Digitized by the Internet Archive in 2016 https://archive.org/details/anintroductiontoOOmute AN INTRODUCTION PHARMACEUTICAL AND MEDICAL CHEMISTRY. AN INTRODUCTION TO PHARMACEUTICAL AND MEDICAL CH EM ISTRY. ARRANGED ON THE PRINCIPLE OF THE COURSE OF LECTURES ON CHEMISTRY, AS DELIVERED AT THE SOUTH LONDON SCHOOL OF PHARMACY. BY DR. JOHN MUTER, M.A., F.C.S., F.I.C, PRESIDENT OF THE SOCIETY OF PUBLIC ANALYSTS. PUBLIC ANALYST FOR LAMBETH, NEWINGTON, SOUTHWARK, BERMONDSEY, ROTHERHITHE, THE WANDSWORTH DISTRICTS, AND THE BOROUGH OF TENTERDEN. AUTHOR OF “A KEY TO ORGANIC MATERIA MEDICA,” ETC., ETC. (SECOND EDITION— RE-ARRANGED.) * Eonijon : PUBLISHED BY W. BAXTER, SECRETARY, AT THE OFFICES OF THE SCHOOL, KENNINGTON CROSS, S.E. ; AND lain'IaiielpDia : PUBLISHED BY P. BLAKISTON, SON & CO., 1012, WALNUT STREET. 1880. Butler & Tanner, The Selwood Printing Works, Frome, and London. PREFACE TO THE SECOND EDITION. In issuing the second edition of this work, I determined to collect all the theoretical and descriptive portion together in one part, and the practical portion in another part, so that if deemed advisable it could either be issued in one or could be divided and bound in two volumes, one for home use and the other for the laboratory. Each portion is thus kept distinct with its own index so as to facilitate ready refer- ence, and I sincerely trust that in its altered form the work will at once prove more handy to students, and be received with the same favour as that already extended to the “first ” and “revised ” editions. As before, I am indebted to my friend Mr. Joseph Ince for his as- sistance in proof reading and in compiling the copious indices. J, M. Winchester House, Kennington, London, S.E. . .'.p ' i • . A . ; - m r- ^ a>‘- . V r . TABLE OF CONTENTS CHAPTER I. Introduction. 1-6. PAGE I. Matter and its Various States OF Existence. 1. Solid 2 . Liquid 3 . Gaseous . i. Extension . ii. Impenetrability. iii. Indestructibility iv. Porosity . V. Inertia PAGE vi. Divisibility ... 2 II. Analysis and Synthesis. Elements and Symbols 2 III. Preliminary Notice of Four Typical Elements 3-6 I. Oxygen ..... 3 2. Hydrogen ..... 4 3- Nitrogen ..... 4 4- Carbon ..... 5-6 2 2 CHAPTER II. Theories of Chemical Action and the Modes of Expressing the Same by Formulse and Equations. 7-25. I. Laws of Combination . . 7-9 i. Quantitative Law ... 7 ii. Law of Multiples ... 7 iii. Law of Reciprocal Proportions 7 VII. Salts, and Mode of For- mulation VIII. Summary of Theories IX. Empirical, Molecular, and Rational or Constitu- II. Chemical Action , 9 TiONAL Formula . III. Combination of Gases BY X. Chemical Equations Volume . 10 XI. Practical Application OF IV. Atomicity 12 Equations to the Cal- V. Graphic Formula . 12 culation OF Quantities VI. Radicals. Acids. Bases. 14 BY Weight and Volume CHAPTER HI. Simple Basylous Radicals. Sources, Isolation, and Characters. I. Malleability . 26 Class II. Dyads . 2. Ductility . 27 Calcium . - . 3. Fusibility . 27 Strontium Table of Alloys . 28 • Barium .... Class I. Monads . . 28-34 Magnesium Hydrogen . . 28-30 Zinc .... Non-Metallic Compounds of Cadmium Hydrogen . 31 Copper .... Lithium . 31 Mercury .... Ammonium . 31 Class HI. Triads. Sodium . 32 Gold .... Potassium 32 Class IV. Tetrads Silver 33 Aluminium 15-17 17 18 20-23 23-25 34-39 34 34 35 35 36 37 37 38 39- 40 39 40- 45 40 Vlll TABLE OF CONTENTS. PAGE Manganese .... 40 Iron ..... 41 Cobalt 42 Nickel 43 Cerium ..... 43 Tin 43 Platinum .... 44 PAGE Lead 45 Class V. Pentads. . ... 46-48 Bismuth ..... 46 Antimony .... 46 Class VI. Hexads ... 48 Chromium .... 48 CHAPTER IV. Fluorine and Chlorine. 49-67. Fluorine .... Hydrogen Fluoride {Hydroflu oric Acid) . Calcium Fluoride Chlorine Metallic Chlorides Hydrogen Chloride {Hydr chloric Acid) Ammonium Chloride Sodium ,, Potassium ,, Argentic ,, Calcium , , Barium ,, ' Magnesium , , Zinc , , Cupric , , Cuprous ,, Mercurous ,, {CalotJiel) Mercuric ,, {Corrosive Sublimate). Ammonio-Mercuric Chloride Auric Chloride Stannic , , Aluminium ,, Manganous , , Stannous ,, Ferrous ,, Ferric ,, 49 49 49 50-52 52-62 52 54 54 54 54 55 55 56 56 56 56 57 5? 58 59 59 59 59 59 60 60 Cobaltous Chloride . Cobaltic jj • Nickelous . Platinic j, . Plumbic • Antimonious . Bismuthous Chloride and Oxy- chloride Chromous Chloride . Chromic ,, Perchrornic . Compounds of Chlorine with Oxygen .... Hypochlorous Anhydride Hydrogen Hypochlorite . Metallic Hypochlorites . Soda Chlorata Calx ,, . . . Chlorous Anhydride Hydrogen Chlorite . Perchloric Oxide Metallic Chlorates . Hydrogen Chlorate {Chloric Acid) Potassium • Perchloric Acid Potassium Perchlorate Euchlorine .... 61 61 61 61 61 61 62 62 62 62 63 63 63 64 64 64 65 65 66 66 67 67 67 CHAPTER V. Bromine and Iodine. 68-78. Bromine 68 Metallic Bromides ... 69 Hydrogen Bromide {Hydrobromic Acid) ..... 69 Ammonium Bromide ... 69 Potassium ,, . . . 70 Argentic ,, . . . 70 Ferrous ,, . . . 70 Compounds of Bromine with Oxygen 70 Hydrogen Bromate {Bromic Acid) 70 Iodine 7i» 72 Metallic Iodides ... 72 Hydrogen Iodide {Hydriodic Acid) 72-76 Ammonium ,, ... 73 Sodium ,, ... 73 Potassium ,, ... 73 Cadmium ,, ... 74 Cuprous Iodide Mercurous ,, . . . Mercuric ,, . . . Ferrous ,, . . . Plumbic 5, . . . Compounds of Iodine with Oxygen Hydrogen lodate {Iodic Acid) Potassium lodate. Hypo-Iodous Acid Hypo-Iodites .... Periodic Acid .... Periodates Compounds of Iodine with Chlorine . . . . Iodine Mono-Chloride. ,, Trichloride 74 74 75 75 76 76-78 77 77 77 77 78 78 78 78 78 TABLE OF CONTENTS. IX CHAPTER VI. Oxygen and its Compounds with Simple Basylous Radicals. 79-105. PAGE PAGE Oxygen • 79-81 Potassium Manganate . 95 Ozone 81 Sodium ,, Permanganic Anhydride 95 Hydrates and Oxides . 82 95 Hydrogen Oxide (Water) 83 Potassium Permanganate 95 Hydric Peroxide . 84 Sodium , , Cobaltous Hydrate 96 Lithium Hydrate . 85 96 ,, Oxide 85 Nickelous ,, 96 Ammonium Hydrate . 85 Ferrous ,, 96 Sodium ,, 86 Ferric ,, 96 Potassium ,, Sodium and Potassium Oxides 86 Ferrous Oxide 98 87 Ferric ,, 98 Argentic Oxide . 87 F errum Redactum 98 Calcium Hydrate . 88 Ferroso- Ferric Oxide . 98 ,, Oxide 88 Stannous Hydrate 99 Strontium Hydrate 89 ,, Oxide . 99 ,, Oxide . 89 Plumbic Hydrate 100 Barium Hydrate . 89 „ Oxide . 100 ,, Oxide 89 Triplumbic Tetroxide . 100 Baric Peroxide Magnesium Hydrate 89 90 Plumbic Anhydride, or Plumbic Peroxide ..... 100 ,, Oxide 90 Bismuthous Hydrate . lOI Zinc Hydrate 90 , , Oxide i Bismuthic ,, lOI ,, Oxide .... Cupric Hydrate . 91 102 91 Antimonious , , 102 Cuprous Oxide . 91 Antimonic ,, 102 Cupric ,, „ Peroxide . 92 Chromium . 102 92 Chromic Hydrate 103 Mercurous Oxide. 92 Chromous Oxide . 103 Mercuric >, • 92 Chromic . Chromoso-Chromic Oxide 103 Aluminium Hydrate . 93 103 „ Oxide 93 Chromic Anhydride 103 Manganous Hydrate . 94 Potassium Chromate . 104 ,, Oxide Manganoso- Manganic Oxide 94 ,, Dichromate. Argentic Chromate 104 94 104 Manganic Oxide . 94 Plumbic ,, 105 ,, Peroxide 94 Bismuthous , , Perchromic Anhydride. 105 ,, Anhydride . . ' 95 105 CHAPTER, VII. Sulphur and its Compounds. 106-134. Sulphur . . . . . ,, Precipitatum . Metallic Sulphides . Hydrogen Sulphide {Sulphuretted Hydrogen) . . . . Hydrogen' Analytical Reactions . Ammonium Sulphide . Potassium ,, Argentic ,, Zinc . Cadmium ,, Cuprous ,, . . ' . Cupric ,, Mercurous „ Mercuric ,, Vermilion Manganous Sulphide . Ferrous ,, . . . Ferric „ . . . „ Disulphide 106 Cobaltous Sulphide 114 107 Nickelous ,, 114 109-116 Stannous ,, 114 Stannic ,, 114 109 Bismuthous ,, 114 no Antimonious ,, 115 III Antimonic ,, 116 III Compounds of Sulphur WITH II 2 Oxygen 116-119 II 2 Sulphurous Anhydride . . I16 II 2 Hydrogen Hyposulphite II7 II 2 ,, Thiosulphate II7 II3 Sodium ,, II8 II3 Hydrogen Dithionate . . I18 II3 ,, Trithionate . II9 II3 ,, Tetrathionate II9 II3 ,, Pentathionate Sulphuric Anhydride . II9 II3 II9 II4 Metallic Sulphates . I2O-I33 1 14 Hydrogen Sulphate I 20 -I 22 X TABLE OF CONTENTS. PAGE PAGE Ammonium Sulphate . 122 Manganic Sulphate 130 Sodium ,, 123 Ferrous ,, 130 Sodium Hydrogen Sulphate. 123 Ferric ,, 131 Potassium Sulphate 123 Ferric Potassium Sulphate 131 ,, Hydrogen Sulphate Argentic Sulphate 124 Ammonium ,, 131 124 Plumbic ,, 132 Calcium ,, . . 124 Bismuthous ,, 132 Strontium ., 125 Chromic ,, 132 Barium ,, . . 125 Chromic Potassium ,, 132 Magnesium ,, . . 125 Hydrogen Pyrosulphate 133 Zinc ,, . . 126 Cupric ,, . . 126 Compounds of Sulphur WITH Ammonium Cupric Sulphate 127 THE Halogens I33-I34 Tetr-Ammonio Cupric ,, 127 Sulphur Monochloride. 133 Mercurous ,, 128 Thionyl Chloride. 133 Mercuric „ 128 Sulphuryl ,, Bromine Monochloride 134 Aluminium Ammonium ,, 128 134 Aluminium ,, 129 Iodine Monosulphide . 134 CHAPTER VIII. ' Carbon. 135-154. Carbon Compounds of Carbon with Hydrogen . . ‘ . Methane . ... . Ethene Ethine Coal Gas Compounds of Carbon with Oxygen .... Carbonous Oxide. Carbonic Anhydride . Metallic Carbonates. Lithium Carbonate Ammonium ,, Ammonium -Hydrogen Carbonate Tetr- Ammonium Carbonate. Carbamates. . . . . Sodium Carbonate „ Hydrogen Carbonate Tetra- Sodium ,, Potassium ,, 135, 136-139 ■ 138 138 138 138 139-140 139 140 141-153 141 141 142 142 142 143 144 145 146 ,, Hydrogen „ Tetra- Potassium ,, Argentic ,, 147 147 147 Calcium Carbonate ,, Hydrogen Carbonate Barium „ Strontium ,, Magnesium ,, ,, Oxycarbonate . Zinc Carbonate .... ,, Oxycarbonate Plumbic Carbonate ,, Oxycarbonate. Cupric Carbonate Mercurous ,, . . . Ferrous ' „ . . . Bismuth Oxycarbonate. Compounds of Carbon with the Halogens Carbon Tetrachloride . ,, Tetrabromide . ,, Tetra-Iodide . Carbonyl Chloride Compounds of Carbon with Sulphur . . . . Carbon Disulphide 148 149 149 149 150 150 150 151 151 151 152 152 152 153 153 153 154 154 154 154 154 CHAPTER IX. Boron, Silicon, Seleninm, and Tellnrium. 155-159. Boron 155 Hy&xogQTi ’QoxzX.t^Boracic Acid) . 155 Borax 155 Silicon 156 Hydrogen Silico-fluoride {Hydro- fiuosilicic Acid) . . . 156 Silicic Anhydride {Silica) . . 157 Selenium 158 Tellurium ' I 59 TABLE OF CONTENTS. XI CHAPTER X. Nitrogen. 160-184. Nitrogen Compound of Nitrogen with Hydrogen . . . . Ammonia . . . . . PAGE i6o 162 162 Compounds of Nitrogen with Oxygen Nitrous Oxide .... Nitric ,, . . . . Nitrous Anhydride Ammonium Nitrite Potassium ,, . . . Argentic ,, . . . Cupric ,, . . . Potassium Cobaltous Nitrite Nitric Peroxide .... ,, Anhydride Hydrogen Nitrate {Nitric Acid) . Nitro-Hydrochloric Acid 163 163 164 165 165 165 166 166 166 166 167 167 168 Metallic Nitrates . . 169-174 Ammonium Nitrate . . . 169 Sodium ,, ... 169 Potassium ,, . . . , 169 Argentic ,, . . . 170 Argent- Ammonium Nitrate . . 171 Calcium Nitrate . . . 171 Strontium ,, . . . 172 Barium ,, ... 172 Cupric ,, ... 172 Mercurous ,, . . . 172 Mercuric ,, . . . 172 Perric „ ... 173 Cobaltous ,, . . . 173 Bismuthous ,, . . . 174 Bismuthous Oxynitrate. . . 174 Plumbic Nitrate . . . . 