ; its solution is a pale green, 
 becoming dark from the absorption of 0. Is tonic and 
 astringent ; should be dried before making into pills. 
 Dose, gr i to v. Mixed with an equal weight of lime, 
 forms a cheap deodouriser for sinks, etc. 
 
 Liquor Ferri Tersulphatis, Solution of Ferric sulphate, 
 Fe 2 3 ,3S0 3 . 
 
 Prep. — R. Acid. Sulphuric, ^ij gr lx, Acid. Nitric. 5j 
 gr ccclx, Aquae Oss. M. Add Ferri Sulphat. pulv. ^xii, 
 one-fourth at a time, to the mixture, previously heated to 
 the boiling-point, stirring after each addition until effer- 
 vescence ceases, and heat until the liquid acquires a reddish 
 colour and loses the odour of N0 4 ; when nearly cold, add 
 Aquae q. s. ad Ojss. The nitric acid is used to raise the 
 ferrous oxide of the FeO,S0 3 to the ferric oxide, and an 
 additional equivalent of HO,S0 3 is used for each of Fe 2 3 
 formed to make a normal salt (243), 6(FeO,S0 3 )-f-N0 5 
 
 = SCFeA^SO^^ N0 2 ; FeA,2S0 3 +HO,S0 3 = Fe 2 3 , 
 3S0 3 +HO. 
 
 Prop. — A permanent clear reddish-brown liquid, s. g. 
 
240 MEDICAIi CHEMISTRY. 
 
 1-320, of an astringent, acrid taste, miscible without decom- 
 position in all proportions with water and alcohol. Is 
 rarely prescribed, being . used chiefly in making other fer- 
 ruginous preparations. 
 
 Liquor. Ferri Subsulphatis, Monsel's solution, 2Fe 2 3 , 
 5S0 3 . 
 
 Prep. — R. Ferri Sulphat. £xii, Acid. Sulphuric. 3j gr 
 xxx, Acid. Nitric. 3j gr ccc, Aquae q. s. The process is 
 the same as that last described, making the quantity of 
 solution at the end of the operation f^xii. 
 
 The name persulphate of iron, commercially given to this prepa- 
 ration, is bad ; persulphate means strictly a compound of per- 
 sulphuric acid, a body unknown. If it is intended to mean 
 sulphate of the peroxide, it is equally unfortunate. The use of 
 the terms peroxide, persulphide, etc., for sesqui compounds should 
 be banished from chemical nomenclature as indefinite. It is a 
 su&sulphate, as it contains an excess of base. 
 
 Prop. — A ruby-red, syrupy solution, s. g. 1552, resem- 
 bling that last described in general properties, but less 
 acrid to the taste and less irritating. Is largely used as a 
 styptic and astringent. On evaporation, yields deliques- 
 cent, readily soluble scales, but, like most sub-salts, does 
 not crystallise. 
 
 Ferri et Ammonias Sulphas, Ammonio-ferric alum, F 2 3 , 
 3S0 3 +NH,0,S0 3 +24HO. 
 
 Prep. — R. Liq. Ferri Ter sulphat. Oij, Ammonias Sul- 
 phat. giv-ss-. - Heat the former to the boiling-point, add 
 the latter with stirring; when dissolved, evaporate and 
 crystallise. By using KO,S0 3 in proper proportion, a 
 potassio-ferric alum, nearly identical in physical proper- 
 ties, is obtained. 
 
 Prop. — Resembles ordinary alum in most respects; the 
 taste is sour, and it is rather more soluble. Is used in the 
 same cases. 
 
CHEMISTRY OF THE ELEMENTS. 241 
 
 322. Phosphates. 
 
 Ferri Phosphas, 2FeO,HO,P0 5 , or 2FeO,Fe 2 3 P0 5 . 
 
 Prep. — Is made by double decomposition of Sodse 
 Phosphas (6 parts by weight) and Ferri Sulphas (5 
 parts by weight); 2NaO,HO,P0 5 , + 2(FeO,S0 3 )=2FeO, 
 HO,P0 5 and 2(NaO,S0 3 _ > ). Should the FeO,S0 3 con- 
 tain Fe 2 3 , it will combine in place of the basic water; the 
 insoluble phosphate is filtered from the solution of the sul- 
 phate, washed and dried. 
 
 Prop. — A bright, slate-coloured powder, insoluble in 
 water, but soluble in acids, which usually decompose it; it 
 may be dissolved unchanged in Metaphosphoric acid, 
 HO,P0 5 , and in HC1. 
 
 Med. Effects. — Those of its constituents. Dose, gr v 
 to x. Combined with phosphates of lime, soda potassa, 
 and rendered soluble by HO,P0 5 or HC1, it constitutes 
 the so-called chemical food. 
 
 Ferri Pyrophosphas. 
 
 Prep.—Sodse Phosphas, 2NaO,HO,P0 5 +24HO, ^viiss, 
 is gradually heated to redness, by which it becomes pyro- 
 phosphate, 2NaO,P0 5 ; it is then dissolved in Aqua Oiij, 
 and Liq. Ferri Tersulphat. added as long as a precipi- 
 tate falls; this is drained and washed; 3(2NaO,P0 5 )+ 
 2(Fe,0 3 ,3SG 3 )=2Fe 2 3 ,3P0 5 +6(NaO,S0 3 _). Acid. Citric. 
 
 3ij is then saturated with Aq. Ammoniee ; the citrate of 
 ammonia formed is mixed with the 2Fe 2 3 ,3P0 5 , and the 
 liquid evaporated to sxvi and poured on glass, when it 
 dries into scales. 
 
 Prop. — Scales of an apple-green colour and acid saline 
 taste, freely soluble in water. Contains 48 p. c. of pyro- 
 phosphate of iron, which is held in solution by the citrate 
 of ammonia. Dose, gr ij to v, in water or syrup. 
 21 
 
242 MEDICAL CHEMISTRY. 
 
 233. Lactate, Ferri Lactas, FeO,C 6 H 5 5 -f 3H0. 
 
 Prep. — By the action of dilute lactic acid on iron 
 filings. Fe+HO,C 6 H 5 5 =FeO,C 6 H 5 5 +H. 
 
 Prop. — Greenish-white crystalline grains, of a sweet- 
 ish taste, soluble in 48 parts cold and 12 boiling water. 
 Dose, gr x to xx. 
 
 324. Tartrates. 
 
 Ferri et Potassse Tartras, KO,Fe 2 O 3 ,C 8 H 4 O 10 +HO. 
 
 Prep. — By heating cream of tartar, mixed with water, 
 to 140°, and adding ferric hydrate as long as it will dis- 
 solve. KO,HO,C 8 H i O 10 +Fe 2 O 3 ,3HO = KO,Fe 2 O 3 ,C 8 H 4 O I0 
 -f4HO. The salt, not being normal (243), does not crys- 
 tallise. The solution is evaporated to the consistence of 
 syrup, and spread upon panes of glass to dry. 
 
 Prop. — Ruby-red, transparent scales, of a sweetish 
 taste, soluble in 4 parts water. Contains about 30 p. c. 
 of Fe 2 3 . Is slightly laxative. Dose, gr x to xxx. 
 Ferri etAmmonise Tartras,lSrH 4 0,Fe 2 3 ,C 8 H 4 1 o+ 4 ? HO. 
 
 Prep. — (1) Saturate ^vi Acid. Tart, dissolved in Oij 
 Aquae destillat. with Ammonias Garb. q. s. ; then add %vi 
 more of Acid. Tart. (2) Saturate the resulting bitartrate 
 of ammonia with ferric hydrate, and proceed as in the last 
 preparation. The reactions involved and the properties 
 and dose are similar. 
 
 325. Citrates, Liquor Ferri Citratis. 
 
 Prep. — By saturating a solution of citric acid at 150° 
 with Fe 2 3 ,3HO. g v£vi of citric acid yield a pint of solution. 
 
 Prop. — A deep reddish, permanent solution, of a slight 
 ferruginous taste ; contains ^ss of FeaC^C^HsOn to the 
 f ^j. By evaporation the solution as directed for the tar- 
 trates, there is obtained the Ferri Citras in scales resem- 
 bling in general properties and dose those preparations. 
 
 Ferri et Ammonias Citras, NH 4 0,Fe 2 3 ,C 12 H 5 O n + 2HO. 
 K. Liq. Ferri Citrat. Oj, Aquas Ammonias f ^vj. M.. The 
 
CHEMISTRY OF THE ELEMENTS. 243 
 
 solution is evaporated at a temperature not exceeding 150° 
 and treated as the citrate. It is more soluble than the 
 latter, but otherwise resembles it ; it contains 245 p. c. of 
 Fe 2 3 . 
 
 Ferri et Quinise Citras, Fe 2 3 , C^H^NgO^C 12 H 5 O n -f- 
 HO? 
 
 Prep. — By saturating Liq. Ferri Citrat. with Quinia 
 obtained by precipitating the sulphate of quinia by am- 
 monia in slight excess. The temperature of the solution 
 during the operation should be 120°. It is evaporated and 
 obtained in scales, of reddish-brown colour, bitter and 
 ferruginous taste, slowly soluble in cold water. Dose, gr 
 v to x. 
 
 Other preparations of iron, as the acetate, tannate, valeri- 
 anate, prototartrate, perchlorate, citrate of iron with strych- 
 nia, magnesia, and zinc; double phosphates of iron and am- 
 monia, iron and lime, etc., etc., have been made and used. 
 Fortunately they are not officinal as the list is already 
 crowded with compounds differing but little in physical 
 and medical properties. 
 
 CHROMIUM, Cr=26. 
 
 326. Sources. — Chrome iron ore, FeO,Cr 2 3 , and, rarely, 
 native chromate of lead, Pb0,O0 3 . The former by fusion 
 with nitre gives the chromate of potassa, KO,Cr0 3 , from 
 which the other compounds are derived. 
 
 Prep, and Prop. — By reduction of the oxide by C. Is 
 a hard, grayish-white metal; s. g. 5*9; difficult of fusion, 
 and does not readily oxidise. 
 
 Chem. Bel. — Resembles closely manganese and iron; 
 with O forms Protoxide, CrO ; Sesquioxide, Cr 2 3 , bases ; 
 Chromic Acid, Cr0 3 , and Perchromic Acid, Cr 2 7 . 
 
 Acidum Chromicum, Cr0 3 , is prepared by the action of 
 
244 MEDICAL CHEMISTRY. 
 
 strong HO,S0 8 upon bichromate of potassa, KO,2Cr0 3 . It 
 crystallises in brilliant red prisms ; very deliquescent and 
 soluble in water. It has been used in medicine as an 
 escharotic. It rapidly dissolves organic matter, except 
 gun-cotton and paraffine, and is a powerful oxidising 
 agent, becoming reduced to Cr 2 3 . The chromates are re- 
 markable for their brilliant colours and are used as pig- 
 ments, especially those of baryta, lead, and antimony. 
 
 Potassse Bichromas, KO,2Cr0 3 , possesses the properties 
 of Cr0 3 , but in a milder degree. It is used as an escharotic 
 and as an oxidising agent. Internally, in large doses, is 
 an irritant poison. Antidotes : mild alkalies, demulcents. 
 Has been used in small doses (gr \, gradually increased) 
 in secondary syphilis. None of the other preparations of 
 chromium are used in medicine. Workmen engaged in 
 manufactures where it is used are liable to painful ulcer- 
 ations. 
 
 NICKEL and COBALT. 
 
 32*7. Two metals, isomorphous with iron, zinc, and cop- 
 per. They occur in nature as arsenides and generally as- 
 sociated. They are not employed in medicine. 
 
 Nickel, Ni=29-5. — A white metal, s. g. 8 to 8*8; dif- 
 ficult of fusion, is magnetic ; occurs in meteoric stones. 
 Its protoxide, NiO, forms salts of a delicate green colour. 
 Nickel is chiefly employed in the manufacture of German 
 silver, which contains 100 parts copper, 60 of zinc, and 40 
 of nickel. 
 
 Cobalt, Co = 29 - 5. — Resembles nickel in properties and 
 chemical relations. Its protoxide, CoO, forms pink salts, 
 but is precipitated by alkalies as a blue hydrate. The 
 chloride, CoCl, is used in dilute solution as a sympathetic 
 ink, being invisible until heated, when it becomes blue, 
 and again fades, if not too highly heated, on cooling. Co- 
 
 
CHEMISTRY OF THE ELEMENTS. 245 
 
 bait is employed to give a blue colour to glass and artifi- 
 cial gems ; also in blowpipe analysis. 
 
 COPPER, Cu=31-7. 
 
 328. Sources. — Occurs native, and as oxide, carbonate 
 (malachite), and sulphide (copper pyrites, Fe 2 S 3 CuS). 
 
 Prop. — A brilliant, sonorous, very malleable and duc- 
 tile metal, of a characteristic colour, slightly nauseous 
 taste, and disagreeable odour when rubbed ; s. g. 8*89 ; 
 fuses at 1996° ; is but little affected in dry air ; in moist 
 air, especially in the presence of acids, becomes coated 
 with a green carbonate. At a red heat it becomes covered 
 with a black scale of CuO. 
 
 Chem. Bel. — Forms three oxides : Suboxide Cu 2 0, Prot- 
 oxide CuO, and an undetermined higher oxide, which is 
 acid. The protoxide is of a black colour, its salts are iso- 
 morphous with those of zinc and of a rich blue or green 
 colour. Those of Cu 2 are colourless. 
 
 The alloys of copper are numerous and valuable. Brass con- 
 tains copper with 28 to 34 p. c. of zinc ; muntz metal, 60 copper 
 to 40 zinc ; gun metal, 90 copper to 10 tin ; aluminium bronze, 
 90 copper, 10 aluminium ; Austrian gun metal, remarkable for 
 tenacity, copper 55*04 p. c, zinc 42*36, tin 8'3, iron 1*77. Bab- 
 bit's antifriction metal, 24 each copper and tin, and 8 of anti- 
 mony. 
 
 Tests. — Ammonia throws down a blue precipitate, sol- 
 uble in excess; Ferrocyanide of potassium a brown, and Hy- 
 drosulphuric acid a black precipitate. 
 
 329. Sulphate, Cupri Sulphas, CuO,S0 3 -f 5HO ; Blue 
 vitriol. 
 
 Prep. — May be obtained by boiling Cu in HO,S0 3 ; 
 S0 2 is given off; Cu+2(HO,S0 3 )=CuO,S0 3 +S0 2 +2HO. 
 On the large scale, by roasting the native sulphide, or by 
 dissolving copper scales (CuO) in HO,S0 3 . 
 21 * 
 
246 MEDICAL CHEMISTRY. 
 
 Prop. — Rich, deep blue, oblique rhomboidal (5th sys- 
 tem) crystals, of a nauseous, styptic taste, soluble in 4 
 parts cold and 2 of boiling water. When heated, it under- 
 goes aqueous fusion, then dries and becomes white ; at a 
 high temperature, is decomposed. 
 
 Med. Effects. — In small doses, tonic, antispasmodic, and 
 astringent ; in large doses, emetic ; externally, escharotic, 
 and in solution astringent. 
 
 In large doses, ^ss and more, an irritant poison, but not 
 likely to be taken, on account of its taste. Antidotes : 
 magnesia, albumen ; the same may be said of all the salts 
 of copper. When copper vessels are used in preparing 
 food, or when workmen are exposed to it, slow poisoning 
 may also take place, giving rise to cramps, diarrhoea, and 
 dysentery. 
 
 Incompat. — Those of the soluble sulphates; metallic 
 iron and zinc ; the alkalies and their carbonates. 
 
 330. Cupri Subacetas, Yerdigris ; impure Subacetate of 
 copper. 
 
 Prep. — Is made by stratifying sheets of copper and 
 refuse of grapes ; the alcohol in the husks becomes acetic 
 acid, and unites with oxide of copper formed upon the 
 plate. Its composition is variable ; contains 3CuO,2C 4 
 H 3 3 -{-6HO, and 3CuO,C 4 H 3 3 +3HO. 
 
 Prop. — Pale, greenish or blue masses composed of 
 silky needles; soluble in ammonia, insoluble in alcohol, 
 and decomposed by water into neutral acetate, CuO,C 4 H 3 
 3 , and trisacetatc, 3CuO,C 4 H 3 3 . 
 
 Med, Effects. — Used only externally as an escharotic 
 and astringent ; internally, like the other salts of copper, 
 is poisonous. 
 
 331. Cuprum Ammoniatum, Ammoniated copper. 
 Prep. — Is made by rubbing (3SS) Cupri Sulphat. with 
 
 gr ccclx (3vi) Ammon.Carb. until effervescence ceases. 
 
CHEMISTRY OF THE ELEMENTS. 241 
 
 Bern. — The composition of this compound is not under- 
 stood ; probably a cupro-sulphate of ammonia, NH 4 0,S0 3 
 -f jS"H 4 0,CuO-}-HO, in which the oxide of copper acts the 
 part of an acid. 
 
 Prop. — A beautiful, deep azure-blue salt, with a strong 
 ammoniacal odour, and styptic, metallic taste ; is freely 
 soluble in water; rapidly decomposes on exposure to 
 the air. 
 
 Med. Effects. — Tonic and antispasmodic. 
 
 Incompat. — All acids; the alkalies and earths gener- 
 ally, and their carbonates. 
 
 332. Of the compounds of copper not used in medicine 
 the following are the most important. The chloride, CuCl 
 -|-2HO, is soluble in alcohol, to the flame of which it com- 
 municates a green colour. The oxy chloride, 3(CuO,HO) 
 + CuCl+ HO, occurs native as atacamite, and is known in 
 commerce as Brunswick green. The carbonate occurs 
 native as malachite, CuO,HO-f-CuO,C0 2 , and azurite, CuO, 
 HO-f 2(CuO,C0 2 ); in commerce the same compounds, ar- 
 tificially prepared, are known as green and blue verditer. 
 
 ZINC, Zn=325. 
 
 Syllabus. 
 
 Metal, Zincum. 
 
 Oxide, ZnO; Zinci Oxidum, Zinc white, Flowers of zinc; 
 Ung. Zinci Oxidi. 
 
 Chlorides, ZnCl; Zinci Chloridum, Butter of Zinc; 
 Burnett's disinfecting solution ; Oxychloride, ZnCl,3ZnO 
 + 2HO. 
 
 Carbonate; Zinci Carbonas Prsecipitata, 8ZnO,3C0 2 
 -f6HO, Ceratum Zinci Carbonatis. 
 
 Sulphate, ZnO ? S0 3 -f7HO; Zinci Sulphas, White Vit- 
 riol. 
 
248 MEDICAL CHEMISTRY. 
 
 Acetate, ZnO,C 4 H 3 3 + 2H0; Zinci Acetas. 
 Valerianate, ZnO,C l0 H 9 O 3 ; Zinci Valerianas. 
 
 333. Sources. — The native sulphide, ZnS (blende) ; car- 
 bonate, ZnO,C0 2 (calamine); and silicate, ZnO,Si0 3 -f HO 
 (electric calamine). It is obtained by roasting and reduc- 
 tion. 
 
 Prop. — A bluish-white, rather hard metal ; s. g. 6*8 ; of a 
 peculiar odour when rubbed. Commercial zinc is somewhat 
 brittle ; between 212° and 300° it becomes malleable, above 
 400° again brittle, and may be beaten into powder. Zinc 
 may be conveniently granulated by holding above a pan of 
 water a common broom thoroughly wetted, and pouring 
 the molten metal over it. It melts at 110°, and is volatile 
 at a bright-red heat; if volatilised in the presence of air, it 
 burns with a bright bluish-white flame and evolution of a 
 cloud of ZnO (philosopher's wool). Exposed to air, it tar- 
 nishes superficially, and the coating of oxide formed pro- 
 tects in a measure the metal within ; acids corrode it 
 rapidly. 
 
 Chem. Bel. — Forms one oxide, ZnO, the salts of which 
 are isomorphous with those of magnesia. Its salts are 
 colourless and generally soluble. Test. NH 4 S,HS throws 
 down a characteristic white sulphide of zinc, HS does so 
 only in neutral solutions. 
 
 Med. Effects. — The salts of zinc are tonic, antispas- 
 modic, and astringent. 
 
 334. Oxide, ZnO, Zinci Oxidum. 
 
 Prep. — On the large scale by burning zinc ; a purer form 
 is obtained by exposing the precipitated carbonate to a low 
 red heat until HO and C0 2 are expelled ; this is the offici- 
 nal process. 
 
 Prop. — A tasteless, inodorous, white powder, insoluble 
 in menstrua except the acids and caustic alkalies. It 
 becomes yellow when heated, but white again on cooling. 
 
CHEiMISTRY OF THE ELEMENTS. 249 
 
 It is the zinc white of commerce used as a substitute for 
 white lead, as being less liable to produce symptoms of 
 metallic poisoning. Dose, gr ij to x. The Unguentum 
 Zinci oxidi is made by rubbing up ^j Zinci Oxidi with 
 Jvi Adipis. Is used externally as a mild astringent. 
 
 335. Chloride, ZnCl ; Zinci Chloridum, Butter of Zinc. 
 
 Prep. — By direct combination of its elements, or by the 
 action of HC1 on Zn=ZnCl-j-H. In the officinal process 
 ^iiss of zinc is dissolved in Acid, muriat. q. s., the solution 
 strained, Acid, nitric, gr lx added, and the whole evapo- 
 rated to dryness. The dry mass is dissolved in fjfv Aquae, 
 and gr lx Cretse Prseparalse added, the whole allowed to 
 stand 24 hours. It is then filtered, evaporated to dryness, 
 fused, poured upon a slab, and when solid broken into 
 fragments which must be kept in a well-stopped bottle. 
 The nitric acid and chalk are to get rid of iron, the for- 
 mer produces a ferric salt which is mostly decomposed by 
 heat, the chalk neutralises any excess of acid and precipi- 
 tates a soluble salt of iron as carbonate. 
 
 Prop. — A white deliquescent salt, wholly and freely 
 soluble in water and alcohol. Burnett's disinfecting solu- 
 tion contains gr cc to ^i, and has a s. g. of 2. It acts by 
 absorbing HS and by preventing decay by coagulating 
 albuminoid matters. ZnCl forms a series of double salts 
 of which the double chloride of zinc and ammonium, ZnCl, 
 NH 4 C1, is used in soldering to dissolve metallic oxides. 
 Zinci Chloridum is used externally as an escharotic, or in 
 dilute solution as an astringent. In large doses is an irri- 
 tant poison ; antidotes, soap, the alkaline carbonates. The 
 oxy chloride, ZnCl,3ZnO-|-2HO, is made by mixing a con- 
 centrated solution of ZnCl with ZnO, recently prepared 
 by burning zinc. It hardens rapidly, is used as a fillip. g 
 for decayed teeth, and as a cement generally. 
 
250 MEDICAL CHEMISTRY. 
 
 336. Carbonate, Zinci Carbonas Prascipitata. 
 
 Prep. — By mixing equal weights of Zinci Sulph. and 
 Sodas Garb, dissolved in water, washing and drying the 
 precipitate. 
 
 Prop. — A smooth, white powder, which should be 
 wholly dissolved with effervescence in dilute HO,S0 3 . Its 
 composition is not constant, is a mixture of the carbonate 
 and hydrate of the oxide, or a carbonate containing an 
 excess of oxide, 8ZnO,3C0 2 +6HO, or (ZnO,C0 2 +HO)+ 
 2(ZnO,HO). Is used as a substitute for the native car- 
 bonate Calamine, which is generally impure. Is used ex- 
 ternally only. Ceratum Zinci Carbonatis, a substitute for 
 the old Ceratum Calaminae, Turner's cerate, is made by 
 mixing ^ij Zinc. Carb. Prsecip. with ^x Ung. Adipis. 
 Resembles the Ung. Zinci Oxidi. The neutral carbonate 
 ZnO,C0 2 occurs native as Calamine. 
 
 337. Sulphate; Zinci Sulphas, White vitriol, ZnO,S0 3 
 -HHO. 
 
 Prep. — By the action of dilute HO,S0 3 upon Zn= 
 ZnO,S0 3 +H. 
 
 Prop. — Colourless, transparent, right rhombic crystals 
 (3d system) much resembling epsom salt ; has a slight acid 
 reaction, is soluble in 2J parts cold and less than its 
 weight of boiling water ; taste styptic, astringent ; when 
 heated, it undergoes aqueous fusion, becomes anhydrous, 
 and finally loses its acid. 
 
 Med. Effects. — Small doses, gr j to ij, tonic, astringent, 
 antispasmodic ; in large, gr xxx, emetic ; in overdose, an 
 irritant poison, rarely fatal, from its producing vomiting ; 
 its effects are combated by mucilage and albumen. Exter- 
 nally applied, is astringent and escharotic. 
 
 Incompat. — The alkalies and alkaline earths, their car- 
 bonates ; lead salts ; vegetable astringents. 
 
CHEMISTRY OF THE ELEMENTS. 251 
 
 338. Acetate, ZnO,C 4 H 3 3 +2HO; Zinci Acet as. 
 Prep. — Plumb. Acetat. ^xii is dissolved in Oijj Aq. 
 
 Destillat. To this is added %\x Zinci (granulated) and 
 the whole shaken occasionally until the liquid does not 
 yield a yellow precipitate upon the addition of KI (ab- 
 sence of Pb). It is then filtered slightly, acidulated 
 with acetic acid, and crystallised; PbO,C 4 H 3 03-f-Zn=ZnO, 
 
 C 4 H 3 3 ~ ,, -f Pb. Should the crystals be coloured, re-dissolve 
 
 i 
 and add Zinci carb. pr&cip. until a portion evaporated 
 yields colourless crystals. 
 
 The use of the carbonate is to remove any iron. The acetate 
 may be rapidly and conveniently prepared by saturating acetic 
 acid, HO,C 4 H 3 3 , with the precipitated carbonate. It is often 
 made extemporaneously by mixing in the same prescription 
 solutions of ZnO,S0 3 -f 7HO and PbO,C 4 H 3 3 +3HO. If equal 
 weights are employed, the latter salt will be slightly in excess. 
 The presence of insoluble sulphate of lead in this case must be 
 borne in mind ; it may be useful in gonorrhoea, etc., but highly 
 improper in a collyrium. ZnO,S0 3 +PbO,C 4 H 3 3 =ZnO,C 4 H 3 3H . 
 + PbO,SO a . 
 
 Prop. — In colourless, efflorescent, hexagonal (6th sys- 
 tem) plates, very soluble in water, somewhat so in alcohol. 
 Is only employed externally ; is a mild astringent. Is in- 
 compatible with the mineral acids, the alkalies, earths, 
 their carbonates, and the vegetable astringents. 
 
 339. Valerianate; Zinci Valerianae, ZnO,C 10 H 9 O 3 . 
 Prep. — By double decomposition of Sodse Valerianat. 
 
 ^iiss and Zinci Sulphat. ^ij gr ccccxx, each dissolved in 
 f^xx Aquae Destillat. and heated to the boiling-point be- 
 fore admixture. ZnO,SO 3 +NaO,C 10 H 9 O 3 =ZnO,C 10 H 9 O 3 "* 
 -f- NaO,S0 3 ->. By evaporation, the less soluble Zinci 
 Valerianae crystallises out first, and the evaporation may 
 be continued until the liquid is but T \, of the original bulk 
 The crystals are washed with cold, distilled water, to re- 
 move any NaO,S0 3 . 
 
252 MEDICAL CHEMISTRY. 
 
 Prop. — In anhydrous, white, pearly scales, soluble in 160 
 parts cold water and 60 of alcohol of 0-833, having a faint 
 odour of valerianic acid, a metallic, styptic taste, and a 
 slightly acid reaction. Used as an antispasmodic. Dose, 
 gr i to ij in pill. Incompatibles, those of the acetates. 
 
 CADMIUM, Cd=56. 
 
 340. Sources. — Cadmium occurs associated with zinc 
 in its ores, and being more volatile comes over with the 
 first portions of the vapour of that metal when it is dis- 
 tilled. The two are dissolved in excess of HC1. HS is 
 passed through the solution, which precipitates only the 
 Cd as an orange-yellow sulphide, CdS. From this the 
 carbonate is readily obtained, and from the latter the 
 metal. 
 
 Prop. — Much resembles tin, but is more volatile, tena- 
 cious, and heavier; when bent or twisted, has a cry like 
 tin; s. g. 8*Y; melts at 440°, volatilises below a red heat, 
 does not oxidise readily at ordinary temperatures. Forms 
 a protoxide, CdO, which is a base forming colourless salts. 
 The sulphide is used in pyrotechny, and the iodide (made 
 by mixing I and Cd filings moistened) as a substitute for 
 Pbl. The metal is officinal as Cadmium. — Test. NH 4 HS 
 gives a yellow precipitate of CdS, insoluble in excess or in 
 KO,HO or NH 4 0,HO, and thus distinguished from the 
 sulphide of arsenic, As,S 3 . 
 
 341. Sulphate, Cadmii Sulphas, CdO,S0 3 +4HO. 
 Prep. — 3j Cadmii is acted upon by f^ij Acid. Nitric. 
 
 diluted with an equal bulk of distilled water, Cd 3 -f-4(HO, 
 N0 5 )=3(CdO,N0 5 )+4HO-fN0 2 . To the nitrate thus 
 formed is added ^iij Sodas Carb. dissolved in fjvi Aquas 
 Destillat. CdO^Os+NaO^O^CdO^+NaO^O^. 
 The precipitated carbonate is washed and treated with 
 
CHEMISTRY OF THE ELEMENTS. 253 
 
 Acid. Bulph. gr ccccxx, diluted with fsiv Aquae Destillat. 
 CdO,C0 2 -f HO,S0 3 =CdO,S0 3 +HO-fC0 2 . This appar- 
 ently circuitous process is rendered necessary by the fact 
 that HO,S0 3 does not readily act on Cd, but rapidly de- 
 composes its carbonate. 
 
 Prop. — In colourless, efflorescent, oblique rhomboidal 
 prisms (5th system), freely soluble in water. Used ex- 
 ternally as a lotion, gr ss to ij to ^j Aquas; or ointment, 
 gr ij to ^j, in ophthalmia and corneal specks. Is esteemed 
 alterative, but is rarely used internally. 
 
 BISMUTH, Bi=210. 
 
 342. Sources. — Occurs native and as oxide. 
 
 Prop. — A brittle, crystalline, (rhombohedral, 6th sys- 
 tem) metal, having a white colour with a reddish tinge, s. g. 
 9'8, fuses at 50T and burns at a higher temperature, giving 
 rise to yellow fumes, which on cooling become white Bi0 3 . 
 
 Chem. Bel. — Forms Bi0 3 , a feeble base, Bi0 5 Bismuthic 
 Acid, and Bi0 4 , which is probably a compound oxide, 2Bi0 4 
 =Bi0 3 ,Bi0 5 . The chloride BiCl 3 may be made by direct 
 combination, or by dissolving Bi0 3 in 3HCl=BiCl 3 +3HO. 
 It is a deliquescent solid (butter of bismuth) decomposed 
 by water into oxychloride and HC1 ; a small quantity 
 remains undecomposed. 3BiCl 3 -J- 6HO = BiCl 3 , 2 Bi0 3 -f 
 QTLC\_^. This precipitate, as well as the subnitrate, is sold 
 as pearl powder and pearl white, and used as a cosmetic ; 
 they both blacken by HS. The other important salts will 
 be considered under the preparations. 
 
 Alloys. — Bismuth and its alloys expand on cooling, and 
 hence are adapted for taking casts. Fusible metal melts 
 at 200, and contains 2 parts of Bi, one of Fb, and one of Sn ; 
 by the addition of Cd and Hg, the fusing-point may be 
 reduced still lower. Test. The salts of bismuth are de- 
 22 
 
254 MEDICAL CHEMISTRY. 
 
 composed by an excess of water, and the precipitates 
 formed blackened by HS. 
 
 343. Nitrates; Bismuthi Subnitras, Bi0 3 ,N0 5 . 
 
 Prep. — When Bi in powder is acted upon by nitric acid, 
 it dissolves with evolution of ]\ T 4 . Bi+4(HO,^s T 5 )=Bi0 3 , 
 3N0 5 -J- 4HO + X0 2 . When crystallised, this normal nitrate 
 of bismuth contains 9 eq. of water of crystallisation. On 
 the addition of water a white precipitate falls, the magistery 
 of bismuth, pearl powder, etc. In this case the water acts 
 as a base and displaces a portion of Bi0 3 , leaving a pre- 
 cipitated subnitrate and an acid supernitrate, 4(Bi0 3 ,3N0 5 ) 
 =3(Bi0 3 ,]S T 5 ) + Bi0 3 ,9NOr. The composition of the 
 
 precipitate is not constant. The commercial subnitrate 
 frequently contains arsenic, and the new process, U. S. P., 
 is designed to avoid this impurity, ^ij Bismuthi are 
 submitted to the action of giv Acid. Nitric, diluted with 
 giv Aquae Destillatas for 24 hours. The resulting Bi0 3 , 
 3N"0 5 is diluted with f3x Aq. Destillat., which is not 
 enough to cause decomposition, but merely a slight turbid- 
 riess. The solution is filtered, and to it is added a solution 
 of Sodas Garb. %x dissolved in f^xx Aquas Destillat. pre- 
 viously filtered, and the whole stirred; the precipitate of 
 carbonate of bismuth is thoroughly washed, and to it is 
 added g vi Acid. Nitric, and the whole heated nearly to the 
 boiling-point, re-forming the nitrate; when cold, Aq. Des- 
 tillat. is added until it begins to produce milkiness. It is 
 then allowed to stand for 24 hours, and is filtered ; Oiv Aquas 
 Dest. is added and then f^vj Aquas Ammonias with con- 
 stant stirring. The precipitate is then washed and dried. 
 The excess of NaO,C0 2 is used to retain any As, as arse- 
 niate of soda; if any arseniate of bismuth be formed, it will 
 be precipitated upon the addition of the small quantity of 
 water to the nitrate. The use of NH 4 0,HO is to more 
 completely precipitate the subnitrate. 
 
CHEMISTRY OF THE ELEMENTS. 255 
 
 Prop. — A heavy, white powder, of a feebly acid taste 
 and reaction, insoluble in water even when carbonated. It 
 should give no trace of As in Marsh's apparatus. See 
 Arsenic. 
 
 Med. Effects. — Used in chronic affections of the stom- 
 ach and bowels, as gastralgia and diarrhoea ; externally, as 
 a desiccating application to burns and ulcers, and sus- 
 pended in water as an injection in gonorrhoea and leucor- 
 rhoea. Dose, gr v to xxx. 
 
 344. Carbonate; Bismuthi Subcarbonas, Bi0 3 ,C0 2 . 
 
 Prep. — By preparing a normal nitrate with the pro- 
 portions and precautions indicated in the last article, pre- 
 cipitating with excess of ammonia, re-dissolving, as before, 
 in dilute HO,N0 5 , and precipitating with carbonate of 
 soda in excess. 
 
 Prop. — A white or yellowish-white, heavy powder, in- 
 soluble in water or carbonic acid water, soluble in nitric 
 acid with effervescence. Should give no indications of 
 As with Marsh's test. Used in the same cases and doses 
 as the subnitrate. 
 
 LEAD, Pb= 103-5. 
 
 Syllabus. 
 
 Oxide, PbO, Plumbi Oxidum, Litharge, Emplastram 
 Plumbi. 
 
 Iodide, Pbl, Plumbi Iodidum. 
 
 Carbonate, Plumbi Carbonas, White lead, PbO,C0 2 ,or 
 2(PbO,C0 2 )-fPbO,HO; Unguentum Plumbi Carbonatis. 
 
 Nitrate, PbO,N0 5 , Plumbi Nitras. Ledoyen's solu- 
 tion contains gr Ix to f^j Aquae. 
 
 Acetates: Plumbi Acetas, PbO,C 4 H 3 3 -h3HO ; Liquor 
 Plumbi Subacelatis, Goulard's extract, 3PbO,C,II 3 3 ; Liq. 
 
256 MEDICAL CHEMISTRY. 
 
 Plumb. Subacetat. dilutus fjiij to Oj Aquae, Lead water : 
 Ceratum Plumbi Subacetalis, G-oulard's cerate. 
 
 345. Sources. — The native sulphide, PbS (Galena), and 
 phosphate Pyromorphite, 3PbO,P0 5 -fPbCl, rarely the 
 binoxide, Pb0 2 , carbonate, PbO,C0 2 , sulphate, PbO,S0 3 . 
 Obtained by roasting and reduction; the sulphide fre- 
 quently contains an important percentage of silver. 
 
 Prop. — A soft, bluish-white, malleable, imperfectly duc- 
 tile metal, s. g. 11-45; melts at 620°, and becomes cov- 
 ered with a coating of oxide, mostly protoxide PbO, is 
 brittle just below its melting point ; soon tarnishes in 
 moist air, from the formation of suboxide Pb 2 ? In pure 
 water, lead becomes coated with scales of oxide, which 
 dissolve and are again precipitated as insoluble oxycar- 
 bonate (Brande and Taylor). The presence of alkalies, the 
 nitrates and chlorides, as well as of C0 2 , increases the 
 action of water upon lead ; it is diminished by carbonates, 
 sulphates, and phosphates, especially of lime, which form 
 a coating on the inside of the pipe or vessel protecting it ; 
 ooVo P ar t °f CaO,S0 3 will produce this effect. As all 
 ordinary river-water contains these salts, lead cannot 
 generally be detected in hydrant water, but may be found 
 in mineral water, and in situations where the solder of 
 the lead may be acted upon by acid or alkaline waters. 
 It is removed by nitration through animal charcoal, or 
 agitation with enough powdered chalk to make a liquid of 
 a creamy consistence. 
 
 Chem. iteZ. — Forms Pb 2 0, suboxide; PbO, Pb 2 3 , and 
 Pb0 2 , puce or brown oxide — plumbic acid ; also minium or 
 red lead, an intermediate oxide Pb 3 4 , or 2PbO,Pb0 2 . PbO 
 is obtained by direct oxidation, by precipitation as a 
 hydrate, or by heating its carbonate. It is a powerful 
 base resembling in some respects the alkalies, in which 
 it is soluble; it is also slightly soluble in water; it readily 
 
CHEMISTRY OF THE ELEMENTS. 257 
 
 unites with silica and the earths and metallic oxides, form- 
 ing fusible, vitreous bodies. It enters into the composition 
 of flint glass. By exposing PbO to a temperature between 
 570° and 580°, it absorbs 0, and becomes of a brilliant 
 red colour, forming minium or red lead, Pb 3 4 . By the 
 action of acids, this oxide yields proto-compounds, and 
 Pb0 2 is left ; the latter is a brown powder, readily giving 
 up its 0, by action of heat or acids, in the form of ozone. 
 The chloride PbCl is soluble in 135 parts cold and 33 of 
 boiling water, and insoluble in alcohol. Other compounds 
 will be considered under the preparations. 
 
 Tests. — HS andNH 4 S,HS give a black precipitate ; KI 
 and KO,Cr0 3 , a brilliant yellow ; HO,S0 3 , or the soluble 
 sulphates, a white. 
 
 Incompabibles. — The soluble chlorides, iodides, sul- 
 phites ; the sulphates, the alkalies and their carbonates ; 
 the vegetable astringents. 
 
 Med. Effects. — The salts of lead are sedative and astrin- 
 gent. In large doses, poisonous ; antidote, the soluble 
 sulphates or dilute sulphuric acid. Persons engaged in 
 manufactures of lead are liable to lead colic and palsy. The 
 best mode of prevention is frequent washing of the hands 
 and body, and the use of a sulphuric acid lemonade. 
 
 341. Oxide, Plumbi Oxidum, Litharge, Massicot, PbO. 
 
 Prep. — On the large scale, by exposing melted lead to 
 a current of air. 
 