174 PAGE Compounds of Nitrogen with THE Halogens ' 175 Nitrogen Chloride 175 ,, Bromide 175 , , Iodide 175 Compounds of Nitrogen Carbon . WITH 175 Cyanogen . 175 Metallic Cyanides . 176-179 Hydrogen Cyanide {Hydrocyanic Acid) . ... . 176 Potassium Cyanide 178 Mercuric ,, 178 Argentic ,, 178 Metallic -Ferrocyanides 179, 180 Hydrogen Ferrocyanide 179 Potassium ,, 179 Potassium Ferrous Ferrocyanide . 180 Ferric Ferrocyanide 180 Metallic Ferricyanides 181 Ferricyanogen 181 Hydrogen F erricyanide 181 Potassium ,, 181 Ferrous ,, Metallic Nitroprussides 181 182 Sodium Nitroprusside 182 Metallic Cyanites . 182 Hydrogen Cyanite 182 Ammonium ,, 183 Metallic Thiocyanates 183 Hydrogen Thiocyanate 183 Ammonium ,, 183 Potassium ,, 184 Ferric ,, 184 Compounds of Cyanogen Halogens WITH 184 CHAPTER XL Phosphorus. 185-196. Phosphorus 185 Compounds of Phosphorus with Hydrogen . . . . 187 Hydrogen Phosphide . . . 187 Compounds of Phosphorus with THE Halogens . . . 188 Phosphorus Chloride . . . 188 Phosphoric „ . . . 188 Phosphorus Oxychloride . . 188 Compounds of Phosphorus with Oxygen .... 189-196 Hydrogen Hypophosphite . . 189 Sodium ,, . . 189 Potassium ,, . . 189 Calcium ,, . . 190 Barium ,, . . 190 Phosphorous Anhydride . . 190 Hydrogen Phosphite . . . 190 Phosphoric Anhydride . . 190 Hydrogen Phosphate ( Ortho- phosphoric Acid) . . . 19 1 Hydrogen Pyrophosphate . . 192 ,, Metaphosphate . . 192 Diammonium Hydrogen - Phos- phate 193 Disodium Hydrogen-Phosphate . 193 Ammonium and Sodium Hydro- gen-Phosphate. . . . 193 AmmoniumMagnesium-Phosphate 194 Tricalcium Phosphate . . . 194 Dicalcium Hydrogen- Phosphate . 195 Monocalcium Hydrogen - Phos- phate 195 Triferrous Phosphate . . . 195 Ferric ,, . . . 196 Bismuthous ,, . . . 196 Ammonium Phospo- Molybdate . 196 Compounds of Phosphorus with Sulphur .... 196 Xll TABLE OF CONTENTS. CHAPTER XII. Arsenic. 197-206. PAGE Arsenic 197 Hydrogen Arsenide 197 Arsenious Anhydride . 198 Cupric Arsenite .... 200 Ferric Oxyarsenite 201 Arsenic Anhydride Hydrogen Arseniate {Arsc 7 iic 201 Acid) . . . . .. 202 Diammonium Hydrogen Arseniate 203 Disodium Hydrogen Arseniate . 203 Triargentic Arseniate . Calcium and Barium Hydrogen 204 Arseniate .... 204 Magnesium Ammonium Arseniate 204 PAGE Zinc Arseniate .... 204 Tricupric Arseniate . . . 204 Triferrous ,, . . . 205 Compounds of Arsenic with THE Halogens . . . 205 Arsenious Chloride . . . 205 ,, Iodide . . . 205 Compounds of Arsenic with Sulphur . . . 205-206 Arsenic Disulphide . . . 205 Ammonium Hyposulpharsenite . 206 Arsenious Sulphide . . . 206 Ammonium Sulpharsenite . . 206 CHAPTER XHI. Hydrocarbons and their Derivatives. 207-221. I. Homologous and Isologous Allylene or Propine 214 Seriesof Hydrocarbons 208 Crotonylene . 214 II. Unsaturated Hydrocarbon VII. Hydrocarbons. Radicals (Basylous) 208 Type, CnHon-e- Typical Formulae 209 (Aromatic Series) 215 HI. Oxygenated Hydrocarbon Benzene .... 215 Radicals (Acid) 210 Nitro-Benzine 215 IV. Hydrocarbons. Cymene . '. . . 216 Type, CnH2n+2> Cinnamein .... 216 or Paraffins 211 Naphthalene 216 V. Hydrocarbons. Anthracene 216 Type, CnH2N, or Olefines 213 VIII. Terpenes. VI. Hydrocarbons. General Formula, C^oHig 217 Type, CnH2n-2. Oleum Terebinthinae . . 217 (Acetylene Series) 214 Camphor . , . . 218 Acetylene or Ethine 214 Olea 2 19-221 CHAPTER XIV. The Alcohols. 222-236. I. Monatomic Alcohols . 229 Methyl Hydrate (Series CnH,n+iHO.) . , . 224 Ethyl Hydrate .... 225 Spiritus Rectificatus . 226 Spiritus Tenuior .... 227 Absolute Alcohol 227 Butyl Hydrate .... 228 Amyl Hydrate .... 228 Hexdecyl Hydrate 229 Ceryl Hydrate .... 229 Myricyl Hydrate. 229 II. Monatomic Alcohols. Series CnHjn-iHO 230 Allyl Alcohol .... 230 III. Diatomic Alcohols, or Gly- cols. (CuH2n)".2lIO 230 Methylene Hydrate . . . 230 Ethylene Hydrate . . . 230 Propylene Hydrate . . . 231 Tetrylene or Butylene Hydrate . 231 IV. Triatomic Alcohols. Series CnH2n-i.3HO . 231 Glyceryl Hydrate [Glycerm) . 231 Nitro- Glycerin . . . . 233 V. Hexatomic Alcohols . . 233 Mannityl Hydrate . . . 233 VI. Alcohols. Aromatic Series. Phenols .... 234 Phenyl Hydi'ate {Carbolic Acid) . 234 Creasote ..... 235 Benzyl Hydrate .... 236 Cinnyl Hydrate . . . . 236 Camphyl Hydrate, or Camphol . 236 TABLE OF CONTENTS. xiii CHAPTER XV. Carbo-Hydrates. 237-248. PAGE I. Amyloses. Carbo - Hydrates. General Formula CeH^oOs 238 Cellulose 238 Starch 239 Inulin ..... 243 Glycogen ..... 240 Dextrin ..... 240 Gums. Arabin 241 Cerasin ..... 241 PAGE Bassorin ..... 241 II. Saccharoses. Sugars. Gene- ral Formula C12H22O11 241 Sucrose {Cane Sugar). 242 Lactose {Milk Sugar) . 244 Sugars. General Formula C6H12O6 Dextrose {Glucose) 245 Levulose ..... 247 Fruit Sugar .... 248 CHAPTER XVI. Organic Acids. 249-286. Acids of the Fatty Series, HI. Diatomic Acids . . 264-269 CnH2n02 . . 250-261 Hydrogen Lactate 264 Formic Acid 251 Argentic ,, . ... 265 Hydrogen Acetate {Acetic Acid) 251 Zinc ,, ... 265 Vinegar .... 252 Mercurous „ ... 265 Acetates .... 254 Ferrous ,, ... 265 Ammonium Acetate . 254 Hydrogen Oxalate {Oxalic Acid). 265 Sodium ,, 254 Ammonium Oxalate . 267 Potassium ,, 254 Ammonium Hydrogen Oxalate . 267 Argentic ,, 255 Sodium Oxalate. 267 Calcium ,, 255 Potassium Dioxalate . 268 Zinc ,, 255 „ Quadr-Oxalate . 268 Cupric ,, . ■ 255 Calcium Oxalate 268 ,, Oxyacetate 256 Cerium ,, ... 268 ,, Aceto-Met-Arsenite . 256 Plumbic ,, 268 Aluminium Acetate 256 Hydrogen Succinate . 269 Ferric ,, 256 Ammonium ,, 269 Plumbic ,, 257 Ferric ,, 269 ,, Oxyacetate . 257 IV. Triatomic and Bibasic Hydrogen Propionate . 258 Acids . ... 270 ,, Butyrate 258 Hydrogen Malate 270 „ Valerianate {Valenamc V. Triatomic and Tribasic Acid) .... 258 Acids .... 270 Sodium Valerianate .* 259 Aconitic Acid .... 270 Zinc ,, 259 Hydrogen Meconate {Meconic Cupric „ 259 Acid) 270 Bismuthous ,, 260 VI. Tetratomic Acids . 271 -280 Hydrogen Caproate . 260 Hydrogen - Tartrate {Tartaric ,, CEnanthylate 260 Acid) 271 ,, Caprylate . 260 Ammonium Hydrogen-Tartrate . 273 , , Pelargonate 260 ,, Tartrate . 273 , , Rutate 260 Sodium- Hydrogen Tartrate . 274 ,, Laurate 260 Sodium Tartrate .... 274 ,, Myristate . 260 Potassium Hydrogen- Tartrate 274 ,, Palmitate . 260 ,, Tartrate . . 274 ,, Stearate 261 ,, Sodium Tartrate. 275 Arachidic Acid . 261 Calcium Tartrate 27 ^ Cerotic . 261 Cupric Tartrate .... ^ i D 275 Melissic „ . . . 261 Ferric Potassium Tartrate . 276 I. Acids of the Series Plumbic Tartrate 276 CnH2n— 2O2 . . 262-264 C Antimonious Tartrate 276 Hydrogen Oleate 262 ( Antimonic Tartrate 276 Ammonium . 262 Potassium Antimonyl Tartrate Sodium „ . 262 ( Tartar Emetic) 276 Potassium „ . 263 Hydrogen Citrate 277 Calcium . 263 Lithium ,, 278 Plumbic . 263 Ammonium ,, . . . 278 XIV TABLE OF CONTENTS. PAGE Sodium Citrate . . 278 Potassium ,, . . . 278 Calcium ,, . . . 279 Magnesium ,, . . . 279 Cupric ,, . ... 279 Ferric ,, ... 279 Ferri et Ammonise Citras . . 279 ,, ,, Quinise Citras . . 280 Bismuthous Citrate . . . 280 VII. Aromatic Acids . . 281-286 Hydrogen Benzoate . . . 281 Ammonium Benzoate . PAGE 282 Potassium „ 282 Calcium ,, 282 Ferric ,, . . 282 Hydrogen Cinnamate . . . 283 Cinnyl ,, Hydrogen Salicylate . . . 283 . . 283 ,, Gallate Ferric ,, . . • 284 . . 285 Veratria . ,, 285 Tannin . . 285 Hydrogen Pyrogallate. 286 CHAPTER XVII. Ethers. 287-301. I. Haloid Ethers . . 287-291 (a) Monatomic . . . 287 Methyl Chloride . . . 288 ,, Iodide . . . 288 „ Bromide . . • . 288 [b) Diatomic .... 288 Methene Chloride . . 289 Ethene Chloride . . . 289 (<:) Triatomic .... 289 Methenyl Chloride ( Chloro- forni) .... 289 ' , Methenyl Bromide {Bromo- form) .... 290 Methenyl Iodide {Iodoform) . 291 II. Simple Ethers . . 291-293 Methyl Oxide {Methylic Ether) . 292 Ethyl Oxide {Ether) . . . 292 III. Compound Ethers . 293-301 {a) Fatty Series . . . 294 Ethyl Nitrite {Nitrous Ether) 294 ,, Acetate {Acetic Ether) 295 „ Nitrate . . . 296 ,, Sulphate . . . 296 „ Hydrogen - Sulphate {Sulphovinic Acid) . . 296 Ethyl Sulphite . . . 296 ,, Hydrogen- Sulphite, or Ethyl Sulphonic Acid . 296 Ethyl Sulphides . . . 297 ,, Hydrosnlphide {Mercap- tan) 297 Ethyl Phosphates . . . 297 ,, Phosphites. . . 298 ,, Borate and Silicate . 298 ,, Oxalate, Tartrate, and Citrate .... 298 Amyl Nitrite ... 298 ,, Acetate . . . 298 ,, Valerianate. . . 299 Cetyl Palmitate . . . ^ 299 Melissyl Palmitate . . 299 {b) Series (CnH2n)"R'2 . . 299 (c) Glycerides .... 299 Glyceryl Trioleate . 300 ,, Tri-Palmitate {Fai- mitin) .... 300 Glyceryl Tristearate {Stearin) 300 {d) Aromatic Ethers . . . 301 Phenyl Hydrogen - Sulphate {Sulphocarbolic Acid) . 3 ^^ Zinc Sulphocarbolate . . 301 CHAPTER XVIII. Aldehyds, Ketones, Phosphines, etc. 302-308. I. Aldehyds . . . 302-306 (u:) From Monatomic Alcohols . 302 (b) Fatty Series .... 302 Acetic Aldehyd . . . 302 Acetal ..... 303 Trichloraldehyd {Chloral) . 303 Chloral Hydrate . . . 303 {c) Acrylic Series . . . 304 Acrylic Aldehyd . . . 304 Crotonic ,, . . . 305 Trichlorocrotinic {Croton Chloral) .... 305 {d) Aromatic .... 305 Benzoic Aldehyd {Oil of Bitter Almonds) .... 305 Cinnamic Aldehyd . . 306 II. Ketones .... 306 Acetone 307 III. Phosphines, Arsines, and Stibines . . . • . . 307 Arsen-Dimethyl {Cacodyl) . . 307 IV. Organo-Metallic Bodies . 308 TABLE OF CONTENTS. XV CHAPTER XIX. Ammonia Derivatives. 309-327. PAGE PAGE I. Amides . . . . 309-312 Quinine Lactate 318 I. Monamides 309 Cinchonine [Cinchonia) 318 Primary Monamides 309 ,, Sulphate . 318 Formamide 310 ,, Hydrogen-Sulphate 318 Acetamide . . . 310 ,, Hydrochlorate . 318 Secondary Monamides 310 Quinidine ( Quinidia) . 319 Alkalamides 310 Cinchonidia 319 Tertiary Monamides . 310 Quinicine . . . . 319 2. Diamides 310 Cinchonicine . . • 319 Urea . . . . 310 Quinamine . . 319 3. Triamides 3II Alkaloids of Opium . 320-322 4. Amic Acids 3II Morphine [Morphia) . 320 Carbamic Acid . 3II „ Hydrochlorate 321 II. Amines . . . , 312-314 ,, Acetate 321 I. Monamines 312 Apomorphine [Apomorphia) 321 Ethylamine 313 Codeine [Codeia) 321 Diethylamine 313 Narcotine [Narcotia) . 322 Triethylamine . 313 Narceine [Narceid) 322 Phenylamine [Aniline) 313 Thebaine ( Thebaia) 322 2, Diamines 314 Meconine [Meconia) . 322 III. Volatile Alkaloids . 315 Alkaloids of Nux Vomica 323-327 Conine [Conia) . 315 Strychnine [Strychnia). 323 Nicotine [Nicotia) 315 Brucine [Brucia) 324 Caffeine [Theine, Tkeia) 316 Atropine [Atropid) 324 Sparteine [Sparteia) . 316 Beberine [Beberia) 325 IV. Fixed Alkaloids 316-327 „ Sulphate 325 Quinine [Qtiinia) 316 Aconitine [Aconitia) . 325 Quinine Sulphate 317 Veratrine ( Veratria) . 326 ,, Hydrogen-Sulphate 317 Jervine [Jervia) . 326 , , Hydrochlorate 317 Delphinine [Delphinia) 327 „ Hypophosphite . 318 Hyoscyamine [Hyocyamia) . 327 ,, Phosphate . 318 Emetine [Emetia) 327 CHAPTER XX. / The Griucosides. 328-337. Amygdalin 328 zEsculin .... 334 Cathartic Acid . 329 Arnicin . . * . 335 Arbutin . . . . 329 Chiratin .... 335 Salicin .... 330 Gelatin . . . * . 335 Crocin . . . . 330 Chondrin .... 335 , Elaterin . . . . 331 Pectin ’ . 