 Prop. — Small, brilliant, red or yellow vitrified scales, 
 fusing at a red heat. Slightly soluble in water; saponi- 
 fies with oils. Absorbs C0 2 by exposure to the air. Is 
 readily dissolved in dilute HO,N0 5 . Is largely emplo} T cd 
 in the arts, in painting, etc. Is not used as medicine, but 
 enters into other officinal compounds, as Emp. Plumbi, 
 lead plaster ; which is made by boiling together Litharge 
 3xxx, Olive Oil §lvi, and Water q. s. 
 22 * 
 
258 MEDICAL CHEMISTRY. 
 
 348. Iodide, Plumbi Iodidum, Pbl. 
 
 Prep. — By double decomposition of Plumbi Nitrat. %'\v 
 dissolved in Oiss Aquae Destillat., and Potass. Iodid. %iv 
 in Aquas Destillat. Oss. The precipitate is washed and 
 dried as usual; PbO,N0 5 -fE:i==PbI-}-KO,N0 5 _^. 
 
 Prop. — A bright yellow, heavy, inodorous powder, 
 fusible and volatilised by heat, soluble in 1235 parts cold 
 and 194 of boiling water. The boiling solution on cooling 
 deposits the salt in brilliant golden-yellow scales. Is used 
 externally only, in ointment. . 
 
 349. Nitrate, Plumbi Mtras, PbO,N0 5 . 
 
 Prep. — By dissolving Litharge in dilute HO,N0 5 ; 
 when crystallised, is in the form of white, nearly opaque, 
 regular octohedra (1st system) ; soluble in water and alco- 
 hol, and having a sweetish, astringent taste. 
 
 Uses. — Is never used internally ; rarely externally. It 
 is employed as a deodoriser. LedoyarVs Disinfecting 
 Solution contains gr lx to |j water. It acts by absorbing 
 HS, giving rise to PbS. 
 
 350. Carbonate, Plumbi Carbonas, White lead, PbO,C0 2 , 
 or 2(PbO,C0 2 ) + PbO,HO. 
 
 Prep. — On the large scale, by exposing metallic lead to 
 the action of vapour of vinegar in a hot-bed. A subace- 
 tate, 3PbO,C 4 H 3 3 , is formed, which becomes carbonate by 
 absorption of C0 2 , liberating the acetic acid, which acts 
 on a fresh portion of metallic lead. 
 
 Prop. — Fine, white, heavy, opaque, iDodorous, nearly 
 tasteless, insoluble powder. Dissolves freely in acids, 
 with evolution of C0 2 . 
 
 Med. Effects. — Is highly poisonous ; cases of acute poi- 
 soning are rare. The alkaline sulphates, generally em- 
 ployed as antidotes, are of little use; dilute HO,S0 3 , or 
 Acid. Sulph. Arom., with emetics and purgatives, should 
 be used. It is the salt which most commonlv causes lead 
 
CHEMISTRY OP THE ELEMENTS. 259 
 
 colic and palsy. It is used externally only, as a sedative 
 astringent. 
 
 Unguentum Plumbi Carbonatis. Prep. — By rubbing 
 up ^ij Plumb. Garb, and Ung. Simp. Ibj ; first softening 
 the latter by heat 
 
 351. Acetates. 
 
 Plumbi Acetas, Sugar of Lead, PbO,C 4 H 3 3 -f3HO. 
 
 Prep. — Is prepared, on the large scale, by the action of 
 acetic acid on lead plates frequently exposed to the air, 
 or by dissolving litharge in the acid. 
 
 Prop. — White crystals (4th system), of a sweetish, as- 
 tringent taste, and slightly efflorescent. Soluble in 1-J parts 
 cold water ; the solution is turbid, on account of the for- 
 mation of carbonate, from the presence of carbonic acid in 
 ordinary water. Is sedative and astringent. Dose, gr v. 
 In overdose, a poison ; antidote, the soluble sulphates. 
 
 Liquor Plumbi Subacetatis, Goulard's extract. 
 
 Prep. — Is made by boiling together, Plumbi Acetat. 
 |;xvj, Plumb. Oxid. Semivit. pulv. subtil, ^ixss, and Aq. 
 Destill. Oiv, for half an hour; adding water to keep 
 up the quantity, and filtering. The s. g. of the solution 
 is 1-267. In this case an additional quantity of PbO is 
 given to the acetate, forming 3PbO,A (trisacetate), or 
 2PbO,A (diacetate). The liquid has a sweetish, astrin- 
 gent taste, and absorbs C0 2 with great avidity, becoming 
 turbid ; hence should be kept in well-stopped bottles ; it 
 forms a dense white precipitate with a solution of gum. 
 
 Med. Effects. — Used only externally ; is more poison- 
 ous than the acetate. Antidotes the same. 
 
 Liquor Plumbi Subacetatis Dilutus, Lead Water. 
 
 Prep. — Is made by diluting the last preparation, f^ijj 
 to Oj. It is turbid when first made, but if kept well- 
 stopped, becomes clear, by the subsidence of the carbonate. 
 
 Geraium Plumbi Subacetatis, Goulard's cerate. 
 
200 MEDICAL CHEMISTRY. 
 
 Prep. — 3iv Cerse Albae is melted with ^vii Ol.Olivse; 
 the mixture is then removed from its fire, and when it 
 begins to thicken, f^iiss Liq. Plumb. Subacetat. is stirred 
 in with a wooden spatula until it becomes cool ; to this is 
 added gr xxx Camphor se dissolved in ^j 01. Olivde. It 
 does not keep well. 
 
 TIN, Sn=59. 
 
 352. Sources. — The native oxide Sn0 2 ; is obtained by- 
 reduction. 
 
 Prop. — A silvery white, malleable, slightly ductile metal, 
 fusible at 442°, volatile at a white heat, s. g. T28. It 
 emits a peculiar odour when heated or rubbed ; when bent, 
 crackles, the cry of tin ; does not oxidise at ordinary tem- 
 peratures, but when melted becomes first SnO, and finally 
 Sn0 2 . Burns in the flame of the compound blowpipe. 
 Tin foil is usually adulterated largely with lead. Tin 
 plate is iron coated with tin, which, being electro-negative 
 to the former, causes rapid oxidation when the surface is 
 abraded (165). Tin is not readily acted upon by chemical 
 agents. 
 
 Chem. Bel. — Forms three oxides : SnO, a feeble base ; 
 Sn 2 3 , unimportant; and Sn0 2 , Stannic acid. SnO is formed 
 by direct oxidation (putty powder), or as a hydrate by 
 precipitation by the alkalies or their carbonates from the 
 chloride SnCl; the latter is soluble in dilute acids and 
 in caustic potassa or soda. Sn0 2 , made by precipitation 
 from SnCl 2 , by alkalies or their carbonates, forms salts with 
 the alkalies of which the stannate of soda, NaO,Sn0 2 + 
 4HO, is used as a mordant (299). It is also soluble in 
 acids. The stannic acid obtained by the action of dilute 
 HO,N0 5 upon tin differs in some important respects from 
 stannic acid obtained by precipitation ; it has been termed 
 
 
CHEMISTRY OP THE ELEMENTS. 261 
 
 metastannic acid ; its salts are not crystallisable. Tin 
 forms SnS, Sn 2 S 3 , and SnS 2 ; the latter is known as aurum 
 musivum, or mosaic gold ; it is only soluble in Aqua Regia, 
 and has a golden lustre ; s. g. 4-5. Is used as a bronzing 
 powder. The protochloride SnCI may be made by the 
 action of HC1 upon Sn ; it easily decomposes ; is a power- 
 ful reducing agent, used to remove ink spots, as a mordant, 
 and as a test for HgCl, from which it precipitates Hg in 
 a finely divided state. SnCl 2 , made by the action of Aqua 
 Eegia on tin, is a colourless, fuming liquid, used as a mor- 
 dant. Tests. Corrosive sublimate, HgCl, gives with the 
 protochloride a gray precipitate of metallic mercury ; chlo- 
 ride of gold, AuCl 3 , a rich purple ; the bichloride is precipi- 
 tated of a dingy yellow colour by NH 4 S,HS, soluble in 
 excess. The oxysalts of tin are rarely met with. 
 
 Med. Effects. — Powdered tin is used as an anthelmintic, 
 and was formerly officinal as Pulvis Stanni. The chlo- 
 rides are poisonous; antidotes, albumen, milk, or flour paste. 
 
 ARSENIC, As=?5. 
 
 353. Sources. — This element is widely diffused, occur- 
 ring generally combined with the sulphides of the metals, 
 as those of iron, copper, nickel, cobalt, and zinc ; also as 
 the native sulphides, Realgar, AsS 2 , and Orpiment, AsS 3 ; 
 it is present in many natural waters. When its ores are 
 heated, arsenious acid, As0 3 , is formed, from which the 
 metal is readily obtained by reduction. 
 
 Prop. — A steel-gray, brittle, crystalline rhombohedral 
 (6th system) metal, s. g. 5^5 ; has a brilliant lustre when 
 freshly broken, but speedily tarnishes and in moist air falls 
 to a brownish powder (suboxide ?) ; it volatilises at 400° 
 without fusion, unless under pressure ; the density of its 
 vapour is 10390 ; if air be present, white fumes of As0 3 
 
262 MEDICAL CHEMISTRY. 
 
 are formed during its volatilisation, and a garlicky odour 
 is exhaled. 
 
 Chem. Bel. — Is more electro-negative than H, and forms 
 a member of a natural group with N, P, and Sb ; does not 
 form a base with any of the amphigens, and is only placed 
 among the metals on account of its metallic lustre, insolu- 
 bility, and power of conducting electricity. With O it 
 forms an undetermined suboxide, arsenious acid, As0 3 , and 
 arsenic acid, As0 5 . Arsenic acid is made by the action 
 of HO,N0 5 on As0 3 ; it is freely soluble in water ; of a 
 sharp, acid taste, highly poisonous, and gives a brick-red 
 precipitate with ammonio-nitrate of silver. Like P0 5 , it 
 is tribasic (2CuO,HO,As0 5 , arseniate of copper), but no 
 compounds corresponding to the pyro and meta-phosphates 
 are known. It is largely employed in the manufacture of 
 aniline colours and in preserving skins of animals. With 
 H, As forms three compounds corresponding to P 2 H, PH 2 , 
 and PH 3 ; the latter, AsH 3 , arsenetted hydrogen, is formed 
 by the union of its constituents in the nascent state (143). 
 It is a colourless gas of a highly offensive odour ; very 
 poisonous ; s. g. 2695 ; liquid at — 40° ; is decomposed into 
 its constituents at a red heat. 
 
 AsH 3 is probably the most poisonous substance known ; death 
 has occurred from the inhalation of a quantity which must have 
 been inappreciable to the balance. There is no direct antidote ; 
 the inhalation of chlorine would probably be of service. 
 
 With S, As forms AsS 2 , Realgar, a red solid, and Orpi- 
 ment, AsS 3 , King's yellow, Sulph arsenious acid ; both are 
 used as paints and in fireworks ; they are sulphur acids. 
 AsS 5 , Sulpharsenic acid, is also known. With CI, As 
 forms the volatile AsCl 3 , which below 270° is liquid, but 
 is not known as a solid ; it is sometimes used in medicine. 
 AsCl 3 is unknown ; Asl 3 is the officinal iodide. The 
 metal is officinal as Arsenicum. 
 
CHEMISTRY OF THE ELEMENTS. 263 
 
 Med. Effects. — The preparations of As are tonic, anti- 
 periodic, antispasmodic, and alterative. 
 
 354. Oxide, Acidum Arseniosum, As0 3 , White Arsenic, 
 Arsenic, Rats-bane. Sublimed Arsenious Acid, in masses, 
 U. S. P. It is obtained, on the large scale, by roasting 
 the ores which contain the metal ; after which it is puri- 
 fied by sublimation. 
 
 Prop. — Is found in two distinct varieties : 1. The trans- 
 parent or vitreous variety is an amorphous, colourless 
 glass ; s. g. 3*2 to 3*8. Is more soluble than the opaque 
 variety, into which it gradually passes upon exposure to 
 the air. 2. The opaque variety crystallises in regular oc- 
 tohedra (1st system), or very rarely in right rhombic 
 prisms (3d system), of a milk-white colour, slightly heavier 
 than the transparent, into which it passes by long boiling. 
 Arsenious acid is tasteless and inodorous ; it dissolves spar- 
 ingly in cold water, 1 part dissolving in from 50 to 480 
 parts of water. In boiling water, both varieties are equally 
 soluble, 1 part dissolving in from T ,f l2 to 24 parts. The 
 boiling solution deposits the greater part upon cooling, but 
 retains more than if the acid were simply added to cold 
 water — about 1 in 30. The solution is tasteless. The 
 solid acid sublimes at 425°, giving no garlicky odour, un- 
 less in the presence of reducing agents ; it condenses on a 
 cold surface, in crystals. 
 
 Adulterations. — When in powder, arsenious acid may 
 be adulterated with chalk or flour. It should be entirely 
 sublimed by heat. 
 
 Med. Effects. — Those of the preparations of arsenic 
 generally. Dose, gr T \ to T 1 <j, in pill or solution. Exter- 
 nally, a powerful escharotic; there is danger of its absorp- 
 tion when thus used. 
 
 Toxicological Effects. — Depend upon the quantity; in 
 large doses, the symptoms are those due to a violent irri- 
 
264 MEDICAL CHEMISTRY. 
 
 tant, and vary in different cases, the nervous system being 
 often affected ; they appear in from one minute to ten hours ; 
 death ensues, in fatal cases, in from 2J hours to 3 days ; 
 the minimum quantity necessary to destroy life at a single 
 dose is two grains ; cases have recovered after taking an 
 ounce. Post-mortem examination reveals inflammation, 
 ulceration, and gangrene of the stomach and intestines. 
 In small doses long continued, or after large doses from 
 which death has not resulted, there is irritation and itch- 
 ing of the eyes and eyelids ; conjunctivitis, oedema, irrita- 
 bility of the stomach, eczematous eruption, desquamation 
 of the cuticle, loss of the hair, emaciation, salivation, and 
 paralysis. The symptoms have been mistaken for those 
 of cholera, perforation of the intestine, gastritis, etc. 
 
 It is now a well-established fact that there exists in Styria a 
 class of arsenic-eaters who consume arsenious acid regularly and 
 in quantities usually considered sufficient to produce death. It 
 is known as Hidrach. A well-authenticated case is given in 
 which a man of 30 years of age ate on one day 4£ grains at once, 
 and on the next day 5-£; arsenic was found in the urine, but no 
 ill effects were perceived.* 
 
 Antidotes. — 1. Hydrated Sesquioxide of Iron (Ferric 
 hydrate) ; it should be freshly precipitated and freely given, 
 a tablespoonful of the magma every 5 or 10 minutes, until 
 the urgent symptoms are relieved; it acts, by giving a por- 
 tion of to the arsenious acid, converting it into Arsenic 
 A., which forms an insoluble basic compound with the 
 protoxide of iron, 2Ee 2 3 +As03=4FeO,As0 5 . 
 
 2. In the absence of this, Ferri Subcarb. may be given, 
 but is often inert, from having been overheated. 
 
 3. Magnesia, recently precipitated, or recently and not 
 too highly calcined, has been found efficient. 
 
 355. Tests. — (a) When solid. 1. Heat to redness in a 
 
 * Dn. II. E. Roscoe, Trans. Manchester Literary and Philos. Soc, Oct. 
 30, 1860. 
 
CHEMISTRY OF THE ELEMENTS. 265 
 
 glass tube, closed at one end, with fragments of charcoal, 
 or powdered and dried, K 2 Cfy; the As0 3 is reduced, the 
 metallic arsenic sublimed, and forms the arsenical mirror 
 or ring in the tube at some distance from the flame. By 
 breaking the tube, and allowing free access of air, the 
 metal is oxidised again into As0 3 , and may be submitted 
 to other tests; the octohedral crystals of As0 3 may be 
 seen in the second sublimate; the mirror must be distin- 
 guished from that produced by antimony, which is always 
 deposited just beyond the red-hot part of the tube (see 
 Test 6). 
 
 2. Arsenious Acid thrown upon live coals or other 
 reducing agents, exhales a peculiar garlicky odour, which 
 is not perceived when it is sublimed from a clean surface ; 
 it is probably due to the formation of suboxide. 
 
 (b) In solution. 3. Ammonio-Nitrate of Silver gives a 
 rich yellow precipitate of arsenite of silver, 2AgO,As0 3 , 
 soluble in excess of ammonia, and in nitric, tartaric, acetic, 
 and citric acid, but not in caustic potassa or soda; a solu- 
 tion of an alkaline phosphate precipitates yellow with 
 nitrate of silver, and a dilute solution of phosphoric acid 
 with the ammonio-nitrate. These are discriminated by 
 the application of the other tests. 
 
 4. Ammonio-Sulphate of Copper gives a brilliant yel- 
 lowish-green precipitate of arsenite of copper (Scheele's 
 Green, 2CuO,As0 3 ), soluble in acids and in excess of am- 
 monia, but not in potassa or soda ; acetic and malic acids 
 give also green precipitates with the ammonio-sulphate 
 of copper, as do certain complex organic mixtures 
 (Taylor). 
 
 5. Hydrosulphuric Acid, HS, gives a golden-yellow 
 precipitate (orpiment, AsS 3 ), soluble in alkalies ; the solu- 
 tion should be therefore slightly acidulated by acetic 
 acid before trial ; other metals (antimony, tin, uranium) 
 
 23 
 
266 MEDICAL CHEMISTRY. 
 
 give somewhat similar precipitates ; they are distinguished 
 by their behaviour with other tests. 
 
 6. Marsh's Test. Add the suspected liquid to pure 
 zinc, and dilute HO,S0 3 ; a little alcohol is useful to 
 check frothing. Arsenetted hydrogen (AsH 3 ) is gener- 
 ated, which may be known by its odour, its violet-coloured 
 flame, and by the metallic stain deposited upon a cold, 
 white surface ; or the gas may be passed through a long 
 tube drawn out, heated at its centre ; the metal deposits 
 as in the reduction test, and may be further examined ; or 
 the gas may be passed into a solution of AgO,N0 5 , 
 metallic silver precipitates and As0 3 +HO,N0 5 remain; 
 6(AgO,N0 5 ) + AsH 3 + 3HO = Ag 6 + AsO^, and 6(HO, 
 
 NOs)^. The utmost care is necessary to avoid inhaling 
 the gas. It may be absorbed by a solution of nitrate of 
 silver, or by fuming nitric acid. 
 
 Antimonetted Hydrogen, SbH 3 ?, gives similar spots 
 from the reduction of the metal ; they may be dis- 
 tinguished, 1. By nitric acid, which converts the metallic 
 arsenic into As0 5 , which is soluble and gives a brick-red 
 precipitate with ammonio-nitrate of silver, while antimony 
 is converted into insoluble antimonic acid. 2. The spot 
 is heated to 500° by an oil-bath ; if arsenic, it disappears; 
 if antimony, it remains. 3. Hypochlorite of Soda dis- 
 solves arsenical spots, but does not affect those of anti- 
 mony. 4. Tincture of Iodine instantly dissolves arsenic 
 spots, leaving, on spontaneous evaporation, a lemon-yellow 
 spot. Antimony is not immediately altered on evapora- 
 tion; is converted after a time into orange-coloured iodide. 
 5. Yapour of Phosphorous Acid (P0 3 ) causes the dis- 
 appearance of As spots in 4 or 5 hours ; Sb spots remain 
 a fortnight, but finally disappear. 
 
 1. Reinsch's Test. A bright slip of copper, or fine cop- 
 per gauze, is boiled in the suspected solution, previously 
 
CHEMISTRY OF THE ELEMENTS. 26f 
 
 acidulated with HC1 ; the metal precipitates upon the cop- 
 per, forming an alloy, from which it may be volatilised 
 and submitted to other tests ; this process has these 
 advantages : 1. It will act in the presence of organic mat- 
 ter ; 2. It gives the metal in condition to be submitted to 
 all the other tests. The reaction is prevented for a time 
 by the presence of a nitrate or a chlorate. 
 
 Appreciation of these Tests. — No single test is to be 
 relied upon, and, wherever practicable, all should be 
 applied. The relative delicacy of the tests is given by 
 Devergie as follows: Ammonio-sulphate of copper, 5,200; 
 Sulphuretted hydrogen, 209,000 ; Ammonio-nitrate of silver, 
 400,000. By the latter, the giroo to * ne to"o~oo" °f a g ram 
 may be rendered evident, if dissolved in but a drop or two 
 of water; in one fluid-drachm of water, it detected the 
 T 4g of a grain. Marsh's Test will detect, according to 
 Danger and Flandin, the ^ooiooo P art °f * ne liquid ex- 
 amined; according to Signoret, the ^oooiooso- Villain 
 states that one grain will give, on an average, 226 metallic 
 deposits, of an average diameter of yV of an inch, or will 
 detect about the 75^00 °f a 8 Tam - Reinsch's Test will 
 detect, when the arsenic forms the -goioo °f the liquid, or 
 the 4^ of a grain (Taylor). 
 
 Remarks. — The wide diffusion of As, which is often found in 
 commercial zinc, sulphuric acid, muriatic acid, and copper, ren- 
 ders it necessary that the reagents should be themselves carefully 
 tested before using. Organic matter renders the liquid tests 
 almost valueless, and causes so much frothing in Marsh's appa- 
 ratus as to seriously interfere with its use. The best process 
 for its separation is that of Taylor. The dried suspected matter 
 is mixed with pure dilute HC1 and distilled to dryness into a 
 cooled receiver containing; distilled water, and if necessary re- 
 distilled. The distillate contains AsCl 3 and free HC1 ; it may be 
 diluted, and, by Marsh's or Reinsch's test, the As obtained in a 
 convenient form for further investigation. As0 8 may be sepa- 
 rated from the contents of a stomach by dialysis ; the organ 
 itself serving as a dialyser (128). It is important to estimate the 
 quantity present, as arsenic is given medicinally, and is some- 
 
268 MEDICAL CHEMISTRY. 
 
 times found in paper, candles, potable -waters, etc. This ia best 
 done by precipitating a given portion of the suspected liquid by 
 HS, redissolving in HC1, and reprecipitating, washing, drying, 
 and weighing 124 grains of AsS-5=100 grains As0 3 . It is a re- 
 markable fact that there exists a compound freely soluble in 
 water, which contains over 50 p. c. of arsenic, yet "which is not 
 poisonous, Kakodylic Acid, (C 4 II a As)0 3 ,HO.) 
 
 Arsenites. 
 
 356. Liquor Potassae Arsenitis, Fowler's solution. 
 
 Prep. — Boil in f^xii Aquae Destillat, gr lxiv each of 
 Acid, arsenics, in small pieces, and Potass, bicarb, until 
 the former is entirely dissolved; then add f^ss Spirit. 
 Lavand. Go. and Aquas. Destillat. q. s. to make Oj. The 
 solution probably contains 2KO,As0 3 . The Spirit of 
 lavender is added to give colour and taste, but decom- 
 poses and gives rise to a sediment ; hence when in care- 
 ful hands it may be replaced by an equal quantity of dis- 
 tilled water. The solution is then without colour and 
 almost tasteless, its reaction is alkaline. Fowler's solu- 
 tion is the preparation of arsenic most usually prescribed; 
 it contains gr iv Potassae Arsenitis to f^ j. Dose, gtt v to 
 jlx. Antidote, the ferric salts ; the ferric hydrate is useless. 
 Arsenites of Copper. Scheele's green, 2CuO,As0 3 , and 
 Schweinfurth or emerald green ; Aceto-arsenite of Copper; 
 2CuO,As0 3 -f-CuO,C 4 H 3 3 . These two compounds are 
 largely used in the arts on account of their brilliant colour; 
 wall-paper, artificial flowers and wreaths are coloured 
 with the latter ; the former has even been used in colour- 
 ing toys and confectionery. Cases of death from their 
 use in this way are recorded. The following is a simple 
 test : Immerse the paper or other body in solution of am- 
 monia, a deep blue liquid will be formed ; pour a portion 
 of this upon some crystals of AgO,N0 5 in a porcelain 
 capsule, the presence of As0 3 will be indicated by a yel- 
 low tinge on their surface. Or the paint may be scraped 
 off and submitted to the reduction test. 
 
CHEMISTRY OF THE ELEMENTS. 269 
 
 357. Iodide of Arsenic, Arsenici Iodidum, Asl 3 . Is 
 made by gently heating together gr lx of powdered metal- 
 lic Arsenic and gr ccc of Iodine. It is an orange-red, crys- 
 talline solid, insoluble in water, and wholly volatilised by 
 heat. Its only use is in the preparation of Donovan's 
 solution. Liq. Arsenici et Hydrargyri Iodidi (367). 
 
 ANTIMONY, Sb=122. 
 
 358. Sources, — The native sulphide SbS 3 ; is obtained 
 by roasting and reduction. 
 
 Prop. — A brittle metal, s. g. 6*8, crystallising in rhom- 
 bohedra (6th system), fusing at 1150°, and volatile at a 
 white heat ; burns with a brilliant white flame, forming 
 Sb0 3 . Does not oxidise in the air ; is attacked and dis- 
 solved by hot HC1 and cold Aqua regia ; nitric acid 
 oxidises it to antimonic acid, 4HO,Sb0 5 , which is insoluble 
 in that menstruum. 
 
 Chem. Bel. — Resembles As in most of its compounds. 
 Its oxides are : Sb0 3 , a feeble base, forming salts with Tar- 
 taric acid only ; Sb0 5 , antimonic acid ; and an intermediate 
 oxide, Sb0 4 , or Sb0 3 ,Sb0 5 . With H, it forms SbH 3 , re- 
 sembling closely AsH 3 , which, when passed into a solution 
 of AgO,N0 5 , throws down solid antimonide of silver, Ag 3 
 Sb; SbH 3 +3(AgO,]S T 5 )=AgSb 3 +3(HO,N0 5 )_ > , Forms 
 two sulphides, SbS 3 and SbS 5 , which are soluble in alkaline 
 solutions. The terchloride SbCl 3 and pentachloride SbCl 5 
 are decomposed by excess of water. 
 
 Tests. — Its few soluble compounds give an orange-red 
 precipitate with HS, soluble in IIC1, which solution is de- 
 composed by water, affording a white precipitate of oxy- 
 chloride, 2Sb0 3 ,SbCl 3 +HO, which is coloured orange by 
 NH 4 S,HS. It may also be submitted to Marsh's and 
 
270 MEDICAL CHEMISTRY. 
 
 Reinsch's tests, after the manner of arsenic. In the for- 
 mer ease, a portion of metallic antimony is precipitated 
 by the zinc in the form of a black powder ; in the latter, 
 the Sb may be dissolved from the copper by boiling KO, 
 HO, the solution acidulated by Tartaric acid, and the char- 
 acteristic reactions obtained. In cases of poisoning it 
 may, if absent from the stomach, be detected sometimes 
 in the urine and tissues. 
 
 359. Oxide, Antimonii Oocidum, Sb0 3 . 
 
 Prep. — Antimonii Sulphuret. (SbS 3 ) in fine powder ^iv 
 is dissolved by the aid of heat in gxviii of Acid. Ifuriat.) 
 HS is evolved; SbS 3 + 3HCl=SbCl 3 - > + 3HS*. To the 
 chloride thus formed, 3j g r cxx Acid. Nitric, is added, to 
 decompose any remaining HS. It is then diluted with Oss 
 Aquae and filtered. This quantity of water is insufficient to 
 cause decomposition. The filtrate is then thrown into Oxii 
 Aquae and stirred, the precipitate allowed to subside, strained 
 and washed. It is the oxychloride Powder of Algaroth, 
 2Sb0 3; SbCl 3 +HO. This is treated for two hours with f^iss 
 Aquse Ammoniae, which converts the terchloride into ter- 
 oxide. This is washed with distilled water until the wash- 
 ings no longer give a precipitate with AgO,N0 5 (absence 
 of SbCl 3 or of XH 4 C1). 
 
 Prop. — A grayish-white powder, insoluble in HO, solu- 
 ble in HC1 and Tartaric acid, 2HO,C 8 H 4 O 10 . It fuses at a 
 dull red heat, forming a yellowish liquid, which concretes 
 on cooling into a pearl-coloured crystalline mass. Its 
 solution in Tartaric acid should give no precipitate with 
 AgO,X0 5 (absence of chlorides), or K 2 Cfy (absence of iron, 
 copper, etc.). Is used in the preparation of Tartar emetic. 
 
 360. Sulphides, Antimonii Sulphuretum, SbS 3 ; Xative 
 Tersulphuret (tersulphide) of Antimony, purified by fusion. 
 U. S. P. 
 
 Prop. — A metallic-looking. steel-gTav, fibrous, brittle. 
 
 
CHEMISTRY OF THE ELEMENTS. 271 
 
 fusible substance ; soluble in HC1 with evolution of HS, 
 and in alkalies and their carbonates. The orange-red pre- 
 cipitate obtained by the action of HS upon a solution of 
 Sb0 3 has the same constitution, but is probably amorphous. 
 The tersulphide is rarely, if ever, employed in medicine. 
 
 Antimonii Oxy 'sulphur etum, Kermes mineral. 
 
 Prep. — Dissolve ^xxiii Sodas carb. in Oxvi Aquae 
 bullientis; to this add 3j Antimonii Sulphuret., pulv. 
 subtillis., and boil for an hour; filter quickly into a warm 
 earthen vessel, which allow to cool slowly ; at the end of 
 24 hours drain the precipitate and wash it with cold, boiled 
 water ; dry without the aid of heat. The reaction here is 
 somewhat obscure. SbS 3 , boiled with NaO,C0 2 , forms some 
 NaS and Sb0 3 ; the former dissolves a fresh portion of 
 SbS 3 , and the latter is dissolved by the remaining NaO,C0 2 . 
 When the liquid cools, the tersulphide SbS 3 , and teroxide 
 SbO, precipitate together, forming the Kermes mineral. 
 
 Prop. — A purplish-brown, tasteless powder, soft and 
 velvety to the touch, freely soluble in HC1 with evolution 
 of HS ; partially (SbS 3 ) soluble in hot KO,HO, leaving 
 a residue (Sb0 3 ) soluble in Tartaric acid. Is sometimes 
 used as a nauseant and diaphoretic and alterative. Dose, 
 gr j to x. 
 
 Antimonium Sulphurahim, Precipitated Sulphuret (Sul- 
 phide) of Antimony. 
 
 Prep. — By dissolving gvi Antim. Sulphuret. pulv. 
 subtillis. in Oiv Liquor Potassae, adding Aquae Destillat. 
 q. s. during the boiling (2 hours) to keep up the measure ; 
 the hot liquid is rapidly strained through a double mus- 
 lin strainer, and, while yet hot, Acid. Sulph. dilut. is 
 gradually dropped in as long as a precipitate falls This 
 is washed with hot water. The product is a variable 
 mixture of Kermes mineral with pentasulphide of anti- 
 mony, SbS,, (Sulphur auratum, Golden sulphur). 
 
272 MEDICAL CHEMISTRY. 
 
 Prop. — A reddish-brown powder, insoluble in HO, but 
 partly soluble in HC1 by the aid of heat, leaving a residue 
 of sulphur. Its medical effects are those of Kermes, but it 
 is weaker ; dose, gr ij to xx. Plummer's Pills, PH. Anti- 
 monii comp., contain each Antim. Sulphured,., Hydrarg. 
 Chlorid., mit. aa gr ss with Guaici, Syrujri Fusci aa gr j. 
 
 361. Tartrate, Antimonii et Potassse Tartras, KO,Sb0 3 , 
 C 8 HAo + 2HO. 
 
 Prep. — By boiling Antimonii Oxid. pulv. subtillis. £ij, 
 Potassse Bitart. pulv. subtillis |jijss in Aqua Deslillata 
 fjxviii, evaporating and crystallising. KO,HO,C 8 H 4 O 10 4- 
 SbO 3 =KO,SbO 3 ,C 8 H 4 O 10 . Tartaric acid is bibasic ; in cream 
 of tartar, one equivalent of water represents a base and is 
 replaced by Sb0 3 . 
 
 Prop. — Transparent, colourless, efflorescent, rhombic 
 octohedra (3d system), of a nauseous, styptic, metallic 
 taste, soluble in 20 parts cold and 3 of boiling water. The 
 aqueous solution has a slight acid reaction and slowly de- 
 composes by keeping ; this may be prevented by the addi- 
 tion of i of alcohol. A dilute solution is not precipitated 
 by BaCl or AgO,N0 5 (absence of sulphates and chlorides), 
 nor by K 2 Cfy, absence of Fe, Cu, Pb, etc. A solution of 
 1 part to 40 of water is not disturbed by an equal volume 
 of a solution of 8 parts of PbO,C 4 H 3 3 in 32 of HO and 15 
 of Acid, acetic, (absence of cream of tartar). 
 
 Med. Effects. — In large doses, an irritant poison; anti- 
 dote, the vegetable astringents (green tea, tannic acid). In 
 moderate doses, gr j to ij, emetic ; gr T \ to J, nauseant and 
 diaphoretic. The Vinum Antimonii contains gr ij tof3J 
 Vini Xerici (sherry wine), and is objectionable in some 
 cases from the alcohol present. 
 
 Incompatible s> — The mineral acids, the alkalies and 
 their carbonates, vegetable astringents. When it is de- 
 sired to add it to a saline purge, the Potassse et Sodae 
 
CHEMISTRY OF THE ELEMENTS. 21B 
 
 Tartras is the best. It is used externally to produce pus- 
 tulation ; the Ung. Antimonii contains gr cxx to ^ j Adipis; 
 the Emplastrum Antimonii contains 3j to %iv Picis 
 Burgundicse. 
 
 362. Cerium, Ce=46, is a metal occurring in certain rare 
 minerals. It forms a protoxide and sesquioxide. The 
 salts of the former are colourless, of the latter red. The 
 oxalate of the protoxide is used in sea-sickness and the 
 vomiting of pregnancy. 
 
 MERCURY {Hydrargyrum), Hg=100. 
 Syllabus. 
 
 As Metal : (a) Hydrargyrum ; (Jb) Pilulse Hydrargyri 
 (blue pills) ; (c) Ung. Hydrargyri (blue ointment) ; (d) 
 Emplastrum Hydrargyri ; (e) Emplastrum Ammoniaci 
 cum Hydrargyro ; (/) Hydrargyrum cum Greta. 
 
 Oxide : Hydrargyrum Oxidum Bubrum, HgO, (red pre- 
 cipitate) ; Ung. Hydrargyri Oxidi Rubri. 
 
 Sulphide: Hydrargyri Sulphuretum Bubrum, HgS, 
 (Cinnabar, Vermilion). 
 
 Chlorides : 
 
 (a) Hydrargyri Chloridum mite, Hg 2 Cl, Calomel. 
 
 (b) Hydrargyri Chloridum corrosivum, HgCl, Corro- 
 sive Sublimate. 
 
 (c) Hydrargyrum Ammoniatum, HgCl,HgNH 2 , Chlor- 
 amide of mercury, White precipitate. 
 
 (d) Ung. Hydrarg. Ammoniati. 
 Iodides : 
 
 (a) Hydrargyri Iodidum Viride, Hg 2 I. 
 
 (b) Hydrargyri Iodidum Bubrum, Hgl. 
 
 (c) Liquor Arsenici et Hydrargyri Iodidi, contains 
 AsI 3 ,HgI, Donovan's solution. 
 
2T4 MEDICAL CHEMISTRY. 
 
 Cyanide : Hydrargyri Cyanidum, HgCy, Fulminate, 
 2Hg 2 0,Cy 2 2 , Percussion powder. 
 
 Nitrates : 
 
 Liquor Hydrargyri Nitratis, HgO,N0 5 , with excess of 
 HO,N0 5 . 
 
 Unguentum Hydrargyri Nitratis, Citrine ointment. 
 
 Sulphates: Hg 2 0,S0 3 ; HgO,S0 3 . 
 
 Subsulphate, Hydrargyri Sulphas flava, 3HgO,S0 3 , 
 Turpeth mineral. 
 
 363. Sources. — The native sulphide Cinnabar, from 
 which it is obtained by distilling with lime or iron filings. 
 
 Prop. — When pure, is a brilliant, silvery liquid, with- 
 out taste or smell ; s. g. 13 6; when finely divided, as in 
 blue mass or precipitated mercury, is grayish and dull. At 
 common temperatures, is unchanged in the air ; heated 
 above 600°, it slowly absorbs 0, and becomes converted in 
 red, HgO ; at a higher heat, this is again resolved into Hg 
 and 0. It boils at 662°, and freezes at — 39°, shrinking, 
 and forming a lead-like solid. Commercial mercury con- 
 tains other metals, as lead, tin, bismuth ; it then tarnishes, 
 and the globules are imperfect, having tails. It may be 
 partially purified by the action of dilute HOjlNTOs, Fe 2 Cl 3 , 
 or HgCl, or by distillation. When required absolutely 
 pure, it must be distilled from the sulphide. 
 
 Chem. Eel. — Mercury forms alloys with the metals gen- 
 erally termed amalgams. That with tin is used for coat- 
 ing looking-glasses ; those with silver and gold, for fire- 
 gilding and plating. It is also used to obtain the latter 
 metals from their crushed matrices when they are in too 
 small quantity to be separated by washing. It forms two 
 sets of binaiy compounds, one containing two eq. of Hg to 
 one of an electro-negative element ; the other, one eq. of 
 each. The latter proto-compounds are more energetic in 
 their effects, and of brighter colour, than the former. The 
 
CHEMISTRY OP THE ELEMENTS. 275 
 
 dioxide, Hg 2 (black or gray oxide), is obtained by pre- 
 cipitating calomel with lime water (^ij to Oj, forming the 
 black wash), Hg 2 Cl-f CaO,HO = Hg 2 0, + CaCUH- HO.,. 
 It forms a series of unimportant salts. It is no longer 
 officinal. The protoxide (red oxide), HgO, Hydrargyri 
 oxidum rubrum, also forms a series of salts more stable 
 than the former. The disulphide, black sulphide, JEthiop's 
 mineral, is made by rubbing together Hg and S, and is a 
 black, nearly inert powder of uncertain constitution ; it 
 generally contains an excess of sulphur. It is no longer 
 officinal. The other compounds of mercury will be con- 
 sidered under the head of its preparations. 
 
 The equivalent of Hg was formerly assumed as 200 ; it has lat- 
 terly been halved. If we combine 200 grains of mercury with 
 126*5 grains of iodine, we get the green iodide ; 100 grains of 
 the metal with the same of I, gives the red iodide. If Hg be as- 
 sumed as 100, the former will be Hg 2 I, and the latter Hgl ; if 
 at 200, the former will be Hgl, and the latter (doubled) Hgl 2 . 
 The change of the equivalent only changes the nomenclature of 
 the compounds ; it cannot affect their character or reactions. 
 As the U. S. Pharmacopoeia does not use the chemical names of 
 the preparations of mercury, but distinguishes them by some phys- 
 ical property, if the officinal titles are always used, no mistakes 
 can occur. 
 
 Med. Effects. — Purgative, alterative, etc. Workmen 
 exposed to its vapours, and persons using its preparations 
 for a long time, become salivated, and are afflicted with 
 tremors and caries. Iodide of potassium converts it into 
 a compound soluble in excess of KI, which may after a 
 time be eliminated with the secretions. For its effects in 
 poisonous doses, see Corrosive Sublimate. 
 
 364. As Metal. — (a) Hydrargyrum. 
 
 (b) Pilulse Hydrargyri, Blue Pills. 
 
 Prep. — By rubbing ^ j Hydrarg. with 3 iss Confect. Rosae 
 until the globules disappear, and adding £ss Pulv. Glycyr- 
 rhizse to make a mass to be divided into 480 (3 gr) pills. 
 
276 MEDICAL CHEMISTRY. 
 
 Is generally made on the large scale, and rarely contains 
 the full proportion of 33 J p. c. of mercury. 
 
 (c) Unguentum Hydrargyri, Blue ointment. 
 
 Prep. — By rubbing ^xxiv Hydrarg. with ^xii Ssevi and 
 q. s. Adipis until the globules are extinguished, and then 
 adding the remainder of ^xii Adipis. Is generally pre- 
 pared on the large scale. 
 
 (d) Emplastrum Hydrargyri. 
 
 Prep. — By rubbing Hydrarg. (Syi) with equal parts 
 (^ij) 01. Olivde and Resinse, previously melted together 
 and cooled, until the globules disappear, and adding these 
 to (3xii) Emp. Plumbi, previously melted, and mixing. 
 Mercury is also employed in the 
 
 (e) Emplast. Ammoniaci cum Hydrargyro. 
 
 (f) Hydrargyrum cum Greta. 
 
 Prep. — By rubbing (^iij) Hydrarg. with (%v) Cretae. 
 Praeparatae until the globules disappear. It combines the 
 antacid effects of the chalk with the alterative powers of 
 the mercury. There is too little chalk to be of much ser- 
 vice ; more may be added at the time of prescribing. 
 When long kept, the mercury oxidises. 
 
 365. Oxide, HgO; Hydrargyri Oxidum Bubrum, Red 
 Precipitate. 
 
 Prep. — By heating HgO,N0 5 until red fumes (N0 4 ) 
 cease to arise. Also by heating mercury to near its boil- 
 ing-point (prsecipitatum per se of the older chemists), and 
 as yellow hydrate by adding HgCl to lime water, HgCl-f 
 CaO,HO=HgO,HO + CaCl->. In the proportion of gr 
 
 xxx to Oj, this forms the yellow wash. 
 
 Prop. — Brilliant red scales soluble in 7000 parts water, 
 entirely dissolved by HC1, and decomposed and dissipated 
 by heat. It is not employed internally. 
 
 Ung. Hydrargyri Oxidi Rubri. — R. Hydrarg. oxid. rub. 
 gr xxx, Ung. Adipis 3j. M. Ft. ung. Used as a stimulant 
 
CHEMISTRY OF THE ELEMENTS. 27T 
 
 application. The precipitated oxide is preferable for 
 making this preparation on account of its being amor- 
 phous, and in fine powder. 
 
 sulphide, Hydrargyri Sulphuretum Rubrum, Cinnabar, 
 Yermilion, HgS. 
 
 Prep. — Melt ^viii Sulphuris; add to it, with constant 
 stirring, %x\ Hydrarg.; continue the heat until the mass 
 begins to swell, cover the vessel and allow it to cool ; then 
 powder and sublime. 
 
 Prop.— In heavy, brilliant red, fibrous masses, insoluble 
 in acids except Aqua regia. Is entirely volatilised by 
 heat. Is used in fumigations; largely in the arts as a 
 pigment. 
 
 366. Chlorides. 
 
 The two most important, Calomel Hg 2 Cl, dichloride, and 
 Corrosive Sublimate HgCl, protochloride, are conveniently 
 considered together as far as their manufacture is concerned. 
 Corrosive Sublimate is prepared as follows: ^xxiv Hy- 
 drarg. are boiled with ^xxxvi Acid. Sulphuric, Hg + 2HO, 
 S0 3 =HgO,SO^-fS(y. The sulphate of the protoxide 
 thus formed is a white powder decomposed by water; it is 
 mixed with ^xviii Sodii Chlorid. and sublimed, HgO,S0 3 -f- 
 NaCl=NaO,S0 3 +HgCl f ; the former remains, the latter 
 condenses in the head of the alembic. In making Calomel, 
 the HgO,S0 3 is rubbed with an additional equivalent ^xxiv 
 Hydrarg., forming Hg 2 0,S0 3 , sulphate of the dioxide. 
 This is sublimed as before, Hg 2 0,S0 3 +NaCl=NaO,S0 3 
 -fHg 2 Cl : . It is carefully washed with boiling water until 
 the washings give no precipitate with Aqua Ammonise 
 (absence of HgCl). These compounds are generally made 
 on the large scale. 
 
 (a) Hydrargyri Chloridum mite; Calomel. — Is a white, 
 or pale-buff powder, insoluble in water, alcohol, and ether, 
 24 
 
2T8 MEDICAL CHEMISTRY. 
 
 entirely volatilised by heat; s. g. 7 "2. Is not poisonous in 
 large doses. 
 
 Incompatible s. — Alkalies, alkaline earths, their carbon- 
 ates, soap, nitromuriatic acid, the chlorides ?, hydrocyanic 
 acid. 
 
 (b) Hydrargyri Chloridum corrosivum ; Corrosive Sub- 
 limate, HgCl. — Is in colourless, transparent crystals (3d 
 system), or white, semi-transparent, crystalline masses; 
 s. g. 5*2; permanent in the air. It is inodorous, of an 
 acrid, persistent, metallic taste; melts and volatilises 
 readily, with dense, acrid fumes ; soluble in 20 parts cold 
 and 3 boiling water, in alcohol and ether; also, without 
 change, in sulphuric, muriatic, and nitric acids; muriate 
 of ammonia, and common salt, render it more soluble in 
 water. It retards putrefaction by coagulating albumen 
 and fibrin. Should dissolve wholly in ether, and be wholly 
 volatilised by heat. Dose, gr y 1 ^ to y'g. 
 
 Incompatibles. — Alkalies, alkaline earths, their carbon- 
 ates, soap, iodides, sulphides, tartar emetic, nitrate of 
 silver, acetates of lead, and many metals, vegetable astrin- 
 gents, albumen, fibrin, gluten. 
 
 Toxicological Effects. — In overdose, gr iii to v, a cor- 
 rosive poison; recovery has taken place after an ounce 
 had been swallowed. Antidotes: Albumen (white of egg, 
 blood), fibrin, gluten (flour), milk, with free evacuation of 
 the stomach ; Quevennes iron or iron filings wrapped in 
 gold leaf. Tests. (1) When in powder, KI produces a bright 
 scarlet colour, jSTH 4 S,HS a black ; NH 4 does not alter it. 
 (2) In solution, KI a yellow precipitate, changing to scarlet, 
 ]S"H 4 a white, and SnCl a gray (precipitated mercury). 
 A bright slip of copper immersed becomes silvery from the 
 deposition of Hg, which may be afterwards sublimed in 
 characteristic globules. (3) In organic mixtures, HgCl is 
 soluble in ether, and can thus often be extracted along 
 
CHEMISTRY OF THE ELEMENTS. 219 
 
 with fatty matters, which are separated by water; it may 
 then be submitted to tests (2). If a slip of gold foil, inter- 
 twined with zinc, be introduced, voltaic action will pre- 
 cipitate the Hg on the former; it may be dissolved by 
 HO,N0 5 and submitted to SnCl, or a portion volatilised 
 and the characteristic globules obtained. This test proves 
 ■ the presence of mercury, but not that it is in the form of 
 HgCl. 
 
 (c) Hydrargyrum Ammoniatum, HgCl,HgNH 2 , Chlor- 
 amide of mercury ; White precipitate. 
 
 Prep. — By dissolving %vi Hydrarg. Chlorid. corros. 
 in Oviii Aquae Destillatse by the aid of heat, adding Aquae 
 Ammonias fjviii with stirring; and washing and drying 
 the precipitate. 2 HgCl + 2 NH 4 = HgNH 2 ,HgCl + NH 4 
 
 cm- ho. 
 
 Prop. — A white, insoluble, heavy powder, decomposed 
 by boiling with water and by a high heat. Is employed 
 externally only; the Ung. Hydrarg. Ammon. contains gr xl 
 to ^j Ung. Adipis. 
 
 367. Iodides. 
 
 (a) Hydrargyrum Iodidum viride, Hg 2 I; Diniodide. 
 
 Prep. — Mix in a mortar Sjj Hydrarg. with gr ccc Iodinii 
 and add f^ss Alcohol, for tior is, triturate until the ingredi- 
 ents are thoroughly incorporated; stir the mixture occa- 
 sionally, and at the end of two hours rub again until 
 nearly dry. Then rub with Alcohol, fort, to a thin paste, 
 and wash with the same until the washings cease to pro- 
 duce a precipitate when dropped into water (absence of 
 red iodide, Hgl). Dry and keep it in the dark, in a well- 
 stopped bottle. The alcohol facilitates the combination of 
 the elements, and removes Hgl. 
 
 Prop. — A greenish-yellow powder, becoming red when 
 heated ; soluble in ether ; exposed to the light, it becomes 
 of a dark olive colour. It combines the properties of its 
 
280 MEDICAL CHEMISTRY. 
 
 constituents; dose, gr j to iij. Is incompatible with Potass. 
 Iodid., which converts it into the red iodide, Hgl. 
 
 Hydrargyri Iodidum rubrum, Protiodide, Hgl. 
 
 Prep. — By double decomposition of Hydrarg. Chlorid. 
 corros. %, dissolved in Ojss Aquae Destillat., and Potass. 
 Iodid. %] gr cxx, in Oss Aquas Destillat. The precipitate 
 is washed, dried, and kept in a well-stopped bottle. 
 
 HgCl+KI=HgI-f KCU. The precipitate is at first yel- 
 
 i 
 low, but becomes red. 
 
 Prop. — A brilliant, crystalline, scarlet powder, (2d and 
 4th systems), becoming }'ellow when heated, and having 
 its colour restored by pressure. This is due to a change 
 of crystalline form (123). It sublimes unchanged chemi- 
 cally. It dissolves in alcohol, also in solution of Potass. 
 Iodid., forming Iodohydrar gyrate of potassium, KI,2HgI, 
 which is valuable as a test for the alkaloids, and is given 
 internally in the same cases as Hgl. It is frequently 
 formed extemporaneously in prescriptions in which cor- 
 rosive sublimate and iodide of potassium are ordered to- 
 gether. The red iodide is much more active than the 
 green. Dose, gr T ^, in alcohol, pill, or solution of Potass. 
 Iodid. ; in overdose, resembles corrosive sublimate, and 
 requires similar treatment. 
 
 Bibron's antidote for snake-bites. — R. Hydrarg. Chlor. 
 corros. gr ij, Potass. Iodid. gr iv, Brominii gr ccc, Alcohol 
 dilut. f^viiss. Dose, gtt x in f^ss Spt. Vini Gallici, re- 
 peated pro re nata. 
 
 Liquor Arsenici et Hydrargyri Iodidi ; Donovan's so- 
 lution. 
 
 Prep. — Rub gr xxv aa Arsenici Iodidi et Hydrarg, 
 Iodid. rub. with f^ss Aquas Destillat., and when dissolved 
 add f^viiss more and filter. It contains Asl 3 and Hgl; 
 has the properties of its three constituents. Is easily de- 
 composed, and should be given alone ; the quantity of 
 
CHEMISTRY OF THE ELEMENTS. 281 
 
 arsenic is relatively small, being only about gr -^ of me- 
 tallic arsenic to f ^j. Dose, gtt v to x. In large doses, 
 produces effects like those of Corrosive sublimate, and re- 
 quires the same treatment. 
 
 369. Cyanide, Hydrargyri Cyanidum, HgCy. 
 
 Prep. — By distilling Hydrocyanic acid, HCy, into a 
 receiver containing HgO, enough of the latter being used 
 with agitation to destroy the odour of HCy. The solu- 
 tion is filtered and crystallised. HgO-f-HCy=HgCy— > 
 + HO_ > . 
 
 Prop. — White, square, prismatic crystals (2d system), 
 wholly soluble in water; gives off Cy by heat, leaving 
 Hg and paracyanogen. On the addition of HC1 evolves 
 HCy, leaving HgCl. Is very rarely used in medicine. 
 Dose, properties, and antidotes, those of corrosive sub- 
 limate. 
 
 Fulminate, 2Hg 2 0,Cy 2 2 . This substance, employed in 
 percussion-caps, may be made by dissolving gr c Hg in 
 f^iss Acid. Nitric., adding ^ij Alcohol, and if necessary 
 more to moderate the action ; the fulminate precipitates, is 
 washed and dried at a heat not exceeding 120°. It is 
 very explosive, and should be kept under water. It 
 evolves, when exploded, C0 2 , N, and Hg. 
 
 370. Nitrates. 
 
 Nitric acid unites with the oxides of mercury to form 
 seven compounds ; only one of these, the normal nitrate 
 of the protoxide, is important. 
 
 Liquor Hydrargyri Nitratis, Acid Nitrate of mercury, 
 HgO,N0 5 +xHO,N0 5 . 
 
 Prep. — Dissolve ^iij Hydrarg. in a mixture of gv 
 Acid. Nitric, and f£vj Aquse Destillat. When red fumes 
 cease to be evolved, evaporate to f^viiss. Hg 3 -M(HO, 
 
 N0 3 ) = 3(HgO,N0 5 )_ > +N6 2 +4HO. An excess of acid 
 is present. 
 
 24* 
 
282 MEDICAL CHEMISTRY. 
 
 Prop. — A colourless, acid liquid, s. g. 2-165. It is not 
 decomposed by an excess of distilled water. It reacts 
 with KI, SnCl, and bright copper, like HgCl. Is used as 
 a caustic. 
 
 Unguent um Hydrargyri Nitratis, Citrine ointment. 
 
 Prep. — ^jss Hydrarg. is dissolved in ^iijss Acid. Nit- 
 ric, forming as above HgO,N0 5 ; this is added to ^xii 01. 
 Bubuli and ^viss Adipis melted together, and the whole 
 stirred with a wooden spatula until the ointment stiffens. 
 A complex change takes place, both the nitrate and the fats 
 being partially decomposed. It is of a yellowish colour, 
 offensive odour, and somewhat liable to change. Used in 
 skin diseases. 
 
 3T1. Sulphates. 
 
 The sulphate of the protoxide HgO, and that of the 
 dioxide Hg 2 0, are prepared as a preliminary step in the 
 manufacture of corrosive sublimate and calomel. 
 
 Subsulphate ; Hydrargyri Sulphas flava, Turpeth 
 mineral. 
 
 Prep. — ^iv Hydrarg. are dissolved in ^vi Acid. Sul- 
 phuric, Hg+2HO,S0 3 =HgO,S0 3 + SC^-MHO.^; this 
 is evaporated to dryness and thrown into boiling water, 
 which decomposes it into yellow trisulphate and soluble 
 tersulphate, 4(HgO,S0 3 )=3HgO,S0 3 +HgO,3S03_^. 
 
 Prop. — A yellow powder, soluble in 2000 parts cold 
 and 600 of boiling water ; moderately heated, it becomes 
 red, but regains its yellow colour on cooling. At a high 
 heat it is decomposed, S0 2 and O being evolved, and metallic 
 Hg sublimed. Is sometimes used as an errhine, and, 
 rarely, internally as an emetic and alterative. Dose, gr £ 
 to v. In overdose, a poison ; the antidotes for HgCl may 
 be employed. 
 
CHEMISTRY OF THE ELEMENTS. 283 
 
 SILVER (Argentum), Ag=108. 
 
 3? 2. Sources. — Occurs native, and as sulphide, chloride, 
 and iodide ; also in the argentiferous galena. Is obtained 
 by amalgamation and cupellation. Pure silver may be 
 obtained from coin which contains 10 p. c. of copper, by 
 dissolving in nitric acid, adding HC1 or NaCl, which pre- 
 cipitates AgCl ; this may be reduced by fusing with mixed 
 carbonates of potassa and soda, with borax, or by im- 
 mersing scraps of zinc or iron. 
 
 Prop. — A brilliant white, malleable, ductile metal, s. 
 g. 10*5 ; fusible and volatile at a white heat, and burning 
 with a green light in the voltaic arc ; it does not oxidise 
 by the action of ordinary oxygen, but is attacked by ozone. 
 When melted, it takes up mechanically many volumes of 
 0, which it ejects on cooling, causing the spirting or spit- 
 ting of the metal. It tarnishes in air, owing to the forma- 
 tion of a superficial layer of sulphide. 
 
 Ghem. Bel. — Forms Ag 2 0, AgO, and Ag0 2 ; AgO, only, 
 is important. AgS is the black tarnish of silver ; AgCl 
 is insoluble in water and acids, but soluble in ammonia, 
 and blackens on exposure to the light. Agl and AgBr 
 are sensitive to light, and largely employed in photog- 
 raphy. The metal is not easily attacked by acids, except 
 the nitric. Test. — Soluble chlorides give a white, curdy 
 precipitate of AgCl, which has the properties above given. 
 It is reduced from solution by iron, copper, and zinc. Is 
 officinal as Argentum. 
 
 373. Oxide, AgO, Argenti Oxidum. 
 
 Prep. — Dissolve %\v Argenti Nitrat. in Oss AqiiBeDestil- 
 lat., and add Liq. Potassse as long as a precipitate is pro- 
 duced ; wash and dry the latter. AgO,N0 5 4- KO,HO= 
 AgO-f KO,N0 5 _ > f-HO^. 
 
284 MEDICAL CHEMISTRY. 
 
 Prop. — An olive-brown powder, decomposed by heat 
 into Ag and ; slightly soluble in water ; having a faint 
 alkaline reaction. By treatment with strong ammonia, 
 which dissolves it in part, a black explosive powder is ob- 
 tained, Ag 3 X? ; this is distinct from fulminate of silver, 
 2AgO,Cy 2 2 , which is analogous to the corresponding 
 mercury compound, but more explosive. AgO is used in 
 medicine for the same purposes as the nitrate, over which 
 it is supposed to have the advantage of not blackening 
 the skin. Dose, gr ss to j. 
 
 374. Cyanide, Argenti Cyanidum, AgCy. 
 
 Prep. — By passing the vapour of HCy into AgO,X0 5 , 
 or by adding Cyanide of potassium, not in excess, to a 
 solution of AgO,X0 5 . AgO,X0 3 + HCy = AgCy + HO, 
 
 Prop. — A tasteless, white, insoluble powder, soluble in 
 KCy and in nitric acid ; is employed for the extempora- 
 neous formation of Acid. Hydrocyanic, dilut. 
 
 375. Nitrates, Argenti Nitras, AgO,X0 5 . 
 
 Prep. — By acting on silver by nitric acid ; Ag 3 -j-4(HO, 
 
 X0 5 )=3(Ago,X0 5 )_>+x6 2 +4HO_ > . If coin be em- 
 ployed, nitrate of copper will be present ; on heating the 
 solution to dryness, this will be decomposed, leaving insol- 
 uble CuO, from which the AgO,X0 5 may be separated by 
 solution and nitration. 
 
 Prop. — Colourless, transparent crystals (3d system), of 
 a metallic and bitter taste, soluble in their weight of cold 
 water and 4 parts of cold alcohol. The salt is decomposed 
 by heat, with a bright flame, leaving spongy metallic sil- 
 ver. It is blackened by the contact of organic matter. 
 
 Med. Effects. — In overdose, an irritant poison; antidote, 
 common salt ; in medicinal doses, gr \ to j, used in the neu- 
 roses and chronic gastritis ; externally in collyria. Should 
 not be mixed with other medicine-, and. if given in pill, it 
 
CHEMISTRY OF THE ELEMENTS. 285 
 
 should be made up with gum ; if dissolved, distilled water 
 should be used. 
 
 Argenti Nitras fusa, Lunar caustic, Lapis infernalis, 
 AgO,N0 5 . Is made by fusing the salt and pouring it into 
 moulds. Is for external use. It sometimes contains chlo- 
 ride, wilich renders it less brittle ; the latter will be left 
 behind upon dissolving it in water. A stick of nitrate of 
 silver may be conveniently pointed by rubbing it with a 
 rotary motion upon a polished silver coin. 
 
 GOLD (Aurum), Au=98. 
 
 376. Occurs native ; is, when pure, soft, yellow, and the 
 most malleable of the metals ; it can then be welded cold, 
 and is used for filling teeth ; s. g. 195; melts at a bright 
 red heat ; is unaltered in the air, and only attacked by 
 Aqua regia, selenic acid, and nascent cyanogen. American 
 coin contains 900-thousandths of pure gold. Its most 
 important compound is the chloride AuCl 3 , used in pho- 
 tography in toning prints. It gives with protochloride of 
 tin a purple precipitate (Purple of Cassius, AuO,Sn0 2 ,SnO, 
 Sn0 2 -f 4HO ?) which is used in glass staining and in paint- 
 ing upon porcelain. Gold is precipitated from solution by 
 ferrous sulphate, FeO,S0 3 . . Polished steel dipped into its 
 ethereal solution acquires a coating of metallic gold on the 
 evaporation of the ether. Fire-gilding is performed by 
 heating a coating of amalgam of gold and mercury applied 
 to the body, the mercury is driven off. Electro-gilding 
 has been already described (166). The preparations of 
 gold have been used in the treatment of syphilis, but are 
 now abandoned. They are highly poisonous ; the anti- 
 dotes for mercury may be used. 
 
286 MEDICAL CHEMISTRY. 
 
 PLATINUM, Pt=985. 
 
 3TT. Is a rare metal, occurring always native, in grains, 
 and associated with other metals of the same group, Iridi- 
 um, Osmium, Palladium, and Rhodium. Of these, the two 
 first form a very hard alloy, irid-osmine, which is used 
 for pointing gold pens. Osmium forms a poisonous, vola- 
 tile, osmic acid, Os0 4 . The grains of platinum may be 
 dissolved in Aqua regia, and the metal precipitated by 
 NH 4 C1, in the form of a yellow double chloride,NH 4 Cl,PtCl 2 , 
 which on exposure to heat leaves the metal finely divided, 
 Platinum sponge; this may be welded into sheets. Plati- 
 num black, another form of the finely divided metal, is 
 made by adding KO,HO to PtCl 2 , and then alcohol. Both 
 of the forms of the metal are remarkable for their power 
 of absorbing and condensing gases (14*7). The grains 
 may also be fused together by the compound blowpipe, 
 forming ingots, as first done by the late Dr. Hare. 
 
 Platinum is the heaviest metal known ; s. g. between 21 
 and 22 ; is highly malleable and ductile, resists all ordi- 
 nary chemical agents even at high temperatures ; is harder 
 than gold, and much used in the laboratory and the arts 
 in the form of wire, foil, crucibles, and retorts. Like iron, 
 it may be welded at a high heat. Its most important com- 
 pound, the bichloride PtCl 2 , is used as a test for potassa 
 and as a means of getting its other preparations. It forms 
 a remarkable series of double chlorides of much theoretical 
 interest. Its compounds are not used in medicine. 
 
PART IV. 
 
 ORGANIC CHEMISTRY. 
 
 378. Organic Chemistry investigates compounds pro- 
 duced under the influence of vitality, and those derivable 
 from them by artificial means. 
 
 This definition, although convenient, is not accurate. 
 Recent researches have shown that many bodies, formerly 
 obtained from the organic kingdoms, may be produced 
 artificially. The compounds of ammonia and cyanogen 
 are no longer considered as organic. Formic acid, alcohol 
 and its derivatives, many of the fatty acids, glycerine, 
 taurine (found in the muscles of the mollusca), urea, oils 
 of mustard and garlic, are examples of organic bodies 
 which may be found of purely inorganic materials. We 
 owe much of our knowledge on this subject to . Berthelot, 
 who, by imitating the gradual processes of nature, rather 
 than the rapid and violent ones of the laboratory, has 
 formed, from carbon obtained from the earthy carbonates, 
 hydrogen from water, and oxygen from air, an extended 
 and important series of artificial organic bodies. Instances 
 of this organic synthesis will be given hereafter. 
 
 379. Constitution of Organic Bodies. — Few elements 
 enter into the constitution of organic bodies, but the num- 
 ber of equivalents is great. Carbon is the essential ele- 
 ment; next in frequency occurs Hydrogen, then Oxygen; 
 a comparatively limited group contains Nitrogen; still 
 more rare are Sulphur and Phosphorus ; and finally, 
 only in certain structures, or in artificially derived bodies, 
 
 (287) 
 
288 MEDICAL CHEMISTRY. 
 
 do we find the other elements. The number of atoms is 
 large. Morphia has the formula C34H 19 N0 6 +2HO, and 
 its equivalent is 303, against 47 for KO or 20 for MgO. 
 Organic bodies also change in the most various and com- 
 plex modes, differing much from those of the simple acids, 
 bases, and salts which have been heretofore considered. 
 The number of possible compounds can be shown to be 
 infinite. Of the compounds of Glycerine with the known 
 acids, Berthelot has shown* that over 200,000,000 are pos- 
 sible, and a similar variety will be shown to be probable 
 under the head of substitution compounds. 
 
 380. Decomposition. — From their complexity, organic 
 bodies are prone to decomposition; the elements re- 
 arranging themselves in simpler forms, hence we have as 
 results ammonia, marsh gas, compounds of sulphur and 
 hydrogen, cyanogen, etc. The following are the most im- 
 portant varieties of natural decomposition : Eremacausis, 
 or decay, which occurs only in non-nitrogenised bodies, as 
 wood, and which is a slow oxidation accompanied by 
 absorption of nitrogen ; Fermentation, occurring in non-ni- 
 trogenised bodies under the influence of a putrefying nitro- 
 genised substance ; Putrefaction, occurring only in bodies 
 containing nitrogen; it is closely allied to fermentation. 
 
 381. Analysis of Organic Bodies. — 1. Qualitative. 
 Organic bodies contain carbon in excess of the quantity 
 of O necessary to consume it. On heating them in a tube, 
 the C remains. This is characteristic of organic matter. 
 Water may be driven off by a heat of 212°. Mineral 
 matters are determined by burning the body in a crucible, 
 by the aid of KO,N0 5 or KO,C10 5 , and examining the 
 ash. Use is made of the solvent powers of various 
 menstrua in separating the proximate constituents, as in 
 the simple example of a gum-resin, where the former is 
 
 * Ghimie Organique fondie sitr la Synthese, Tome ii. p. 33. Paris, 1860. 
 
ORGANIC CHEMISTRY. 289 
 
 dissolved by water and the latter by alcohol. Fractional 
 distillation is also usefully employed to separate bodies of 
 different degrees of volatility. The other methods of dis- 
 tinguishing organic bodies, and of separating them into 
 their proximate constituents, will be explained hereafter. 
 The Ultimate analysis of organic bodies is effected by 
 burning the body and weighing the products of combustion. 
 This is generally effected by mixing the body, carefully dried 
 and weighed, with CuO or PbO,Cr0 3 in a tube, sealed at one 
 end, and applying heat ; the products of combustion are 
 caused to pass through a tube containing fragments of 
 fused CaCl, and then through bulbs filled with a solution of 
 KO,HO. The former intercepts the watery vapour formed 
 by the combustion of the H, and the latter the C0 2 formed 
 by that of the C. The tube and bulb are weighed carefully 
 before and after the combustion; i of the increase of the 
 weight of the former is H, and T 3 T of the latter C. The O 
 is estimated by the difference of the combined weight 
 of these elements with the ash and that of the body an- 
 alysed. The presence of nitrogen in an organic body is 
 generally manifested by the evolution of NH 4 0, when 
 heated alone or with KO,HO ; its amount may be deter- 
 mined by collecting it as it issues from the potash bulb. 
 Sulphur is detected by heating the body with an alkali 
 and testing with nitro-prusside of sodium ; it may be 
 burned into S0 3 and precipitated by Baryta. Phosphorus 
 may be converted into phosphates and tested in that form. 
 382. Theoretical Considerations. — The result of ulti- 
 mate analysis is merely a knowledge of the elements con- 
 tained in a body, and their amounts per cent. We know 
 nothing of the arrangement of the elements of any body, 
 organic or inorganic. Theory supposes them to be ar- 
 ranged in a certain way for the purpose of conveniently 
 arranging and studying the facts. Thus, sulphate of po- 
 25 
 
290 MEDICAL CHEMISTRY. 
 
 tassa contains one atom of sulphur, one of potassium, and 
 four of oxygen; we suppose these to be arranged as KO, 
 S0 3 ; we may suppose them to be K,S0 4 , or K0 2 S0 2 , or 
 K0 3 SO, or K0 4 S, etc. We assume the former of these 
 to be true from probability and convenience. Alcohol, 
 C 4 H 6 2 , may be regarded as C 4 H 5 0,HO, or C 4 H 4 2HO, or 
 
 4 tt 5 [■ 2 , etc. The formula given by ultimate analysis is 
 
 termed the empirical formula; that which represents the 
 supposed arrangement, the rational formula. 
 
 Compound Radicals. — We assume the existence of com- 
 pound bodies which, like ammonium (274) and cyanogen 
 (235), act as elements ; these are called quasi elementary 
 bodies or radicals; they are exceedingly numerous. By 
 far the largest number contain only C and H, the equiva- 
 lents of the former being even and of the latter odd. They 
 form oxides, hydrates, and compounds with the acids and 
 halogens strictly analogous to the corresponding com- 
 pounds of the metals. 
 
 Thus the radical Ethyl, C 4 H 5 , forms CJI 5 0, Ether, C 4 H 5 0,HO 
 Alcohol, C 4 H 5 0,N0 3 Nitrite of the Oxide of Ethyl, C 4 H 5 C1 Chlo- 
 ride of Ethyl, etc. These cannot in many cases be made directly, 
 and it should be remembered that the whole assumption is merely 
 a convenient theory. 
 
 383. Substitution Compounds. — In inorganic chemistry, 
 H is replaced by the metals, HCl-f-Zn=ZnCl+H; and 
 the amphigens (184) and halogens (224) replace each 
 other. In organic chemistry, not only do these replace- 
 ments take place, the quasi metals or radicals being in- 
 eluded as metals, but the halogens and N"0 4 replace H. 
 These substitution compounds often present a marked re- 
 semblance to those from which they are derived. Thus, 
 
 TT 
 
 Pyroxyline or gun-cotton, C 2i , r ^- r . , O 20 , made by the 
 
 action of HO,N0 5 on cotton, C^H^O^ has six of N0 4 in 
 place of three of the H of the latter. The most remark- 
 
ORGANIC CFIEMISTRY. 291 
 
 able bodies of this group are to be found under the head 
 of the substitution ammonias (425). 
 
 384. Isomeric, Metameric, and Homologous Bodies. — In 
 inorganic chemistry, we have seen that the same elements 
 in the same proportions produce the same compound. In 
 organic chemistry, we have frequent instances of bodies of 
 precisely the same composition, but of different chemical 
 and physical properties. Thus : Cellulose (cotton) Starch, 
 Dextrin, and Gum Tragacanth, all have the formula C 24 
 H 30 O 20 . Such bodies are termed isomeric (Gr. isos, equal, 
 meros, weight). Their widely different properties are 
 attributed to a difference in the arrangement of their atoms. 
 Metameric todies (Gr. meta, beyond, meros, weight) are 
 isomeric bodies of which the rational formula? are sup- 
 posed to have been determined, and thus this difference 
 of arrangement made clear. Thus, Acetate of oxide of 
 methyl C 2 H 3 0,C 4 H 3 3 , Formate of oxide of ethyl C 4 H 5 0,C 2 
 H0 3 , and Propionic Acid C 6 H 5 3 ,HO, have each the em- 
 pirical formula C 6 H 6 4 . Homologous bodies (Gr. homoios, 
 similar, logos, ratio) differ from each other by a fixed 
 amount of C and H, and those belonging to the same 
 series have generally a similarity of properties and chemi- 
 cal characters. Thus, the following acids, Formic C 2 H,0 3 
 HO, Acetic C 4 H 3 3 ,HO, Propionic C 6 H 5 3 ,HO, Butyric C 8 
 H 7 3 ,HO, increase by C 2 H 2 or a multiple of it; their 
 boiling-points have also been noticed to rise about 34° F. 
 for each increase of C 2 H 2 . We have many such series. 
 
 385. Arrangement. — Organic bodies will ' be consid- 
 ered under the following heads: 
 
 1. The Starch group, including the sugars, gums, and 
 
 woody fibre. 
 
 2. Radicals homologous with Ethyl, having the general 
 
 formula C. 2 nH 2 n-j-,; their compounds and deriva- 
 tives. 
 
292 MEDICAL CHEMISTRY. 
 
 3. Radicals not homologous with Ethyl. 
 
 4. Organic Acids not oxides of known radicals. 
 
 5. Substitution Ammonias, the alkaloids and allied prin- 
 
 ciples. 
 
 6. Fats and Oils. 
 
 i. Colouring Matters. 
 
 8. The proximate principles of animals and vegetables 
 
 and otherwise classified, with the chemistry of the 
 
 animal solids and fluids. 
 
 I. STARCH GROUP. 
 
 The most important members of this group are : — 
 
 Cellulose, C 24 H 20 O 20 . 
 
 Starch, C^H^O^. 
 
 Dextrin, CmII^O*,. 
 
 Gum Arabic, C^H^O^. 
 
 Gum Tragacanth, C 24 H 20 O 20 . 
 
 Pectin, C 64 H 48 64 . 
 
 Cane Sugar, C24H 22 22 . 
 
 Grape Sugar, C^H^O^. 
 
 Fruit Sugar, C 24 H 24 2 4. 
 
 Milk Sugar, C 24 H 24 24 . 
 
 They all, except Pectin, contain the same proportion of 
 C, and the H and O are in the proportions to form water. 
 They have been termed Carbohydrates, but the word is 
 objectionable ; it cannot be assumed that they are com- 
 posed of carbon and water. 
 
 386. Cellulose, C 24 H 20 O 20 . Is the fundamental material 
 of the structure of wood constituting the cell-wall. It is 
 
ORGANIC CHEMISTRY. 293 
 
 seen nearly pure in fine linen, cotton wool, or fine unsized 
 paper. It has been detected in certain diseased conditions 
 of the human brain. 
 
 Cellulose is white, inflammable, insoluble in ordinary 
 menstrua. It may be dissolved in the cold by a solution 
 of ammonio-sulphate of copper (330), by strong alkalies at 
 high temperatures and pressures, and it is decomposed by 
 CI and I. Cold HO,S0 3 converts it into dextrin, and finally 
 into grape sugar ; when pure, it is not immediately black- 
 ened by this reagent. By the immersion for half a minute 
 in HO,N0 5 , and washing, it is converted into explosive 
 gun-cotton, or pyroxylin. A mixture of equal parts of com- 
 mercial nitric and sulphuric acids, allowed to cool, will 
 answer. A less explosive variety, freely soluble in ether, 
 is made by the action on the cotton wool for 24 hours of 
 
 a mixture of KO,N0 5 , in fine powder ^x, and sulphuric 
 
 •pi- 
 acid s. g. 1*843 gxvss. The formula C 24 — O 20 has 
 
 (N0 4 ) 4 
 
 TT 
 
 been assigned to the explosive, and C 24 - t u O20 to the 
 
 (JN(J 4/ ) 6 
 
 soluble variety. 
 
 Collodion, Collodium,V. S. P., is a solution of pyroxi- 
 line gr lvi in a mixture of f^iiiss of ether and f3j of 
 stronger alcohol. Its tendency to contract may be obviated 
 by the addition of 5 to 10 p. c. of castor oil or Venice 
 turpentine. 
 
 Explosive compounds resembling pyrox}<line in compo- 
 sition have been made by the action of HO,N0 5 on starch, 
 glucose, mannite, etc. By the action of FeCl or of KS.1IS. 
 pyroxiline is reconverted into cotton. 
 
 Wood consists of cellulose, with incrusting and other 
 materials, to which the names of vasculose, fibrose, etc. 
 have been given; they are grouped under the general 
 term of inicrcelluloxe. By the action of caustic alkali 
 
294 MEDICAL CHEMISTRY. 
 
 under pressure, the intercellulose is dissolved and cellulose 
 remains. Yery strong alkaline lyes under pressure attack 
 the cellulose. By the action of a mixture of caustic potassa 
 and soda on sawdust, oxalic and finally ulmic acid (C 40 H 14 
 12 ) are formed. Cotton goods immersed in a cold, strong 
 solution of caustic alkali are rendered thicker and stronger, 
 a portion of the alkali entering into combination with the 
 fibre. XJd sized paper dipped for an instant into a mixture 
 of 2 vols. HO,S0 3 and one of water, and then well washed, 
 becomes converted into a parchment-like substance. 
 
 Decomposition. — Wood exposed to the air undergoes 
 slow decay, eremacausis, due to the absorption of oxygen ; 
 carbonic acid and water are produced. This may be re- 
 tarded by impregnating it with antiseptics, which coagu- 
 late the albuminous matters. The most important are, 
 ZnCl, HgCl, CuO,S0 3 , and coal-tar. In dry air, or wholly 
 submerged, wood will last for centuries. Vegetable mould 
 contains certain principles which have been described as 
 humus, geine, ulmin, geic, humic, and ulmic acids ; they 
 sometimes contain ammonia, the nitrogen of which is sup- 
 posed to have been obtained from the atmosphere. 
 
 When vegetable fibre undergoes decomposition, par- 
 tially excluded from the air, either under water or ground, 
 it is converted into peat, and gradually into lignite and 
 coal. 
 
 By the destructive distillation of wood and coal, a variety 
 of complex products are produced ; these vary with the 
 temperature, moisture present, etc. They may be classed 
 as, (1) Gases, CO, C0 2 , C 2 H 4 , C,H 4 , NH 4 0, and C 2 N ; and 
 volatile, complex, hydrocarbons, among which naphthaline, 
 C 20 H 8 , a white crystalline body, solid at ordinary tempera- 
 tures, may be mentioned. (2) Tar, which is a very complex 
 body. Wood tar, Pix liquida, contains wood spirit CaB^O,, 
 acetic acid C 4 H 4 4 , paraffine and creasote C 14 H ? 2 . Wood 
 
ORGANIC CHEMISTRY. 295 
 
 spirit and acetic acid will be considered under Group II. 
 Paraffine (parum, little, affinis) is a beautiful transparent 
 solid, unaffected by any ordinary chemical agents. It is 
 used in making candles, waterproofing, and for greasing 
 the stoppers of chemical reagent bottles. It consists of 
 C and H, but its formula has not been determined. Naph- 
 thaline, C 20 H 8 , is a white crystalline body, solid at ordinary 
 temperatures. Creasote, Creasotum, Ci 4 H 8 2 , is a colour- 
 less, oily liquid, of a burning caustic taste, and peculiar 
 smell, is inflammable, boils at 397°. It coagulates albu- 
 men, and is antiseptic, as is seen in smoked meats. Is used 
 externally, mixed with water, as a stimulant and detergent 
 wash, and pure as a caustic ; the Unguent. Creasoti con- 
 tains f^ss Creasoti to §j Adipis. Creasote is sometimes 
 given internally as an astringent and anti-emetic. Dose, 
 gtt ss to j, in water. In overdose, is an irrit'ant poison, 
 antidote, albumen. Carbolic or Phenic acid, coal-tar, crea- 
 sote, C 12 H 6 2 , or Ci 2 H 5 0,HO, hydrate of the oxide of phenyl 
 (417), closely resembles the former, and is perhaps iden- 
 tical. It is in transparent crystals, having the odour and 
 other properties of creasote, and is soluble in water by the 
 aid of acetic acid. Used in the same cases as the former. 
 Ridgewood's disinfectant consists of carbolic acid, lime, and 
 clay. Carbolic acid is one of the most reliable of the Anti- 
 septics (199). Coal-tar gives on distillation Naphtha, which 
 contains benzole, C 12 H 6 , and its homologues (417) ; dead oil, 
 containing naphthaline, paraffine, and a residue of pitch. 
 By chemical agents, the beautiful aniline dyes and other 
 colouring and even fragrant matters are obtained from 
 coal-tar. These will be discussed hereafter. 
 
 387. Starch, C 24 H 2 o0 2 o. — Is obtained chiefly from the 
 roots and seeds of vegetables, by mixing the crushed or 
 rasped matter with cold water, which dissolves albuminoid 
 matters, and allows the starch to fall to the bottom of the 
 
296 MEDICAL CHEMISTRY. 
 
 vessel. It is also found in the brain, the liver and kidneys, 
 spleen, and raucous surfaces. The following are the most 
 important varieties of starch: corn starch, wheat starch 
 (amylum), potato starch, Maranta (arrow-root), Sago, Ta- 
 pioca, and Canna (Tons le mois). 
 
 Prop. — Is a white shining powder, exhibiting under the 
 microscope irregular grains, the size of which varies; 
 those of Canna measure the 2 ^ of an inch, those of Ma- 
 canta q^-q, of amylum y^oo* °^ r ^ ce Woo- These grains 
 consist of layers covered by an external membrane, each 
 globule having on it a mark or hilum. It is insoluble in 
 water, but when boiled, the membrane bursts, and the 
 whole forms a transparent jelly, probably not a true solu- 
 tion, amidin, clear starch; this gives a characteristic blue 
 colour with free iodine. 
 