335 Digitalin . . . . 331 Smilaciii or Parillin, 336 Guaiacin . . . . 332 Saponin .... 336 Glycyrrhizin 332 Santonin . . . . 333 The Aloins .... 336, 337 Convolvulin 334 Barbaloin .... 336 Jalapin . . . . 334 Socaloin or Zanaloin . 336 Colocynthin 334 Nataloin . ‘ . • 337 CHAPTER XXI. Albuminous and Pigmentary Bodies. 338-348. I. Albuminous Bodies Albumen Casein Fibrin Haemo or Hsemato-Globin Ptyalin and Pancreatin Pepsin Gluten 338-342 Legumin "... 338 II. Pigmentary Substances 339 Brown .... 340 Black .... 340 Blue .... 341 Green .... 341 Yellow .... 342 Red 343-348 343 343 343 • . 345 346 346 XVI TABLE OF CONTENTS. APPENDIX A. 349. Showing the Quantities of the various Ingredients (in parts by weight) to be added to one hundred parts of Alcohol to produce the chief Artificial Fruit Essences. APPENDIX B. 350. Table showing the Relation between the Density and Flashing Point of Paraffin Oils. ■ CHAPTER I. INTRODUCTION, L MATTER AND ITS VARIOUS STATES OF EXISTENCE. The subject of Chemistry is matter. By matter we mean everything which we see, feel, taste, or smell ; in short, anything which affects our senses. All matter exists in one of three states : — 1. Solid. — In which condition the ultimate particles or molecules are closely pressed together, and which is consequently the least porous and mobile form of matter, requiring, as a rule, to be cut or pressed so as to suit its size to any particular vessel in which it is desired to be placed. 2. Liquid. — In this state, the molecules are not so closely pressed, but can move freely about each other. Liquids are consequently more porous than solids, and of themselves assume the form of any receptacle into which they are introduced. 3. Gaseous. — Matter in the gaseous state is the most porous, and the molecules appear to have so little attraction for each other that they would become altogether dissociated, were it not for the pressure exercised by . surrounding bodies. The integral particles of gases are considered as being in continual movement. One solid body placed against another refuses to mix with it except by continual pulverization ; liquids mix more readily, with a slight amount of stirring ; while gases mix of their own accord. This property takes place by a fixed law, called the law of diffusion,, which is usually stated as follows : — Gases mix with each othef' of their own accord at a rate which is inversely proportioned to the square 7 'oot of their relative densities. Thus, the density of hydrogen being i, and oxygen 16, the square roots are respectively i and 4; and by inverse proportion, we see that hydrogen will diffuse itself in oxygen four times as quickly as the latter will mix with hydrogen. Gases also possess in an eminent degree the property of elasticity ; that is, they may be reduced to a smaller volume by pressure, but immediately on its removal they will assume their original bulk. The greater the pressure the less the volume of gas \ and the less fhe pressure the greater the volume. There are certain general properties which all matter shares in common. 1. Extension. — By this we mean that every body occupies a certain bulk, or that it must have a certain degree of length, breadth, and thickness, irrespective of its form or of how that form may be changed. 2. Impenetrability, — which signifies that no two bodies can occupy the same space at the same time. 3. Indestructibility. — We may change and decompose matter as we please, but we cannot destroy the minutest particle. B 2 INTRODUCTION. 4. Porosity. — All bodies, no matter how hard in appearance, are nevertheless porous ; consequently we can alter and modify their shape and size by heat, pressure, and other means. 5. Inertia. — By this term is indicated the fact that matter is incapable of either setting itself in motion or arresting its own progress when in movement. 6. Divisibility. — All substances are capable of separation into minute particles, and the extent to which this division may be carried with some compounds is remarkable. For instance, a pail of water holding two gallons may be distinctly coloured with one grain of indigo dis- solved in sulphuric acid, and yet each grain of the water in the vessel will only contain ^ grain of the pigment. Here the question arises. Is matter really infinitely divisible, or is there a point at which divisibility ceases ? , The latter view is in the present state of science most commonly held to be the correct hypothesis ; all matter being conceived as the aggregate of certain inappreciable particles named molecules, which in turn are derived from the union of infinitely more minute portions of elements called atoms. The atom of an element is thei^efore held to mean the smallest quantity capable of existence^ and is considered absolutely indivisible. Matter in the condition in which it is perceptible to our senses is said to be in the free state ; and since, previously to its detection by our organs of perception, it must consist of myriads of atoms, it is believed that atoms cannot exist m this free state., but that they must be combined with other atonis of the same or of a different element in order to form molecules, which alone can assume that condition. If, therefore, we wish to express that an element, — hydrogen, for example, — is in a free state, we must not write simply H, but Hg ; thus intimating that at least two atoj?is have coalesced to produce a molecule capable of existing m the free state. II. ANALYSIS AND SYNTHESIS. ELEMENTS AND SYMBOLS. With regard to matter, the chemist makes two inquiries; ist : What are its ingredients ? and 2nd : Having isolated such constituents, how are they to be combined so as to reproduce the original substance ? The process by which an answer is obtained to the former question is called analysis ; and to the latter, synthesis. Analysis is the chemical pulling to pieces of a substance in order to discover its component parts ; whilst synthesis is the building up of a com- pound from its ingredients. For example : If we take a piece of alum and submit it to analysis, we can prove that it contains oxides of aluminium and potassium, sulphuric anhydride, and water. If we then take these substances and separately analyze them, we find that they in turn consist of aluminium, potassium, sulphur, oxygen, and hydrogen ; but a further attempt to analyze this last group ends in failure. We have reduced our alum to certain in- gredients which defy our best efforts to ascertain of what they are composed. The result of analysis, therefore, has been to acquaint us with a certain number of simple bodies which we call elements P by the mutual combination of which all matter is formed. When we use the term “ simple bodies,” the student must understand that the elements are not really to be so considered in the fullest sense of the word. They are only so regarded, because our present state of knowledge fails to enable us to discover their ultimate composition. ELEMENTARY BODIES,— OXYGEN 3 There are about sixty-five of these simple bodies or elements known ; but as many of them have no practical or commercial use, the pharmacist has really to do with only about thirty-eight. By universal consent, each element is represented by an appropriate letter, or a combination of letters, so that chemists adopting this arrangement may invariably understand what element is meant by a written symbol. The con- ception of expressing simple bodies by means of symbols is by no means modern, but dates back to the days of the alchymists. Thus, gold was represented by a rough drawing of the sun ; while an equally uncouth sketch of a half-moon denoted silver. The names of the elements at present are purely arbitrary, and have been bestowed by the discoverers from some fancied special property : such as the designation hydrogen, derived from two Greek words, signifying “to beget water.” The following is a list of the elements used in Pharmacy with their symbols, the committing of which to memory is the first duty of the learner :* Elementary Bodies. Symbols. Elementary Bodies. ' Symbols. Aluminium . Al. Iron (Ferrum) Fe. Antimony ^[Stibium) . . Sb. Lead i^Plu7nbuni ) . Pb. Arsenic . As. Lithium • • • • L. Barium . Ba. Magnesium . Mg. Bismiith . Bi. Manganese Mn. Boron . B. Mercury {^Hydrargyrum^ . Hg. Bromine . Br. Nitrogen • • N. Cadmium . Cd. Oxygen . 0. Calcium . Ca. Phosphorus P. Carbon . C. Platinum • • • • Pt. Cerium . Ce. Potassium {Kaliimi) . K. Chlorine . Cl. Silver {Arge)itum) Ag. Chromium . Cr. Sodium {Natrium ) . Na. Copper (^Cuprum) . . Cu. Sulphur • • • • S. Gold (Aurum) . . Au. Tin {Stannum) Sn. Hydrogen . H. Zinc • • t ^ • Zn. Iodine • . I. III. PEELIMINARY NOTICE OF FOUE TYPICAL ELEMENTS. All the elementary bodies will be duly considered, and carefully described in their proper places, but meantime, the student may familiarize himself with a few preliminary facts about the most common elements as follows : — I. Oxygen. — Take a few crystals of potassium chlorate, and having gently rubbed them to powder in a clean mortar, place the powder in a perfectly clean and dry test-tube, and apply the heat of a Bunsen burner. The contents of the tube will fuse and then the liquid will be seen to effervesce, and a colourless gas will be given off. This is the element oxygen in the free state, and its presence may be shown by holding the end of a piece of stick in the gas flame until it is well burned, then blowing out the flame and holding the incandescent point just over the mouth of the tube. Oxygen being the great supporter of the combustion of organic bodies, the spark will glow * The entire list of elements will be found in the Appendix. 