 The starch from elecampane, etc., Inulin, and from lichens 
 and algae, cetrarin, chondrin, differs somewhat in composition 
 from the ordinary starch. The former is coloured yellow, and 
 the latter brownish-gray, by iodine. 
 
 Chemical Changes. — Dilute acids (except phosphoric), 
 diastase, and saliva convert starch into dextrin. Cold 
 strong nitric acid dissolves it; and, on the addition of 
 water, a precipitate of xyloidine, an explosive body resem- 
 bling pyroxyline, is deposited. Dilute nitric acid converts 
 it into a variety soluble in cold water, and finally into dex- 
 trin. Hot nitric acid oxidises it to oxalic acid, C24H20O20+ 
 12(HO,NO 5 )=12(HO,C 2 O 3 ->) + 20HO->+12NO^. Iodine 
 and bromine combine with starch, and it, on the other 
 hand, forms amylates with baryta, lime, and oxide of lead. 
 It is insoluble in a solution of ammoniated copper, and is 
 destroyed by strong alkalies. 
 
 Dextrin, C^H^CV 
 
 Prep. — (1) By boiling starch with dilute acids, ceasing 
 when the liquid no longer reacts with iodine. (2) By the 
 
ORGANIC CHEMISTRY. 291 
 
 action of saliva or of diastase, a nitrogenous principle 
 existing in germinating seed, at about 80° F. The process 
 should be arrested by heating to the boiling-point, when 
 the iodine reaction ceases ; otherwise the dextrin is con- 
 verted into grape sugar. One part of diastase will convert 
 2000 of starch into dextrin, or sugar. (3) British gum, 
 which is identical with dextrin,* is prepared by roasting 
 starch at about 400°, or by heating to 220° 500 of starch, 
 150 of water, and 1 of nitric acid for two hours. In all 
 these cases the action of the acid is catalytic, it is itself 
 unchanged. Dextrin has a sweetish taste, is very adhe- 
 sive, and is used in coating labels, envelopes, etc. It does 
 not ferment. 
 
 388. Gum Arabic, Acacia, Arabin, C^H 22 22 , or C^HnOu. 
 Forms a viscid mucilage with water; by dilute acids it 
 is converted into grape sugar. Nitric acid converts it into 
 mucic acid, C 14 H80 14 ,2HO ; it is precipitated by the sub- 
 acetate of lead, forming a definite compound with the oxide 
 of lead, PbO,C 12 H n O n . Besides Arabin, Acacia contains 
 lime. 
 
 389. Gum Tragacanth, Tragacantha, C24H20O20, or C 12 H 10 
 O 10 . — Consists almost wholly of bassorin. It swells with 
 water to a bulky mass, which when long boiled acquires the 
 general properties of Arabin. It is chiefly used in making 
 paste. The gum of the cherry, plum, and apricot tree 
 appears to be a mixture of Arabin and bassorin. The 
 mucilage of quince-seed, flaxseed, elm, and marshm allow 
 closely resemble the gums. 
 
 390. Pectin, C 64 H 40 O 56 ,8HO. — The well-known property 
 of gelatinising possessed by the juice of fruits, as currants, 
 raspberries, etc., is due to Pectin. In the unripe fruit, 
 pectose, a substance insoluble in water, alcohol, and ether, 
 exists; during ripening, this is converted in great part into 
 
 * GMELIN, Handbook Cav. E<1, vol. xv. p. 1ST. 
 
298 MEDICAL CHEMISTRY. 
 
 pectin; the change is accelerated by boiling; it is brought 
 about by a sort of fermentation or catalytic change due to 
 the action of the acids present in the fruit favoured by 
 warmth and light. Parapeptin and Metapeptin are modi- 
 fications; by the action of weak alkaline solutions, these 
 are changed into pectic acid, 2HO,C 32 H2o0 28 , which may be 
 further converted into meta and para-pectic acids. 
 
 391. Cane Sugar, Saccharum, C^H.^Oaa. 
 
 Sources. — The sugar-cane, sorghum, beet-root, the 
 ascending sap of the maple, corn-stalks ; is also found in 
 the date and cocoa palm, melons, bananas, pineapple, nec- 
 taries, of flowers, etc. 
 
 Prep. — The expressed juice is heated to coagulate 
 albuminous matter, which is skimmed off, lime is added to 
 neutralise acids which would convert it into fruit sugar 
 (molasses) ; the juice is evaporated under diminished 
 pressure. The raw or brown sugar thus obtained is re- 
 fined ; it is dissolved in lime-water, filtered first through 
 woollen bags and then through animal charcoal. The so- 
 lution, evaporated and crystallised, gives loaf-sugar, or, in 
 large, oblique rhombic crystals (4th system), rock-candy. 
 
 Prop. — A sweet substance, s. g 1*6, soluble in -| its 
 weight of water, at 60° forming syrup ; boiling absolute 
 alcohol dissolves ^ of its weight, which deposits on cool- 
 ing ; commercial alcohol dissolves a larger proportion. 
 Heated a little above 320° F., it cools to an amorphous 
 mass, — barley sugar, candy ; above '618°, loses 4 eq. water, 
 becoming caramel or burned sugar, used for colouring 
 liquids and syrups. It combines with lime and other 
 bases, forming definite crystallisable salts, the formula of 
 the lead salt at 212° being 4PbO,C24H l8 ]8 ; it is probable 
 that the rational formula of cane sugar is 4HO,C 2 4H 18 0,8. 
 It also forms compounds with salts, as common salt, which- 
 are deliquescent and crystallise with difficulty. Strong 
 
ORGANIC CHEMISTRY. 299 
 
 sulphuric acid chars it ; the dilute acids generally, and 
 diastase, convert it into fruit sugar; nitric acid forms oxalic 
 acid (see Starch). The changes produced by fermenta- 
 tion will be considered hereafter. 
 
 392. Fruit Sugar, C 24 H 24 24 . Occurs in the juice of ripe 
 acid and subacid fruits, the descending sap of the maple, 
 honey, etc. Is frequently associated in these with cane- 
 sugar, which is converted into it by the action of dilute 
 acids and diastase. It is very sweet, soluble, and uncrj^s- 
 tallisable. It passes readily into grape sugar. Molasses, 
 Syrupus fuscus, is fruit sugar, containing a considerable 
 quantity of cane sugar in suspension. Glycogen, a starch- 
 like substance obtained from the liver, has the same com- 
 position. 
 
 393. Grape Sugar, Glucose, C 24 H 28 28 . — Forms the white 
 crystals on the outside of dried fruits ; exists in diabetic 
 urine, normally in the liver, and is readily formed by the 
 action of dilute acids upon starch, gum, and the other 
 sugars. 
 
 Prop. — In warty imperfectly crystallised grains, less 
 sweet than cane sugar in the proportion of 2 to 5 ; it is 
 also less soluble in water, requiring one and a half times 
 its weight, but is more soluble in alcohol. By the action 
 of heat at 140° F., loses 4 equivalents of water and is con- 
 verted into a body isomeric with fruit sugar ; at a higher 
 temperature forms caramel. Sulphuric acid combines with 
 it to form Sulphosaccharic acid, the lime and barj^ta salts 
 of which are soluble. Nitric acid converts it into oxalic 
 acid. It forms certain unstable compounds with bases ; 
 is decomposed by strong alkalies. The tests for glucose 
 will be considered under Urine. Its rational formula is 
 probably 4HO,C 24 H 24 24 . 
 
 394. Milk Sugar, C^H^O^, or C^HnOn. — Is obtained 
 by evaporating the whey of milk. 
 
300 MEDICAL CHEMISTRY. 
 
 Prop. — In hard, gritty crystals, (3d system), soluble 
 in *l parts of cold water, insoluble in alcohol and ether. 
 Is converted into glucose by dilute acids ; nitric acid forms 
 oxalic and mucic acids ; it forms a hydrate 2HO,C 24 H22022, 
 and readily undergoes the lactic fermentation. Other 
 sugars, or quasi sugars, as Mannite C 12 H 14 12 , Glycyrrhizin 
 C 36 H 24 14 , Quercite, Pinite, Sorbin, My cose, etc., are de- 
 scribed. Inosite, sugar of flesh, Glycocoll, sugar of gela- 
 tine, and Glycerine, the sweet principle of fats, are not 
 true sugars ; they will be described hereafter. 
 
 395. Glucosides. — This term is applied to bodies which 
 by boiling with dilute mineral acids, or aqueous alkalies, 
 or by certain ferments, split up into glucose and one or 
 more other compounds. They occur in both the vegetable 
 and animal kingdoms, have never been produced syntheti- 
 cally, and are very numerous. The following are familiar 
 examples : Gallo-tannic acid, yielding glucose and gallic 
 acid, C 14 H 6 O 10 ; Salicin into glucose and saligenin, C H H 8 
 4 ; Scammony resin into glucose and scammonolic acid, 
 C^HgoCV, Amygdalin into glucose, oil of bitter almonds, 
 C 14 H 6 2 , and hydrocyanic acid, HCy. 
 
 396. Fermentation.— Certain decomposing bodies — fer- 
 ments — have the power of inducing decomposition in those 
 with which they may, under favourable circumstances, be 
 placed in contact. A very minute portion of a ferment is 
 sufficient to set up the action, which then proceeds with 
 more or less rapidity, producing, in the presence of com- 
 pounds of ammonia and the phosphates, a much larger 
 quantity of the ferment among the products of the change. 
 The following circumstances are essential in all varieties 
 of fermentation : (1) Contact of the ferment ; (2) Presence 
 of air; this is not essential after fermentation has once 
 begun; (3) A temperature not below the freezing nor 
 above the boiling point of water. It is retarded by too 
 
ORGANIC CHEMISTRY. 301 
 
 high or too low a temperature between the limits named, 
 and may be arrested by filtration, temperature, and anti- 
 septics. The atmosphere contains always certain germs 
 which have the power of inducing fermentation ; these are 
 destroyed by boiling, etc., and arrested by filtering the air 
 through cotton. The forms of diseases grouped under the 
 title of zymotic, are supposed to be due to the action of 
 ferments ; hence the use of the sulphites, carbolic acid, etc. 
 as prophylactics and remedies. 
 
 The most important varieties of fermentation are the 
 vinous, the acetic, the lactic, the butyric, and the viscous. 
 
 397. Vinous Fermentation. — The varieties of sugar which 
 are truly fermentable appear to be the fruit and grape su- 
 gars, the other members of the group being converted into 
 these by the action of chemical agents. The circumstances 
 most favourable to the action are a temperature of 68-10° 
 F., a weak solution of the sugar, say 10 p. c, and a proper 
 proportion of the ferment. Yeast is composed of vegeta- 
 ble egg-shaped cells, which increase by budding during the 
 fermentation of other than pure saccharine solutions ; this 
 increase in brewing may amount to | the original weight; 
 it generally rises to the surface, but when the process takes 
 place at a low temperature, sinks. Other nitrogenised 
 bodies, as albumen, casein, etc., will induce fermentation 
 and the formation of yeast. During fermentation the fol- 
 lowing changes are noticed : (1) The evolution of CO., 
 causing frothing, which begins at the sides of the vessel, 
 and after a time covers its whole surface ; (2) An agreea- 
 ble, vinous odour ; (3) A gradual diminution of the sweet- 
 ness and s. g. of the liquid, and evidence of the presence 
 of alcohol. The decomposition is never complete ; a cer- 
 tain portion of unconvertible dextrin, saccharine matter, 
 and other bodies remain. The chemical change taking- 
 place is the splitting up of the sugar into the simpler forms 
 26 
 
302 MEDICAL CHEMISTRY. 
 
 of water, carbonic acid, and alcohol (C 4 H 6 2 ). Thus grape 
 sugar, C ai H 28 28 =8C0 2 +4(C 4 H 6 2 ) + 4HO; it yields 46-46 
 p. c. of alcohol ; fruit sugar yields 51* 12 p. c, and cane su- 
 gar 53-22 p. c, supposing the fermentation to be complete. 
 We may arrest the process by nitration to remove yeast, 
 boiling or freezing, or by antiseptics, of which carbolic 
 acid, sulphurous acid, or the sulphites, are practically the 
 best. 
 
 Processes depending upon Fermentation. — Bread-Mak- 
 ing. When flour is mixed with water, the gluten makes a 
 tough paste, dough. The yeast added causes a portion of 
 the starch to ferment ; after becoming sugar, the carbonic 
 acid given off swells up the pasty dough, and the bread is 
 raised. The carbonic acid and alcohol formed are driven 
 off during the baking. By Dauglish's process the flour is 
 impregnated with C0 2 , under pressure, no fermentation 
 being allowed ; thus a portion of the starch is saved, and 
 a purer and more palatable bread obtained. 
 
 Wines. — The generic term wine may be applied to the 
 fermented juice of fruits. We may distinguish Grape wine, 
 wine proper ; that from currants, gooseberries, etc., Domes- 
 tic wines ; Cider from apples, Perry from pears, etc. 
 
 The juice of grapes exposed to the air ferments, owing 
 to the presence of albuminous matters in the pulp ; it is 
 then put into casks. A second fermentation takes place 
 in the succeeding spring, after which its impurities sub- 
 side. The quantity of alcohol gradually increases, owing 
 to the further change of the sugar, and the cream of tartar 
 existing in grape juice is deposited as argols ; thus true 
 wine improves up to a certain point by age ; beyond this, 
 it again becomes acid or pricked from the formation of 
 acetic acid. Sparkling wines are bottled before the second 
 fermentation, and contain the C0 2 , due to it. Domestic 
 wines contain malic acid, which does not deposit ; hence 
 
ORGANIC CHEMISTRY. 303 
 
 they are sour, unless this acid is disguised by sugar ; gen- 
 erally a considerable quantity of spirits is added to make 
 them keep. They cannot compare in wholesomeness with 
 the wine of grapes. The varying properties of wines de- 
 pend upon the percentage of alcohol and sugar. The for- 
 mer may be determined by distilling off one-half of the 
 wine, diluting the distillate with water enough to make up 
 the original bulk, and testing with the hydrometer (IT) ; 
 the latter by evaporation. The following is a general 
 average statement. Port, Madeira, and Sherry contain 20 
 p. c. ; Hock, Claret, and Champagne, 11 p. c, and domestic 
 wines 10 to 20 p. c, of alcohol. The quantity of sugar is 
 least in the Hocks, and greatest in the syrupy wines, as 
 some kinds of Port, Angelica, Malmsley, etc. The acidity 
 of true wines is due to cream of tartar ; if the grapes were 
 green, citric acid may be present, and in old wines acetic 
 acid. Cider contains lactic acid. Moselle and Rhine 
 wine are the most acid, Port and Sherry the least so. 
 Tannic acid imparts roughness or astringency to wines, 
 and prevents their becoming ropy (viscous fermentation). 
 Wine casks are fumigated with S0 2 , to prevent their con- 
 tents from souring (acetic fermentation). Wine is offici- 
 nal as Vinum Portense, Port Wine, and Vinum Xericum, 
 Sherry. 
 
 Beer. — In brewing, a mash is made of malt, barley, which 
 has been allowed to germinate after steeping in water, by 
 which its starch is converted into dextrin and sugar ; to 
 this mash yeast is cautiously added, and fermentation 
 allowed to take place to a certain point, leaving a consider- 
 able proportion of unchanged dextrin and sugar. To the 
 worts thus obtained is added an infusion or decoction of 
 hops, by which a bitter flavour is given and ferment at ion 
 checked. A slow fermentation goes on after the beer is 
 barrelled, and causes the liquid to be charged with CO* 
 
304 MEDICAL CHEMISTRY. 
 
 In the brewing of lager, the fermentation is conducted 
 at a low temperature, 33° to 46^° F. The yeast sinks to 
 the bottom, carrying much albuminous and gummy matter, 
 and leaving a very clear beer. It is put in casks coated 
 inside with resin, and stored for a long time before using. 
 The amount of alcohol in beer varies from 2 p. c. in some 
 kinds of lager and small beer to 8 in XXX ale and brown 
 stout. The high colour of porter and stout is due to the 
 use of malt which has been slightly charred in the kiln, 
 used for checking the germination of the malt. 
 
 Spirits are distilled from fermented liquids; Brandy, 
 Spiritus Vini Gallici, from wine ; Whiskey, Spiritus Fru- 
 menti, from a mash of corn or rye ; Hum, from the juice of 
 the sugar cane, or from molasses, etc. They contain about 
 50 p. c. of absolute alcohol, by volume, when at proof. 
 Their strength can be ascertained directly by the hydro- 
 meter. They all improve by age when kept in wood, 
 owing to the oxidation of injurious bodies, known as fusel 
 oils, to fragrant and harmless ethers. The presence of 
 fusel oil is disguised by sugar and mucilages, and it may 
 be removed by filtering through charcoal mixed with 
 Mn0 2 . 
 
 398. Acetous Fermentation. — A weak solution of alcohol, 
 exposed to the air in contact with a ferment, absorbs oxy- 
 gen and becomes acid. This change will be studied under 
 the head of Acetic Acid. 
 
 399. Lactic Fermentation. — Sugar of milk, under the 
 influence of the casein present in that fluid, or by the con- 
 tact of certain animal membranes (rennet), ferments, lactic 
 acid being formed. This is the cause of the souring of 
 milk. It may be retarded by boiling, and prevented by 
 boiling under a pressure of 1*5 atmospheres (Pasteur), or 
 by evaporating the milk to a solid form (condensed milk). 
 Lactic acid may also be produced from cane fruit or grape 
 
ORGANIC CHEMISTRY. 305 
 
 sugar, by mixing with stale milk, putrid cheese, and chalk. 
 Lactate of lime is formed abundantly. 
 
 Lactic acid, Acidum lacticum, HO,C 6 H 5 5 , has an in- 
 tensely sour taste and acid reaction ; it forms well-marked 
 salts, of which that of FeO is officinal, Ferri Lactas. It 
 exists in the gastric juice, the juice of flesh, in Sauerkraut, 
 and in the albuminous liquid left in the manufacture of 
 starch. It has been used in the free state and as lactate 
 of soda in dyspepsia. 
 
 400. Butyric Fermentation. — By a continuance of the 
 fermentation of the mixture ' described above, the lactic 
 acid passes into butyric, an acid found in rancid butter, 
 putrid flesh, etc.; 2(HO,C 6 H 5 5 )=HO,C 3 H 7 3 +4C0 2 +H 4 . 
 Its properties will be considered in the next group (413). 
 
 401. Viscous Fermentation. — The sugar of the beet 
 at about 100° undergoes a peculiar change. But little 
 alcohol is formed, the products being lactic and butyric 
 acids, mannite and gum; C0 2 and H are given off. Ordi- 
 nary sugar undergoes this change to a certain extent when 
 treated as directed for obtaining lactic and butyric acid. 
 The ropiness of wines and beer present examples of it. 
 
 402. Theories. — The phenomena of fermentation and 
 putrefaction were attributed by Berzelius to catalysis (159). 
 Liebig supposes that the change taking place in the mole- 
 cules of the ferment is communicated to those of the solu- 
 tion in which it is placed, a process which he terms decom- 
 position by example (160). These merely give a name to 
 the change, but do not explain it. Schwann, Blondeau, 
 and Schmidt referred them to the unexplained action of 
 microscopic plants and animals; which view received sup- 
 port from experiments in supplying fermentable matter 
 with air drawn through cotton or a red-hot tube, in which 
 case the change did not take place.* 
 
 *Gmeun, Handbook Car. Ed., vol. vii. p. 108. 
 20 * 
 
HOC MEDICAL CHEMISTRY. 
 
 Pasteur comes to the following conclusions, which are 
 probably nearest the truth. No fermentation or putrefac- 
 tion occurs without the generation of multitudes of low ani- 
 mal or vegetable (?) organisms, known to the microscopists 
 as mycodcrms, torulas, vibrios, bacteriums, monads, etc. 
 Some of these, as the vibrios, live only in an atmosphere 
 deprived of oxygen; others, as the bacteriums and mo- 
 nads, absorb oxygen. Each variety of fermentation has 
 an organism peculiar to itself; thus the mycoderma vini 
 causes sugar to break up into alcohol and carbonic acid ; 
 the mycoderma aceti, mother of vinegar, serves to oxidise 
 alcohol to acetic acid, and the latter, in the absence of 
 alcohol, to water and carbonic acid ; pencillium glaucum 
 converts sugar into lactic acid. Butyric fermentation and 
 animal putrefaction are due to the combined action of the 
 bacteriums and monads, which absorb oxygen, and of the 
 vibrios, which act in the interior of the liquid away from 
 oxygen. The phenomena vary according as the body is 
 freely exposed to the air, or partially or wholly secluded. 
 They are instantly arrested by a temperature of 130°, or 
 by the action of antizymotics, as sulphurous. acid, the sul- 
 phites, carbolic acid, etc. 
 
 II. KADICALS OF THE GENERAL FORMULA 
 C 2 nH 2 n-f-l. 
 
 403. Theoretical Considerations. — The hypothesis 
 of the existence of compound bodies which act as elements 
 — quasi elementary bodies, radicals — is exceedingly con- 
 venient. In inorganic chemistrv we have alreadvhad ex- 
 
ORGANIC CHEMISTRY. 307 
 
 amples of a perfect quasi metal, ammonium, NH 4 , and of 
 a quasi halogen, cyanogen, C 2 N. Without discussing the 
 arguments in favour or opposed to such a view, it may be 
 stated that it brings a large number of organic compounds 
 under the same type as those generally regarded as inor- 
 ganic, and is at least as probably true as any other which 
 has been suggested. As we know nothing of the arrange- 
 ment of the elements in compounds, that theory is prefer- 
 able which is the most simple. The great majority of the 
 radicals contain C and H only, and the atoms of C are even, 
 those of H odd. The protoxide of a radical is generally 
 termed its ether (although the word is also applied to the 
 compounds of acids with this oxide) ; its hydrated oxide, 
 the alcohol of the series. The quasi metallic radicals may 
 be divided into those which form a single basic protoxide, 
 like zinc, as the ethyl type, positive radicals ; and those 
 which tend to form higher acid oxides, like Cr, — the acetyl 
 type, negative radicals. Generally speaking, the com- 
 pounds of the former and the radicals themselves are 
 obtained from their alcohols, which act with acids and 
 halogens like the hydrates of the metallic oxides. The 
 alcohols and ethers by oxidation yield the oxides of the 
 negative radicals. The following are the most important 
 members of the series ; others, especially among the acids, 
 will be incidentally considered under other heads. 
 
 
 +Radical. 
 
 Ether. 
 
 Alcohol. 
 
 Formula 
 
 ..^1111211+, 
 
 C 2 iiHori+ 1 ,0 
 
 C 2 nH2n-K,0,IIO 
 
 Methyl, 
 
 C 2 H 3 
 
 C 2 H 3 
 
 C 2 H 3 0,HO 
 
 Ethyl, 
 
 C 4 H 5 
 
 C 4 H 5 
 
 C 4 H 5 0,HO 
 
 Propyl, 
 
 C 6 H 7 
 
 6 H 7 
 
 C 6 H 7 0,HO 
 
 Butyl, 
 
 C 8 H 9 
 
 C 8 H 9 
 
 C s H 9 0,HO 
 
 Amyl, 
 
 C 10 Ha 
 
 CUHuO 
 
 C 10 H n O,IIO 
 
— Radical. 
 
 Aldehyde. 
 
 C 2 nH 2 n— , C 2 nH 2 n— !,0,H0 
 
 C 2 H Formyl, 
 
 C 2 HO,HO 
 
 C 4 H 3 Acetyl, 
 
 C 4 H 3 0,HO 
 
 C 6 H 5 Allyl, 
 
 C 6 H 5 0,HO 
 
 . C 8 H 7 Butyryl, 
 
 C 8 H 7 0,HO 
 
 C 10 H 9 Yalyryl, 
 
 C 10 H 9 O,HO 
 
 308 MEDICAL CHEMISTRY. 
 
 Acid. 
 G 2 nH 2 n— ^Q^HO 
 
 C 2 H0 3 ,HO Formic. 
 C 4 H 3 3 ,HO Acetic. 
 C 6 H 5 3 ,HO Propionic. 
 C 8 H 7 3 ,HO Butyric. 
 C 10 H 9 O 3 ,HO Yalerianic. 
 
 As an illustration of the changes taking place, we may take 
 the ethyl series. Alcohol, C 4 H 5 0,HO, by losing water, becomes 
 C4H5O, Ether. By the action of iodide of phosphorus, C 4 H 5 I, 
 iodide of ethyl, is formed ; by digesting this with zinc, ethyl is 
 obtained, C 4 H 5 I -f Zn=ZnI+C 4 H 5 . By the action of HO,N0 5 
 (with urea) on alcohol, nitrate of ether is formed, C 4 H 5 0,IIO-f- 
 HO,N0 5 =C 4 H 5 0,N0 5 + 2HO. By oxidation, alcohol first loses 
 two of hydrogen and becomes aldehyde, C 4 H 5 0,HO+Oo=C 4 H 3 0, 
 HO + 2HO, and finally acetic acid, C 4 H 5 0,HO-f 4 ==C 4 H 3 3 ,HO-|- 
 4HO. These are but types of the reactions occurring in the 
 whole series. All the alcohols above named have been isolated ; 
 the aldehydes are not yet complete. The list of acids might be 
 continued uninterruptedly up to C^H^O^ HO, Stearic ; and with 
 interruptions to CeoHsgOgjHO, Mellisic acid. These acids are gen- 
 erally known as the fatty acids. Their boiling-point rises about 
 35*88° F. for each increase of C 2 H 2 . The whole series is homolo- 
 gous. Only the more important members of the series will be 
 considered. 
 
 405. Methyl Alcohol, Wood Spirit, C 2 H 3 0,HO.— Is 
 
 among the products of the destructive distillation of wood. 
 Is a colourless, inflammable, mobile liquid, miscible in all 
 proportions with water and alcohol, s. g. - 798, boils at 
 152°, has a peculiar odour and taste. Its solvent powers 
 resemble those of alcohol. Methylated spirit contains 10 
 p. c, and may be used for most purposes as a substitute for 
 alcohol. Wood spirit is often confounded with acetone, 
 C 6 H 6 2 , obtained by distilling the acetates. It has been 
 used as a stimulant expectorant in Phthisis. 
 
 406. Formic Acid, HO,C 2 H0 3 . — Exists in ants, certain 
 caterpillars, nettles, and the sweat. May be made by direct 
 oxidation by the action of platinum black on wood spirit. 
 
ORGANIC CHEMISTRY. 309 
 
 Is preferably prepared by the decomposition of oxalic acid, 
 by heat, in the presence of glycerine ; the latter remains 
 unchanged. The proportions are not important; the 
 mixture is heated until C0 2 is evolved, when more HO, 
 C 2 3 is added until no more C0 2 is given off; formic acid dis- 
 tils over. 2(HO,C 2 3 +2HO)=HO,C 2 H0 3 +4HO + 2C0 2 . 
 . It may also be obtained by distilling red ants with water. 
 The monohydrated acid is obtained by the action of HS 
 upon PbO,C 2 H0 3 . It resembles its homologue glacial 
 acetic acid; it is very corrosive, blisters the skin, s. g. 
 1-235, boils at 209°; mixes with water and alcohol in all 
 proportions. Its vapour is inflammable. It reduces the 
 salts of silver and gold. 
 
 Berthelot has made formic acid by the action of CO upon KO, 
 HO, 2CO+ KO,HO=KO,C 2 II0 3 : an interesting example of a body 
 originally derived from the animal kingdom obtained from purely 
 animal sources. By destructive distillation the formates yield 
 compounds of carbon and hydrogen of a more complex nature. 
 
 407. Chloroform, Chloroforum, C 2 H,C1 3 . — May be re- 
 garded as the terchloride of formyl, or formic acid, in 
 which 3 have been replaced by Cl 3 . 
 
 Prep. — On the large scale, distilling chloride of lime, 
 CaO,C104-Ca01, with alcohol, wood spirit, or acetone, — 
 Chloroformum venale. It is used in this state as a sol- 
 vent. Chloroformum purificatum is prepared by agitat- 
 ing occasionally for 24 hours ^cii Chloroformi venalis 
 and ^xvii Acid, Sulphuric, then separating the lighter 
 chloroform and adding to it f^vj Alcohol, fortioris and 5ij 
 Potass. Garb, previously heated to redness and rubbed to 
 powder; the mixture is then stirred thoroughly and dis- 
 tilled. 
 
 Prop. — A limpid, colourless, volatile, neuter liquid, 
 of an agreeable, ethereal odour, and a sweetish, burning 
 taste. Water dissolves but one p. c ; Alcohol dissolves it 
 freely. It dissolves caoutchouc, gutta-percha, the resins, 
 
310 MEDICAL CHEMISTRY. 
 
 camphor, iodine, bromine, and most of the alkaloids. It 
 is not inflammable. Its s. g. is 1-490 to 1-494 ; it boils at 
 140°. When dropped into water, it should sink without 
 milkiness (absence of oils). Mixed with an equal weight 
 of HO,S0 3 , no sensation of warmth should be communi- 
 cated to the hand by the containing vessel, and after stand- 
 ing 24 hours, the acid should have but a faint, yellow tinge 
 (absence of water, alcohol, and oils). A small portion being 
 evaporated from a porcelain plate, the last portions should 
 have a faint, aromatic odour, without pungency or em- 
 pyreuma, while the plate is covered with a film of moisture 
 free from smell or taste (absence of oils and free CI). It 
 does not affect a solution of AgO,N0 5 (absence of free CI). 
 Its uses are too well known to be detailed. It is employed 
 in the Linimentum Chloroformi, the Mistura Chloroformi, 
 and in the Liquor Guttae-Perchse. Similar compounds with 
 Br and I — C 2 H,Br 3 and C 2 HI 3 — are known. 
 
 408. Ethyl Alcohol; Alcohol, C 4 H 5 0,HO. 
 
 Prep. — By the distillation of liquids which have under- 
 gone the vinous fermentation. Synthetically, by prolonged 
 agitation of olefiant gas, mercury, and sulphuric acid. C 4 
 H 4 +2(HO,S0 3 )=C 4 H 5 0,HO,2S0 3 , Sulphovinic acid;C 4 H 5 
 0,HO,2S0 3 -f 2HO=C 4 H 5 0,HO + 2(HO,S0 3 ). This pro- 
 cess has been tried upon the large scale, but was not suc- 
 cessful in an economical point of view. Although alcohol 
 boils at 112°, yet, owing to the adhesion between its 
 vapour and that of water, and the evaporation of the 
 latter, they always distil over together. To obtain 
 alcohol free from water, it must be redistilled with fused 
 chloride of calcium and excess of lime ; it then forms abso- 
 lute alcohol. 
 
 Prop. — Absolute alcohol is a colourless, transparent, 
 volatile liquid, boiling at IT 2°, not frozen at any known 
 temperature, inflammable, s. g. 0-7938. It has a slight, 
 
ORGANIC CHEMISTRY. 311 
 
 agreeable odour, distinct from that of ordinary alcohol. 
 It attracts water, and when the two are mixed, the bulk 
 of the resulting liquid is less than that of its components, 
 while an elevation of temperature is noticed. The absence 
 of water may be shown by introducing a bit of anhydrous 
 baryta, which will fall to pieces if water be present. Al- 
 cohol is officinal as Alcohol, fortioris, s. g. 0.811, which con- 
 tains 92 p. c. of alcohol ; Alcohol, s. g. 835, 85 p. c. ; and 
 Alcohol dilutum, proof spirit, made by diluting alcohol 
 with an equal measure of water, s. g. 0*941, 39 p. c. 
 
 The term proof spirit was applied originally to alcohol strong 
 enough to set fire to gunpowder when lighted. If 100 vols, of a 
 spirit require 10 vols, of water to bring it to proof, it is said to 
 be 10 over proof; if it require 10 vols, of spirit, s. g. 825, to raise 
 it to proof, it is said to be 10 under proof. The strength of 
 proof spirit varies in different localities, and it would be well if 
 so ambiguous a designation were no longer used. The officinal 
 alcohol dilutum is below the proof spirit of England and most of 
 the United States. 
 
 Alcohol has a stronger odour than the absolute, and 
 contains fusel oils, which may be removed by filtering 
 through charcoal, distilling over soap or permanganate 
 of potassa (Attwood's patent). The solvent powers of 
 alcohol are considerable; it dissolves sulphur and phos- 
 phorus in small quantity, iodine and ammonia freely ; 
 caustic potassa, soda, and lithia; most of the alkaloids, 
 tannic acid, grape sugar, camphor, resins, balsams, vola- 
 tile oils, soap ; the fixed oils sparingly, except castor oil, 
 which is abundantly soluble in stronger alcohol. Most 
 acids and their salts give with it, on distillation, their 
 characteristic ethers. All deliquescent salts, except car- 
 bonate of potassa, most of the soluble chlorides, and some 
 nitrates, are soluble in alcohol; all efflorescent salts, those 
 insoluble, or sparingly soluble in water, and the metallic 
 sulphates, are insoluble. Solutions in alcohol are called 
 Tinctures, or Spirits. 
 
312 MEDICAL CHEMISTRY. 
 
 The uses of alcohol are well known ; the officinal pre- 
 parations into which it enters are numerous. Whiskey, 
 brandy, port and sherry wines are officinal (391). When 
 burned, alcohol yields HO and C0 2 ; slowly oxidised, it 
 furnishes aldehyde and acetic acid. 
 
 409. Ether, Wine ether, Sulphuric ether, C 4 H 5 0. 
 
 Prep. — By the action of HO,S0 3 upon alcohol. The 
 products depend upon the temperature at which the mix- 
 ture boils, which, in turn, depends upon the relative pro- 
 portions of its constituents. Below 260°, alcohol distils 
 unchanged ; between 260° and 310°, ether comes over 
 with some alcohol and water ; above 320°, the mixture 
 chars; oil of wine, C 4 H 4 ,S0 3 -|-C 4 H 5 0,S0 3 , olefiant gas, 
 C 4 H 4 , and other products are obtained. By the continuous 
 ether process, a mixture is made in such proportions as 
 to boil at about 286°, and fresh alcohol is constantly sup- 
 plied so as to maintain that temperature. The sulphuric 
 acid undergoes no change, and may be used for the con- 
 version of an indefinite quantity of alcohol into ether. 
 The theory is not well understood. It is certain that 
 alcohol, C 4 H 5 0,HO, under the influence of the HO,S0 3 , 
 splits up into C 4 H 5 and HO, but why is not yet ascer- 
 tained. It is generally supposed that sulphovinic acid, 
 C 4 H 5 0,HO,2S0 3 , is formed and again decomposed; C 4 H 5 0, 
 HO,2S0 3 +2HO=C 4 H 5 0-fHO + 2(HO,S0 3 ). The ether 
 and water which distil over form distinct layers, and are 
 easily separated. The ether is then agitated with KO, 
 C0 2 , and redistilled, forming the officinal Mther. This 
 yet contains alcohol and water, to remove which it is 
 shaken with water to remove alcohol, then mixed with 
 fused CaCl and quicklime, allowed to stand twenty-four 
 hours (to remove water) and redistilled. JEther fortior, 
 washed ether, letheon. 
 
 Prop. — Pure ether is a colourless liquid, of a peculiar, 
 
ORGANIC CHEMISTRY. 313 
 
 pleasant odour, boiling at 98°, not frozen as yet, s. g. 
 O'llS, producing from its volatility cold by evaporation; 
 it is very inflammable, and its vapour mixed with air ex- 
 plodes. Is soluble in 10 parts water, or will take up j\ 
 of that liquid. When held in the hand, it will boil vio- 
 lently, if a fragment of glass be dropped into it. On 
 evaporation, it should leave no empyreumatic odour, but 
 only a film of tasteless moisture. It dissolves fats and 
 oils; also I, Br, P, HgCl, and most of the alkaloids. 
 Is used as an anaesthetic and diffusible stimulant ; ex- 
 ternally, its spray is used to produce local anaesthesia 
 (195). 
 
 410. Spiritus JEtheris Compositus, Hoffman's Anodyne. 
 Prep. — R. JEtheris Oj, Alcohol Oj, Olei JEtherei f£vj. 
 
 M. The ethereal oil Oleum JEthereum, heavy oil of 
 wine, is obtained by distilling alcohol and sulphuric acid 
 at a temperature between 312° to 322°; it is diluted 
 with an equal measure of washed ether. It is regarded 
 as a double sulphate of ether and ethylene, C 4 H 5 0,S0 3 + 
 C 4 H 4 S0 3 . It is a heavy oil, sinking in water, in which it 
 sparingly dissolves ; it does not precipitate with baryta, 
 but forms a soluble sulphovinate of that base. 
 
 Prop. — But little true Hoffman's Anodyne is found in 
 the shops. It is sometimes adulterated with fixed oils. 
 It should give no precipitate with Bad, or only a slight 
 cloudiness (absence of HO,S0 3 ). When a few drops are 
 burned on a glass or porcelain plate, there is no visible 
 residue, but the surface will be left with an acid taste and 
 reaction. A pint of water is rendered slightly opalescent 
 upon the addition of 40 drops. It is a popular stimulant 
 and antispasmodic. 
 
 411. Spiritus JEtheris Nitrosi, Sweet Spirit of Nitre. 
 Prep. — By distilling Acid. Nitric, and Alcohol in ex- 
 cess, and redistilling over carbonate of potassa. It is a 
 
 27 
 
314 MEDICAL CHEMISTRY. 
 
 solution of 4-3 to 5 p. c. of nitrite of ether, C 4 H 5 0,X0 3 , in 
 alcohol. Pure nitrite of ether is a yellowish liquid, of an 
 agreeable smell like apples, s. g. 0*947, and boiling at 62°. 
 
 Prop. — A colourless volatile liquid, of a fragrant, ethe- 
 real odour; boils at 145°; s. g. 0*837. Becomes acid 
 when kept in badly stoppered bottles, acetic acid being 
 formed. It may also contain aldehyde; this gives a 
 brown colour when mixed with solution of potassa. The 
 presence of any acid in excess is shown by its action on 
 litmus and by the usual tests. It is often adulterated by 
 mere dilution with alcohol and water. 
 
 Other Compounds of Ether. — The Nitrate, Sulphate, 
 and Sulphite have been obtained. The acetate of ether 
 (acetic ether), and chloride of ethyl, C 4 H 5 C1 (muriatic 
 ether), are sometimes used in medicine. The iodide of 
 ethyl is much used in chemical research ; the bromide and 
 cyanide are also known ; in fact, the entire series of com- 
 pounds of ethyl with the amphigens and halogens, and of 
 ether with the acids, is nearly complete. 
 
 412. Acetic Acid, HO,C 4 H 3 3 . 
 
 May be formed, (1) By the direct oxidation of alcohol ; 
 
 (2) by the oxidation of alcohol by means of a ferment; 
 
 (3) by the distillation of wood. It exists in the sweat 
 and some other secretions. 
 
 1. Platinum black possesses the power of directly oxi- 
 dising alcohol, being itself unchanged. This plan has 
 been tried in the manufacture of vinegar (Dobereiner's 
 process), but is not economical on account of the high 
 first cost of platinum black. 
 
 2. Weak (not over 10 p. c.) alcohol, such as stale beer, 
 cider, wine, etc., mixed with a ferment (vinegar is the ' 
 best), and exposed to a somewhat elevated temperature, 
 "74° to 86°, absorbs oxygen, and gradually becomes acetic 
 acid. The stronger the alcoholic solution, the slower the 
 
ORGANIC CHEMISTRY. 315 
 
 process ; under favourable circumstances it is complete in 
 from 4 to 6 weeks. The process is often accompanied 
 by the development of a plant, the mycoderma aceti, or 
 mother of vinegar. Frequently flies, muscse cellaris, and 
 eels, vibriones aceti, are found ; and if made of weak alco- 
 hol, it will sometimes undergo a sort of viscous or putre- 
 factive fermentation. This is prevented by adding a little 
 alcohol after the change is complete (402). 
 
 In the quick vinegar process, the "wash" or weak 
 alcohol is passed through beech shavings or powdered 
 charcoal moistened with vinegar, air being freely supplied. 
 A perceptible elevation of temperature is noticed, fusel 
 oils are oxidised into ethers, and the process is complete 
 in a day. On the large scale, common whiskey is used. 
 
 3. During the distillation of wood, especially the harder 
 varieties, a large quantity of acetic acid is formed which 
 is charged with tarry matters, crude pyroligneous acid. 
 By saturating this with lime, the tarry matters are left, 
 and by decomposition with HO,S0 3 , the acetic acid is 
 obtained. 
 
 Monohydrated acetic acid, glacial acetic acid, ice vinegar, 
 may be procured by distilling 83 parts by weight of fused 
 acetate of soda and 100 of HO,S0 3 . It is a volatile, in- 
 flammable liquid, boiling at 248°, and solid at 40°. It 
 blisters the skin, and is soluble in water, alcohol, and 
 ether ; dissolves camphor, the volatile oils, and several 
 resins. The anhydrous acid has been obtained. Acetic 
 acid is officinal as Acetum, Acetum destillatum, Acidum 
 aceticum, and Acidum Aceticum dilutum. The Aceta 
 Colcheci, Lobelise, Opii, Sanguinarise, Scillee, are also 
 officinal. 
 
 Acetum, Yinegar. — Impure dilute acetic acid, obtained 
 by fermentation. 
 
 Prop. — A well-known liquid, of an agreeable, acid smell 
 
316 MEDICAL CHEMISTRY. 
 
 and taste. It contains, besides acetic acid and water, 
 gum, sugar, gluten, sulphates, and often tartaric and malic 
 acids, Sulphuric acid is detected by boiling with CaCl, 
 (Bad would be decomposed by sulphates existing nor- 
 mally), HC1 by AgO,X0 5 , and injurious metals by HS. 
 A fluidounce is saturated by not less than gr xxxv Potass, 
 bicarb., and after saturation the liquid is free from acrid 
 taste. 
 
 Acetum destillatum, made by distilling from Oviii Aceti 
 to Ovij. It contains a little aldehyde. It is wholly volatil- 
 ised by heat, and is not affected by the tests for the metals 
 generally. It is of about the same strength as Acid, 
 acetic, dilut.; 100 grains should saturate not less than T'6 
 grs Potass, bicarb. (5 p. c. of HO,C 4 H 3 3 ). 
 
 Acidum Aceticum. — Acetic acid, s. g. 1*047. 
 
 Prop. — A colourless liquid, having a pungent odour ; is 
 wholly volatilised by heat, and not affected by the tests 
 for HO,S0 3 , HC1, or the metals. One hundred grains satu- 
 rate gr lx Potass, bicarb., and contain gr xxvi HO,C 4 H 3 3 . 
 A convenient method of determining the strength of vin- 
 egar is to suspend in it a weighed fragment of pure marble ; 
 when action has ceased, wash, dry, and weigh it. The 
 loss will be five-sixths of the HO,C 4 H 3 3 present ; CaO, 
 CO 2 =50; HO,C 4 H 3 O 3 =60. 
 
 Acidum Aceticum dilutum. — R. Acid, Acetic. Oj, Aquae 
 Destillatae Ovii, M. ; s. g. 1-006. 100 grs saturate 7'6 grs. 
 Potass, bicarb. It contains 5 p. c. of monohydrated acid. 
 
 413. Butyric Acid, HO,C 8 H 7 3 . 
 
 Prep. — By the butyric fermentation (401). Exists free 
 in putrid flesh, sweat of the feet, armpits, etc. ; privies, 
 sauerkraut, Limburger cheese, etc. ; and combined in butter 
 and cheese. 
 
 Prop. — Is an offensive, inflammable liquid, boiling at 
 157°, and solid at —133°. The butyrate of ether, butyric 
 
ORGANIC CHEMISTRY. 311 
 
 ether, C 4 H50,CsH 7 3 , when diluted, has the odour of pine- 
 apples, and is used in making confectionery and factitious 
 brandy. 
 
 414. Amylic Alcohol, Alcohol Amylicum, fusel oil, C 10 
 H n O,HO. 
 
 Prep. — By continuing the distillation of crude corn 
 or potato whiskey, after the greater part of the alcohol 
 has come over. The name is also applied by distillers to 
 the light oils which come over at the beginning of the 
 process. 
 
 Prop. — When pure, a colourless, oily liquid, of char- 
 acteristic odour, producing much irritation of the fauces 
 when inhaled, and poisonous ; s. g. 0*818 ; boils at 269°, 
 solid at — 4°. Is sparingly soluble in water, freely so in 
 alcohol and ether. It burns with difficult}^, dissolves fats, 
 resins, camphor, sulphur, and phosphorus. 
 
 Amylene, C 10 H 10 , has been used as an anesthetic, but 
 abandoned as dangerous. 
 
 415. Valerianic Acid, Acidum Valerianiciim, HO,Ci 
 H 9 3 . 
 
 Prep. — By oxidising fusel oil ; generally, by the action 
 of KO,2Cr0 3 and HO,S0 3 . Exists in valerian root and 
 other vegetables ; does not exist in the animal organism. 
 The same is true generally of the acids of this group, the 
 carbon of which is not divisible by 4. 
 
 Prop. — A colourless liquid, of an acrid, burning taste, 
 boiling at 176°, and soluble in 26 parts water. The vale- 
 rianates of soda, ammonia, zinc, and quinia are officinal, 
 and that of morphia is much used. They are all anti- 
 spasmodic. The acid is not given in the free state. 
 
 The acids homologous (384) with valerianic, and higher in 
 the series, are numerous ; some will be considered under 
 the head of Fats. Caproic, IIO,C 12 H u 3 ; Caprylie, HO, 
 C 16 H H 3 ; Capric, HO,C 20 TI li ,O„ accompany butyric acid in 
 
318 MEDICAL CHEMISTRY. 
 
 the sweat, etc. ; Pelargonic acid, combined with C 4 H 5 0, 
 in the bouquet of wine, and in the quince ; it may be made 
 artificially by the oxidation of oil of rue. 
 
 Valerianate of the oxide of amyl, C 10 H n O, C 10 H 9 O 3 , di- 
 luted, gives artificial apple essence ; acetate of the same, 
 C 10 H u O, C4IL3O3, the pear essence ; coccinate of oxide of 
 ethyl, C4H5O, C26H 25 03, the quince. Mixtures of these give 
 various other fruit essences. Butyric ether has been be- 
 fore mentioned. 
 
 III. RADICALS NOT HOMOLOGOUS WITH 
 ETHYL. 
 
 416. Benzyl, or Benzoxyl, C u H 15 2 . — Has been isolated 
 as a colourless, fragrant liquid. 
 
 Hydride of Benzyl, C 12 H 5 2 ,H, Oil of bitter almonds; 
 Oleum Amygdalae amarae. 
 
 Prep. — By distilling the bitter almond with water. It 
 does not pre-exist in the kernels, but results from a quasi 
 fermentation of Amygdalin, C 4 oH 27 N0 22 , under the influence 
 of a pulpy, albuminous substance, Syneptase; glucose and 
 hydrocyanic acid being formed at the same time. 
 
 Prop. — The officinal (crude) oil has a yellowish colour, 
 bitter, acrid, burning taste, and characteristic odour, s. g. 
 1-052 to 1*082. It contains HCy, and is sometimes pre- 
 scribed as a sedative. As the proportion of this active in- 
 gredient is variable, bitter almond oil should never be em- 
 ployed. When used as a flavoring material for cakes, the 
 HCy is driven off during the baking. The pure oil is 
 colourless, s. g. 1*043, inflammable, soluble in 30 parts 
 water, and freely in alcohol and ether ; it is not poisonous. 
 On exposure to the air it oxidises to benzoic acid. 
 
ORGANIC CHEMISTRY. 319 
 
 417. Benzoic Acid, Acidum Benzoicum, C 14 H 5 02,0,HO, 
 
 is the alcohol of the series ; the anhydrous acid has been 
 obtained. 
 
 Prep. — From the true balsams, generally by sublima- 
 tion from gum benzoin ; also by boiling the gum with 
 lime, and precipitating the benzoic acid by HC1. Is also 
 procured from the putrid urine of horses and cows, occur- 
 ring here from the decomposition of hippuric acid. 
 
 Prop. — When obtained by sublimation, is in light, 
 feathery, colourless crystals, having a faint, agreeable 
 smell, melting a little below 212°, soluble in 200 parts 
 cold and 25 of boiling water; its solubility may be in- 
 creased by the addition of borax or phosphate of soda. It 
 is freely soluble in alcohol. Benzoic acid is an ingredient 
 in paregoric ; it has been used in renal and vesical affec- 
 tions. The benzoates are all soluble. By distilling the 
 benzoate of copper, an oil having the odour of the rose 
 geranium is obtained, which is Benzyl, the radical of the 
 series ; by the action of KO,HO it is converted into ben- 
 zoic acid. Among the products of the destructive distilla- 
 tion of benzoate of ammonia is benzonitrile, Ci 2 H 5 C 2 N, 
 which has exactly the odour of the bitter almond oil; it 
 must not be confounded with nitrobenzol, C J2 H 5 N0 4 , which 
 has somewhat similar properties. 
 
 418. Benzole, C 12 H 6 . 
 
 Prep. — By distilling benzoic acid with lime, or in the 
 more volatile portion of the oil obtained by distilling coal- 
 tar. The benzine obtained from petroleum is a distinct 
 body ; it is used as a substitute for turpentine, and to dis- 
 solve grease, India-rubber, etc. 
 
 Prop. — A thin, limpid, colourless, inflammable liquid, 
 s. g. 0-855, boils at 176°, solid at 32°. It may be re- 
 garded as the hydride of the radical Phenyl, C\.,H5, of 
 which benzonitrile is the cyanide, 0,_,H 5 C , .,N'. Nit robe n- 
 
320 MEDICAL CHEMISTRY. 
 
 TT 
 
 zole, a substitution compound, C 12 — — , and Phenic or car- 
 
 N0 4 
 
 bolic acid, C,2H 5 0,HO, the alcohol. 
 
 Nitrobenzole, Essence of 3Iirbane, C 12 H 5 N0 4 . 
 
 Prep. — By the action of HO,N0 5 upon C^He. Ben- 
 zine from petroleum does not yield it. 
 
 Prop. — A heavy, yellowish, sweet liquid; s. g. 1-209; 
 having an odour resembling somewhat that of bitter 
 almonds, or the vernal grass. It boils at 415°, is insolu- 
 ble in water. Is used in perfumery. Is highly poisonous, 
 whether inhaled or swallowed; the symptoms in some 
 cases not appearing for days after it has been taken 
 (Letheby). Is converted by nascent hydrogen into ani- 
 line, C 12 H 5 N0 4 +H 6 =NC 12 H 7 +4HO, and is found as such 
 in the tissues and secretions after death. 
 
 Phenic, or Carbolic Acid, C 12 H 5 0,HO. 
 
 Prep. — Is among the products of the distillation of 
 coal-tar. 
 
 Prop. — When pure, a colourless, deliquescent, crystalline 
 solid, having an odour like creasote, and a caustic taste. 
 It fuses at 95°, and vaporises at 370°. Is used as a caus- 
 tic and antiseptic. Cresylic acid, C 14 H 8 2 , also obtained 
 from coal-tar, resembles carbolic acid in its properties. 
 
 418. Cinnamyl, C 18 H 7 2 . 
 
 Is the radical of a series of which the hydride C 18 H 7 2 , 
 H, Oil of Cinnamon, Oleum Cinnamomi, is the only mem- 
 ber employed in medicine. Oil of cinnamon may be arti- 
 ficially prepared by the oxidation of Styrone, which is ob- 
 tained by the distillation of storax with caustic potassa. 
 
 419. Salicyl, C 14 H 5 4 . 
 
 Is the radical of a series of which the hydride is iden- 
 tical with the Oil of Spiraea ulmaria, or Meadow-sweet. 
 It is obtained from Salicin (C 26 H 1S I4 ), a crystalline, bitter 
 principle, derived from the bark of the willow, poplar, etc. 
 
ORGANIC CHEMISTRY. 321 
 
 Salicin may be artificially made by the action of caustic 
 potassa upon the Oil of Gaultheria procumbens, Oleum 
 Gaultherise. Salicin is employed as a substitute for quinia. 
 Phloridzin, C 42 H^O 20 +4HO, is an analogous substance 
 found in the bark of the root of the cherry, apple, etc. 
 
 420. Kakodyl, C 4 H 6 As==2(C 2 H 3 )As, or Kd. 
 
 Forms a large series of compounds mostly of a highly 
 offensive and poisonous character. The radical itself has 
 been isolated as a thin, colourless liquid, and from it all 
 the compounds maybe directly formed, giving us the most 
 perfect example of a quasi metal known. It may be 
 regarded as a conjugate compound of two eq. of methyl 
 and one of arsenic. 
 
 Oxide of Kakodyl, C 4 H 6 As,0, or KdO, Alkarsin, Fuming 
 Liquor of Cadet. 
 
 Prep. — By distilling equal weights of acetate of po- 
 tassa and arsenious acid. May be formed by the direct 
 union of kakodyl with oxygen. 
 
 Prop. — A colourless, ethereal liquid, of a highly offen- 
 sive smell, irritating the nose and eyes, and very poison- 
 ous. Boils at about 302°; s. g. 1-462. Takes, fire sponta- 
 neously in the air, burning with a pale flame, producing 
 carbonic acid, water, and arsenious acid. 
 
 From the oxide, the other members of the series may be 
 formed. The chloride and cyanide are especially poison- 
 ous. Kakodylic acid, Kd0 3 , Alkargen, formed by the oxi- 
 dation of Kd or KdO, is a solid, soluble in water and 
 alcohol, and not poisonous. 
 
322 MEDICAL CHEMISTRY. 
 
 IV. OBGANIC ACIDS. 
 
 Not oxides of known radicals, and not otherwise classi- 
 fied. 
 
 Tartaric, 2HO ; C 8 H 4 O 10 . 
 
 Racemic, 2HO,C 8 H 4 O 10 . 
 
 Citric, 3HO,C 12 H 5 O n -fHO. 
 
 Malic, 2HO, C 8 H 4 8 . 
 
 Tannic, 3HO,C 54 H 19 31 . 
 
 Gallic, 3HO,C u H 3 7 . 
 
 Pyrogallic, C 12 H 6 6 . 
 
 Metagallic, C 12 H 4 4 . 
 421. (a) Tartaric Acid, Acidum Tartaricum, 2HO,C 8 
 H 4 O 10 . 
 
 The acid of grapes, tamarinds, etc.; is obtained from the 
 deposit in wine casks (Argols, Crude Tartar), which is im- 
 pure Acid Tartrate (Bitartrate) of Potassa. 
 
 Prep. — By decomposing the acid tartrate of potassa, by 
 carbonate of lime; and the resulting tartrate of lime, by 
 sulphuric acid. 
 
 Prop. — Transparent, colourless crystals (4th system), 
 containing two eq. of basic water. It is soluble in its 
 weight of cold, and one-half its weight of boiling water. 
 Forms tartrates, of which those of potassa, and the double 
 salts of potassa and soda, of iron and potassa, and of anti- 
 mony and potassa, are officinal. 
 
 Tests. — Gives white precipitates with lime and baryta 
 water, and acetate of lead ; soluble in excess. With po- 
 tassa, when the acid is in excess, a sparingly soluble white 
 acid tartrate (Bitartrate). Used in preparing effervescing 
 mixtures, as the soda and Seidlitz powders ; also, as a 
 cheap substitute for lemon-juice or citric acid. 
 
ORGANIC CHEMISTRY. 323 
 
 (b) Racemic Acid, 2HO,C 8 H 4 O 10 . — Is found in the 
 juice of sour grapes. It is isomeric with tartaric acid, 
 which it closely resembles in all its physical and chemical 
 properties. It may be distinguished by its affording a pre- 
 cipitate with CaCl. 
 
 422. (c) Citric Acid, Acidum Citricum, 3HO,C 12 H 5 O n . 
 The acid of lemons, limes, etc. 
 
 Prep. — By saturating lemon-juice with chalk, and de- 
 composing the citrate of lime thus formed by sulphuric 
 acid. 
 
 Prop. — Transparent, right rhomboidal crystals (4th 
 system), permanent in the air ; soluble in f its weight of 
 cold and -J of boiling water. The crystals contain four 
 eq. water, three of which are basic ; it is, therefore, tri- 
 basic. It forms citrates, of which those of potassa, mag- 
 nesia, and iron are officinal. It should give no precipitate 
 with a potassa salt. 
 
 Tests. — The citrates of lime, baryta, strontia, lead, 
 and silver are insoluble and white. 
 
 Med. Effects. — Used in making acidulous drinks and 
 effervescing draughts. 
 
 (d) Malic Acid. — The acids of apples, pears, garden 
 rhubarb, etc. 
 
 Prop. — It is bibasic, and forms malates. Is not used 
 in medicine. 
 
 (e) Tannic Acid, Acidum Tannicum. 
 
 423. (/) Gallic Acid, Acidum Gallicum. 
 
 These acids constitute the astringent principle of vege- 
 tables. Their acid character is not very marked. 
 
 Prep. — Tannic acid is best prepared on the small scale, 
 by pouring ordinary ether upon powdered galls in a dis- 
 placement apparatus. The water of the ether dissolves 
 the tannic acid, while the ether retains the impurities. 
 The two separate into layers ; they are separated, and 
 
324 MEDICAL CHEMISTRY. 
 
 the tannic acid obtained by careful evaporation of the 
 lower. 
 
 Prop, — Tannic acid is a slightly yellowish, friable, 
 porous mass, without the slightest tendency to crystalli- 
 sation. It has a pure, astringent taste ; is freely soluble 
 in water, alcohol, ether, and glycerine ; reddens litmus. 
 It precipitates albumen, gelatin, starch, gluten ; the salts 
 of lead, copper, silver, mercury, teroxide of antimony, 
 protoxide of tin, sesquioxide of iron ; sulphuric, nitric, 
 hydrochloric, phosphoric, and arsenic acids insoluble in 
 excess of acid ; the alkaloids, the precipitate being solu- 
 ble in the vegetable acids, — hence it is not to be fully 
 relied on as an antidote. 
 
 A number of varieties of tannic acid are .enumerated, that 
 from galls being distinguished as gallo-t^nnia acid. The most 
 important of these are : Catechu-tannic, from catechu ; this does 
 not precipitate tartar emetic, but throws down a grayish-green 
 precipitate with the ferrous, and a brownish-green one with the 
 ferric salts. Cocco-tannic, from kino, does not precipitate tartar 
 emetic. Querco-tannic, from oak-bark, does not yield gallic 
 acid. 
 
 424. Gallic Acid. — Prep. By the spontaneous fermen- 
 tation of tannic acid when kept moist in a warm place for 
 about a month. Oxygen is absorbed and an equal volume 
 C0 2 evolved. 
 
 Prop. — In white, silky crystals, which melt and burn 
 when heated, soluble in 100 parts of cold and 3 of boiling 
 water. It does not precipitate gelatine or albumen. It 
 gives a blue-black precipitate with the ferric salts, which 
 disappears on heating the liquid. 
 
 Pyrogallio Acid, C 12 H 6 6 , is prepared by heating gallic 
 acid to about 420° ; it sublimes in the form of brilliant 
 white plates. C 14 H 6 O 10 =C 12 H 6 O 6 +2CO 2 . 
 
 Prop. — It is soluble in water, has energetic reducing 
 powers, and hence is used as developer in photography. 
 The pyrogallate of potassa absorbs a considerable por- 
 
ORGANIC CHEMISTRY. 325 
 
 tion of oxygen, and has been used in the analysis of air. 
 Upon the application of heat, water is evolved, and meta- 
 gallio acid remains; C 12 H 6 6 ==C 12 II 4 4 -{- 2 IIO. It is a 
 black, shining mass, resembling charcoal, insoluble in 
 water, soluble in alkaline solutions, from which it is again 
 precipitated black by acids. 
 
 V. ARTIFICIAL ORGANIC BASES. 
 
 425. These are exceedingly numerous ; they are mostly 
 substitution compounds (383). The following examples 
 will illustrate the almost infinite number which may exist. 
 
 (1) In dry ammonia, NH 3 , one, two, or three equivalents 
 of H may be replaced by the same or by different radicals. 
 Thus, NH 2 ,C 4 H 5 ethyl-&mme, NH(C 4 H 5 ) 2 diethy famine, 
 and N(C 4 H 5 ) 3 trithyl-&m.me ; NC 2 H 3 , C 4 H 5 , C 10 H ]0 , methyl-, 
 ethyl-, amyl-&mme. These bodies have all more or less 
 physical analogy to NH 3 , and are all well-marked bases. 
 Where one of H is replaced, an amidogen base is formed ; 
 where two of H, an imidogen, and where all the H, a 
 nitrite. 
 
 (2) Ammonium, NH 4 , is known only in combination 
 (215). In its compounds we may in like manner replace 
 the H. Thus NH 4 C1 may become chloride of ethylammo- 
 nium, NH 3 C 4 H 5 C1, or diethylammonium, NIIo(C 4 H 5 ) 2 Cl, 
 etc. ; or we may replace the H by distinct radicals, as NC 3 
 H 3 , C 4 H 5 C, 2 H5,CioH n Cl, chloride of methyl-, ethyl-, phenyl-, 
 amyl-ammonium. Like ammonium, these substitution 
 products are not isolable, but as hydrated oxides they 
 form bases analogous to NII 4 0,HO. 
 
 (3) The H of the introduced radical may bo further re- 
 28 
 
326 MEDICAL CHEMISTRY. 
 
 placed by the halogens, N0 4 ,and certain metals and radicals. 
 Thus in the aniline series : 
 
 Aniline, Phenyl-amine, NH 2 ,C 12 H 5 . 
 Chloraniline, NH 2 C 12 H 4 C1. 
 
 Bromaniline, NH 2 C 12 H 4 Br. 
 
 Bibromaniline, NH 2 Ci 2 H 3 Br 2 . 
 
 Tribromaniline, NH 2 C 12 H 2 Br 3 . 
 
 Nitraniline, NH 2 C 12 H 4 (N0 4 ). 
 
 Zincaniline, ]STH 2 C 12 H 4 Zn. 
 
 Ethylaniline, NH 2 C ]2 H 4 (C 4 H 5 ). 
 
 (4) The nitrogen of the ammonia, or ammonium, ma}* 
 be replaced by P, As, or Sb. Thus : 
 P(C 4 H 5 ) 3 , Triethylphosphine. 
 Sb(C 4 H 5 ) 4 I, Iodide of tetrethylestibammonium. 
 As(C 4 H 5 ) 3 , Triethylarsine. 
 These compounds are sometimes found in organic bodies, 
 or as products of their decomposition. 
 
 426. Propylamine, C 6 H 9 N=NH 2 C 6 H 7 , is metameric(384) 
 with Ethylmethylamine, NH,C 2 H 3 ,C 4 H 5 , and Trimethyl- 
 amine, !N"(C 2 H 3 ) 3 . 
 
 It may be obtained from the following bodies by distil- 
 lation with lime or potassa — narcotina, codeia, and ergot ; 
 it exists also in bone oil, the leaves of Chenopodium vul- 
 varia, several species of Crataegus (white thorn), herring 
 or cod-fish pickle, alcohol in which anatomical preparations 
 have been kept, human urine, etc. It is probable that in 
 some cases the bodies extracted are not identical ; that 
 from herring pickle is trimethylamine. 
 
 Prop. — It is a clear liquid, of a pungent, ammoniacal 
 odour, and giving white fumes when a rod dipped in HC1 
 is held near it. That from narcotine and herring pickle 
 has a fish-smell like many of the methyl compounds. The 
 muriate has been used in rheumatism, in dose of gr iij to v. 
 
ORGANIC CHEMISTRY. 32? 
 
 Aniline, Phenylamine, NH 2 C 12 H 5 . 
 
 Prep. — By the action of nascent H upon Nitrobenzole 
 (418) ; C 12 H 5 N0 4 +H 6 =NH 2 C 12 H 5 +6HO. 
 
 Prop. — A colourless oil, of an aromatic odour and vi- 
 nous taste ; s. g. 1*2 ; boils at 360°. Its salts and deriva- 
 tives are used as colouring matters. It is poisonous like 
 Nitrobenzole, but the symptoms are not delayed as in the 
 former. Its sulphate is less poisonous ; it has been ad- 
 ministered in chorea in doses of gr j to vii. It produces 
 a transient blueness of the skin and lips. Aniline is de- 
 tected by the blue colour it affords with hypochlorite of 
 lime. 
 
 VI. THE ALKALOIDS AND ALLIED 
 PKINCIPLES. 
 
 Syllabus. 
 
 Morphia, C 34 H 19 N0 6 + 2HO. 
 
 Narcotina, C 44 H 23 N0 14 + 2HO. ? 
 
 Codeia, C 36 H 21 N0 6 + 2HO. 
 
 Thebaina, C 3s H u N0 6 . 
 
 Narceina, C 46 H 29 N0 1S . 
 
 Opiana, (^H^Oa, 
 
 Papaperina, C4 H 21 NO 8 . 
 
 Phormia, C 27 H 9 N0 7 . 
 Metamorphia, ? 
 
 Quinia, C 40 H 24 N 2 O 4 4- 6110. 
 
 Quinidia, C 40 H 24 N 2 O 4 + 2HO. 
 
 Cinchonia, C 4 oH 24 N 2 2 . 
 
 Cinchonidia, C 40 Il24N 2 O 2 . 
 
 Strychnia, C 42 II 22 X 2 0, 
 
 Brucia, C, G II 2tj N.,O s -f 8TIO. 
 
328 MEDICAL CHEMISTRY. 
 
 Igasuria, C^H^^Og. 
 
 Yeratria, C 64 H 52 N 2 16 . 
 
 Aconitia, C 60 H 47 NO 14 . 
 
 Atropia, C^H^NOe. 
 
 Emetia, C 20 H 15 NO 5 . 
 
 Berberina, C 40 H 17 NO 8 . 
 
 Bebeerina, C 38 H 21 N0 6 . 
 
 Delphia, C^H^NO* 
 
 Piperina, C^S^NOe. 
 
 Caffeina, C 16 H 10 N 4 O 4 + 2HO. 
 
 Theobroniina, C 14 H 8 N 4 4 . 
 
 Conia, C 16 H 15 N. 
 
 Conhydrina, C 16 H 17 N0 2 . 
 
 Nicotina, C 10 H 7 1S\ 
 
 Picrotoxine, C 20 H 12 O s . 
 
 Santonine, C3oH ls 6 . 
 
 Phloridzin, C^HsAo-f 4HO. 
 
 THE ALKALOIDS. 
 
 427. The term alkaloid has been applied to the bases ex- 
 isting in vegetables and upon which their activity depends ; 
 closely allied to them are certain neuter and acid bodies 
 derived from similar sources. The alkaloids always exist 
 in combination with an acid, which is generally common 
 to all the bases of the same plant. Only the most impor- 
 tant will be considered. 
 
 Prep. — This is almost always conducted on the large 
 scale. The following may be given as a sketch of the 
 process, which however varies greatly. A solution of the 
 principles of the plant is made in water ; acid being 
 added, if necessary. To this is added a base which unites 
 with the vegetable acid, and the alkaloids, being insoluble 
 in water, precipitate. They are dissolved by hot alcohol, 
 and purified by animal charcoal. 
 
ORGANIC CHEMISTRY. 329 
 
 Prop. — They are generally solid and crystalline, in- 
 soluble or nearly so in water, more soluble in alcohol, 
 ether, and chloroform, and freely so in dilute acids with 
 which they combine. They have all a more or less distinct 
 alkaline reaction. Their taste as well as that of their 
 salts is bitter, and they are mostly poisonous. Tannic 
 acid, which precipitates all of them from solution, and ani- 
 mal charcoal, are most to be relied on as antidotes, the 
 stomach being always promptly and thoroughly evacuated, 
 and the general symptoms combated by appropriate meas- 
 ures. BouchardeVs Antidote consists of gr iij Iodinii, gr 
 yj Potass, iodid. in Oj Aqua?, given in wineglassful doses ; 
 it is contraindicated in poisoning by digitaline. 
 
 Tests. — The separation of the alkaloids in cases of 
 poisoning is difficult, and it is impossible to enter into 
 details in a work of this compass. The general methods 
 followed are : 
 
 (1) Dialysis. — The contents of the stomach, acidulated 
 with acetic acid, are placed in a basin over which a bladder 
 is tied; it is then inverted in a vessel of distilled water. 
 In the course of 48 hours the alkaloid will be found in the 
 latter, which is then to be cautiously evaporated to dry- 
 ness (Letheby). 
 
 (2) By Animal Charcoal. — The suspected liquid, neutral 
 or nearly so, is digested for several hours, with occasional 
 shaking with two or three ounces of pure animal charcoal, 
 which absorbs the alkaloid. After draining and washing 
 with cold water, the charcoal is boiled with about half a 
 pint of stronger alcohol for half an hour, in a long-necked 
 vessel to prevent much loss by evaporation. The alcohol 
 is distilled off, the residual aqueous solution of the alkaloids 
 heated with a few drops of liq. potassse, and agitated with 
 ether. This will remove all alkaloids soluble in that men- 
 struum (Graham and Hofmann). 
 
 28" 
 
330 MEDICAL CHEMISTRY. 
 
 (3) Merck's process consists in the use of strong acetic 
 acid, and afterwards of alcohol alone and acidulated with 
 acetic acid, evaporating nearly to dryness, neutralising 
 with carbonate of potassa to precipitate the alkaloids; 
 these are washed with cold distilled water, and again dis- 
 solved in concentrated acetic acid. 
 
 (4) Stas's process consists in extracting the alkaloids by 
 digesting with strong alcohol acidulated with tartaric acid, 
 precipitating by bicarbonate of soda, and redissolving in 
 ether. 
 
 Even when the alkaloids are obtained in a tolerably 
 pure state, the tests require great caution to avoid fallacy. 
 For the quantitative determination of alkaloids in phar- 
 maceutical preparations the iodohydrargyrate of potassium 
 (36?) may be used. Aconitia and Berberina require an 
 amount of the solution equal to one equivalent of mercury ; 
 Atropia, Strychnia, Brucia, Narcotina, and Yeratria, equal 
 to 2 eqs. ; Morphia and Conia, 3 eqs. ; Xicotina 4, and 
 Cinchona alkaloids 6 eqs. 
 
 428. Alkaloids of Opium. — These are Morphia, Nar- 
 cotina, Codeia, Thebaina, Xarceina, Papaverina, Phormia, 
 Opiana, and Metamorphia, They exist in combination 
 with Meconic acid, 3HO,C 14 HO n -f 6HO. 
 
 General Tests for Opium. — The presence of meconic 
 acid is conclusive. It is extracted by means of alcohol 
 acidulated with HC1, the solution evaporated to dryness, 
 redissolved, neutralised with magnesia, and again acidu- 
 lated with HC1. The solution strikes like the sulphocy- 
 anides a blood-red colour with ferric salts. That of Me- 
 conic acid is not affected by a solution of terchloride of 
 gold. 
 
 Morphia. — Prop. Small, brilliant, transparent, colour- 
 less, rectangular crystals (3d system), soluble in 1000 
 parts cold, 400 boiling water, 14 parts boiling and 20 of 
 
ORGANIC CHEMISTRY. 331 
 
 cold alcohol, 200 of chloroform; freely in fixed alkalies, 
 sparingly in ammonia; is insoluble in ether. By the 
 action of acids forms a series of soluble, colourless, bitter 
 salts. It is fusible without decomposition, and entirely 
 volatilised by heat. It strikes a blood-red colour with 
 nitric acid; (so do Brucia, Delphia, and commercial Strych- 
 nia.) It decomposes iodic acid, liberating iodine. In 
 powder or concentrated solution, it gives a Characteristic 
 blue colour with Fe 2 Cl a . The salts of morphia, which are 
 made by direct combination, are colourless, soluble in 
 water and alcohol, and insoluble in ether. Morphise sul- 
 phas is in feathery crystals, sometimes mistaken for 
 Quinide sulphas ; it is freely soluble ; the crystals contain 
 5 eq. of water of crystallisation. The Liquor Morphise 
 Sulphatis contains gr j to f^j Aquae. Morphise Murias is 
 rather more soluble ; Morphise acetas is generally in pow- 
 der, requiring a little free dilute acetic acid to render it 
 freely soluble. The "Valerianate is much used. Dose of 
 Morphia and its salts, gr ^ to J. 
 
 Narcotina, C^H^NO^ -f 2HO ? — Is separated from 
 opium or morphia by ether, in 100 parts of which cold or 
 50 boiling it is soluble. It is insipid, feebly basic, gives 
 an orange tint with nitric acid, and a greasy stain to paper 
 when melted on it ; sulphuric acid, with a trace of nitric, 
 gives a blood-reel colour. It is not narcotic, and has been 
 employed as an antiperiodic in as large a dose as gij. 
 Proper dose, gr v to x. Is but little used. 
 
 Codeia, C 36 H 21 N0 6 +2HO. — Is freely soluble in alcohol, 
 ether, and in 80 parts cold and 11 of boiling water. It does 
 not react with ferric salts ; is coloured yellow by nitric acid. 
 It produces tranquil sleep and much itching of the skin. 
 Is less active than morphia ; is given in doses of 1 to $ gr. 
 It is generally present in commercial salts of morphia. 
 
 Xarceia, C 46 H 29 NO,^. — Is insoluble in ether, soluble in 
 29 * 
 
332 MEDICAL CHEMISTRY. 
 
 230 parts of boiling water, and readily in alkaline solu-_ 
 tions ; it combines with difficulty with mineral acids ; its 
 salts are coloured blue by a little water, become colourless 
 on dilution, and blue again on abstracting a portion of the 
 water by fused chloride of calcium. It is the most nar- 
 cotic of the alkaloids, the sleep produced by it being tran- 
 quil and not easily broken (Bernard). It appears to have 
 a special action on the lumbar portion of the spinal cord 
 (Ozanman). 
 
 Thebaina, or Paramorphia, C3sH n X0 6 . — Resembles in 
 appearance narcotina ; soluble in ether and alcohol, but 
 nearly insoluble in water. It is crystallisable with diffi- 
 culty ; the same is true of its salts. The solution of its 
 muriate leaves a resinous mass on evaporation. It is the 
 most poisonous of the opium alkaloids, but is not narcotic ; 
 causes tetanus (Magendie) ; is excitant to the cervical part 
 of the spinal cord (Ozanman). 
 
 Papaverina, C 40 H 21 XOg. — In small crystals, which give 
 a blue colour with HO,S0 3 ; with HC1 in excess forms in- 
 soluble crystals of a high refractive power. It is insoluble 
 in water, and sparingly soluble in alcohol and ether. It is 
 rather stimulant than narcotic in its effects. 
 
 Phormia, or Pseudomorphia, C 27 H 9 X0 7 , occurs but sel- 
 dom in opium. Its reactions with nitric acid and the ferric 
 salts are similar to those of morphia, but it is not poison- 
 ous. It does not decompose iodic acid. 
 
 Opiana, Q^R^ 2 2l . — Is soluble in alcohol and ether. 
 Paper moistened with it becomes red on exposure to the 
 fumes of HC1 (Merck's test for opium). Metamorphia is 
 unimportant. 
 429. Alkaloids of Cinchona. 
 
 These are Quinia, Quinidia, Cinchonia, and Cinchonidia, 
 which exist in combination with Kinic acid, 2HO,C u II 10 O 10 . 
 Quinia, C 40 H, 4 X 2 O 4 +6HO. 
 
ORGANIC CHEMISTRY. 333 
 
 Prop. — Is generally flocculent, but may be obtained in 
 crystals ; fuses at 300° without change 5 is soluble in 400 
 parts cold and 250 of boiling water ; in two parts of alco- 
 hol or chloroform, and 60 of ether; also soluble in the 
 fixed and volatile oils. Its salts are sparingly soluble in 
 water, unless an excess of acid be present. The tannate, 
 tartrate, oxalate, and acetate are insoluble ; tartaric acid 
 does not cause a precipitate with acid watery solutions of 
 the sulphate. The alkaloid and its salts are characterised 
 by the emerald-green colour produced by the action of 
 chlorine water followed by ammonia. Quinidia, which 
 gives a similar result, is distinguished by sparing solu- 
 bility in ether. A solution of the sulphate, mixed with a 
 little acetic acid and alcohol, gives with tincture of iodine 
 emerald-green plates, which are nearly colourless by trans- 
 mitted light, which they polarise (Herapath's salt, artificial 
 tourmaline). Aqueous solutions of its salts are fluores- 
 cent, that is, render visible the chemical rays of light. 
 The sulphate and valerianate are the only officinal salts. 
 A fluorescent substance resembling quinia has been found 
 in the tissues of animals by Dr. H. Bence Jones and Dr. 
 Dupre.* As it is uncrystallisable, they have named it 
 A nima I Q uinoidin. 
 
 Quiniw Sulphas. — In silky crystals, containing 6 eq. of 
 water of ciystallisation and two of constituent water. It 
 loses 4 eq. of the former at 212°, and two more at 240°. 
 It melts at the latter temperature into a waxy mass. Is 
 soluble n ^40 parts of cold or 30 of boiling water; the 
 latter deposits the excess on cooling ; in 60 parts cold 
 alcohol, very slightly in ether, freely in glycerine. Two 
 drops to the grain of Acid. Sulph. Aromat., dissolve it, 
 and gtt xxiv to gr xx make an excellent pilular mass 
 
 * Gheiu. News, No. 334, p. 197. 
 
334 MEDICAL CHEMISTRY. 
 
 (Parrish) ; the officinal pills, which contain each gr j, be- 
 come hard and are difficult of solution. Incompatible s. — 
 The alkalies, their carbonates, the alkaline earths, vege- 
 table astringents, salts of lead and baryta. Adultera- 
 tions. — Water, known by the loss of weight in drying at 
 212°. Quinine is hydroscopic, absorbing in a moist 
 atmosphere 53 p. c. Chalk, magnesia, mannite, gum, 
 and other similar adulterations, are insoluble in alcohol. 
 The salt should be entirely volatilised at a red heat, and 
 should not effervesce or blacken with HO,S0 3 . Salicin 
 gives a blood-red tinge with HO,S0 3 ; Phloridzin, a yel- 
 low ; Cinchonia gives a precipitate with K 2 Cfy, insoluble 
 in excess ; also with CaCl. 
 
 Quinise- Valerianas. — Is in white tables, having the 
 odour of valerianic acid, and an unpleasant taste ; is sol- 
 uble in 110 parts cold or 40 of boiling water, which de- 
 composes it ; 6 of cold and 1 of hot alcohol, and in ether. 
 It slowly decomposes. Dose, gr i to v. 
 
 Quinidia is isomeric with Quinia, and only distinguished 
 by its slight solubility in ether, and by its affording a 
 sparingly soluble precipitate with KI. Its medical effects 
 and dose are the same. 
 
 Cinchonia, Q i0 S.^S 2 ^2- — Differs from quinia only in 
 containing 2 equivalents less of 0. It is insoluble in 
 ether, yields, when treated like quinia with iodine, a brick- 
 red deposit ; with ammonia and chlorine water gives a 
 white deposit. Is used as a substitute for Quinia, but 
 requires to be given in larger doses.- Cinchonise Sulphas 
 is officinal. Its crystals are anhydrous, distinct, and not 
 silky like those of Quinise Sulph. 
 
 Cinchonidia, C 40 H 2 i,X 2 O 2 . — Isomeric with Cinchonia; 
 constitutes the bulk of commercial quinidia. It gives the 
 same reaction as quinia with the iodine test, and as cin- 
 chonine with chlorine water and ammonia. The oxalate 
 
ORGANIC CHEMISTRY. 335 
 
 of commercial quinidia (a mixture of quinidia and cincho- 
 nidia) is soluble and may be crystallised ; that of quinia 
 is insoluble. 
 