4 INTRODUCTION. with great brilliancy, and once more burst into flame. It is to the fact of oxygen being a constituent of the air we breathe, that we owe the support of our life, which is, after all, only a slow combustion. When we inhale air into our lungs the oxygen passes into the blood, and unites with some of the carbon to form carbonic acid gas, which is then exhaled. Oxygen is colourless and inodorous ; and, although it supports the combustion of carbonaceous matter, it will not itself in- flame in contact with the air. It can only be reduced to a liquid under an immense pressure, and even then only appears as a fog in the tube when the pressure is suddenly released so as to produce intense cold. 2. Hydrogen. — Place a few fragments of zinc in a small bottle, add a little water and then some sulphuric acid, when a powerful effervescence will take place, and a colourless gas will, be evolved. This is the element in question in a free state. Now procure a cork which will well fit the neck of the bottle, and by means of a round file, make a hole through it. Into this hole a short glass tube, drawn out so as to form a jet, is tightly fitted, and the bottle is then closed by the cork so that the gas issues from the jet, and when the whole of the air has been expelled from the bottle^ cautiously apply a light. Perfect safety may be ensured by first collecting portions of the gas in a small test-tube placed upside down over the end of the jet. Apply a light to ascertain the presence of the gas. Faraday recommended that the bottle should not bb too large, so that the atmospheric air might easily “ be swept out of the space above the water. The hydrogen will take fire and burn with a very feebly luminous bluish flame. This flame depends on the union of the hydrogen with the oxygen of the air to form steam, which fact can be proved by holding a cold glass shade over the flame, when the steam produced will be condensed into water and form in drops on the glass. The flame of hydrogen, although feebly luminous, is exceed- ingly hot, as may be seen by holding a fine platinum wire in it, when it will become intensely incandescent. A small fragment of lime will also be strongly heated, and it is thus that the lime light is produced, with the exception that oxygen and hydrogen are mixed just before combustion, and the flame urged upon the cylinder of lime by pressure. Hydrogen is colourless and inodorous ; and, although it will thus burn in the air, a lighted match suddenly plunged into a bulk of the pure gas will be extinguished. With regard to ordinary combustion, hydro- gen is thus exactly the reverse of oxygen. Like oxygen, it can be liquefied, but at a pressure even more extreme. The elements just described are respectively the types of the two great classes into which elements are divided. As will be afterwards more fully explained, we have : — ( i ) The metallic elements, typified by hydrogen, which usually form the basylous or electro-positive portion of compounds; and, (2) The non-metallic elements, or metalloids* which, either by themselves or when united with oxygen, form the acidulous or electro-negative part of compound matter. Just as hydrogen and oxygen are typical of the opposing forces of elementary matter, so is the water produced by their combination typical of compound matter, made up by the union or mutual saturation of the opposing elementary forces. 3.. Nitrogen.^ — Take a soup-plate and nearly fill it with water. Put a fragment of phosphorus in a small porcelain crucible and carefully float it on the surface of the water. Apply a light to the phosphorus, and quickly invert over it a receiver or a large beaker. The phosphorus will continue to burn until all the oxygen of the air in the beaker is NITROGEN.— CARB'ON. 3 abstracted, when it will be extinguished, and the receiver will be filled with white fumes of phosphoric acid (anhydrous) formed by the union , of the phosphorus with the oxygen. After the whole has stood for a few minutes these white fumes will dissolve in the water and disappear, and only a colourless gas will be left in the receiver. This is nitrogen in a free state, separated from the oxygen with which it was mixed, not combined — in the air we breathe. It is noticeable that at the con- clusion of our experiment the water has been observed to rise in the receiver, and what was originally all air, is now only four-fifths nitrogen, the remaining space being occupied by the water which has taken the place of the oxygen. This shows us that our atmosphere is mainly a mixture of one-fifth of oxygen and four-fifths of nitrogen. Now intro- duce a light into the gas, it goes out, and the gas itself does not take fire, therefore nitrogen is neither combustible like hydrogen, nor is it a supporter of ordinary combustion like oxygen. Of what use then is it in the air ? Why, simply as a perfectly neutral and negative body acting as a diluent of the activity of the oxygen. Nitrogen is an im- portant constituent in the food of animals and plants, and all those curious and highly active bodies the vegetable alkaloids are rich in it. 4. Carbon. — Take some ordinary animal charcoal and wash it free from mi- neral impurities by hydrochloric acid, as directed in the Pharmacopoeia under Carbo anbnalis purijicatus. The resulting black powder is the nearly pure element in the free state. Heat a little of the powder on a piece of platinum foil ; it glows and burns away. This is owing to its uniting with the' oxygen of the air to form carbonic anhydride, which is a heavy colourless gas soluble to some extent in water, and when passed into liquor calcis turns it milky, owing to the formation of an insoluble compound called calcium carbonate. All organic matters contain car- bon ; and, in fact, the study of the compounds of carbon, other than metallic carbonates, is usually known as organic chemistry. To prove this, take an ordinary tallow candle and light it, when it appears to burn away ; but this combustion is nothing more than the combination of the carbon and hydrogen of the tallow with the oxygen of the air, to form carbonic anhydride and water respectively. Invert a perfectly dry wide-mouthed bottle over the flame and hold it there until the flame is extinguished ; then quickly insert the stopper and notice that a deposit of moisture has taken place on the glass, owing to the con- densation of the water above mentioned. Next introduce a little clear aqua calcis and shake, when a deposit of calcium carbonate will be formed, proving the presence of the carbonic anhydride. All ordinary combustion is therefore due to a chemical action between the burning body and the oxygen of the air, so violent as to heat the body to such an extent that it becomes luminous. Candle and ordinary gas flames thus produced are hollow, and consist of three distinct zones ; — (i) The inner portion, where no combustion is going on, but which is simply filled with the combustible matter volatilized by the heat. (2) The luminous portion, or zone of imperfect combustion, in which the carbon has become deposited and highly incandescent. This is explained by the fact that when carbon and hydrogen are burnt together, the latter has a much more powerful attraction for the oxygen, and burns first, especially when, as in the present case, the air only plays round the outside of the flame. Thus, some of the hydrogen being abstracted, the carbon and the remainder of the hydrogen deposits as soot (a mix- ture of compounds of C and H rich in carbon) which becomes incan- descent and gives the light. (3) The outer portion, or zone of perfect 6 INTRODUCTION. combustion, which is a pale and almost invisible coating enclosing the entire flame, where the whole of the carbon and hydrogen unites with the oxygen of the air and produces intense heat. When the air is partly mixed with the gas before arriving at the point of ignition, the middle zone is supplied with sufflcient oxygen from the interior to aid the air in fully burning it at once, and thus, although luminosity is sacrificed, the chemical action is more complete and the flame conse- quently much hotter. This is the principle of the Bunsen burner^ which is fully described hereafter. (See the Author’s Analytical Chemistry, Chap. I., page 25.) _ Carbon also exists in the form of the diamond and of graphite, or plumbago \ and elements which are capable of thus assuming a number of forms totally distinct in physical appearance and properties, are said to be allotropic bodies. Having thus familiarized himself with a few facts about the four most common elements, the student may proceed to study the first princi- ples 'of the theories of chemistry and the notation based thereon. CHAPTER II. THEORIES OF CHEMICAL ACTION AND THE MODES OF EXPRESSING THE SAME BY FORMULAE AND EQUATIONS. L LAWS OF COMBINATION. The idea that matter is composed of atoms is very ancient, as we find it expressed by Democritus and other Greek philosophers ; but no definite ^sys- tem as to the combination of atoms had been established until about 1804, when the researches of the eminent English chemist, Dalton, enabled him to lay down the following laws, which form the basis of all our present notions of chemical combination : — 1. Atoms combine with each other in a fixed and definite proportion by weight and volume. 2. As compound bodies are produced by the union of a given number of such atoms, it follows that the molecules of these compounds must also possess in their turn a fixed and definite combining proportion by weight and volume. • 3. If a body can unite with another in more than one proportion, these proportions, which only represent the weights of the several atoms, must necessarily be simple multiples of the weights of any one of them. These laws are usually stated as follows : — i. The duantitative Law. — A definite compound always contains the same elements in the same fixed proportion. ii. The Law of Multiples. — When the same bodies combine in more than one proportion, the resulting compounds contain a fixed pro- portion of one element in a varying proportion of the others ; the second, third, and fourth proportions, etc., of the latter being always simple multiples of the first. iii. The Law of Reciprocal Proportions. — The proportions in which any two elements unite with a third are the same proportions in which they unite with each other, or multiples of these proportions. As an example of the first law, let us take water. No matter from what source it may be obtained, spring, river, or rain, it invariably contains oxygen and hydrogen in the relative proportions of 16 of the first to 2 of the latter by weight. An instructive example of the second rule is found in the com- pounds of oxygen and nitrogen. The simplest relation in which those bodies combine is 28 of nitrogen and 16 of oxygen. The next compound contains 28 of nitrogen and 32 of oxygen ; the third, 28 of nitrogen and 48 ot oxygen ; the fourth, 28 of nitrogen and 64 of oxygen ; and the fifth, 28 of nitrogen and 80 of oxygen. Thus, dismissing the nitrogen, which remains constant, let us look at the numbers 16, 32, 48, 64, 80 : are they not all multiples of 16, 8 THEORIES OF CHEMICAL ACTION. the simplest proportion ? As an example of the third law : — Chlorine unites with hydrogen in the proportion of 35'5 to i, and iodine also unites with hydrogen in the proportion of 127 to i ; therefore, chlorine combines with iodine in the proportion of 35 ‘5 to 127. Seeing that these combining pro- portions by weight are only relative, it follows that they must all be referred to one standard ; and as hydrogen is the lightest known body m nature, it is taken as unity, when other bodies are found to combine with it in the following proportions by weight, which figures it is necessary to commit to memory : — Hydrogen ... H. ... 1. Elementary Bodies. Combin- ing OR Atomic Weights. Elementary Bodies. Combin- ing OR Atomic Weighis. Aluminium 27’5 Iron . . kc . . . 56 Antimony 122 Lead ... 1 ... . 