 By the action of heat on the acid sulphates of quinia 
 and cinchonia, isomeric bodies, quinicia and cinchonicia are 
 obtained. They are not important. 
 
 Quinoidine, or Chinoidine, appears to be a mixture of 
 uncrystallisable Quinia and Cinchonia ; it is sold as Ex- 
 tract of Bark. It is soluble in Acid. Sulph. aromat., and 
 is given for the same purposes as Quinia, in doses twice 
 as large. 
 
 430. Strychnia, C^H^NaO^ 
 
 Sources. — Together with Brucia, and combined with 
 Igasuric acid, C 8 H 6 O 10 ?, in Nux Vomica, St. Ignatius* 
 bean, false Augustura, and the Upas. 
 
 Properties. — Is generally in powder, but may be ob- 
 tained in right square prisms (2d system) of an intensely 
 bitter taste said to be perceptible in 600,000 parts of water. 
 Soluble in 666? parts of water at 50°, and 2000 at 212°, 
 in 38? of officinal alcohol, 1?9 of absolute alcohol, 682 of 
 ether, and 5 of chloroform, its best solvent ; also in the 
 volatile oils and acid solutions. It melts, but does not 
 volatilise. Its salts are soluble, crystalline, and, like the 
 alkaloid, highly poisonous, one grain having proved 
 fatal. It produces tetanic symptoms which come on soon 
 after it has been taken. Lard and camphor have been 
 proposed as special antidotes in addition to the general 
 ones already mentioned. The tetanic symptoms are best 
 combated by chloroform. 
 
 Tests. — (1) Evaporate the suspected solution to dryness, 
 add a drop of concentrated sulphuric acid, and then a 
 small crystal of bichromate of potassa ; a blue colour is 
 produced which changes to purple, violet, and crimson. 
 
 This, it is stated, will detect the ^Wcss P art °f a grain- 
 
336 MEDICAL CHEMISTRY. 
 
 (2) The suspected solution is applied to the back, pre- 
 viously dried, of a young frog fresh from the pond, or is 
 injected into the stomach. Tetanic symptoms reveal the 
 presence of the poison. Pure strychnia is coloured yellow 
 by HO,N0 5 , but owing to the presence of Brucia, the 
 commercial drug is tinged orange or red. 
 
 Strychnia^ Sulphas. — In colourless, efflorescent crystals, 
 wholly volatilised by heat and soluble in water. Dose of 
 strychnia and its salts, 7 \ gr. gradually increased. 
 
 Brucia, C^H^NaOg-f 8HO. — Is more soluble than 
 strychnia, requiring but 850 parts of cold and 500 of boil- 
 ing water ; is very soluble in alcohol, insoluble in ether. 
 Tests. — A blood-red colour with HO,N0 5 , changing to 
 yellow with heat, and violet with SnCl (distinction from 
 Delphia, which becomes black and carbonaceous by SnCl). 
 Does not decompose I0 5 (distinction from morphia). In 
 its effects it resembles strychnia, but is only about j 1 ^ as 
 strong. 
 
 Igasuria, C 4 JE[ 28 N 2 08-f- 6HO. — Closely resembles Brucia 
 in all its properties, but is soluble in 200 parts of cold 
 water. Its salts are precipitated in the presence of tartaric 
 acid by the bicarbonate of the alkalies. Sulphuric acid 
 imparts a rose-colour which turns greenish. According to 
 Schiitzenberger, there are nine distinct alkaloids in what is 
 known as igasuria. 
 
 431. Ver atria, C^B^Ae. 
 
 Sources. — Veratrium Album and V. Viride. 
 
 Prop. — As obtained by the officinal process, it is in 
 powder, and contains Sabadillia C^H^N^O^, and Jervia 
 CeoH^NaOe, along with true veratria. It is errhine and 
 causes pricking when applied to the skin. Is characterised 
 by a red colour with HO,S0 3 , and a yellow with HO,jST0 5 . 
 It is not volatile. 
 
 432. Aconitia, C (S0 1 B. 4 tN0 ia . 
 
ORGANIC CHEMISTRY. 33? 
 
 Sources. — Aconitum napellus. 
 
 Prop. — As obtained by the officinal process, is a yellow- 
 ish-white powder without smell, of a bitter, acrid taste, pro- 
 ducing a characteristic sense of numbness on the tongue. 
 Soluble in 150 parts cold and 5 of boiling water ; readily 
 soluble in alcohol, ether, and chloroform. Is the most 
 poisonous of the alkaloids, dangerous symptoms having 
 been produced by J-q of a grain of the pure base. 
 
 Tests. — The alkaloid fuses and burns with a yellowish, 
 smoky flame ; its salts evaporate to a gummy residue ; 
 heated in a tube, it fuses and gives off at first alkaline, then 
 acid vapours. HO,N0 5 dissolves it without change of 
 colour; HO,S0 3 gives a yellow colour, and on adding a 
 crystal of KO,2Cr0 3 , a green (Cr 2 3 ) is produced. The 
 numbness produced upon application of even yi^ of a grain 
 dissolved in alcohol and rubbed into the skin, or cautiously 
 applied to the tongue, is characteristic. 
 
 433. Atropia, C^H^NOg, from Atropa belladonna. 
 Prop. — In silky crystals resembling somewhat those of 
 
 sulphate of quinia. Soluble in 300 parts cold and 50 of 
 boiling water, 1 -J parts cold alcohol and 25 parts of cold 
 ether; freely in dilute acids. Fuses at 194°, and vola- 
 tilises at 212°. Is only suitable for external use; the Ex- 
 tract. Belladonnse being safer for internal administration. 
 Used to dilate the pupil and in neuralgia. 
 
 Tests. — These are not very reliable. It turns yellow 
 with HO,N0 5 , is dissolved by HO,S0 3 , forming a colour- 
 less solution which becomes red on heating ; its salts are 
 coloured red by tincture of iodine. 
 
 Atropise Sulphas, is soluble in water, insoluble in ether. 
 Is used as a local anaesthetic. Daturia, from stramonium, 
 is said to be identical with Atropia. 
 
 434. Emetia, C^H^NOs, from Cephaelis ipecacuanha. 
 Prop. — In white, uncrystallisable powder, fusing at 
 
 29 
 
338 MEDICAL CHEMISTRY. 
 
 122° ; very soluble in alcohol, and freely in boiling water. 
 Its reactions resemble those of morphia, except with the 
 ferric salts and iodic acid. It is but little used. 
 
 435. Berberina, C 40 H 17 ^ T O 8 . 
 
 Sources. — In species of Cocculus (Calumba) Coptis, 
 Hydrastis, Berberis, Podophyllum, and Xanthoxylum. 
 
 Prop. — In yellow needles, insoluble in ether, readily 
 soluble in boiling water and alcohol. HO,S0 3 dissolves it, 
 giving an olive-green (HO,N0 5 ) red with fumes of N0 4 . 
 Its muriate is sold as hydrastin, which should not be con- 
 founded with hydrastia, a base obtained from Hydrastis 
 Canadensis. The alkaloid and its salts are tonic ; dose, 
 gr iij. It is also used as a dye. 
 
 436. Bebeerina, Nectandria, C3SH21, ^N"0 6 ?, from Xectandra. 
 Prop. — A pale -yellow, amorphous, resinous body, 
 
 slightly soluble in water, freely in alcohol and ether. Is 
 fusible at 356° and inflammable. Its salts are uncrystal- 
 lisable. The sulphate has been used as a tonic and anti- 
 periodic ; dose, gr ij or more. 
 
 437. Delphia, C 27 H 46 X0 2 ; from Delphinium. 
 
 Prop. — A white powder, slightly soluble in cold water, 
 freely so in alcohol and ether. Reacts like morphia with 
 HO,N0 5 , but is blackened by the after-action of SnCl, and 
 does not decompose I0 5 . 
 
 438. Piperina, C^H^XOe, from pepper. 
 
 Prop. — Colourless crystals, slightly soluble in water, 
 more so in ether, and still more in alcohol. Melts at 212°, 
 losing 2 eq. water. HO,S0 3 dissolves it, producing a deep 
 red colour. It is decomposed by HO,N0 5 ; has a hot and 
 not bitter taste. By long boiling in an alcoholic solution 
 of KO,HO, splits into Piperic Acid C24H ]0 O 8 and Piperi- 
 dina CaoHuN (ethyl-allyl-amine IS T H(C 4 H 5 ,C 6 H 5 ). Pipe- 
 rina is frequently added to Quinise Sulphat. in dose of gr 
 ij, or more to increase its antiperiodic effects. 
 
ORGANIC CHEMISTRY. 339 
 
 439. Caffeina, Tbeina Guarina, C 16 Hi N 4 O4. 
 Sources. — The berry and leaves of the coffee-tree, Caffea; 
 
 tea, Thea Chinensis; guarana, Paullinia sorbilis ; and 
 Paraguay tea, Ilex Paraguayensis. Guarana contains 
 5'07 p. c, black tea T97, green tea 1, and coffee 0*8 to 1 ; 
 Paraguay tea, 1*2 of the base. 
 
 Prop. — In transparent, hexagonal plates or needles (6th 
 system) ; is soluble in alcohol, ether, chloroform, and hot 
 water. Melts at 352°, and volatilises unchanged at 725° ; 
 is not bitter. It forms well-defined salts. Is said to be 
 poisonous, but the citrate has been given in grain doses in 
 sick-headache. Theobromine,, C 14 H 8 N~ 4 6 , from the cocoa- 
 nut, resembles caffeina, but has a bitter taste, and is much 
 less soluble. 
 
 440. Conia and Nicolina are oily liquids, of an alkaline 
 reaction, not pre-existing in the plants, and containing no 
 oxygen. 
 
 Conia, C 16 H 15 N, from Conium maculatum, by distillation 
 with KO,HO. Is colourless, s. g. SI, of a characteristic 
 odour, soluble in 100 parts cold water, freely in alcohol, 
 ether, and the fixed and volatile oils. It is very poisonous. 
 It may be regarded as bibutyrylamine, NH(C 8 H 7 ) 2 ; by 
 oxidation it yields butyric acid. The plant contains a dis- 
 tinct alkaloid, Conhydrina, C 16 H 17 N0 2 . 
 
 Nicotina, C 10 H 7 N, from Nicotiana tabacum,by distilling 
 with KO,HO. Is colourless, s. g. 1"048 ; has the odour 
 of tobacco, and is more sparingly soluble than Conia ; 
 very poisonous. Havanna tobacco contains 2, Maryland 
 2*3, Virginia 6'81, and Kentucky 6'09 per cent. 
 
 441. Substitution Products of the Alkaloids. — By acting 
 on the alkaloids with iodides of methyl, ethyl, etc., a portion 
 of the hydrogen of the alkaloid may be replaced by the radi- 
 cal. This fact is interesting in a theoretical point of view, as 
 indicating the probable constitution of these bodies, placing 
 
340 MEDICAL CHEMISTRY. 
 
 them among the substitution ammonias and compounds 
 of ammonium (425). The natural alkaloids are found to 
 
 • TT 
 
 be nitrile bases (425). Methyl strychnia, C u " ±s 2 4 , is 
 
 said not to be poisonous. 
 
 442. Neuter or Acid Bitter Organic Principles. — These 
 are even more numerous than the alkaloids ; they contain 
 no nitrogen ; many of them are glucosides (395) ; of others 
 only the empirical formula is known. The following are 
 sometimes employed in medicine : Salicin, Phloridzin (C 42 
 HaiOarf 4110); Colocynthin, Santonin (C3oH 18 6 ); Colchi- 
 cin, Digitalin (C^HjsOgo ?), an active poison and aloin. Pi- 
 crotoxin, C 2 oH 12 8 , is the active principle of the Cocculus 
 indicus. Phloridzin, santonin, and picrotoxin are regarded 
 as acids. It may be said that every vegetable substance 
 employed in the materia medica contains one or more 
 alkaloids, acid or neuter bitter organic principle, and often 
 both. The plants yielding fixed and volatile oils are some- 
 times exceptions to this rule. 
 
 VII. FATS AND OILS. 
 
 I. FIXED ; H. VOLATILE. 
 
 I. Fixed Oils. 
 
 443. Sources. — The animal and vegetable kingdoms. 
 From the former, by gently heating the natural fatty 
 matters {rendering) when the true fat runs out of the 
 cellular tissue and is collected. From the latter by ex- 
 pression, sometimes aided by heat ; by boiling and by the 
 solvent action of benzine. 
 
ORGANIC CHEMISTRY. 341 
 
 Prop. — Are greasy to the touch, lighter than water, 
 and leave a spot on paper which does not disappear when 
 heated. When pure, are mostly colourless and free 
 from smell and taste ; in some cases they are accompa- 
 nied by volatile acids which give characteristic odour and 
 flavour ; these may often be removed by the action of 
 animal charcoal and magnesia. They are insoluble in 
 water, nearly so in alcohol, except castor oil which will 
 dissolve in its own weight of stronger alcohol ; ether, the 
 volatile oils, benzine, and bisulphide of carbon dissolve them 
 freely. Heated alone, above 500°, they are decomposed, an 
 acrid body, acrolein C 6 H 4 2 , and other odorous substances 
 being evolved ; if decomposed by steam at this tempera- 
 ture, they merely separate into their proximate constitu- 
 ents, glycerine C 6 H 8 6 , and volatile fatty acids. At a 
 higher temperature, marsh gas C 2 H 4 , olefiant gas C4H4, 
 and complex organic products are produced. Exposed to 
 the air, they either dry into a varnish, as linseed and poppy 
 oils, or become rancid. The drying quality of oil is in- 
 creased by the addition of 10 per cent, of PbO or Mn0 2 . 
 
 Saponification. — By the action of alkalies, alkaline 
 earths, and certain metallic oxides, soaps are formed, glyce- 
 rine being at the same time set free. The soaps of KO and 
 NH 4 are soft, of NaO hard, of CaO and PbO insoluble. 
 The latter constitutes Emplastrum plumbi. The soaps 
 formed with vegetable oils, as castile, Sapo (olive oil), and 
 palm (palm oil), are soluble in cold alcohol. 
 
 444. Fatty Acids. — These may be obtained by decom- 
 posing soap by a mineral acid, or directly as above stated. 
 They are generally homologous (384) with acetic acid ; 
 some of the lower members of the series are found free 
 in the animal secretions, etc. (415). They are liquid, 
 volatile, and of decided and generally offensive odour. 
 
 The higher members of the series are solid, white, fusible, 
 29 * - * 
 
342 MEDICAL CHEMISTRY. 
 
 volatile, tasteless, and inodorous. Oleic acid belongs 
 to another series. The combinations of the fatty acids 
 with oxide of allyl, C 6 H 5 3 , are distinguished by the ter- 
 mination in, as stearin, margarin, and olein. These three 
 bodies constitute the bulk of solid fats. Olein remains 
 liquid when the fat is exposed to cold, and may be sepa- 
 rated by decantation or pressure. 
 
 Stearic Acid, HO,C 36 H 35 3 . — Is white, inodorous, taste- 
 less, of a slight acid reaction, fusing at 160° ; may be 
 distilled in vacuo, but not in air. Is insoluble in water, 
 cold alcohol, and ether. 
 
 Margaric Acid, HO^^H^Os. — Closely resembles the 
 former, melts at 140°. It is probably a mixture of stearic 
 with palmitic acid, HO,C32H 31 03, obtained from palm oil. 
 
 Oleic Acid, ^KO,C^3.^0 s , is a colourless liquid, insol- 
 uble in water, soluble in alcohol and ether, of an acid 
 reaction and sharp taste ; it is solid at 50°. It is readily 
 oxidised. The following acids are among the remaining 
 most important fatty acids. 
 
 Butyric HO,C 8 H 7 03, Caproic HO,C 12 H n 3 , Caprylic 
 HO,Ci 6 H ]5 3 , Capric HO,C 20 Hi9O 3 , exist in butter and 
 the animal secretions. They are colourless and offensive ; 
 the first has been described (413). Caproic acid has a 
 smell resembling acetic acid ; Caprylic acid, that of the 
 sweat of the negro, and Capric, that of the goat. They 
 are all liquid, colourless, and their boiling-points vary 
 with the proportion of C and H present (384). 
 
 Laurinic Acid, HOjC^H^Oa, exists in the cocoa-nut 
 oil and in spermaceti ; Myristic HC^C^H^Os, in the ex- 
 pressed oil of nutmegs ; Palmitic HO,C 32 H 31 3 , in palm 
 oil, butter, lard, olive oil, and probably in all fats in 
 which margaric acid has been supposed to exist. 
 
 It will be noticed that the homologous series of fatty 
 acid runs from butyric acid C s to stearic C 36 , — omitting 
 
ORGANIC CHEMISTRY. 343 
 
 every other term. We have no animal fatt} 7 " acid of this 
 series, the C of which is not evenly divisible by 4. Ce- 
 rotic acid, HO,C 54 B[ 53 3 , is the highest member of the 
 series found in nature. Homologous with oleic acid we 
 have, Acrylic acid, HO,C 6 H 3 3 , all the salts of which are 
 soluble ; Crotonic, HO,C 8 H 5 3 , from croton oil ; Dumaluric, 
 HO,C, 4 H n 3 , from urine ; Moringic, HOjCaoB^Og, from 
 oil of ben ; Hypogseic, HO,C 32 H 2 90 3 , from whale and por- 
 poise oil ; and others of even less importance. Ricinoleic 
 acid, HO,C 38 H 35 3 , is obtained from castor oil. The fatty 
 acids have been formed artificially from inorganic matters. 
 
 445. Glycerine, Glycerina, C 6 H 8 6 =C 6 H 5 3 ,3HO.— Is 
 obtained from fats by the action of steam at about 500°, by 
 saponification, or by inverse saponification by HO,S0 3 . 
 That obtained by the first-named process is the purest. 
 
 Prop. — A colourless, inodorous, syrupy liquid, of a 
 sweetish taste and fermentable (Berthelot) ; s. g. I 213 ; 
 officinal s. g. 125 ; is soluble in all proportions in water 
 and alcohol, insoluble in ether; does not dry or become 
 rancid on exposure to the air ; it cannot be distilled alone, 
 but gives off acrolein, C 6 H 3 0,HO, and which by oxidation 
 yields acrylic acid, HO,C 6 H 3 3 . It combines with acids. 
 
 rr 
 
 Nitroglycerine, or glonoine, C 6 5 6 , is formed by 
 
 (A(J 4 ) 3 
 
 the action of a cooled mixture of sulphuric and nitric acids 
 (386) on glycerine. It is an explosive, colourless, oily 
 liquid ; s. g. 1*6 ; freezing at 46° ; soluble in 180 parts of 
 water, and freely in alcohol and ether. A single drop ap- 
 plied to the tongue produces intense headache, with vascular 
 excitement. Death from a larger quantit) 7- has been re- 
 corded. There is no known antidote. With sulphuric 
 and phosphoric acids, glycerine forms stilpho- and phospho- 
 gly eerie acids. The latter exists in the brain and in 
 the yolk of eggs. The solvent poicers of glycerine are 
 intermediate between those of alcohol ancl water. It 
 
344 MEDICAL CHEMISTRY. 
 
 will dissolve 2 of one p. c. of phosphorus, one of iodine, 
 33 of KI, ten of HgCl, 2 of Quinias sulphas, 6 of Acid, 
 tannic, 4 of strychnia salts, 2 of Atropia. Bromine, am- 
 monia, and nitrate of silver, are soluble in all proportions 
 in pure glycerine. Generally speaking, all deliquescent 
 salts are soluble in it, also the vegetable acids. Alum, 
 and the sulphates of iron, copper, and zinc, are soluble to 
 the extent of from 25 to 40 p. c. It is miscible with Gou- 
 lard's Extract and lead water. It is used as a vehicle for 
 the administration of medicines, and as an emollient. It 
 should afford no precipitate with AgO,N0 5 (absence of 
 chlorides), or with NH 4 S,HS or K 2 Cfy (absence of the 
 heavy metals). 
 
 Glycerine does not pre-exist in fats, but is formed at the 
 time of saponification. The so-called oxide of glyceryle, 
 or of lipyl, C 6 H 5 3 , is the oxide of allyl, the base proper 
 of fats. When glycerine and fatty acids are heated to- 
 gether in sealed tubes, they unite, re-forming the fats. 
 Hence a fat is considered to be a compound of a fatty acid 
 with oxide of allyl. Glycerine is regarded as a triatomic 
 alcohol, in which one, two, or three eq. of the water may 
 be replaced by an acid. Thus in Stearine, a component 
 of the solid portion of fats, we may have : 
 
 Monostearin, C 42 H 42 8 = C 6 H 5 3 , 2110,036^03 (Stearic 
 acid). 
 
 Bistearin, C^H^Ou^CeHsO^HO^^H^Oa). 
 
 Tristearin, C 114 H I1 o0 12 =C 6 H 5 3 ,3(C 86 Hs 5 8 ). 
 
 Xot only does glycerine unite with the organic, but also 
 with some of the inorganic acids. The number of com- 
 pounds which may be formed is very great (379). 
 
 Synthesis of Gbjcerine. — This subject is interesting on account 
 of the possible production of a natural fat from purely inorganic 
 materials. 
 
 Terhromide of allyl, C 6 H 5 Br 3 . may be obtained by the action 
 of iodide of phosphorus, and afterwards of Br, upon glycerine. 
 
ORGANIC CHEMISTRY. 345 
 
 This reacting with acetate of silver, AgO,C 4 H 3 3 , yields triaceiine ; 
 C 6 H 5 Br 8 + 3(AgO,C 4 H 8 8 ) = C 6 H 6 3 ,3(C 4 H 3 3 )-f 3AgBr. Tria- 
 
 cetine, boiled with KO.HO, yields glycerine; C 6 H 4 3 ,3(C 4 H 3 3 )4- 
 3(KO,HO)=C 6 H 5 3 ,3J-IO^+3(KO,C 4 H 3 3 )^. As most of the fatty 
 acids may be synthetically obtained, and as they may be directly 
 combined with glycerine, it only remains to determine whether 
 C 6 H 5 Br 3 may be formed from inorganic materials. An isomeric 
 compound, C 6 H 5 BrBr 2 , Bromide of bromopropylene, may be pre- 
 pared by the action of bromine upon the products of the decom- 
 position of amylic alcohol, C 10 H n O,HO, at a red heat. With the 
 silver salt, however, this yields chiefly a compound, 6 H 4 O 2 ,2C 4 H 3 
 3 , but at the same time a small quantity of triacetin, C 6 H 5 3 , 
 3C 4 II 3 3 , is produced by a secondary reaction.* As amylic alco- 
 hol may be formed from purely inorganic substances,! it would 
 seem that the synthesis of a fat is possible. 
 
 II. Volatile Oils. 
 
 446. Sources. — From plants by distillation with water; 
 by expression, or by maceration in fat (enfleurage). 
 
 Prop. — They are fragrant, of a hot taste, lighter than 
 water (except those of sassafras, gaultheria, pimento, and 
 cloves), inflammable, and do not leave a permanent stain 
 on paper. They dissolve in small quantity in water, to 
 which they communicate their odours (Aquse medioatse), 
 freely in alcohol and ether. Nitric acid, iodine, and bro- 
 mine act upon them violently, sulphuric acid more quietly ; 
 they do not saponify. They are conveniently divided into 
 those containing (a) carbon and hydrogen; (6) carbon, 
 hydrogen, and oxj^gen; (c) containing also sulphur. 
 
 (a) Containing G and H. 
 
 447. These are all isomeric with oil of turpentine, C, H 16 , 
 but vary in s. g. and boiling-point; when absolutely pure, 
 are inodorous, but as met with have various odours, which 
 appear to be developed hy oxidation. But little is known 
 of their true chemical character. 
 
 * Wuirrz, cited in Gmelin's Handbook, Cavendish Ed., vol. xiii. p. 553. 
 "j" Brrthelot, Cliemie ovganiqnc fondf.e any la Synthexe, t. i. pp. S3, 119. 
 
346 MEDICAL CHEMISTRY. 
 
 Oil of Turpentine, C 20 H 16 . — Is too well known to need 
 description. By the action of HC1 is converted into arti- 
 ficial camphor, C 20 H 16 HC1; similar compounds are formed 
 with other hydrogen acids. The following are other mem- 
 bers of this class : oils of camphor, elemi, myrrh, copaiba, 
 black pepper, hemlock, juniper, savin, lemon, orange, and 
 cedar. 
 
 (b) Containing C, H, and 0. 
 
 448. They form the great bulk of the volatile oils. On 
 exposure to cold, they generally separate into an oily por- 
 tion isomeric with oil of turpentine (elaeopten), and a crys- 
 talline, solid, camphor-like body (stearopten) containing 
 oxj^gen. With nitroprusside of copper, Cu 2 Fe 2 Cy 5 N0 2 , they 
 give marked, and in some cases characteristic colours. The 
 action of this reagent is interfered with by the presence 
 of the hydrocarbon volatile oils. In some cases, as the oils 
 of cinnamon, gaultheria, spirea, and bitter almonds, their 
 rational formula has been determined, and they have been 
 formed artificially. The following are officinal: Oil of 
 anise, bergamot, chenopodium, cajuput, cloves, cinnamon, 
 Canada fleabane, fennel, gaultheria, pennyroyal, juniper, 
 lavender, the mints, allspice, roses, rosemar}^, sassafras, 
 thyme, and valerian. 
 
 (c) Containing Sulphur. 
 
 449. They are highly pungent, and of powerful odour. 
 They may be considered as sulphur compounds of the radi- 
 cal allyl C 6 H 5 . According to some, a distinct radical, feru- 
 lyle, C 12 H n , exists in assafcetida. Oil of garlic is sulphide of 
 allyl, C C H 5 S; Oil of mustard, a sulphocyanide, C 6 H 5 C 2 NS 2 . 
 It has been formed artificially by the reaction of KCsy 
 with C 6 H 5 I. Oil of horseradish is identical with oil of 
 mustard. 
 
ORGANIC CHEMISTRY. 34T 
 
 CAMPHORS AND RESINS. 
 
 These are the products of the oxidation of volatile oils ; 
 they are too numerous for special consideration. 
 
 450. Camphor, Camphora, C 20 H 16 O 2 , may be taken as the 
 type of the group. It is solid, colourless, volatile, inflam- 
 mable; soluble in 1000 parts water (Aqua Camphor se), and 
 freely in alcohol {Spiritus Gamphorse), also in chloroform 
 and strong acetic acid. A clean fragment of camphor 
 thrown upon water rotates in a remarkable manner ; the 
 least trace of grease instantly arrests the movement. 
 
 Resins. — Those containing benzoic acid, C u H 6 4 , are 
 called balsams, as tolu; when they contain gum, gum re- 
 sins, as assafcetida. The latter form a milky emulsion 
 with water; alcohol dissolves only the resinous portion. 
 Oleo-resins contain volatile oils, as crude turpentine and 
 copaiba. 
 
 VII. COLOURING MATTERS. 
 
 451. Indigo. 
 
 Sources. — Various species of Indigofera and genera of 
 other families ; an allied substance is sometimes found in 
 the urine. It appears to exist in the plant in the form of 
 a soluble, colourless compound ; it is extracted by fermen- 
 tation as a yellow liquid which yields a precipitate of blue 
 indigo upon the addition of lime. 
 
 Prop. — Commercial indigo is in deep blue, insoluble 
 masses, which on heating yield a blue vapour which con- 
 denses into crystals. It contains 50 p. c. of indigo-blue, 
 indigoiine, C !6 H 5 N0 2 , which by reducing agents, as HO, 
 
348 MEDICAL CHEMISTRY. 
 
 So 3 , lakes up an atom of H and becomes indigo-white, 
 Indigogene C 16 H 6 N0 2 , which again becomes blue on ex- 
 posure to the air. Nordhausen sulphuric acid, HO,2S0 3 , 
 dissolves indigo, forming sulphindigotic or sulphindylic 
 acid, C 16 H 4 N02,S 2 2 , and sulphopurpuric acid, C 32 H 10 N 2 O 4 , 
 2S0 3 ,HO. These are used in dyeing. By oxidising agents 
 and KO,HO, it yields various products, among others ani- 
 line and picric acid, HO^^H^NO^O. 
 
 452. Aniline, NH 2 C 12 H 5 , is obtained indirectly from coal- 
 tar (417). By the action of K0,2O0 3 , As0 3 , SnCl, HgCl, 
 etc., it yields colours of various shades, chiefly crimson and 
 purple, and known as magenta, mauve, solferino, etc. By 
 combination, all tints have been obtained. The composi- 
 tion of these colours is complex, and in many cases un- 
 known. They have been successfully used in injecting 
 tissues for microscopic examination. 
 
 453. Picric Acid, Carbazotic acid, Trinitrophenic acid, 
 HO,C 12 H 2 (N0 4 ) 3 0, may be regarded as a substitution 
 compound in which 3 eq. of H of Phenic acid (41*7) are 
 replaced by JTO 4 . It is obtained by the action of nitric 
 acid upon oil of tar, also upon silk, indigo, salicin, and 
 aniline. 
 
 Prop. — In yellow crystals, soluble in 86 parts water, 
 of a bitter taste, and decomposed by heat with explosion. 
 It is used as a yellow dye, as a test for potassa, and has 
 been administered as an antiperiodic. It is said to be 
 used to adulterate beer, but may readily be detected, not 
 being removed by animal charcoal. 
 
 454. Litmus, is obtained from various lichens by oxida- 
 tion and the action of ammonia. Is usually in the form 
 of cubes of plaster of Paris, saturated with the colouring 
 matter. It is soluble in water and alcohol, is reddened by 
 acids, and the red colour restored by neutralising agents. 
 Hence its use as a test. It contains three colouring prin- 
 
ORGANIC CHEMISTRY. 349 
 
 ciples, — Lecanosic acid, HO,C 16 H 8 8 , Orcin, C 14 H 8 4 ,HO, 
 and Orceine, C 14 H 8 N0 6 ,HO. Turmeric, the root of Cu- 
 curma longa, yields a yellow tincture which is turned 
 brown by alkalies. Quercitron, the inner bark of Quercus 
 nigra, Fustic, the wood of Morus tinctoria, Saffron, por- 
 tions of the flowers of Crocus saliva, and Annoto, from the 
 seeds of Bixa orellana, are all used as yellow dyes. 
 
 455. Madder. — The root of Rubia tinctorum. It con- 
 tains three colouring principles : Xanthin, C H yellow ; 
 Alizarine, C 20 H 6 O 6 , red ; and Purpurine, C 18 H 6 6 , purple. 
 Artificial alizarine obtained from naphthaline cannot be 
 considered identical with that from madder. The root is 
 officinal and is used as an emmenagogue. The madder 
 colours are remarkable for purity and permanence. 
 
 456. Logwood. — The wood of Hsematoxylon Campe- 
 chianum. It contains Hsematoxyline, C 16 H 7 6 ,3HO. Is 
 used for purple and black dyes. Is officinal and used as a 
 tonic and astringent. 
 
 Brazil Wood is used for red dyes, red ink, etc. ; with 
 alum, forms a crimson lake; it contains Braziline, C 36 H, 4 14 . 
 It is not used in medicine. 
 
 45*7. Carthamine, Safflower, the petals of Carthamus 
 tinctorius, is used as a fine red dye and in the preparation 
 of rouge. It contains Carthamine, C 26 H 9 5 ,2HO, a yellow 
 substance which by oxidation yields red Carthamic acid, C 26 
 H 9 7 . Alkanet, the root of Anchusa tinctoria, yields a red 
 tincture used in thermometers, etc. ; it contains Anchusine, 
 C 17 H 10 O 4 . Santalum, Red Sanders, is the wood of Ptero- 
 carpus Santalinus ; it contains a white crystalline prin- 
 ciple, Santaline, which oxidises to red Santaleine, C 16 II s 3 ? 
 
 458. Lac. — Is a resinoid substance exuding after the 
 
 puncture of an insect from species of Ficus. It yields a 
 
 scarlet dye. It is especially used in the preparation of 
 
 varnishes, sealing-wax, etc. ; it is freely soluble in alcohol. 
 
 30 
 
350 MEDICAL CHEMISTRY. 
 
 459. Cochineal. — The female of a species of coccus. The 
 insect yields its colouring matter to water and alcohol. By 
 precipitation with alumina it yields carmine. The insect 
 is sometimes used as a reputed antispasmodic. 
 
 460. Colouring Matter of Leaves and Flowers. 
 Chlorophylle, the green colouring matter of leaves and 
 
 herbage, yields Chlorophylline, C 18 H 9 N0 8 . It is freely 
 soluble in ether * long exposed to the air, it forms Xan- 
 thophylline, which is also found in the yellow leaves of 
 autumn ; the red leaves contain Erythrophylline. The 
 colouring matters of flowers are not well understood. 
 Some of them, from their sensitiveness to the action of 
 chemical agents, are used as tests. Yiolets give a blue 
 juice, or infusion, which is changed to red by acids, and 
 green, and finally yellow, by alkalies. The infusion of 
 petals of the red rose is turned red by acids, and green hy 
 alkalies. An infusion of the common purple cabbage is 
 similarly changed. These tests are best preserved by 
 saturating porous papers with the juices, and drying care- 
 fully. All test-papers must be kept from air and light. 
 The red cabbage-leaves may be preserved by careful 
 drying. 
 
 VIII. PEOXIMATE PEINCIPLES NOT OTHEE- 
 WISE CLASSIFIED. 
 
 461. This includes the proximate principles of animals 
 and vegetables, and the analysis of their secretions and 
 excretions. The non-nitrogenised proximate principles of 
 vegetables were considered in group L, and their nitrogen- 
 ised crystallisable bases in group V. The results of 
 
ORGANIC CHEMISTRY. 351 
 
 researches on this part of the subject are exceedingly dis- 
 cordant. This may be explained by the fact that the 
 proximate principles cannot be obtained crystallised, and, 
 therefore, no absolute certainty as to their composition 
 exists. The same principle also varies according to its 
 source ; the varieties of albumen from the egg, the serum, 
 the brain, the skin, etc., are not identical. The secretions 
 or excretions of the body vary much in health, and greatly 
 in disease. It is often difficult to say whether a substance 
 pre-exists in an organised body, or is the result, in some 
 degree, of the methods employed in its extraction, upon 
 some other body. Some principles, as fibrin, are different 
 when living and dead. 
 
 462. Albumen. — Is the most widely diffused of the prox- 
 imate principles in the animal body. It exists in a liquid 
 form in the serum of the blood (seralbumen), in white of 
 egg (ovalbumen), in lymph, chyle, saliva, pancreatic and 
 seminal fluids, humours of the eye, and, in disease, in the 
 bile and urine. As a solid, it exists in the brain, nerves, 
 glands, cellular membrane, skin, hair and nails. In vege- 
 tables, as emulsion or- syneptase, it is also abundant, 
 existing in the juices of some, as the potato, carrot, and 
 asparagus ; in grain and in nuts. 
 
 Prop. — In solution, is clear, slightly viscid, leaving a 
 glairy streak on paper ; when dried, is yellowish, trans- 
 parent, and horny, and not then prone to decomposition. 
 Exposed to heat, the solution coagulates at about ltO°. 
 It is then insoluble in water, but soluble by continued 
 boiling in hydrochloric acid or in strong alkalies. When 
 dried, this is indistinguishable from uncoagulated albumen, 
 except by its insolubility. Heat will detect 1T ^ °f albu- 
 men in solution. It is coagulated by nitric and meta- 
 phosphoric acids ; Tannic acid forms with it an insoluble 
 compound analogous to that produced with gelatine. Sul- 
 
352 MEDICAL CHEMISTRY. 
 
 phuric and hydrochloric acid precipitate it soluble in 
 excess ; acetic, tartaric, oxalic, and gallic acids do not affect 
 it. It forms cements with the alkaline earths ; that made 
 of lime and white of egg is very adhesive and resists 
 many chemical agents. With the salts of most of the 
 heavy metals it forms insoluble compounds ; hence it is 
 used as an antidote. Conversely, corrosive sublimate or 
 sub acetate of lead form delicate tests for albumen, and 
 the metallic salts are useful as antiseptics. It is also co- 
 agulated by alcohol, creasote, and phenic acid, and its 
 acetic solution by chloride of sodium, nitrate of potassa, 
 and sulphate of soda. 
 
 Coagulation by heat is prevented by the presence of 
 excess of alkali or of small quantities of mineral acid. 
 The chemical changes taking place during the process are 
 not understood. Seralbumen is not affected by ether and 
 oil of turpentine, which coagulate ovalbumen. The fol- 
 lowing bodies closely resemble albumen in composition 
 and properties: Musculin, from fibre of flesh; Globulin. 
 which constitutes the greater part of the red corpuscles of 
 the blood : it is coagulated by strong alcohol, and redis- 
 solved by that reagent when dilute and boiling ; Pepsin. 
 from the gastric juice ; Pancreatin, from pancreatic juice : 
 it is coagulated by sulphate of magnesia ; Ptyalin, from 
 saliva ; Mucosin, found in mucus ; Neurine, the semi- 
 fluid substance of the tubes and corpuscles of the brain 
 and nerves. Pyein from pus, Echidnine from viper poi- 
 son, and Crotaline from that of the rattlesnake, are highly 
 poisonous when introduced into the circulation. Yegetable 
 albumen, Emulsin, differs in being coagulated, like casein, 
 by rennet and by tribasic phosphoric acid, 3HO,P0 5 . 
 
 463. Fibrin. — From its property of spontaneous coagu- 
 lability, is unknown chemically in the soluble state. It is 
 maintained in the soluble state in the blood by ammonia. 
 
ORGANIC CHEMISTRY. 353 
 
 As obtained from blood by whipping with twigs, it is in 
 white filaments, which gelatinise and dissolve in dilute 
 acetic and hydrochloric acid, and in 3HO,P0 5 . It is also 
 soluble in alkalies, which convert it into a substance 
 closely resembling albumen. Tannic acid forms with it 
 an insoluble imputrescible compound. The fibrin of 
 venous and arterial blood differs, and that of flesh, 
 musculin, more nearly resembles albumen. 
 
 Gluten, from wheat flour and seeds, appears to be 
 identical with fibrin. 
 
 ^-64. Casein. — Exists in milk, and perhaps in the blood. 
 It closely resembles albumen, but is coagulated by acetic 
 acid. Is a white, curdy substance, insoluble in water, 
 soluble in weak alkaline solutions, from which it is again 
 precipitated by acids. When dried, is transparent and 
 horn-like. Is not coagulated by heat. Certain animal 
 membranes, as rennet, coagulate it, and this action is 
 aided by heat. Legumin, obtained from peas, beans, etc., 
 is considered to be identical with casein. 
 
 466. The three bodies just described are known as the 
 protein compounds. The following analyses represent their 
 composition, but can only be considered as approximate. 
 
 
 Albumen. 
 
 Fibrin. 
 
 Casein. 
 
 Carbon, 
 
 535 
 
 52-7 
 
 53-83 
 
 Hydrogen, 
 
 T-0 
 
 6-9 
 
 M5 
 
 Nitrogen, 
 
 155 
 
 154 
 
 1565 
 
 Oxygen, 
 
 220 
 
 23-5") 
 
 l-2j 
 
 23.3T 
 
 Sulphur, 
 
 1-6 
 
 
 Phosphorus, 
 
 
 0-4 0-3 
 
 
 Liebig gives the following as their formulas : 
 Albumen, C, 16 II 1G9 N 27 6S S 2 
 Fibrin, C.; 9S H, 2 , 8 N 4 oOcA 
 
 Casein, C^H^N^O*^ 
 
 30* 
 
354 MEDICAL CHEMISTRY. 
 
 467. Protein. — Mulder observed, that when any one of 
 the foregoing compounds was digested in caustic potassa 
 until no precipitate was afforded with a lead salt, and pre- 
 cipitated by acetic acid, a snow-white flocculent substance 
 was obtained, which, he stated, could be procured entirely 
 free from sulphur and phosphorus. This substance, com- 
 bined with sulphur and phosphorus, he stated, gave albu- 
 men, fibrin, and casein. The formula C 24 H 17 X 3 8 has been 
 assigned to it. Its existence is doubted by many, but the 
 designation protein compounds is a convenient one. 
 