207 Arsenic 75 ! Lithium 7 Barium 137 i Magnesium .... 24 Bismuth 210 Manganese 55 Boron 1 1 Mercury 200 Bromine 80 ' Nitrogen 14 Cadmium 112 ! Oxygen 16 Calcium 40 Phosphorus .... 31 Carbon 12 Platinum 197 Cerium 92 Potassium 39 Chlorine 35'5 Silver 108 Chromium 52*5 Sodium 23 Copper 63*5 [ Sulphur ’ 32 Gold 196-5 ; Tin • . 118 Iodine 127 Zinc 65 If we take a pint of hydrogen and a pint of oxygen, a pint of nitrogen and a pint of chlorine (all measured at the same temperature and pressure), we shall find that although the bulks are equal, the oxygen weighs 16 times, the nitrogen 14 times, and the chlorine 3 5 '5 times as much as the pint of hydrogen. We conclude, therefore, from this simple experiment that matter in the state of vapour (its simplest condition) is equal in volume but different only in weight ; and what is thus proved to be true as to a given volume, is viewed as also holding good\with regard to the individual atoms which compose that volume. Hence it is reasoned that the atoms of the elements, although equal in bulk, differ in ukight, and that the combining proportions referred to in the above table mu, St be the actual difference in weight of the individual atoms themselves. Acting upon this theory, these proportions are called the atomic weights of the respective elements. That those combining proportions are really the true atomic weights of the various elements, is considered to be proved by physical as well as chemical means. The amount of heat required to raise equal quantities of various bodies through one degree of temperature is called their specific heat. If this specific heat be taken, as compared with that of water, as unity, it is found that bodies so examined give a series of numbers without any apparent connection ; but if the atomic heats of the elements be taken (that is the amount of heat required to raise atomic weights of the respective bodies through one degree) it is found that nearly all elements give a similar result. In other words, SPECIFIC HEAT.-CHEMICAL ACTION. 9 that when the specific heats of the elements are multiplied by their atomic weights an almost equal product is obtained. The following table will illustrate this uniformity : — Elements. Specific Heat. Atomic Weight. Specific Heat X Atomic Weight. Sodium 0-2934 23 675 Potassium .... 0-1696 39 6-61 Bromine 0-0843 80 6*75 Iodine 0-0541 127 6-87 Mercury 0*0333 200 6-66 Tin 1 0-0562 118 6-63 If we extend our researches from elements to compounds, we find that equal volumes of compound gases also differ in weight in the same fixed manner. This difference is therefore regarded as representing the relative weights of the molecules of the compound ; and for similar reasons to those already given, /ke combining weight of a compound body is called its molecular weight, and is always equal to the sum of the atomic weights of its constituent ele 77 ients. Thus, one molecule of hydrochloric acid consists of i atom of chlorine weighing 35*5 and i atom of hydrogen weighing i ; the molecular weight of this acid is therefore 36‘5. From these explanations it follows that we are always to speak of the combining proportions by weight as the ato 77 iic weights of ele 77 ients., and the 77 wlecular weights of co 77 ipou 7 ids or of ele 7 ne 7 its m a free state. II. CHEMICAL ACTION. This action is characterized by the grand distinction, that whenever it is induced a complete change is caused to take place in the bodies affected. It is by this thorough transmutation that true chemical energy is invariably recognised, in contradistinction to the tame effect resulting from a merely mechanical mixture. For example : — If we rub together some sugar and potassium chlorate we obtain a white powder, in which the ingredients are intimately mixed together, but are not in a state of chemical union ; for by digesting the powder in spirit we can dissolve the sugar, leaving the potassium chlorate exactly as it was. Let us now add to the same powder a drop of sulphuric acid, and watch the astonishing result. The whole mass instantly inflames ; a cloud of steam arises, and a black residue is left, from which no human dexterity can recover the original sugar or potassium chlorate. This experiment illustrates a true chemical combination, involving an entire change in the bodies acted upon. Chemical action is always accompanied by an alteration in the temperature of the substances combining, and frequently an appreciable amount of heat and even light is produced. The tyro who desires to be made sensible of the heat produced by chemical action, has only to grasp a test-tube containing water, and add quickly about one sixth of strong sulphuric acid, when he will receive a convincing proof of this assertion. Many circumstances affect the rapidity and even determine the occurrence of chemical action. Chief among these is solution. This is exemplified in the ordinary granulated citrate of magnesia, as it is erroneously named, but which, as commonly sold, is chiefly a mixture lo THEORIES OF CHEMICAL ACTION. of tartaric acid and sodium acid carbonate. The mixture remains without change until dissolved in water, when a violent effervescence occurs, the in- gredients combining to form a new substance, called sodium tartrate. Next to solution, heat is probably the most potent inducer and assistant to chemical action. We may rub a fragment of sulphur against a bar of iron for any length of time without affecting either ; but let us heat the iron to whiteness,’ and apply, the sulphur, and iron sulphide will be at once produced ; a sub- stance having no chemical resemblance to either of the ingredients used. Chemical action manifests itself much more strongly between certain bodies than between others, and it is by reason of this property that we are enabled to produce one compound from another. For example : — If we mix a solu- tion of mercuric chloride and potassium iodide together in proper proportions, a bright scarlet substance quickly forms, and sinks to the bottom of the liquid. This is mercuric iodide, and its formation has been accomplished by chemical force. The mercury has a much greater affinity for iodine than the potassium possesses, consequently, the former displaces the latter, and unites with the iodine. This result could not occur except by reason of the superior mani- festation of chemical force between the atoms of mercury and iodine. There are cases, however, in which the force between certain elements is so nearly balanced, that a slight change of circumstances is sufficient to determine in what direction the action shall be manifested. For example : — Oxide of iron heated to redness in a tube, and hydrogen gas passed over it, becomes re- duced to metallic iron ; while its oxygen, combining with the hydrogen, pro- duces steam. If, however, the process be reversed, and steam be passed over the heated metal, oxide of iron will result, and hydrogen will escape. Thus we see that the chemical force acting between the elements is so nearly equal that the presence of an atmosphere of either hydrogen or steam is sufficient to determine the direction of the action. There is a very singular aid to chemical action, called catalysis, wherein the mere presence of a substance induces or hastens chemical action, the catalytic substance itself remaining perfectly unchanged and apparently in a neutral state. For example, if w^e heat potassium chlorate, it does not evolve oxygen until a tolerably high temperature has been attained ; but should we previously mix a little man- ganese peroxide with the potassium chlorate, the gas is liberated at a much lower degree of heat. The manganese apparently has undergone no change, and yet, by its presence, has hastened the decomposition of the potassium chlorate. Catalysis has been accounted for by supposing that any element may exercise an influence over another element, even when circumstances entirely preclude the formation of a definite combination. Thus, in the above example, the metal manganese possesses an attraction for an additional atom of oxygen over the two already contained in manganese peroxide ; and although, at a raised temperature, that third atom cannot actually be brought into union, yet the attraction so exercised causes the oxygen to be much more readily set free from the potassium chlorate than it would otherwise be. III. COMBINATION OF GASES BY VOLUME. We have already seen that equal volumes of elementary gases differ in weight exactly in the same ratio as their atomic weights. The weight of any portion of matter, compared with that of an equal bulk of another portion taken as a standard, is called its specific gravity. In the cases of liquid or solid bodies, their specific gravity is taken as referred to the standard of an equal bulk of distilled water at a fixed temperature ; but in the case of gases we use hydro- gen measured and weighed at o° Centigrade (French thermometer) and 760 COMBINATION OF GASES BY VOLUME II millimetres pressure (French barometer) as a standard of comparison ; and when so taken the specific gravity is usually called density. By a series of experiments it has been found that the density of all elementary gases is equal to their atomic weights. One gramme of hydrogen weighed at o° C. and 760 mm. barometrical pressure, occupies a space of ii’2 litres; and if we empty out the hydrogen and substitute oxygen, we find that the same bulk weighs 16 grammes ; if nitrogen, 14 grammes; and if chlorine, 35*5 grammes ; therefore we establish the rule that the atomic weight of any elementary gas, weighed in graifiifies, always occupies 11*2 litres. Turning to compound gases, we discover that their density, referred to hydrogen, is equal to exactly half their molecular weight ; accordingly, we conclude that the molecule of a com- pound gas occupies a space exactly double that filled by an atom of hydrogen. If we weigh out 36"5 grammes of hydrochloric acid (H = i + Cl= 35’5) we find that it fills a space of 22-4 litres; and extending the experiments to other compound vapours we ascertain that the results agree, and that the molecular weight of any coitipound gas, weighed in grammes, always occupies 2 2 ’4 litres. It is evident, therefore, that no matter how complicated a molecule may be, it is only equal in volume to two atoms, and its whole bulk is exactly hvice the volume of any one atom of the constituent eletneiits used hi its production. A glance at the following table will explain this, and in order that the meaning may be perfectly clear we have adopted the familiar volume of one gallon : — 1 gallon H and i gallon Cl = 2 gallons HCl (hydrochloric acid). 2 „ H „ I „ 0 = 2 „ HgO (steam). ^ 3 „ H „ I „ N = 2 „ NH3 (ammonia). But we rarely meet with a general rule which is universally applicable ; therefore it is not astonishing to find several exceptions to the axioms just propounded. It has been proved by experiment that the densities of the vapours of phosphorus and arsenic, instead of coinciding with their atomic weight, are double ; so it follows that the atoms composing such fumes only occupy half the volume of an atom of hydrogen. Instead of 31 grammes of phosphorus vapour occupying 11*2 litres, it requires 62 grammes to fill the space ; and similarly, instead of 75 of arsenic, 150 are required. Thus ; — 3 galls. H and ^ gall. P = 2 galls. PH3 (phosphuretted hydrogen). 3 „ H „ „ As = 2 „ ASH3 (arseniuretted „ ). On the other hand, mercury and cadmium, when in vapour, are found to possess a density only half as great as their atomic weights ; therefore 200 grammes of mercury vapour will occupy 22*4 litres instead of 11*2; and it follows that two volumes of mercuric chloride (HgClg) must contain two volumes of Hg and two volumes of Cl. The complete law of the combination of elements in a gaseous state by volume is usually stated as follows : — The combining volumes of all elementary gases are equal, excepting those of phosphorus and arsenic, which are only half the others ; and those of mercury and cadmium, which are double those of the other elements. There are several compounds which do not appear to follow the law of their molecules in a state of vapour, each being equal in volume to two atoms. This is accounted for by the explanation that it is impossible to take their correct densities as regards hydrogen, as they evidently undergo some change, denominated dissociation, when a sufficiently high temperature is applied in order to obtain them in the gaseous condition. Ammonium chloride, for instance, which is one of these exceptional bodies, appears to become disso- ciated into hydrochloric acid and ammonia gases when heated to the state of vapour ; but again reunites and returns to its original partnership whenever the temperature is permitted to fall. 12 THEORIES OF CHEMICAL ACTION. IV. ATOMICITY. On glancing at the table of combination by volume just given, it is notice- able that while i atom of H combines with one atom of Cl to produce a molecule of HCl, yet that i atom of O requires 2 atoms of H to form i molecule of HgO. In this latter case it is evident that a condensation takes place, and that the atom of oxygen possesses the power of fixing and saturating, as it were, 2 atoms of hydrogen. Here, therefore, we discover a relation between atoms totally distinct from their atomic weights. The following table exhibits this new relation : — I molecule HCl contains i atom of H and i atom of Cl. I HgO „ 2 „ H „ I „ 0 . I jj ^^3 j) 3 ,, H „ I N. I » CH 4 (Marsh Gas.) 4 H „ I „ C. This relation of bodies to each other in atom-fixing power is called atomicity, and occasionally quantivalence. Atomicity, therefore, may be described as the measure of the power which one atom possesses of invariably attracting to itself a given number of other atoms. It is the value or, as it were, the capacity for saturation, which atoms bear to each other. This value, which must be kept totally distinct in the student’s mind from the idea of atomic weight, is, however, like the latter, referred to hydrogen as unity. Atoms which are capable of fixing only i atom of hydrogen to form a stable compound, are called monads, like chlorine ; those which, like oxygen. can always fix 2 atoms of a monad are called djads ; those that can fix . . 3 ,, „ triads; ,, „ . . 4 ' „ „ tetrads; „ „ . . 5 „ „ pentads ; „ „ . . 6 ,, „ hexads. The atomicity of bodies is represented by small ticks and Roman figures placed over the symbol, as follows : — Monad Dyad Triad Tetrad Pentad Hexad H' O" Bi'" Civ pv S'" V. GHAPHIC FORMULA AS EXPONENTS OP THE DOCTRINE OF ATOMICITY. In order to render the theory of atomicity easy of comprehension, it has been assumed that atoms possess a certain number of points of saturation, which must be joined to other atoms before a stable molecule can be pro- duced, capable of existence in a free state. It is sometimes customary to represent this junction by hieroglyphics, called graphic formulae, in which the symbols of the atoms are represented as being united to each other by certain lines equalling in number the bonds of union they are supposed to possess. In using such formulae, care must be taken to distinguish between the theo- retical and the actual ; the diagrams are intended for purposes of explanation only, and they cannot he held as actual representations of the real con- stitution of the molecules they illustrate. For example : — If the atom of ' GRAPHIC FORMUHH. 13 hydrogen, which is a monad, be represented by H, then hydrogen in the free state is produced by a saturation of the bond of union by another atom of H ; consequently a molecule of free hydrogen is graphically portrayed thus, H — H. Following up this system, the molecules represented in the last table of examples are graphically formulated as follows : — I molecule of hydro- chloric acid I molecule of 1 xr q i molecule of 1 steam. j ^ • marsh gas / H H— Cl. H— O— H H— C— H H In the same manner in which two atoms of hydrogen unite to form a molecule, may the atomicity of other atoms be modified by self-saturation. Thus, carbon which 'is represented above as exhibiting its full atomicity in CH^, may form an almost illimitable series of compounds with hydrogen by self-saturation of one or more of its bonds of union with other carbon atom.s, thus : — Methyl hydride. Ethyl hydride. Propyl hydride. H H H > 1 1 H H H 1 1 1 1 H— C— H 1 1 1 H— C— C— H 1 1 1 1 1 H— c— c— c— : 1 1 1 1 H 1 1 H H 1 1 1 H H H or CH,. or C 2 H 0 . or CgHg. Many elements, in this manner, form various series of compounds in which they exhibit totally different atqmicitiesi. Among these ought to be specially mentioned nitrogen, phosphorus, . arsenic, antimony, and bismuth. Those atoms which are truly pentad, possessing the power of fixing five atoms of a monad, may become triad by the self-saturation of two of their bonds. For example : — Nitrogen forms a compound, called ammonia, which can exist at liberty ; but should it be brought into contact with hydrochloric acid, the two selfisaturating bonds will at once unite with the elements of the acid, when a new and more stable compound, named ammonium chloride, will be formed, in which the nitrogen will exhibit its full pentad atomicity, thus : — Ammonium Chloride, NH^Cl. H H V H— N— H I Cl. Many metals likewise exhibit this property in a marked degree. For instance, mercury is in its fullest state a dyad, Hg''', but by two atoms self- saturating each other at one bond, a combination Hgg is produced, which also acts as a dyad. The first forms -a class of salts called mercuric, and the second gives birth to mercurous compounds. Their respective chlorides may be thus represented : — Mercuric chloride, Hg"Cl 2 '. Mercurous chloride, HggClg. Cl-Hg— Cl. Cl— Hg— Hg— Cl. Ammonia, NHg. H H— N— H V When a metal behaves in this manner, the terminations A and ous are adopted : the former to distinguish the compounds in which the fullest atomicity is 14 THEORIES OF CHEMICAL ACTION. exhibited, and the latter to mark the partially self-saturated salts. Thus we have cuprous and cupric, stannous and stannic, ferrous and ferric compounds, each class owning conspicuous reactions which enable us to discern between the two states of the same metal. VI. EADICALS, ACIDS, AND BASES. When a molecule is not fully saturated in all its atomicities, it cannot exist in the free state, except by union with another molecule of itself. Such unsatu- rated molecules may, however, be transferred from one compound to another without decomposition, and are then named Radicals. The atomicity of radi- cals is always equal to the amount of unsaturated bonds which they possess. H I For example,' CH^ (marsh gas) is a fully saturated compound, H — C — H I • H which, although it can exist in the free state, cannot combine with any more atoms. On the other hand, the radical CHg (methyl) has one bond unsaturated, H I . . H — C — , and it cannot of itself become free, but it can combine with other I • H elements or radicals, behaving as a monad ; and thus its chloride is CH3CI, H I or graphically H — C — Cl. A radical is, therefore, an unsaturated compound H which can enter into combination and be transferred from one compound to another without decomposition, exactly like an element. Many chemists prefer to use the word radical for all bodies which behave as elements, the latter being called simple radicals, and the unsaturated groups of atoms, compound radicals. When radicals are examined, they are discovered to be in opposite states as regards electricity, some being electro-negative, and others electro-positive. In forming compounds, it is but rarely that the two radicals in the compound are in the same electric condition ; as a rule, a com- pound body is composed of an electro-positive and an electro-negative radical, thus restoring the balance of electrical force in the new substance formed. Before further developing the theory of atomicity of radicals, it is necessary that the definition of certain familiar chemical expressions be laid down and clearly understood. 1. All Acid is a compound of an electro-negative radical with hydrogen, which hydrogen it can part with in exchange for a metal or basylous radical. This hydrogen is called the “ replaceable hydrogen.” 