 468. Gelatin. — Exists in the skin, tendons, etc., and is 
 derived from the ossein of bones by long boiling. 
 
 When pure and dry, is a transparent, colourless, inodo- 
 rous, insipid solid; insoluble in alcohol and ether, soluble in 
 boiling water, to which one per cent, will communicate the 
 property of gelatinising; the facility with which the liquid 
 becomes firm is greater as the temperature is lower, and 
 varies with the variety of gelatin. The solution, exposed 
 to the air, soon putrefies. It is soluble in all dilute acids 
 except tannic, which precipitates it and forms an impu- 
 trescible mass (leather). It is not precipitated by alum, 
 the acetate or subacetate of lead. Is precipitated by chlo- 
 ride and nitrate of mercury, but not generally by the salts 
 of the heavy metals. Tannic acid will detect ^-qqq of 
 gelatin in solution; it is not precipitated by gallic acid. 
 The doubtful formula C 13 H ]0 XO5 has been assigned to 
 gelatin. 
 
 Strong nitric acid with gelatin yields oxalic acid. Sul- 
 phiirie acid gives leucin, C 12 H, 3 X0 4 , tyrosin, C^HnXOe, 
 and glycocoll, or sugar of gelatine, C 4 H 5 X0 4 ; the latter is 
 sweet, of sparing solubility, and does not ferment. Tyro- 
 sin, C 18 H„X0 6 , is also obtained with leucin by the action 
 of KO,HO upon casein. 
 
ORGANIC CHEMISTRY. 355 
 
 Isinglass, Ichthyocolla, is a pure form of gelatin ob- 
 tained from the swimming-bladder of fishes; it is more 
 slowly soluble than ordinary gelatin. The finer varieties 
 of gelatin are also known and sold indiscriminately as 
 gelatin or isinglass. Glue is an impure gelatin ; liquid 
 glue is a solution of gelatin in strong acetic acid or in 
 water, with the addition of nitric acid. Size is a very 
 impure glue used to give a surface to paper, etc. 
 
 Chondrin, obtained by the action of boiling water upon 
 Cartalagin found in the cartilages, differs from gelatin in 
 being precipitated by acetic acid (soluble in excess), also 
 by nitric acid and subacetate of lead. Its formula is given 
 as C 32 H 26 N 4 14 . 
 
 469. Kreatin, C 8 H 9 N 3 4 ,2HO. — Maybe extracted from 
 the juice of flesh. Is a neutral body, in brilliant colourless 
 crystals, readily soluble in boiling water, the solution 
 having a bitter, somewhat acrid taste. By the action of 
 acids it loses the elements of water, and becomes Kreatin- 
 in, C 8 H 7 N 3 2 , which pre-exists to a small extent in the 
 juice of flesh. It is also in colourless crystals, of an 
 alkaline reaction, which combine readily with acids to 
 form distinct salts. It is freely soluble in cold water. 
 Inosic acid exists also in the juice of flesh; it does not 
 crystallise, and has been obtained as a white amorphous 
 powder, to which the formula HO,Ci H 6 N 2 O, has been 
 given. Inosite, C 12 H 12 12 +2HO, is a sweet crystalline 
 body, capable of undergoing the lactic, but not the vinous 
 fermentation; it is obtained from the juice of the flesh of 
 the heart and kidneys, also from unripe kidney-beans. 
 
 4T0. Blood. 
 
 Prop. — When freshly drawn, is a homogeneous, slightly 
 viscid, alkaline liquid, of a peculiar odour, and saltish taste; 
 its average s. g. is 1055 ; the colour varies from the bright 
 red of arterial to the dark purple of venous blood. Under 
 
35G MEDICAL CHEMISTRY. 
 
 the microscope, is seen to consist of a transparent, nearly- 
 colourless fluid (plasma or liquor sanguinis), in which 
 float red discs, the red corpuscles, and colourless globules, 
 the white corpuscles. It soon coagulates after being 
 drawn, forming a clot, which consists of fibrin and blood- 
 globules, and a liquid serum containing albumen and 
 salts. It consists proximately of 
 
 Water, 
 
 
 784- 
 
 Red Corpuscles, 
 
 
 131- 
 
 Albumen, 
 
 . 
 
 TO- 
 
 Salts, 
 
 
 6-03 
 
 Extractive, Fatty Matters, 
 Fibrin, 
 
 etc., 
 
 6-17 
 22 
 
 100000 
 
 The red corpuscles consist of Globulin, a substance 
 which has not been satisfactorily separated, but resembling 
 albumen, and of Haematin, the red colouring matter. 
 This contains a large proportion of iron. Mulder's analysis 
 gives 
 
 Carbon, . 
 
 Hydrogen, . 
 
 Nitrogen, 
 
 Oxygen, 
 
 Iron, 
 
 10000 
 
 The colour of haematin does not depend wholly upon 
 its iron, as it is not lost upon the removal of that metal. 
 The proportion of globulin to haematin is stated as 123-5 
 
 to r-4. 
 
 The Extractive matters consist principally of Kreatin 
 and Kreatin in; the fatty matters, of a peculiar fat Sero- 
 
 65-84 
 
 5-37 
 
 10-4 
 
 11-75 
 
 6-64 
 
ORGANIC CHEMISTRY. 35t 
 
 lin, Cholesterin, a fat found in the bile, Cerebrin, a fat 
 found in the brain, with oleate and margarate of soda and 
 other fats free and saponified. 
 
 The Salts are chlorides of sodium, potassium, tribasic 
 phosphate of soda, carbonate and sulphate of soda, and 
 phosphates of lime, magnesia, and iron. Urea, biliary- 
 colouring matter, sugar, salivary matter, oxygen, nitrogen, 
 and carbonic acid, are also found in varying quantities. 
 
 4U. Chyle and Lymph. 
 
 Differ from blood chiefly in the absence of the red cor- 
 puscles, and in containing a less proportion of fibrin. The 
 chyle, as taken from the lacteals, contains a large propor- 
 tion of fatty matter. 
 
 412. Saliva. 
 
 A transparent, watery fluid, of an alkaline reaction; s.g. 
 1-006 to 1-009. Contains, besides water, mucus, albumen, 
 fatty matter, and the usual^ salts, a peculiar principle, 
 Ptyalin, and sulphocyanide of potassium, KC2NS2. Saliva 
 contains 12 per cent, of chloride of sodium, a larger pro- 
 portion than any other animal fluid. The Pancreatic Juice 
 resembles saliva in composition, but does not contain sul- 
 phocyanogen. 
 
 413. Milk. 
 
 Under the microscope, is seen to consist of a clear liquid, 
 in which are suspended numerous globules; these consist 
 of fat (butter), surrounded by an albuminous envelope, 
 which may be broken by mechanical violence (churning), 
 or dissolved by caustic potassa. Milk contains water, 
 butter, casein, milk sugar, and the usual salts of animal 
 secretions. It is at first alkaline, but becomes acid, owing 
 to the formation of lactic acid. 
 
 474. Gastric Juice. — Contains free muriatic and lactic 
 acids, and phosphate of lime, the chlorides of potassium, 
 sodium, calcium, and magnesium, and a peculiar principle, 
 
358 MEDICAL CHEMISTRY. 
 
 Pepsin. Pepsin possesses the property of digesting most 
 alimentary substances, when kept at the temperature of the 
 stomach, and in contact with a dilute solution of muriatic, 
 lactic, or phosphoric acid. The substance sold as pepsin 
 for use in dyspepsia consists of starch containing pepsin 
 obtained from the stomach of the sheep, hog, or calf, or of 
 the same in solution in diluted hydrochloric acid. 
 
 475. Sweat. — Under ordinary circumstances, the average 
 quantity secreted is nearly two pounds avoirdupois daily ; 
 under the influence of active exercise, or high temperature, 
 this quantity is greatly increased. Its reaction is acid ; 
 the odour varies with the individual, and differs in differ- 
 ent parts of the body. It is due to volatile acids, as the 
 acetic, lactic, butyric, capric, and caproic ; caprylic acid 
 probably exists in that of the negro. It contains also ani- 
 mal matters, which when retained in the clothing become 
 offensive and breed typhus, etc. Its salts are chlorides of 
 sodium and potassium, acetates, lactates, etc. of soda and 
 potassa. 
 
 476. Bile. — Is a liquid of a dark, golden-brown colour 
 in man, s. g. 1018, probably neutral in reaction ; it 
 bleaches test-paper ; has a bitter taste, and on agitation 
 with air gives a soap-like foam. It is extremely prone to 
 decomposition, and cannot on this account be obtained fit 
 for analysis from man. The following is the composition 
 of ox-bile : 
 
 Water, HO, 880* 
 
 Glykocholate of Soda, NaO,C 52 H 42 XO xl , ] 9Q . 
 Taurocholate of Soda, XaO,C 52 H 45 XS 2 4 , J 
 
 Biliverdine, "J 
 
 Fats, \ 13-42 
 
 Cholesterine, C^H^O, ( 
 
 983-42 
 
ORGANIC CHEMISTRY. 359 
 
 Chloride of Sodium, NaCl, 
 Phosphate of Soda, 3NaO,P0 5 , 
 
 " Potassa, 3KO,P0 5 , 
 
 " Lime, 3CaO,P0 5 , 
 
 " Magnesia, 3MgO,P0 5 , 
 Carbonate of Soda, NaO,C0 2 , 
 
 " Potassa, KO,C0 2 , 
 Mucus of gall bladder, . . . .1*34 
 
 1000-00 
 
 Glyhocholic Acid. — A crystalline body, which, when 
 boiled with dilute KO,HO, splits, with the assimilation of 
 two eq. of water, into cholic acid, HO,C 48 H390 9 , and gly co- 
 coll, C 4 H 5 N0 4 (468). 
 
 Tauro-cholic Acid. — Crystallises with great difficulty, 
 and it is doubtful whether it has been obtained pure. By 
 boiling with dilute KO,HO, it splits into cholic acid and 
 taurin, C 4 H 7 NS 2 6 . Both the glyco- and tauro-cholates 
 of soda are precipitated by the subacetate of lead ; the 
 glyco-cholate is also precipitated by the neutral acetate. 
 
 Taurin. — Is found in the decomposed bile of the intes- 
 tines, and in the muscles of the mollusca. It has been ar- 
 tificially formed by heating isasthionate of ammonia to 410°- 
 428°, NH 4 0,C 4 H 5 0,2S0 3 = C 4 H 7 NS 2 6 +2HO (Strecker). 
 It is in colourless, hexagonal prisms, with no odour, but 
 little taste; is permanent in the air, and burns with the 
 evolution of sulphurous acid. 
 
 Cholic Acid. — Has been obtained crystallised ; itis to 
 it that the characteristic reaction of bile with Pettenkoffer's 
 test is due. 
 
 Cholidic Acid, C 4S H 39 09, and Dijslisin, C 4S H 36 6 , are two 
 resinous bodies obtained from glykocholic acid by boiling 
 with strong hydrochloric acid. The so-called resin of bile, 
 or Bilin, is an impure mixture of the glyco- and tauro- 
 cholate of soda. 
 
360 MEDICAL CHEMISTRY. 
 
 Biliverdine. — Is the colouring matter of bile ; it con- 
 tains nitrogen and iron, but no satisfactory analysis has 
 been made. It exists in very small quantity. 
 
 Cholesterine, C^H^O. — A fat-like body, but not sapon- 
 ifiable ; exists in very small quantity in bile, but is abun- 
 dant in gall stones. It is also found in the fluid of hydro- 
 cele, and in encysted tumours, the spleen, and largely in 
 the brain and nervous tissue. It is not found in the faeces. 
 It is in thin, colourless, transparent, rhomboidal plates, in- 
 soluble in water, but freely so in alcohol and ether. 
 
 Tests for Bile. — Nitric acid produces with Biliverdine 
 a grass-green colour. This does not necessarily indicate 
 the presence of bile proper. Pettenkoffer's test: This de- 
 pends upon the reaction of sulphuric acid and grape sugar 
 upon cholic acid. A drop of a solution of one part of 
 sugar (cane sugar will answer) in 4 parts of water is 
 added to the bile in watery solution ; to this five drops of 
 sulphuric acid are added, and the whole gently warmed 
 (not above 120°). A red colour changing to purple is 
 produced, which is destroyed by adding excess of water. 
 
 4TT. Urine. 
 
 Prop. — A clear liquid, of an amber colour and faint aro- 
 matic odour. Its mean s. g. is 1024, but varies with the 
 ingesta from 1017 to 1030, the difference being due to the 
 quantity of fluid, that of the solid constituents remaining 
 nearly constant. Hence the specific gravity is inversely 
 as the quantity which averages f^xxiv per diem. If either 
 the quantity or s. g. vary directly, it is an evidence of dis- 
 ease. It may be nearly colourless, as in hysteria, where 
 the s. g. sometimes falls to 1006 with large increase of 
 quantity, or may be of a deep red colour, and so scanty as 
 to deposit its salts. In health, it has nearly always an 
 acid reaction due to the acid phosphate of soda, ]S T aO,2HO, 
 P0 5 , contained in it. It is most acid early in the morning, 
 
ORGANIC CHEMISTRY. 
 
 361 
 
 and has then a high s. g. ; in the forenoon is pale, more 
 abundant, of lower s. g., neutral, and even alkaline (Dalton). 
 After this the colour, acidity, and density increase to a 
 maximum towards night. These changes are liable to 
 variations due to ingesta, temperature, etc. The alkalies, 
 their carbonates, acetates, tartrates, and citrates, give to it 
 an alkaline reaction. Although transparent when first 
 passed, it may become turbid on cooling, from the deposi- 
 tion of mucus and salts ; it readily putrefies, exhaling a 
 peculiar offensive ammoniacal odour. This change is said 
 to be due to the presence of a peculiar albuminoid ferment, 
 Nefrozyomase (Bechamp). It may be prevented by filter- 
 ing, or by the use of a drop of crude phenic acid to the pint 
 of urine. The alkalinity of urine in cases of retention or 
 
 of chronic vesical disease is due to this cause, and must be 
 
 * 
 
 distinguished from that produced by ingesta, which give to 
 the secreted urine an alkaline reaction. 
 
 The following analysis gives the average composition 
 of human urine : 
 
 Water, 
 
 Urea, C 2 H 4 N 2 2 , 
 
 Kreatine, ...... 
 
 Kreatinine, 
 
 Urate of Potassa, 2KO,C 10 H 2 N 4 O 4 , ) 
 " " Soda, £ . 
 
 " " Ammonia, ) 
 
 Colouring Matter and Mucus, 
 Acid Phosphate of Soda, NaO,2HO,P0 5 , 
 Rhombic " " " 2NaO,HO,P0 5 , 
 
 " Phosphate of Potassa, 2KO,HO,P0 5 , 
 11 Magnesia, 3MgO,P0 5 , 
 " Lime, 3CaO,P0 5 , 
 
 93800 
 
 30-00 
 
 1.25 
 
 1-50 
 
 1-80 
 
 •30 
 
 1245 
 
 985-30 
 
 31 
 
362 MEDICAL CHEMISTRY. 
 
 985/30 
 
 Chlorides of sodium and potassium, . . T80 
 
 Sulphates of soda and potassa, . . . 6'90 
 
 1000-00 
 
 478. Urea, C2H4N2O2. — Constitutes nearly one-half of the 
 solid constituents of the urine. About 400 grains are dis- 
 charged daily ; the amount varies with the size, habits, etc. 
 of the individual, but is greater after the use of animal 
 food. It may be obtained by concentrating the fluid to a 
 syrupy consistence and adding nitric acid. The resulting 
 nitrate which deposits in crystals is decomposed by car- 
 bonate of lead, the urea dissolved out by alcohol, and 
 crystallised. 
 
 Prop. — Is in colourless, neutral prisms resembling 
 nitre in appearance ; quite permanent and soluble in their 
 own weight of cold water and in 45 parts cold and 2 of 
 boiling alcohol ; are insoluble in ether. Although neutral 
 in composition, it forms salts with the acids. Heated with 
 alkalies, it evolves ammonia. In contact with a ferment, it 
 breaks up into carbonate of ammonia, C2H 4 N 2 02+3HO = 
 2(NH 4 0,C0 2 ) ; the same effect is produced by long boil- 
 ing. It has been artificially formed, being identical (or 
 isomeric) with cyanate of ammonia, NH 4 0,CyO. It is 
 always present in the blood, but in small quantity, being 
 constantly eliminated by the skin and kidneys. If retained 
 in the blood, as in albuminuria, it causes coma and other 
 symptoms — Ursemia. It has been proposed to administer 
 urea as a diuretic. 
 
 Kreatin and Kreatine have been described (469). 
 
 Urates. 
 
 Of these the urate of soda, 2NaO,Ci H 2 N 4 O 4 , is by far 
 the most abundant ; the average amount discharged daily 
 being 25 grains. It forms the great part of the Chalk 
 stones seen in the joints of gouty people. It is sparingly 
 
ORGANIC CHEMISTRY. 363 
 
 soluble in cold water, more so in boiling water, which 
 deposits it again upon cooling. It dissolves readily in 
 alkaline solutions ; acids set free uric acid. The urates of 
 potassa and ammonia resemble the former. The acid urate 
 of ammonia, NHAHO^CwH^O,), forms the bulk of 
 the red deposits of the urine and of certain calculi. 
 
 4T9. Uric Acid, 2HO,C 10 H 2 lSr 4 O 4 . — Exists, if at all, in 
 very small quantity in healthy urine. It may be abun- 
 dantly obtained from the excrement of birds (guano) and 
 serpents, by boiling with caustic potassa, and neutralising 
 the resultant urate of potassa with HC1. 
 
 Prop. — A soft, white, inodorous, insipid, crystalline 
 powder, of a slightly acid reaction. Is soluble in 10,000 
 parts of cold and 1800 of boiling water ; insoluble in alco- 
 hol and ether. By the cautious addition of nitric acid, 
 and afterwards of ammonia, Murexide, Ci 2 H 6 N 5 8 , is ob- 
 tained ; it is of a beautiful purple, and when in mass, the 
 crystals reflect light of a metallic-green colour, like the 
 wing-cases of certain insects. It has been used as a dye, 
 but is now generally replaced by the aniline purple. 
 
 480. Hippuric Acid, HO,C 18 H 8 N0 5 . — Exists largely in 
 the urine of the Herbivora ; also in human urine, when Ben- 
 zoic acid has been taken, or under vegetable diet. 
 
 Prop. — It crystallises in long, slender, milk-white 
 prisms, of a bitter taste and acid reaction ; soluble in 400 
 parts cold water and in boiling alcohol. Forms Hippu- 
 rates. By boiling Hydrochloric acid is converted into 
 Benzoic acid and Glycocoll (468). When urine containing 
 Hippuric acid is allowed to putrefy, Benzoic acid is formed. 
 That of commerce is sometimes thus obtained. 
 
 The colouring matter of urine has been variously termed, 
 Urochrome, Uroxanthine, Urolnematine, Urohodine, Uro- 
 glaucine, Uropittin, Uromelanine, etc. But little is known 
 of its true character, and the statements of experimenters 
 
364 MEDICAL CHEMISTRY. 
 
 are very discordant. The odorous principle appears to 
 consist of a resinous matter and a volatile oil. It is some- 
 times absent in the beginning of Bright's disease. 
 
 481. The Phosphates of the urine are tribasic. The 
 acid Phosphate of soda, NaO,2HO,P0 5 , is probably formed 
 by the action of uric acid upon the rhombic phosphate, 
 2NaO,HO,P0 5 . The phosphates of lime and magnesia 
 are held in solution by the acid phosphate, and to a small 
 extent by chloride of sodium. When the urine becomes 
 alkaline, they are deposited. 
 
 482. Tests. 
 
 For Sugar. — 1. Trommer's. Add a few drops of a solu- 
 tion of sulphate of copper, then an excess of caustic 
 potassa ; hydrate of the protoxide of copper, CuO,HO, 
 will be precipitated. On boiling the mixture, this is in- 
 stantly reduced to red suboxide of copper, Cu 2 0, if grape- 
 sugar be present ; otherwise, to black CuO. Prolonged 
 boiling should be avoided, as other organic matters present 
 may then reduce the oxide of copper. Certain organic 
 matters interfere with this reaction ; they are removed by 
 mixing the urine with pure animal charcoal and filtering 
 (Dalton). 2. Fermentation. — A small portion of yeast 
 added to diabetic urine will cause vinous fermentation. 
 The evolved C0 2 may be collected and examined. Various 
 other tests have been proposed, but the above are sufficient. 
 
 For Albumen. — Nitric acid coagulates it, rendering the 
 liquid turbid or opaque ; the same effect is produced by a 
 heat of H0° or more. Both tests should be applied, and 
 when taken together are conclusive. 
 
 Bile is detected, after concentration, by Pettenkofifer's 
 test ; its colouring matter by nitric acid ; pus, spermato- 
 zoa, blood, etc., by the microscope. 
 
 483. Urinary Deposits and Calculi. 
 
 Lithic or Uric Acid. — The sediment is reddish; the 
 
ORGANIC CHEMISTRY. 365 
 
 urine strongly acid. The powder, heated on platinum foil 
 or mica, or before the blowpipe on charcoal, burns, leaving 
 no ash ; it is insoluble in water, soluble in caustic potassa 
 without evolution of ammonia, and, on the addition of 
 nitric acid, is precipitated in white crystals. By the cau- 
 tious addition of nitric acid, and, when cold, of ammonia, 
 the characteristic purple of murexide is developed. The 
 uric acid calculi are the most common. 
 
 Urate of Ammonia. — When heated, behaves as uric 
 acid ; when dissolved by caustic potassa, evolves ammo- 
 nia, and then reacts as uric acid. It is soluble in boiling 
 water, and precipitates again slowly on cooling. Calculi 
 of this form are rare. 
 
 Phosphate of Lime. — The calculi are white, smooth, 
 polished, and readily separate into layers. They are in- 
 fusible before the blowpipe, and dissolve in dilute nitric 
 acid. On the addition of ammonia, a gelatinous precipi- 
 tate, 3CaO,P0 5 , is formed, which may be redissolved in 
 acetic acid. To this add a drop of ferric chloride, a green- 
 ish-white precipitate of ferric phosphate will be formed ; 
 or add oxalate of ammonia, when a white precipitate of 
 oxalate of lime will fall. 
 
 Phosphate of Magnesia and Ammonia, Triple Phosphate, 
 MgO,NH 4 0,HO,P0 5 . — Calculi of this composition are 
 rare, but often the salt is found alternating with others. 
 The urine during its deposit is alkaline, and often offen- 
 sive ; an iridescent pellicle is seen on its surface. The cal- 
 culi are usually colourless, and often rough and crystalline 
 on the surface. Before the blowpipe it chars, exhales am- 
 monia, swells, and ultimately fuses. Heated with caustic 
 potassa, ammonia is evolved and magnesia precipitated; 
 the latter may be redissolved by acid and tested with 
 phosphate of soda and ammonia, 
 
 Fusible Calculus, is n mixture of the last-named with 
 
366 MEDICAL CHEMISTRY. 
 
 phosphate of lime, 3CaO,P0 5 . It is, next to uric acid, the 
 most common. The urine is neutral or alkaline during its 
 formation. The calculi are white, soft, and friable, resem- 
 bling chalk. It readily fuses before the blowpipe, leaving 
 a mixture of the tribasic phosphates of lime and magnesia. 
 The latter may be detected by the methods mentioned 
 above, and the presence of lime by the addition of oxalate 
 of ammonia to the solution in acetic acid. 
 
 Oxalate of Lime. Mulberry Calculus. — Oxalate-of-lime 
 deposits are frequent. They are seen under the micro- 
 scope in octohedral crystals, and more rarely in the dumb- 
 bell form. The calculi are usually rough and of a blood- 
 stained appearance; sometimes they are small and smooth, 
 forming the hemp-seed calculus. Before the blowpipe they 
 burn away to carbonate, and ultimately to caustic lime. 
 They are soluble without effervescence in dilute nitric and 
 hydrochloric acids; the solution is precipitated white by 
 ammonia. The residue, after exposure to the blowpipe 
 flame, if not too hot, dissolves with effervescence in dilute 
 hydrochloric acid, and is again precipitated by oxalate of 
 ammonia. 
 
 Cystine (CsHgNO^Sa) boiled with caustic potassa gives 
 evidence of the presence of sulphur on testing with nitro- 
 prusside of sodium. 
 
 Xanthine, C 10 H 4 N 4 O 4 , dissolves in caustic potassa, and 
 is reprecipitated by hydrochloric acid. When dissolved 
 in nitric acid, it leaves a yellow residue on evaporation, 
 which is not reddened by ammonia. The two last-named 
 calculi are verv rare. 
 
APPENDIX. 
 
 I. WEIGHTS AND MEASUEES. 
 
 Apothecaries' weight is used in compounding prescrip- 
 tions. Its pound, lb= 12 troy ounces, ^ = 96 drachms, 3; 
 = 5,796 grains. The scruple, 9j = 20 grains. Only the 
 grain and troyounce are used in the TJ. S. P. ; the latter 
 contains 480 grains. 
 
 Troy weight agrees in the pound, ounce, and grain with 
 apothecaries' weight, its pennyweight, dwt. = 24 grains. 
 
 Avoirdupois weight is the ordinary commercial weight. 
 Its pound, Ih = 16 oz. = 7000 grains. Its ounce contains 
 437*5 grains. The grains are equal in all these standards. 
 In the British Pharmacopoeia the avoirdupois pound and 
 its subdivisions are used. 
 
 One lb Troy=0822857 lb avoirdupois =13 oz., 725 grs. 
 
 One lb Avoirdupois=l-215227 lb troy=l lb, 2 3, 280 grs. 
 
 For Measures of Capacity, the wine gallon and its 
 subdivisions are used in the U. S. ; it contains 231 cubic 
 inches. The British Pharmacopoeia employs the Impe- 
 rial gallon of 277,274 cubic inches. The minim, rti, of the 
 former weighs *95 of a grain, of the latter -91. The former 
 contains 16 fluidounces to the pint, the latter 20. Only 
 the minim, fluidrachm, fluidounce, and pint are used in the 
 
 U. S. P. 
 
 (367) 
 
36# MEDICAL CHEMISTRY. 
 
 Wine Measure, ( U. S. P.) 
 
 60 minims = f^j = n^lx = 55*9 grs. water. 
 480 " = f^j = f^viii = 455*7 " 
 7,680 " =Oj = f^xvi= 1,291-2 " 
 61,440 " =Congj= Oviii =58,328-8 " 
 
 Imperial Measure, (B. P.) 
 
 60 minims = f 3j = i^lx = 54*6 grs. water. 
 480 « =f3j = f3viii= 431-5 " 
 9,600 ;.' =Oj= fjxx= 8,750 " 
 76,800 " = Congj = Oviii = 70,000 " " 
 
 THE DECIMAL SYSTEM, 
 
 Adopted in France and on the Continent, is used in this 
 country in scientific research. The standard of length is 
 the metre (7^,0 oV.uu o °f a quadrant of the earth's meridian), 
 which is equal to 39*3685 inches, or, roughly, about 3£ feet. 
 This, as well as the measures of capacity and weight, is 
 increased or divided decimally. The prefixes are deca (10 
 times), hecto (100 times), kilo (1000 times), and myria 
 (10,000 times); deci (y^), centi ( T £o), mille GoW)- The 
 kilometre is equal to about two-thirds of a mile. 
 
 The cubic decimetre is the unit of a capacity, and is 
 called a litre, and is equal to 1*765 imperial pints, or 2-1135 
 wine pints (the latter are used in the United States). The 
 weight of 1 litre of water, at 39*10°, is called a kilogramme, 
 and that of a millilitre of water a gramme= 15*434 graius. 
 The kilogramme is rather less than 2J lbs. avoirdupois. 
 The metrical pound of France is half a kilogramme. One 
 fluidonnce equals in capacity 29*53 cubic centimetres. 
 
APPENDIX. 
 
 869 
 
 Comparative Table of Decimal with Avoirdupois and 
 Apothecaries 1 (U. S.) Weights. 
 
 Name. 
 
 Equivalent 
 inGrammes. 
 
 Equivalent in 
 Grains. 
 
 Equivalent in 
 Avoirdupois. 
 
 lb. oz. gr. 
 
 Equivalent in 
 
 Apothecaries' 
 
 Weight, (U.S. P.) 
 
 
 
 
 lb. oz. dr. grs. 
 
 Milligramme = 
 
 •001 
 
 •0154 
 
 
 
 Centigramme = 
 
 •01 
 
 •1543 
 
 
 
 Decigramme = 
 
 •1 
 
 1-5434 
 
 
 1-5 
 
 Gramme = 
 
 1- 
 
 15-4340 
 
 
 15-4 
 
 Decagramme = 
 
 10- 
 
 154-3402 
 
 0i -45 
 
 2 34-0 
 
 Hectogramme = 
 
 100- 
 
 1543-4023 
 
 3£ 12-152 
 
 3 1 430 
 
 Kilogramme* = 
 
 1,000- 
 
 15434-0234 
 
 2 3i 12-173 
 
 2 8 1 14- 
 
 Myriagramme = 
 
 10,000- 
 
 154340-2344 
 
 22 0| 12- 
 
 26 9 4 20- 
 
 Comparison of Decimal Measures of Capacity with Wine 
 ( U. S. P.) and Imperial Measures. 
 
 Wine Measure. 
 
 Eng. Cubic Inches. ^^aTur?. ^ 
 
 Millilitre = -061028 = 16-2318 minims. 
 
 Centilitre =* -610280 = 
 
 Decilitre = 6-102800 = 
 
 Litre = 61*028000 = 
 
 Decalitre = 610-280000 = 
 
 Hectolitre = 6102-800000 
 
 Kilolitre = 61028-000000 
 
 2-T053 fluidrachms. 
 3-3816 fluidounces. 
 2-1135 pints. 
 2-6419 gallons. 
 
 Imperial Measure. 
 1 litre = 0-22017 galls., 0-88066 qts., 1-76133 pts. 
 Stere (cubic metre) = 220-16643 galls. 
 
 * Abbreviated, kilo. 
 
370 MEDICAL CHEMISTRY. 
 
 II. OF INCOMPATIBLES. 
 
 Substances which, when mixed, combine or mutually 
 decompose, are said to be chemically incompatible. 
 
 It by no means follows that the new bodies formed are 
 inert, and often two substances which are incompatible 
 are mixed with the object of extemporaneously forming a 
 third, as HgCl and KI. At other times, poisonous com- 
 pounds are formed by mixing those which are compara- 
 tively inert, as Hg 2 Cl and CaO,HO, or Hg 2 I and KI. 
 
 The following general rules will be of use to the begin- 
 ner in prescribing. 
 
 (1) Neutral salts containing the same base or the same 
 acid do not decompose each other. Thus we may mingle 
 the iodide and bromides of potassium, or these with the 
 chlorate of potassa ; or we may prescribe tartar emetic 
 with tartrate of potassa and soda. 
 
 (2) Substances are incompatible with their tests and 
 antidotes, as the very action of these depends upon 
 chemical change. Thus, baryta and lead compounds with 
 the soluble sulphates, tartar emetic with the vegetable 
 astringents. 
 
 (3) The free acids generally unite with the oxides and 
 decompose the carbonates ; the same is true of salts hav- 
 ing an acid reaction. 
 
 (4) The alkalies and alkaline earths and their carbonates 
 generally precipitate the salts of the heavy metals (243). 
 
 (5) The vegetable astringents precipitate most of the 
 salts of the heavy metals, the alkaloids and alumina. 
 Hence, vegetable and mineral astringents are chemically 
 incompatible. 
 
 (6) The iodides and bromides precipitate most of the 
 salts of the heavy metals; the chlorides, the lead, mer- 
 cury, and silver salts only. 
 
APPENDIX. 3U 
 
 The following preparations should either be given alone, 
 or, if combined, it should be with caution, as they are 
 readily decomposed: Lugol's, Donovan's, and Fowler's 
 solutions; lime-water, solution of potassa, hydrocyanic 
 and nitro-muriatic acids, tartar emetic, cyanide of potas- 
 sium, acetate of zinc, nitrate of silver. 
 
 III. ANTIDOTES OF THE MOEE COMMON 
 POISONS. 
 
 Note. — In all cases, the poison or its compound with the anti- 
 dote should be as speedily as possible removed from the stom- 
 ach, and its constitutional and local effects combated by general 
 measures. 
 
 Strong Acids. Alkaline carbonates, chalk, magnesia, 
 soap, etc. 
 
 Oxalic and Tartaric Acid and their soluble salts. Chalk, 
 whitewash. 
 
 Alkalies, caustic and carbonated. Weak acids (vin- 
 egar, lemon-juice), fixed oils. 
 
 Baryta, Lime, and Lead Salts. The soluble sulphates 
 (Epsom or Glauber's salt). 
 
 Alum. Alkaline carbonates. 
 
 Tin Salts. Magnesia, carbonate of soda, milk. 
 
 Zinc and Iron Salts. The alkaline carbonates, the 
 vegetable astringents. 
 
 Copper and Mercury Salts. Creasote ; albumen, milk. 
 
 Nitrate of Silver. Common salt. 
 
 Tartar Emetic. The vegetable astringents ; green tea. 
 
 Chloride of Antimony. Magnesia, carbonate of soda. 
 
 Arsenious Acid. Ferric hydrate j magnesia. 
 
 Fowler's Solution. Ferric salts. 
 
 Iodine. Boiled starch. 
 
 Phosphorus. Magnesia (?). 
 
372 MEDICAL CHEMISTRY. 
 
 Hydrocyanic Acid. Ammonia ; chlorine by the mouth 
 and inhaled (cautiously) ; ferric salts, followed by alkaline 
 carbonates ; cold douche to the spine. 
 
 Hepar Sulphuris. Sulphate of zinc. 
 
 The Alkaloids, Poisonous Mushrooms, and the organic 
 poisons generally. Tannic acid ; animal charcoal. 
 
 Stings rf Insects. Ammonia, locally. 
 
 Bites of Serpents, etc. Bibron's Antidote (367) ; 
 whiskey in large doses ; cauterisation of the wound ; a 
 cupping-glass or suction of the wound ; a ligature between 
 the wound and the trunk. 
 
 Bites of Rabid Animals, dissecting wounds, pustula 
 maligna. No known antidote. Use the general measures 
 indicated in the last paragraph. 
 
 Precautions in Medico-Legal Examinations for Poisons. 
 
 (1) The viscera to be examined should immediately 
 upon their removal be put into clean glass vessels — new, 
 if possible — and sealed; the seal is to remain unbroken 
 until the vessel is opened in the laboratory. 
 
 (2) All the tests, vessels, and implements employed in 
 the investigation must be absolutely pure and clean. The 
 glass and porcelain ware should be new. 
 
 (3) No one should have access to the laboratory in the 
 absence of the investigator. 
 
 (4) The preliminary operation of dialysis should always 
 be employed ; previously soaking the viscera, cut fine, for 
 48 hours in distilled water at 90°. The dialyser may be 8 
 inches in diameter, and the liquid should not be more 
 than one-half inch deep in it; the quantity of distilled 
 water in the outer vessel should be four times that in the 
 dialyser ; the operation may be continued for forty-eight 
 hours. This gives us the crystalline poison nearly free 
 from organic matter. 
 
APPENDIX. 373 
 
 (5) The suspected substance should be divided into 
 several equal portions, and never all employed in a single 
 trial. 
 
 (6) It is important to detect, if possible, the poison as 
 it was administered ; thus As0 3 , not merely the presence 
 of As. 
 
 (7) The tests should be so employed that, if more than 
 one poison be present, all may be detected. 
 
 (8) "When the poison has been administered some time 
 before death, it may not be found in the stomach, and the 
 other viscera must be examined. Yomited matters, etc. 
 should always be examined, if they can be procured. 
 
 IV. EEACTIONS FOE PKACTICE. 
 
 When the student is unable to work out the right-hand 
 number of the following equations, he will find it by refer- 
 ring to the paragraph indicated. 
 
 To make (181) : 
 
 KO,C10 5 (heated) = 
 To make H (186) : 
 
 Zn + HO,S0 3 =* 
 
 Zn+HCl= 
 To make NO (204): 
 
 NH 4 0,N0 5 (heated) = 
 To make N0 2 (203) : 
 
 Cu 3 +4(HO,N0 5 )=f 
 TomakeHO,NO 5 (201): 
 
 KO,N0 6 +2(HO,S0 3 )== 
 
 * The excess of water present is not regarded (1S6). 
 ■f HO,NO& is too strong for uso in practice ; 4HO,NOj is more accurate, 
 but the excess of water is omitted for the sake of simplicity. 
 32 
 
3?4 MEDICAL CHEMISTRY. 
 
 To make C0 2 (208) : 
 
 CaO,C0 2 + HO,S0 3 = 
 
 CaO,C0 2 +HCl= 
 To make HO,S0 2 (216): 
 
 2(HO,S0 3 ) + C = 
 
 2(HO,S0 3 )-fCu= 
 
 2(HO,S0 3 )-fS= 
 To make HO,S0 3 (approximate), (216): 
 
 2S0 2 +NG 4 = 
 
 2(FeO,S0 3 )= 
 To make HS (21?): 
 
 FeS-fHO,S0 3 = 
 
 SbS 3 -f3HCl= (364) 
 Hypophosphite (221) : 
 
 3(CaO,HO) + P 4 = 
 Phosphoric Acid (220) : 
 
 P 3 +5(HO,N0 5 )= 
 The 3 varieties of P0 5 with AgO,N0 5 (220) 
 
 AgO,N0 5 +NaO,P0 5 = 
 
 2(AgO,N0 5 )-f2NaO,P0 5 = 
 
 3(AgO,N0 5 ) + 2NaO,HO,P0 5 = 
 To make CI (223) : 
 
 2HC1+Mn0 2 = 
 To make HC1 (228) : 
 
 NaCl+HO,S0 3 = 
 To make a Chlorate (226) : 
 
 6(K0,H0)+C1 6 = 
 To make a Hypochlorite (22T): 
 
 2(CaO,HO)+Cl 2 = 
 Hydriodic Acid (233) : 
 
 I+HO+HS= 
 Hydrofluoric Acid (234) : 
 
 CaF+HO,S0 3 = 
 Hydrocyanic Acid (236) : 
 
 AgCy-fHCl= 
 
APPENDIX. 3?5 
 
 Caustic Potassa (248) : 
 
 KO,C0 2 +CaO,HO= 
 Iodide of Potassium (251) : 
 
 6(KO,HO) + I 6 = 
 Bromide of Potassium (252) : 
 
 FeBr+KO,C0 2 = 
 Acetate of Potassa (259) : 
 
 KO,C0 2 + HO,C 4 H 3 3 == 
 Carbonate of Soda (approximate) (265) : 
 
 NaCl+HO,S0 3 = 
 
 NaO,S0 3 +C 4 +CaO,C0 2 = 
 Labarraque's Solution (269) : 
 
 CaO,C10+CaCl+2(NaO,CQ 2 )== 
 Rochelle Salt (260) : 
 
 KO,HO,C 8 H 4 O w -f-NaO,C0 2 = 
 Ammonia : 
 
 NH 4 0,S0 3 +CaO,HO= 
 Sesquicarbonate of Ammonia (2*78) : 
 
 3NH 4 Cl+3(CaO,C0 2 )= 
 Precipitated Carbonate of Lime (288) : 
 
 CaCl+NaO,C0 2 = 
 Chloride of Calcium (281) : 
 
 CaO,C0 2 +HCl« 
 Hydrated Sesquioxide of Iron (314) : 
 
 Fe 2 3 ,3S0 3 4-3(NH 4 0,HO)«: 
 Ferric Chloride (316): 
 
 Fe 6 +9HC1+H0,N0 5 = 
 Ferrous Sulphate (321): 
 
 Fe+HO,S0 3 = 
 Ferric Sulphate (321) : 
 
 6(FeO,S0 3 ) + HO,N0 5 +3(HO,S0 3 )== 
 Ferric Nitrate (319): 
 
 Fe 2 +4(HO,N0 5 )= 
 Ferrous Carbonate (320) : 
 
 FeO,SO,4NaO,CO a =x 
 
376 MEDICAL CHEMISTRY. 
 
 Ferric Pyrophosphate (322) : 
 
 3(2NaO,P0 5 ) + 3(Fe a O s ,3SO.) 
 Subnitrate of Bismuth (343) : 
 
 Bi+4(HO,N0 5 )= 
 
 4(Bi0 3 ,3N0 5 )+nHO= 
 Oxides of Mercury (363) : 
 
 Hg 2 Cl+KO,HO= 
 
 HgCl+KO,HO= 
 Chlorides of Mercury (366) : 
 
 HgO,S0 3 + NaCl= 
 
 Hg 2 0,S0 3 -fNaCl= 
 Sulphate of Mercury (3U) : 
 
 Hg+2(HO,S0 3 )= 
 Nitrate of Silver (375) : 
 
 Ag 3 + 4(HO,N0 5 ) = 
 Nitro-benzole into Aniline (41 T) : 
 
 C 12 H 5 N0 4 + H 6 = 
 
 V. LIST OF MINERALS WITH THEIR CHEM- 
 ICAL COMPOSITION. 
 
 SELECTED FROM DANA'S MINERALOGY. 
 