2. An Acidulous Radical is an element, or unsaturated group of elements, possessing electro-negative properties, and capable of combining with hydrogen to form an acid or with a basylous radical to form a salt. 3. A Basylous Radical is a metal or unsaturated group of elements possess- ing electro-positive properties, and capable of displacing the replaceable hydrogen of an acid to produce a silt. EASY LOUS RADICALS, 15 VII. SALTS, AND THEIR MODE OF FORMULATION. AS BASED ON A KNOWLEDGE OF ATOMICITY. A salt is the result of the displacement of hydrogen from an acid by a basylous radical^ and is therefore composed of an electro-negative and an electro-positive radical, in union with each other. All acids are capable of giving birth to a long series of salts by the displacement of their hydrogen by various basylous radicals ; but it is a matter -of indifference which of the latter performs this function, the acidulous radical remains unchanged as the type by which such class of salts are always characterized. Take, for example, hydrochloric acid (HCl). This is proved to be an acid, because by pre- senting a metal to it we can displace the H, and form a metallic chloride, such as potassium chloride (KCl). This chloride is the result of such dis- placement, and is a salt containing the basylous radical K in union with the acidulous radical Cl. We may displace the K by any other basylous radical, and form a chloride of the new radical, but the Cl remains through all chlorides as the unchangeable portion without which chloride cannot exist. Again, (SO4)" is an unsaturated group which acts as a dyad, and which, combined with two atoms of monad hydrogen, forms sulphuric acid, Hg' (SOJk The hydrogen may be displaced with any basylous radical, forming a class of salts called sulphates. We can thus have potassium sulphate Kg' (SO4)", or sodium sulphate Na^' {SO4)" j but the (SO4) never varies, and is the in- destructible group without which no sulphate can exist. It will be seen, therefore, that it is of the utmost importance to become familiar with the names, formulae, and atomicities of the commoner radicals, both basylous and acidulous. The following tables are subjoined, and ought to be thoroughly committed to memory. Table of the Active Atomicities of the Chief Basylous Radicals. ELECTRO-POSITIVE. Name. MONADS. Formula. DYADS {continued'). Name. Formula. Hydrogen . H. Mercury (mercuric) . . . Hg. Potassium . K. „ (mercurous) . . (Hga). Sodium . . Na. Tin (stannous) .... Sn. Lithium . . Li. • Cerium (cerous) .... Ce. Silver . . • Ag. Iron (ferrous) .... Fe. Ammonium , (NH,). Cobalt (cobaltous) . . •. Co. Methyl . • (CH3). Nickel (nickelous) . . Ni. Ethyl . . (CgH,). TRIADS. Amyl . . ■ (C5H1,). Gold (auric) Au. Phenyl . ■ (CeH^). Antimony (antimonious) . Sb. Calcium . DYADS. . Ca. Bismuth (bismuthous) . . Glyceryl Bi. (C3H5). Barium . . Ba. TETRADS. Lead . . . Pb. Tin (stannic) Sn. Zinc . . . Zn. Platinum Pt. Magnesium . Mg. HEXADS. (F^). Cadmium . Cd. Iron (ferric) Copper (cupric) . . , . Cu. Aluminium (aluminic) . . (Ay. „ (cuprous) . . . (CUg). Chromium (chromic) . . (Cr^). i6 THEORIES OF CHEMICAL ACTION. Table of the Active Atomicities of the commoner Electro-negative . or Acidulous Radicals. MONADS. Name. Formula. Hydrides . . . . H. Hydrates . . . . HO. Chlorides . . . . Cl. Hypochlorites . CIO. Chlorates ‘. . . CIO3. Iodides .... . • I. lodates'. . . . . IO3. Bromides . . Br. Bromates . . . . Br03. Fluorides . . . . F. Nitrates . . . . NO3. Nitrites. . . . . NO2. Cyanides . . . . CN Cy. Acetates . . . > . C2H3O2. Valerianates . • C5H9O2. Sulphocyanides . . CNS. Hypophosphites . . PH2O2. Metaphosphates . . PO3. Benzoates . . . . C7H5O2. Cyanates . . . . CNO. Formates . . . . CHO2. Oleates. . . . DYADS. Oxides . . Sulphides . . O. . 'S. DYADS {continued). Name. Formul.e. Sulphites Thiosulphates {or SO3. hyposulphites) . S2O3. Sulphates SO4. Carbonates CO3. Oxalates ^ 2 ^ 4 * Tartrates C 4 H 40 g. Lactates C3H503. Succinates C4H404. TRIADS. ■ Phosphates P04. Arseniates AS04. Citrates ^ 6 ^ 5 ^ 7 * Malates C4H40g. Meconates ...... C7H07. TETRADS. Ferrocyanides . . . CH3COHO. j Dividing as before by the atomic weight, we have, — 70 -f 56 - 1*25 iron. 30 16= 1-875 oxygen. 'I'aking now the lower number as unity, we have, — 0(i -875) -fFe (1-25) = rs O. MOLECULAR AND RATIONAL FORMULA. 19 But as half, or any fraction, of an atom cannot exist, therefore FeO^.g is im- possible ; Hence we multiply both elements by 2, thus getting FegOg, which is the simplest possible relation in whole numbers, and therefore the correct empirical formula. Molecular formulae are obtained by submitting the results of the calcu- lation of the empirical formulae to the tests of either density or atomicity. If the substance be volatile we take its vapour density {see Vapour Density in Author’s Analytical Chemistry, chapter i. section 13), and by the rule that all cotnpounds m a state of va^f^our have a de?isity equal to half their molecular weight, we obtain the true formula. For example, we have alrea”dy found the empirical formula of acetic acid to be CHgO, giving a molecular weight of 30 ; thus, — • C = 12 Ho- 2 0=^6 But on taking the vapour density we find that the weight of a given volume ' of acetic acid vapour divided by that of an equal volume of hydrogen is 30, so that we see that the true molecular weight of the acid must be 60, or just double, and the true molecular formula is then — €3 = 24 H4= 4 02=3^ 60 If, however, the compound be not volatile, or should it suffer dissociation when heated, we cannot get at its vapour density ; but we must determine its molecular formula by co 7 nbining it with some body of which we already know the true combinmg weight and atomicity For the sake of making this clear we will still take the same example, namely, acetic acid, although it would, being volatile, not really require this process except as a confirmation. Suppose, therefore, the taking of the density to be for some reason incon- venient, we should make some pure and dry argentic acetate. Of this com- pound we should weigh out a certain quantity, say one gramme, and submit it to ignition, thus driving off the acetic radical, and leaving '6468 gramme of metallic silver. Having now proved that one gramme of argentic acetate con- tains ’6468 gramme of silver, the balance of ’3532 gramme must represent the weight of the acetic radical. By simple proportion we next inquire. If ’6468 gramme of silver combined with '3532 gramme of acetic radical, how much of the latter would be required to combine with an atomic weight of silver taken in grammes (108)? thus, — '6468 : *3532 ‘ 3532 X 108 •6468 " : ; 108. 58-98. But now atomicity steps in and says that silver is a monad and must there- fore have displaced an atom of H from the acid in forming the salt, so it is clear that the atomic weight of H = i must be added to the above, giving us 59-98. Knowing, from the atomic weights of C, H, and O, that we must neglect the fraction, we have 60 for the nearest whole number, thus once more confirming the idea that the true molecular formula of acetic acid is CgH^Og- 60, and not CHgO = 30, as found for the simple empirical formula. 20 THEORIES OE CHEMICAL ACTION. X. CHEMICAL EQUATIONS. The mode in which bodies react upon each other is represented by a series of letters, numerals, and signs, called a chemical equation. In such diagrams the ordinary signs of arithmetic are used, such as + (plus) added to ; - (minus) deducted from ; = (equals). As the thorough understanding of a chemical equation is of the utmost consequence, we shall trace the idea from its simplest form. Let us say that 2 equals 2, a fact comprehensible by the most ordinary uneducated intellect \ yet, although it be an equation, it conveys little instruction even when symbolized chemically ; thus, Hg = represents no chemical action, and we have already learned that the delineation of such action, which produces complete changes in the bodies acted upon, is one of the essences of the science of Chemistry. Jf, however, we say that 2 added to I equals 3 (2 + 1 = 3), we look upon an equation which teaches and suggests something for the due appreciation of which a certain amount of education is required. An untutored savage knows intuitively that two stones he may pick up equal in number any other two ; but some education must evidently be required ere he can confidently assert that one stone added to two stones will show a result of three. Reducing this to a chemical equation, we have H2 + O = H2O. Here then is a true example of what we mean, because it teaches something ; the individual atoms on either side of the sign balance each other in point of numbers, and a totally new substance is produced from the ingredients em- ployed. These are the essential characteristics of a true chemical equation. An equation in which two substances unite to produce a third body is said to represent a single decomposition. Such an equation may be reversed, when it will indicate the splitting up of a body into two different products, but still the action portrayed is that of a single decomposition. Thus, potassium chlorate, on being heated, yields potassium chloride and oxygen, which reac- tion would be represented as follows : — ■ KC103 = KC1 + 03: a correct equation, exhibiting all the essential points already mentioned, (i) It teaches the fact that oxygen and potassium chloride can be produced from potassium chlorate ; (2) the same number of atoms of K, Cl, and O, respect- ively, are found on each side of the equation ; (3) from the substance operated upon, two entirely different bodies have been produced. Of this simple form of equation there are necessarily very few, the more usual specimens being those of double decomposition. By this we mean the production of at least two distinct bodies from the reaction upon one another of an original two. Take, for example, the reaction of potassium iodide on mercuric chloride (already referred to when chemical action was under consideration), which ex- hibits a type of a vast number of equations representing actions wherein the acidulous radicals of the substances employed merely interchange their base. F rom mercuric chloride and potassium iodide we produce mercuric iodide and potassium chloride, which is thus represented as an equation : — Hg'CJa' + 2KT' = Hg'T2' + 2K'Cr. ' We place the large figure 2 before the KI and the KCl, in order to show that we use two molecules of the former, and produce two molecules of the latter. That this must be so becomes evident from the fact that Hg, as a dyad, requires two atoms of monad iodide ; and there being only one I in each molecule of KI, two molecules must be employed to yield the I2 demanded. In this equation the mercuric chloride and potassium iodide are called the ingredients ; the mercuric iodide, the chief product ; • and the potassium CHEMICAL EQUATIONS. 2T chloride, the hye-product. In equations these bye-products are often a source of considerable difficulty, especially when they happen to be numerous, and ihe equation does not represent a simple interchange like the one just considered ; but a knowledge of the bye-products of any particular action is only to be acquired from a study of the chief elements and their compounds. Such study may, however, be greatly facilitated by committing to memory examples of a series of familiar actions, and establishing in the rhind a set of typical equa- tions. In this we shall endeavour to assist the learner by noting some examples of some of the most common chemical actions seriatim : — I. When a metal dissolves in hydrochloric acid, a chloride of the metal is produced and free hydrogen is evolved. Take for example the manufacture of zinc chloride : Zn being a dyad will require two atoms of Cl to form the chloride ; and as each molecule of hydrochloric acid only contains one atom of Cl, we shall require to use two molecules of the acid, and the equation will be : — Zn" + 2H'Cr = Zffi'CV + Hg'. Applying the same rule to iron, we have — Fe"-F2H'Cr-Fe"CV-hH2'. 2. When a metal which is soluble in diluted sulphuric acid dissolves in that fluid, a sulphate of that metal is produced, and free hydrogen gas evolved. In this case the sulphate being a dyad, as well as the metals which we find behaving in this way in Pharmacy, one of each only is required, and the action is usually represented as a simple displacement of the hydrogen of the acid by the metal. Thus with zinc and iron respectively, we have — Zn" -f- H/(SO = Zn"(SO + H.'