 Note. — The name of a mineral is often applied to bodies of 
 different but isomorphous composition. When this is the case, 
 the replacing bases are written together in a parenthesis, or 
 one above the other, and the formula is necessarily more or less 
 indefinite. 
 
 Sassolin, B0 3 +3HO. 
 Heavy Spar, BaO,S0 2 
 Celestine, SrO,S0 3 . 
 Witherite, BaO,C0 2 . 
 
APPENDIX. 37 Y 
 
 Strontianite, SrO,C0 2 . 
 
 Periclase, MgO. 
 
 Brucite, MgO,HO. 
 
 Gypsum (alabaster), CaO,S0 3 4-2HO. 
 
 Anhydrite, CaO,S0 3 
 
 Calcite (calc-spar, satin-spar, dog-tooth spar), CaO,C0 2 . 
 
 Dolomite, CaO,C0 2 + MgO,(FeO)C0 2 . 
 
 Apatite, 3(3CaO,P0 5 ) + Ca(Cl,F). 
 
 Sapphire, Corundum, Emery, A1 2 3 . 
 Diaspore, Al 2 3 ,HO. 
 Gibbsite, Al 2 3 ,3HO. 
 Alunogen, Al 2 3 ,3S0 3 +18HO. 
 Turquoise, 2(A1 2 3 ),P0 5 + 5HO. 
 Cryolite, 3NaF,2Al 2 F 3 . 
 
 Quartz (chalcedony, carnelian, onyx, sardonyx, heliotrope, 
 
 amethyst), Si0 3 . 
 Opal, Si0 3 -f xHO. 
 Okenite, 3CaO,4Si0 3 +6HO. 
 Datholite, 3CaO,4Si0 3 -f 3(CaO,B0 3 )-f 3HO. 
 
 Talc, 4MgO,Si0 3 . 
 Meerschaum, MgO,Si0 3 -fHO. 
 Serpentine, 9MgO,4Si0 3 +6HO. 
 
 Wollastonite, 3CaO,2Si0 3 . 
 
 Edelforsite, CaO,Si0 3 . 
 
 Pyroxene, 3(CaO,MgO,PeO,MnO,ZnO)2Si0 3 . 
 
 Hornblende, 4(CaO,MgO,FeO,MnO,ZnO,)3Si0 3 . 
 
 Kaolin, Al 2 3 ,Si0 3 +2HO 
 
 Zeolites. 
 Heulandite, 3(CaO,Si0 3 ) + 4(Al 2 3 ,2Si0 3 ) + 18HO. 
 Stilbite, CaO,Si0 3 -f Al 2 3 ,3Si0 3 4-6HO. 
 32* 
 
818 MEDICAL CHEMISTRY. 
 
 Mesotype, (]S T aO,CaO,)Si0 3 +Al 2 3 ,Si0 3 +2HO. 
 Kyanite, 3Al 2 3 ,2Si0 3 . 
 Andalusite, 3Al 2 3 ,2Si0 3 . 
 Staurotide, 2(Al 2 3 ,Fe 2 3 )Si0 3 . 
 
 Feldspar Family. 
 
 Orthoclase, KO,Si0 3 -f Al 2 3 ,Si0 3 . 
 Albite, ]N T aO,Si0 3 +Al 2 3 ,Si0 3 . 
 Oligoclase, (CaO,NaO)Si0 3 +Al 2 3 ,2Si0 3 . 
 Labradorite, (CaO,NaO)Si0 3 +Al 2 3 ,Si0 3 . 
 Petalite, 3(LiO,NaO)4Si0 3 + 4(Al 2 3 ,4Si0 3 ). 
 Spodumene, 3(LiO,NaO)4Si0 3 +4(Al 2 3 ,2Si0 3 ). 
 
 Garnet, 3 \ FeO I Si0 3 + {j^qJ 1 Si0 3 . 
 
 Epidote, 3CaO,Si0 3 +2(Al 2 3 ,Fe 2 3 ,Si0 3 ). 
 Mica, KO,Si0 3 +4(Al 2 3 ,Fe 2 3 )Si0 3 . 
 Topaz, 2(Al 2 F 3 ) + 5(Al 2 3 ,Si0 3 ). 
 Sodalite, 3XaO,Si0 3 +3(Al 2 3; Si0 3 )-f NaCl. 
 
 (MgO ) 
 Spinel, -^ZnO }■ A1 2 3 . 
 
 (FeO,MgO) 
 Beryl, 3BeO,2Si0 3 +Al 2 3 ,2Si0 3 . 
 Chrysoberyl, BeO,Al 2 3 . 
 Zircon, Zr 2 3 ,Si0 3 . 
 
 The Heavy Metals. 
 
 Cassiterite, Sn0 2 . 
 
 Tin Pyrites, 2(Cu,Fe,Zn)S + SnS 2 . 
 
APPENDIX. 379 
 
 ise, VTi0 3 . 
 ■lie, ) 
 
 Rutile, 
 Anatase, 
 Brookite, 
 Molybdenite, MoS 2 . 
 
 Sphene, 3CaO,2Si0 3 +3Ti0 3 , 
 Wolfram, (FeO,MnO)W0 3 . 
 Pitchblende, TJO,U 2 3 . 
 TTr an ochre, U 2 3 . 
 
 Uranite, j ^| P0 5 +4U 2 3 ,P0 5 +16HO. 
 
 Antimony Glance, SbS 3 . 
 Arsenical Antimony, SbAs 3 . 
 Realgar, AsS 2 . 
 Orpiment, AsS 3 . 
 
 Pyrites, FeS,. 
 Marcasite, FeS 2 . 
 Magnetic Pyrites, Fe 7 S 8 
 Leucopyrrite, FeAs. 
 Mispickel, FeAs,FeS 2 . 
 
 Specular Iron Fe 2 3 . 
 
 Magnetite, FeO,Fe 2 3 . 
 
 Franklinite, (FeO,MnO,ZnO)(Fe 2 3 ,Mn 2 3 ). 
 
 Chromic Iron, (FeO,MgO)Cr 2 O s . 
 
 Brown Hematite, Fe 2 3 ,3HO. 
 
 Lepidokrokite, Fe 2 3 ,HO. 
 
 Spathic Iron, FeO,CO z . 
 Vivianite, 3(FeO),P0 5 +8HO. 
 Scorodite, Fe 2 3 ,As0 5 +4HO. 
 
 Manganblende, MnS. 
 Hauerite, MnS 5 . 
 
380 MEDICAL CHEMISTRY. 
 
 Pyrolusite, Mn0 2 . 
 Hausmannite, MnO,Mn 2 3 . 
 Braunite, Mn 2 3 . 
 Polianite, Mn0 2 . 
 Manganite, Mn 2 3 +HO. 
 Wad, MnOifcMnAiMnO,. 
 
 Rhodonite, 3MnO,2Si0 3 . 
 
 Millerite, NiS. 
 Syepoorite, CoS. 
 Copper Nickel, Ni 2 As. 
 Smaltine, CoAs. 
 Cobaltine, CoS 2 -j-CoAs. 
 
 Emerald Nickel, NiO,C0 2 +6HO 
 
 Blende, ZnS. 
 
 Greenockite, CdS. 
 
 Red Zinc Ore, ZnO. 
 
 Electric Calamine, 3Zn0,Si0 3 +l|H0. 
 
 Willemite, 3ZnO,Si0 3 . 
 
 Smithsonite, ZnO,C0 2 . 
 
 Galena, PbS. 
 
 Clausthallite, PbSe. 
 
 Plumbic Ochre, PbO. 
 
 Cerusite, PbO,C0 2 . 
 
 Anglesite, PbO,S0 3 . 
 
 Caledonite, (PbO,CuO)(S0 3 C0 2 ). 
 
 Pyromorphite, 3(3PbO,P0 5 ) + PbCl 
 
 Crocoisite, PbO,Cr0 3 . 
 
 Copper Glance, CuS. 
 
 Covelline, CuS 2 . 
 
 Erubescite, (CuFe)S + 3CuS + Fe 2 S 3 . 
 
APPENDIX. 381 
 
 Copper Pyrites, CuS-f Fe 2 S 3 . 
 
 Domeykite, Cu 3 As. 
 Algodonite, Cu^As. 
 Whitneyite, Cu 18 As. 
 
 Red Copper, Cu 2 0. 
 
 Tenorite, CuO. 
 
 Atacamite, CuCl-f CuO,HO. 
 
 Azurite, 2(CuO,C0 2 )+CuO,HO. 
 Malachite, CuO,C0 2 +HO. 
 
 Cinnabar, HgS. 
 Calomel, Hg a Cl. 
 
 Silver Glance, AgS. 
 Pyrargyrite, 3AgS,SbS 3 . 
 Proustite, 3AgS,AsS 2 . 
 Horn Silver, AgCl. 
 
 VI. GLOSSARY. 
 
 [Where no definition is given, it will be found by referring to 
 the paragraph indicated.] 
 
 A 
 
 Acetone. C 6 H 6 2 (406). 
 Acid. (149.) 
 Acrolein. C 6 H 4 0„. 
 
 Actinism. The chemical effects of light. 
 iEoLOPiLE. An instrument for producing a blast by 
 means of the vapour of a liquid heated in a close vessel. 
 /Erugo. Verdigris (330). 
 
382 MEDICAL CHEMISTRY. 
 
 JEthiops. Black sulphide of mercury. 
 
 Aerometer. Hydrometer (16). 
 
 Alembic. A form of still, used also in sublimation. 
 
 Alkarsin. Oxide of kakodyl. C 4 H 6 AsO (420). 
 
 Allotropic. A modification of a body, in which its phys- 
 ical but not its chemical properties differ, as phosphorus 
 and red phosphorus. 
 
 Alloy. Amalgam (242). 
 
 Amadou. Agaric, punk. 
 
 Amide. Amidogen, NH 2 . Also used as an adjective. 
 
 Amidon. Starch. 
 
 Amorphous. Without crystalline form. 
 
 Amphigen, Amphide. (184.) 
 
 Analysis. (173.) 
 
 Anhydrous. Free from water. 
 
 Anode. The + pole of a voltaic circuit. 
 
 Apple Oil. Yalerianate of amyl oxide (415). 
 
 Aqua Fontana. Aqua, IT. S. P. (191). 
 
 Aqua Fortis. Crude nitric acid. 
 
 Aqua Phaged^enica. Yellow wash (365). 
 
 Aqua Regia. Mtromuriatic acid. 
 
 Aqua Yitje. Brandy. 
 
 Argentine Flowers op Antimony. (Sb0 3 .) 
 
 Argillaceous. Containing clay. 
 
 Argols. Crude cream of tartar. 
 
 Atom. The ultimate portion of an elementary body. 
 
 Atomic Number. The specific gravity of a substance di- 
 vided by its equivalent. 
 
 Atomic Volume. The equivalent of a substance divided 
 by its specific gravity. 
 
 Atomic Weight. Equivalent (148 
 
 Atomiser. An instrument for diffusing the spray of 
 liquids (195). 
 
 A uripigmentum. Orpiment, AsS s . 
 
APPENDIX. 383 
 
 Lustral. The southern polarity of a magnet. 
 Lzote. Nitrogen. 
 Azotic Acid. Nitric acid. 
 
 B. 
 
 Baldwin's Phosphorus. Fused CaO,N0 5 . 
 
 Balsam of Sulphur. A solution of S in 01. olivse. 
 
 Bananna Essence. (415.) 
 
 Barilla. The ashes of sea-plants and of Salsola Soda. 
 
 Basacigen. Amphigen (184). 
 
 Base. A substance capable of combining with acids to 
 form salts. 
 
 Basic. (1) A substance having the properties of a base. 
 (2) A salt containing an excess of base. 
 
 Basyl. A term applied to the electro-positive group com- 
 prising hydrogen, the metals, and the quasi metals. 
 
 Battery. An apparatus for the accumulation of elec- 
 tricity. 
 
 Baume. The name of the inventor of a hydrometer ; it is 
 applied to distinguish the degrees, which are arbitrary. 
 
 Bestuchuf's Tincture. An ethereal solution of Fe 2 Cl 3 . 
 
 Bibron's Antidote. (361.) 
 
 Binary. A compound of two elements, as HO. 
 
 Bittern. The solution remaining after extracting NaCl 
 from sea-water. 
 
 Black Ash. Impure NaO,C0 2 . 
 
 Black Flux. Made by deflagrating cream of tartar with 
 one-half its weight of nitre ; contains carbon and KO, 
 C0 2 . 
 
 Black Lead. Plumbago, a variety of carbon. 
 
 Black Salts. The ley of wood-ashes evaporated nearly 
 to dryness. 
 
 Black Wash. Contains suboxide of mercury, Hg 2 0, 
 (363). 
 
384 MEDICAL CHEMISTRY. 
 
 Bleaching Powder. Calx chlorinata (291). 
 Blende. Native sulphide of zinc. 
 Blue Mass. Pilulse Hydrargyri (364). 
 Blue Ointment. Unguentum Hydrargyri (364). 
 Blue Yitriol, or Bluestone. Sulphate of copper. 
 Bole. An argillaceous earth. 
 Bone Ash (218). Bone black (206). 
 Borax. Biborate of soda. 
 Boreal. The northern polarity of a magnet. 
 Brass. An alloy of copper and zinc. 
 Brimstone. Roll sulphur. 
 British Barilla. Black ash. 
 British Gum. Dextrin (387). 
 Bronze. An alloy of copper and tin. 
 Brunswick Green. Oxychloride of copper. 
 Burnett's Disinfecting Fluid. Contains ZnCl. 
 Butter op Zinc, Antimony, and Bismuth. Their chlor- 
 ides. 
 
 C. 
 
 Cadet's Liquid. Alkarsin. 
 
 Calamine. Impure, native carbonate of zinc. 
 
 Calcareous Spar. Calcite, CaO,C0 2 . 
 
 Calcedony. Si0 3 . 
 
 Calcination. Exposure of substances to a high heat in 
 an open vessel, so that the oxygen of the air may com- 
 bine with their oxidisable constituents. 
 
 Calcined Mercury. HgO. 
 
 Calomel. Hg 2 Cl (366). 
 
 Camphene. Oil of turpentine. 
 
 Canton's Phosphorus. CaS. 
 
 Caput Mortuum. The residue after sublimation. 
 
 Caramel. Burned sugar. 
 
 Carbolic Acid. Phenic acid. 
 
APPENDIX. 385 
 
 Catalysis. The action of a body in promoting combina- 
 tion, or decomposition, by its presence, the body itself 
 remaining unchanged. 
 
 Cathode. The negative pole of a voltaic circuit. 
 
 Chalk. An amorphous carbonate of lime, CaO,C0 2 . 
 
 Chameleon Mineral. Manganate of potassa, KO,Mn0 3 . 
 
 Chemical Food. (330.) 
 
 Chloroid. The negative pole, or that connected with the 
 zinc plate of a battery. 
 
 Choke Damp. Carbonic acid. 
 
 Chrome Green. A mixture of chrome yellow and prus- 
 sian blue ; or sesquioxide of chromium. 
 
 Chrome Vermilion. Dichromate of lead, 2PbO,Cr0 3 . 
 
 Chrome Yellow. Chromate of lead, PbO,Cr0 3 . 
 
 Cinnabar. Native HgS. 
 
 Citrine Ointment. Ointment of the nitrate of mercury. 
 
 Clay. Impure silicate of alumina. 
 
 Clay Ironstone. Contains FeO,C0 2 . 
 
 Cohobation. Returning the distillate to the retort, and 
 repeating the operation. 
 
 Colcothar. Fe 2 3 . 
 
 Colloids. Jelly-like bodies. See Dialysis (128). 
 
 Colophony. Common resin, or rosin. 
 
 Combining Weight. Equivalent. 
 
 Condy's Solution. Contains permanganate of potassa. 
 KO,Mn 2 7 . 
 
 Common Salt. NaCl. 
 
 Copperas. Green vitriol, FeO,S0 3 -fTHO. 
 
 Corrosive Sublimate. HgCl. 
 
 Cream of Tartar. Bitartrate of potassa, KO,HO,T. 
 
 Crocus of Antimony, or Crocus Metallorum. Oxysul- 
 phide of antimony 
 
 Crocus Martis. Colcothar. 
 
 Crystals of Venus. CuO,C 4 H 3 3 -f HO. 
 
 83 
 
386 MEDICAL CHEMISTRY. 
 
 Crystalloids. See Dialysis (128). 
 Cubic Nitre. X aO.X0 5 . 
 
 Cupellation. See Analysis 173). 
 
 I). 
 
 Decantation, Decoction, and Displacement. (191.) 
 
 Decrepitation. The crackling of certain salts, when 
 suddenly heated. 
 
 Deflagration. A rapid and scintillating combustion. 
 It takes place in certain mixtures containing the nitrates, 
 or chlorates. 
 
 Deliquescent. A term applied to those substances which 
 attract moisture from the air. and liquefy. 
 
 Destructive Distillation. Dry distillation 
 
 Detonation. Rapid chemical action, accompanied by 
 flame and noise. 
 
 De Yalan gin's Arsenical Solution. Contains As0 3 in 
 dilute HC1. 
 
 Dew-point. The temperature at which the moisture of 
 the air begins to deposit. 
 
 Dialysis. (128.) 
 
 Diamagnetic. Repelled by both poles of a magnet. 
 
 Digestion and Displacement. (191.) 
 
 Dimorphous. Crystallising in two distinct systems. 
 
 Distillation. The process for separating a liquid from 
 a solid or less volatile liquid, by heating the mixed sub- 
 stances, and collecting the condensed vapour. 
 
 Donovan's Solution. Contains the iodides of arsenic 
 and mercury (367). 
 
 Dry Distillation. The process by which solid, or or- 
 ganic bodies, are subjected to heat in a close vessel. 
 
 Ductile. Capable of being drawn out into wire. 
 
 Dutch Gold. A species of brass. 
 
APPENDIX. 38T 
 
 Dutch Liquid. C 4 H 4 C1. 
 
 " White. Impure white lead. 
 
 E. 
 
 Eau De Javelle. A solution of chlorinated potassa. 
 
 Ebullition. The bubbling of a boiling liquid. 
 
 Educts. The proximate principles of which bodies are 
 supposed to be formed. 
 
 Effervescence. The bubbling due to the escape of gas 
 from a liquid. 
 
 Efflorescence. 1. A property peculiar to certain salts, 
 which, exposed to the air, crumble, #wing to the loss of 
 a portion of their water of crystallisation. 2. The crust 
 formed by the drying of certain salts upon the surface 
 of bodies, in which they are not visible. 
 
 El;eoptane. (448.) 
 
 Elayle. C 4 H 4 . 
 
 Electrode. The pole of a voltaic circuit. 
 
 Electrolysis. Voltaic decomposition. 
 
 Element. A simple, undecomposable substance. 
 
 Elixir of Yitriol. Aromatic sulphuric acid. 
 
 Elutriation. (191.) 
 
 Emerald Green. Schweinfurth green (356). 
 
 Epsom Salt. MgO,S0 3 + ?HO. 
 
 Equivalent. The proportional numbers, according to 
 which, or their multiples, bodies combine. 
 
 Eremacausis. The slow decay of organic substances not 
 containing nitrogen (380). 
 
 Essential Oils. Volatile oils. 
 
 Eudiometer. An instrument for ascertaining the amount 
 of oxygen in a gaseous body, by introducing an excess 
 of hydrogen, exploding the mixture, and noting the dimi- 
 nution of volume. 
 
388 MEDICAL CHEMISTRY. 
 
 Evaporation. Conversion into vapour, without ebul- 
 lition. 
 
 F. 
 Fermentation. (396.) 
 Filter. A porous substance used to separate a solid and 
 
 liquid by allowing the latter to pass through, while the 
 
 former is retained. 
 Fire Damp. Light carbonetted hydrogen (Marsh gas) 
 
 mixed with air. 
 Fixed Air. C0 3 . 
 Flint. Si0 3 . 
 
 Flowers or Antimony. Oxide of antimony, Sb0 3 . 
 Flowers of Benzoin. Benzoic acid. 
 Flowers or Sulphur. Sulphur sublimatum , U. S. P. 
 Flowers of Zinc. Oxide of zinc, ZnO. 
 Fluorescence. The property possessed by certain bodies, 
 
 as quinia salts, of rendering visible the dark chemical 
 
 rays (156). 
 Fluor Spar. CaF. 
 
 Foliated Earth of Tartar. KO,C 4 H 3 3 . 
 Fowler's Solution. Solution of the arsenite of potassa 
 
 (356). 
 French Chalk. Silicate of magnesia. 
 Fructose. Fruit sugar (392). 
 Fuming Liquor of Libavius. SnCl 2 . 
 Fusel Oil. Amylic alcohol, C 10 H 12 O 2 . 
 Fusible Calculus. (483.) 
 Fusible Metal. (342.) 
 Fusion. The passage of a solid into the liquid state. 
 
 G. 
 Galena. PbS. 
 
 Gas. An easily compressible elastic fluid. 
 Glass. (304.) 
 
APPENDIX. 389 
 
 Glass of Antimony. Roasted and fused tersulphide of 
 
 antimony, SbS 3 . 
 Glass of Borax. Fused borax, NaO,2B0 3 . 
 Glauber's Salt. NaO,SO 3 +10HO. 
 Glonoine. Mtro-glycerine (445). 
 Glucose. Grape sugar. 
 Glucoside. (395.) 
 Glycocoll. Sugar of gelatin. 
 Glycogene. Liver sugar. 
 Golden Sulphur. (365). 
 Goniometer. An instrument for measuring the angles of 
 
 crystals. 
 Goulard's Extract and Cerate. Contain subacetate of 
 
 lead. 
 Graphine. Carbon deposited in gas-retorts. 
 Graphite. Plumbago. 
 Green Yitriol. Copperas, FeO,S0 3 -|-THO. 
 Gypsum. CaO,S0 3 + 2HO. 
 
 H. 
 Halogen and Haloid Salt. (224.) 
 Harle's Solution. Contains arsenite of soda. 
 Hartshorn. Ammonia. 
 Hepar Sulphuris. Liver of sulphur (249). 
 Hoffmann's Anodyne. Spirit JEther. Go. (410). 
 Homberg's Pyrophyrus is made by heating potash alum 
 
 and charcoal to ignition. 
 Homologous Bodies. (384.) 
 Hydracid. Hydrogen-acid. An acid consisting of a 
 
 halogen united with hydrogen (224). 
 Hydrate. A combination of water. 
 Hydriodate. A salt of hydriodic acid. Is an incorrect 
 
 term; Iodide of the metal should be used. 
 Hydrometer. (11.) 
 
390 MEDICAL CHEMISTRY. 
 
 Hygrometer. An instrument for the determination of the 
 relative amount of moisture in the air. 
 
 I. 
 
 Ice Vinegar. Glacial acetic acid, HO,C 4 H 3 3 . 
 
 Imponderable. Without weight ; sometimes employed to 
 designate light, heat, electricity, and magnetism. 
 
 Incandescence. The glow of a highly-heated body. 
 
 Incineration. The reduction of a substance to ashes. 
 
 Incompatible. Incapable of being mixed without chemi- 
 cal change. 
 
 Infusion. (191.) 
 
 Inosite. Sugar of flesh. 
 
 Iodic JSther. Iodide of aethyl, C 4 H 5 I. 
 
 Ion. A body going to the positive (anode) or negative 
 (cathode) pole of a galvanic battery during electrolysis. 
 
 Iron Pyrites. Native sulphide of iron. 
 
 Isinglass. A variety of gelatin. 
 
 Isomeric Substances having the same composition, with 
 different properties. (384.) 
 
 Isomorphous. Substances having the same crystalline 
 form. (245.) 
 
 Ivory Black. Animal charcoal made by distilling ivory 
 scraps; is generally applied to bone black. 
 
 K. 
 
 Kelp. Ashes of sea-weeds; used as a source of iodine 
 
 and carbonate of soda. 
 Kermes' Mineral. (365.) 
 King's Yellow. Orpiment, AsS 3 . 
 
 Labarraque's Disinfecting Liquid. Solution of chlori- 
 nated soda. 
 
APPENDIX. 391 
 
 Lac Sulphuris. Precipitated sulphur. 
 
 Lactin. Sugar of milk. 
 
 Lake. A compound of alumina with an organic colouring 
 
 matter. 
 Lampblack. (206.) 
 
 Lapis Infernalis. Lunar caustic, AgO,N0 5 . 
 Laughing Gas. Nitrous oxide, NO. 
 Lead Water. Diluted Goulard's extract (350). 
 Ledoyen's Disinfecting Liquid. Solution of nitrate of 
 
 lead. 
 Levigation. The reduction of a substance to an impal- 
 pable powder, by rubbing on a moist slab with a flat 
 
 pestle, called a muller. 
 Limestone. A carbonate of lime, CaO,C0 2 . 
 Liquefaction. The conversion of a solid or a vapour 
 
 into liquid. 
 Litharge. Semivitrified oxide of lead, PbO. 
 Lithic Acid. Uric acid, C 10 H 4 N 4 O 6 . 
 Liver of Sulphur. Fotass. sulphuret. (249). 
 Lixiviation. The separation of the soluble portions of 
 
 a substance by causing water to filter through it. (191.) 
 Loadstone. The native magnetic oxide of iron, Fe 3 4 . 
 Lugol's Solution. Compound solution of iodine. 
 Lunar Caustic. Nitrate of silver. 
 Lute. An adhesive mixture for closing the joints of 
 
 apparatus, to prevent the escape of vapours, etc. 
 
 M. 
 
 Maceration. The long-continued soaking of a substance 
 
 in water at common temperatures 
 Macquer's Salt. KO,2HO,As0 5 . 
 Magistery of Bismuth. Subnitrate. 
 Magma. A molasses-like mass. 
 Magnesia Alba. Magnexiir carbonos. 
 
MEDICAL CHEMISTRY. 
 
 Malleable. Capable of being wrought under the ham- 
 mer. 
 
 Marble. Crystallised carbonate of lime. 
 
 Marine Acid. Muriatic acid. 
 
 Martial JSthiops. F 3 4 . 
 
 Massicot. Protoxide of lead, PbO. 
 
 Matrass. A glass vessel, with a long neck, used for 
 digestion. 
 
 Menstruum. A solvent. 
 
 Merc apt an. Alcohol in which the ox} r gen is replaced by- 
 sulphur, C 4 H 6 S 2 . 
 
 Metalloid. A non-metallic body. 
 
 Metameric Bodies. Those having the same empirical 
 with different rational formulae (384). 
 
 Microcosmic Salt. NaO,NH 4 0,HO,P0 5 . 
 
 Milk of Sulphur. Precipitated sulphur. 
 
 Milk op Lime. Whitewash. 
 
 Mineral Water. Water charged with carbonic acid; 
 also, natural waters holding medicinal substances in 
 solution (50). 
 
 Mineral Yellow. Oxychloride of lead 
 
 Minium. Red oxide of lead, Pb 3 4 . 
 
 Molecule. The ultimate portion of a compound body. 
 
 Monsel's Salt. Subsulphate of iron. 
 
 Mountain Blue. Azurite. 
 
 Mountain Green. Malachite. 
 
 Mulberry Calculus. Oxalate of lime (483). 
 
 Muriate. The compound of muriatic acid with a base. 
 Properly, the chloride of the metal, except in case of 
 the alkaloids. 
 
 Muriated Tincture of Iron. Tinct. Ferri Chlorid. 
 
 Muriatic Acid. Hydrochloric HC1. 
 
appendix. 393 
 
 N. 
 
 Naphtha. A natural, oily carbohydrogen, C 14 H I5 . 
 
 Nascent. Being liberated from combination (143). 
 
 Natron. Native carbonate of soda. 
 
 Neutral. 1. Possessing neither acid nor alkaline re- 
 action. 2. Having no tendency to combine with acids 
 or bases. 3. Applied to salts, where the number of 
 equivalents of the acid is equal to those of the oxygen 
 in the base. 
 
 Neutral Mixture. Solution of citrate of potassa (261). 
 
 Nitre. Saltpetre, KO,N0 5 . 
 
 Nitrile. A base derived from ammonia by the replace- 
 ment of three equivalents of H (425). 
 
 0. 
 
 Obsidian. Volcanic glass. 
 
 Ochre. A native mixture of clay and scsquioxide of iron. 
 
 Oil of Vitriol. HO,S0 3 . 
 
 Orpiment. AsS 3 . 
 
 Osmose. The diffusion of liquids through porous septa 
 (132). 
 
 Oxyacids. Oxygen acids ; acids, the electro-negative con- 
 stituent of which is oxygen. 
 
 Oxychloride. The combination of the chloride and oxide 
 of a metal. 
 
 Oxysalt. The union of an oxygen acid with a base con- 
 taining oxygen. 
 
 Oxysulphide. The combination of the oxide and sulphide 
 of a metal! 
 
 P. 
 Packfong. A variety of German silver. 
 Particle. A minute portion of matter. 
 Pearl Ash. Impure carbonate of potassa. 
 
394 MEDICAL CHEMISTRY. 
 
 Pearl Powder. Subnitrate or oxychloride of bismuth. 
 
 Pearson's Salt. 3NaO,As0 5 +24HO. 
 
 Picric Acid. Carbazotic acid (453). 
 
 Pinchbeck. A species of brass. 
 
 Plaster of Paris. Calcined sulphate of lime. 
 
 Platinum, Black and Sponge. Finely divided platinum. 
 
 Plumbagine. Carbon deposited in gas retorts. 
 
 Plumbago. Native carbon. 
 
 Potash. Impure carbonate of potassa. 
 
 Powder op Algaroth. Oxychloride of antimony, 2Sb0 3 , 
 
 SbCl 3 , + HO. 
 Precipitate. The insoluble compound formed on mixing 
 
 certain incompatible bodies. 
 Precipitatum per se. HgO, made by direct oxidation. 
 Preston Salts. Carbonate of ammonia with essential 
 
 oils. 
 Prussic Acid. Hydrocyanic acid, HCy. 
 Prussian Blue. Ferrocyanide of iron, Fe 4 Cfy 3 . 
 Pseudomorph. A mineral body crystallised in the form 
 
 that belongs to another mineral. 
 Puceoxide of Lead. Pb0 2 . 
 
 Purgative Mineral Water. Liq. Magnes. eitrat. 
 Putty Powder. Stannic acid, Sn0 2 . 
 Pyrites. Native sulphide of iron or copper. 
 Pyro. A prefix to distinguish a body altered by heat from 
 
 the one from which it is derived. 
 Pyroligneous Acid. Impure acetic acid, obtained by the 
 
 distillation of wood. 
 Pyrophorous. A powder capable of igniting sponta- 
 neously in the air. 
 Pyroxilic Spirit. Wood alcohol, C 2 H 4 2 (405). 
 Pyroxyline. Gun-cotton (386). 
 
APPENDIX. 395 
 
 Quaternary. A compound containing four elements. 
 Quevenne's Iron. Ferrum redactum. 
 Quicklime. Caustic lime, CaO. 
 Quicksilver. Mercury. 
 
 R. 
 
 Radical Vinegar. Glacial acetic acid, HO,C 4 H 3 3 . 
 Reagent. An agent employed as a chemical test, or in 
 
 chemical operations. 
 Realgar. Red sulphide of arsenic, AsS 2 . 
 Red Precipitate. Red oxide of mercury, HgO. 
 Red Prussiate of Potash. Ferricyanide of potassium. 
 
 K 3 Cfdy. 
 Red Tartar. Argols. 
 Regulus op Antimony. Metallic antimony. 
 Rochelle Salt. Tartrate of potassa and soda, KO, 
 
 NaO,T. 
 Roche and Roman Alums are varieties of potash alum. 
 Rock Crystal. Quartz. 
 
 Roman Vitriol. Sulphate of copper, CuO,S0 3 -f 6HO. 
 Rouge. Sesquioxide of iron ; carthamine. 
 Rust. Oxide of iron ; generally, hydrated sesquioxide. 
 
 S. 
 
 Saccharum Saturni. Acetate of lead, PbO,C 4 H 3 3 . 
 Sal Acetosella. Binoxalate of potassa, KO,2C 2 3 . 
 Sal Aeratus. Bicarbonate of potassa, KO,HO,2C02. 
 Sal Alembroth. Double chloride of mercury and am- 
 monium, NH 4 Cl,HgCl. 
 Sal Ammoniac. Chloride of ammonium, NH 4 C1. 
 Sal Diureticus. Acetate of potassa, KO,C 4 H 3 3 . 
 Sal Enixum. Bisulphate of potassa, KO,HO,2S0 3 . 
 
396 MEDICAL CHEMISTRY. 
 
 Sal Gummosum. A mixture of borax and cream of tartar. 
 
 Sal Mirabile. Sulphate of soda, NaO,S0 3 -f 10HO. 
 
 Sal Perlattjm. Phosphate of soda, 2NaO,HO,P0 5 . 
 
 Sal Prunelle. Fused nitre, KO,N0 5 . 
 
 Sal Volatile. Ammonise, Carbonas, 2NH 4 0,3C0 2 . 
 
 Salogens. Salt radicals. 
 
 Salt. The union of an acid with a base, or of a halogen 
 
 with a metal. 
 Salt Radicals. The electro-negative group: Oxygen, 
 
 sulphur, the halogens. 
 Salt of Lemons and Salt of Sorrel. Binoxalate of 
 
 potassa, KO,2C 2 3 . 
 Salt of Phosphorus. Microcosmic salt, NH 4 0,NaO,HO, 
 
 P0 5 . 
 Salt of Tartar. Pure carbonate of potassa, KO,C0 2 . 
 Saltpetre. Nitrate of potassa, KO,N0 5 . 
 Saturation. 1. The solution of a body in a liquid until 
 it refuses to dissolve more. 2. The neutralisation of a 
 base by an acid, or of an acid by a base. 
 Scheele's Green. Arsenite of copper, 2CuO,As0 3 . 
 Schweinfurth Green. 3(CuO,As0 3 )-f CuO,C 4 H 3 3 (356). 
 Sedative Salt. Boracic acid, B0 3 . 
 Seidlitz Powders. (260.) 
 
 Seignette's Salt. Rochelle salt, KO,NaQ,T (260). 
 Similor. A species of brass. 
 Smalt. Glass coloured by oxide of cobalt. 
 Soda Ash. Crude carbonate of soda. 
 Soda Saltpetre. Nitrate of soda, NaO,N0 5 . 
 Soluble Tartar, Neutral tartrate of potassa, 2KO,T. 
 Solution. The union of a solid, liquid, or gas, with a 
 
 liquid, in which it disappears or becomes liquid. 
 Speculum Metal. An alloy of copper and tin. 
 Speiss. Impure, fused arsenide of nickel. 
 Spelter. Commercial zinc. 
 
APPENDIX. 39? 
 
 Spirit of Hartshorn. Spirit of ammonia. 
 
 Spirit op Mindererus. Solution of acetate of ammonia, 
 NH 4 0,C 4 H 3 3 . 
 
 Spirit op Nitre. Spirit of nitrous ether. 
 
 Spirit op Salt. Muriatic acid, HC1. 
 
 Spirit op Wine. Alcohol, C 4 H 6 2 . 
 
 Stearoptane. (448.) 
 
 Sublimation. The process of separating a volatile solid 
 from one more fixed, by the application of heat. The 
 condensed body is called a Sublimate, the residue 
 Caput mortuum. 
 
 Substitution. The replacement of an element or com- 
 pound by another. 
 
 Sugar op Lead. Acetate of lead, PbO,C 4 H 3 3 . 
 
 Sulphuret. Sulphide. 
 
 Sulphuretted Hydrogen. Hydrosulphuric acid, HS. 
 
 Sulphuric JEther. Ether, C 4 H 5 0. 
 
 Sulphur Acid. An acid in which sulphur is the electro- 
 negative element. 
 
 Sulphur Base. A sulphide capable of combining with a 
 sulphur acid. 
 
 Sulphur Lotum. Washed sulphur. 
 
 Sulphur Salt. The union of a sulphur acid and sulphur 
 
 base. 
 Sulphur Yivum. Impure sulphur, Horse Brimstone. 
 Supercarbonate. Bicarbonate. 
 
 T. 
 
 Tartar Emetic. Tartrate of antimony and potassa, KO, 
 
 Sb0 3 T. 
 Tasteless Purging Salt. Phosphate of soda, 2XaO, 
 
 HO,P0 5 . 
 Ternary. A compound containing three elements. 
 34 
 
398 MEDICAL CHEMISTRY. 
 
 Thenard's Blue. A compound of alumina and oxide of 
 
 cobalt. 
 Tincal. Native borax, NaO,2B0 3 . 
 Tincture. A solution in alcohol. When in ether, is called 
 
 an Ethereal Tincture. 
 Tombac and Tutenag. Species of brass. 
 Trituration. Rubbing in a mortar. 
 Trona. Native sesquicarbonate of soda, 2NaO,3C0 2 . 
 Turnbull's Blue. Ferricyanide of iron, Fe 3 Cfdy. 
 Turner's Cerate. Calamine cerate. 
 Turner's Yellow. Oxychloride of lead, PbCl+VPbO. 
 Turpeth Mineral. Yellow sulphate of mercury, 3HgO, 
 
 S0 3 . 
 Tutty. Impure oxide of zinc. 
 
 TJ. 
 
 TJmber. A silicate of alumina, with oxides of iron, man- 
 ganese, and water. 
 
 V. 
 
 Yallet's Mass. Pil. Ferri carb. contain FeC^CO* 
 Yerd Antique. Precious serpentine. 
 Yerdigris. Impure subacetate of copper. 
 Yerditer, CuO,C0 2 +HO,C02. 
 Yermilion. Artificial HgS. 
 
 W. 
 
 White Arsenic. Arsenious acid, As0 3 . 
 
 White Lead. Carbonate of lead. 
 
 White Precipitate. Chloramide of mercury, HgCl,Hg 
 
 NH 2 . 
 White Yitriol. Sulphate of zinc, ZnC^SQs-f-VHO. 
 
APPENDIX. 399 
 
 Whiting. Prepared chalk, CaO,C0 2 . 
 
 Wood Naphtha and Wood Spirit. Methyl alcohol, 
 
 C 2 H 4 2 . 
 Wood Vinegar. Pyroligneous acid. Impure acetic acid. 
 
 Y. 
 
 Yellow Prussiate of Potash. Perrocyanide of potas- 
 sium, K 2 Cfy. 
 
 Yellow Wash. Made by adding corrosive sublimate to 
 lime water ; hydrated protoxide of mercury is formed. 
 
 Z. 
 
 Zaffre. Impure oxide of cobalt. 
 
 Zincoid. The positive pole of a battery ; that connected 
 
 with the copper or platinum plate. 
 Zinc White. Oxide of zinc, ZnO. 
 Zymosis. Decomposition by example (160, 396). 
 
 the end 
 
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