. Fe" + H2XSO4)" = Fe"(SO,r + H/. 3. When an acid acts upon a carbonate, a salt is produced by the union of the metal of the carbo 7 iate with the acidulous radical of the acid employed., and carbonic anhydride, COg (commonly called carbonic acid gas) and water (HgO) are produced. Thus calcium carbonate dissolves in hydro- chloric acid to produce calcium chloride, and carbonic anhydride is evolved with effervescence and water formed, thus ; — ■ ' Ca"(C 03 )" + 2H'Cr = Ca"Cl2' + COg + HgO. The CO3, being an unsaturated radical, cannot exist at liberty, and it therefore gives up one atom of oxygen to two atoms of hydrogen from the acid, forming water and leaving COg, which, being a fully saturated molecule, comes off in the free state. Two molecules of HCl are required to yield the two CFs necessary for the formation of the calcium chloride. Extending this prin- ciple to other actions, we have magnesium carbonate dissolving in sulphuric acid and yielding magnesium sulphate. Mgr(C03)" + Hj'CSO*)' = Mg"(SO,)'' + CO 3 + H^O. The sulphate radical being a dyad as well as the magnesium, we only require one molecule of each. Again, potassium carbonate and acetic acid yield potassium acetate ; thus : — K 2 '(C 03 )" -f 2H'(C2H302)' - 2K'(C2H302)' + COg + H 2 O. Here we have two atoms of monad K in the carbonate, which require two molecules of the monad acetate radical, and yield two molecules of the potassium acetate, together with the usual bye-products. An equation of this class becomes more complicated when the action takes place between the carbonate of a dyad metal and an acid having a triad 22 THEORIES OF CHEMICAL ACTION. radical. Thus, to form calcium citrate we require three molecules of calcium carbonate, and two molecules of citric acid, because the simplest way in which a dyad and a triad can be brought to balance each other is by multiplying the former by 3 and the latter by 2. When we thus employ three molecules ot a carbonate, it is evident that we must produce three molecules of each of the bye-products, therefore the finished equation will be : — sCa'XCOg)" + 2H3'(C6H507)'" = Ca3"2(C6H507)"' -f 3CO2 -f 3H,0. 4. When some metals are heated with strong sulphuric acid they dissolve, forming a sulphate, evolve sulphurous anhydride (SOg, commonly called' sulphurous acid gas) and produce water. This reaction takes place at the expense of a molecule of H2SO4, which becomes divided into SOg and HgO, thus leaving one atom of oxygen, which in its turn combines with the Hg of a second molecule of sulphuric acid, and liberates the SO4 to combine with the metal used. In such an equation, therefore, we must employ one of a dyad metal to two of sulphuric acid, forming a sulphate of the metal and the above- named bye-products. Examples are found in the equations for cupric and mercuric sulphates : — • Cu" -f 2H2'(S0 J' = Cu"(S04)" -f SO2 + 2H2O. Hg" -f 2H2'(S04)" = HgXSO^)" -F SO2 + 2H2O. 5. When a metal dissolves in slightly diluted nitric acid, a nitrate is produced, and two molecules of nitric oxide gas (2 NO) are usually evolved and water formed. The nitric oxide gas is produced at the expense of 2 molecules of HNO3, which become broken up into 2 NO and H2O, thus leav- ing three atoms of oxygen, which combine with the hydrogen of 6 other molecules of nitric acid to form 3 more molecules of water, thus liberating 6 molecules of NO3 to combine with an equivalent quantity of the metal; and the total bye-products of this reaction are, therefore, 2N0-t-4H20. Con- sequently it is clear that in all such equations we must use 8 molecules of HNO3 and enough metal to combine with 6NO3 °f the 8, according to the atomicity of the metal, producing as many molecules of the nitrate as we use atoms of the metal. Thus with a monad metal like silver, a dyad like mercury, and a triad like bismuth, we have respectively the following equations : — Age' + SHXNOg)' = 6Ag'(N03)' + 2NO 4 - 4H2O. Hg3" + 8H'(N03)' = 3Hg"2(N03)' -f 2NO -f- 4H2O. BV" + 8H'(N03)'- 2Bi'"3(N03)' + 2NO + 4H2O. Such are a few typical equations ; and it is to be hoped that their careful study, conjoined with a return to their consideration when the facts involved are more prominently brought forward, will smooth the way towards, and lighten the task of acquiring, this all-important section of Chemistry. The student is therefore earnestly urged to learn equations (not merely by heart in order to pass the ordeal of an examination), but to search out the reasons involved, so that he may retain, and be able to use, the whole of his chemical knowledge through life. The theories of atomicity and equations ought to be so thoroughly mastered that the young pharmacist may, without a moment’s hesitation, write down the formula representing any ordinary reaction without reference to any chemical work. In former times chemical reactions were represented by what was called a diagram. This was a series of lines drawn from one element to another to show that they combined in a particular manner. The following examples of diagrams will explain themselves. They were very useful things in the hands of a teacher, but are now considered obsolete. CALCULATIONS BY WEIGHT 23 Diagram showing the result of heating potassium chlorate to be the forma- tion of potassium chloride and oxygem KCl, Potassium Chloride. Oxygen, Diagram of the action of potassium iodide on mercuric chloride. Hgig, Mercuric Iodide. 2 KCl, 2 molecules of Potassium [Chloride, XI. PRACTICAL APPLICATION OP EQUATIONS TO THE CALCULATION OF QUANTITIES BY WEIGHT AND BY VOLUME. The equation is the starting-point, from which all calculations of the quantity of any substance required to perform a given decomposition, are determined. The two ideas must, however, be kept quite distinct. / I. Calculations hy Weight are made by reducing the equations to figures, and then intelligently applying the rule of three. For instance, taking the simple equation already given for the making of oxygen, let us inquire how much oxygen would be obtained by heating 100 grammes of Potassium Chlorate. Reducing the equation to figures, we have : — I ( K = 39 Cl-35'5 03 = 48 = JK = 39 t Cl = 35-5 + O3 - 48 74*5 + 48 That is, in theory, 122*5 parts by weight of KCIO3 would yield on heating 74*5 parts of KCl and 48 parts of oxygen. Ordinary simple rule of three would then enable us to inquire, If KCIO3 would yield in theory O3, what would 100 grammes of potassium chlorate produce ? Thus we have the proportion ; — KCIO3 : O3 : : 100 or in figures, 122*5 : 48 :: Working this out, we find that 48 X 100 = 39* r 8. So from 100 grammes of KCIO3 we should get 39*18 grammes of oxygen. To any one with the most elementary knowledge of the rule of three, such calculations are very simple, the whole thing turning on (i) a correct state- ment of the equation and an accurate reduction to its combining weights. 24 THEORIES OF CHEMICAL ACTION. and (2) the consideration that in rule of three we always work from the fact we know to that we want to know. One more example will suffice. Supposing we are required to convert four ounces of mercuric chloride into mercuric iodide by precipitation' with potassium iodide. How much potassium iodide is necessary, and what weight of mercuric iodide ought we to get, pro- vided the process be accurately conducted ? By the equation : — HgClg + 2KI = Hgig + 2KCI. One molecule of mercuric chloride requires two molecules of potassium iodide to form one molecule of mercuric iodide. Having arrived' at this fact, we next proceed to reduce the equation to molecular weight, thus : — Hg = 200 K= 39 Hg = 200 H = 39 Q II M 1=127 ” 7 ^ 2 = 254 Cl = 35 '5 74*5 2 271 + 332 — 454 + 149 Therefore, 271 parts by weight of HgClg, mixed with 332 parts by weight of KI, will yield 454 parts by weight of Hgig. By the rule of three we then calculate : — ^ As HgClg is to 2KI so are 4 ounces to the amount of KI required, stated in ounces or figures : — 271 : 332 : : 4 4 27i)i 328(4’9 ounces is therefore the quantity of potassium 1084 iodide sought. 2440 2439 Again, as HgClg is to Hgig so are 4 ounces to the amount of Hgig which should be produced, stated in ounces. 271 : 454 :: 4 4 27 i ) i 8 i 6(6’7 is the quantity ofHgIg we ought to obtain. 1626 1900 1897 ' ^ By these calculations we learn, that having started with 4 ounces of HgClg, we must employ 4-9 ounces of KI ; and our precipitate, when dried, ought to weigh 67 ounces. It being the practice in manufacturing to disregard minute fractions, the British Pharmacopceia instructs us to use 4 ounces of HgClg, and 5 ounces of KI, quantities which are based upon such calculations as the above. As a useful check upon the cost of the manufacture of any particular chemical, similar calculations are invaluable ; thus, at the present prices (Nov., 1878) of the above ingredients, their cost would be 5.r. ^d . ; but as the yield of red iodide of mercury would be nearly 6| ounces, it follows that the actual cost when made would be \od. per ounce, to which would require to be added the usual estimate' for labour and the wear and tear of plant. CALCULATIONS BY VOLUME. 25 V , 2. Calculations by yoliime are very much more simple, and it is only neces- sary to bear in mind that in the gaseous state all atoms are supposed to be equal in volume to H, and all molecules to Hg. If therefore, in an equation, a molecule produces a molecule, no alteration in bulk takes place ; but if a molecule produces an atom or two molecules respectively, then the size is, in the first case, halved, and in the latter, doubled. For example, we know that — H + CUHCl; or, in other words, — I atom H + I atom Cl = i molecule HCl ; so — I gallon H + I gallon Cl= 2 gallons HCl, or any other volume-measure that might be required, in the same proportion. Supposing, to make the question m.ore complicated, we had to consider what would happen if we exploded 10 gallons of H and 15 gallons of Cl. It is clear that in this case the 10 gallons of H would combine with the same volume, viz., 10 gallons of Cl, to form 20 of HCl, while there would be 5 gallons of Cl left over untouched. In all the equations for gases throughout this work, the quantities by volume will be found attached, and the student is advised to look them over, and compare them with the above example. 3. Calculations from weight to volume, and vice versa, are based upon the two propositions already laid down, that ii'2 litres of an elementary gas, and 2 2 '4 litres of a compound gas weigh respectively their atomic or molecular weights in grammes. Suppose we inquire what the 39*18 grammes of oxygen, already found in a former calculation, would measure. By proportion we have the statement — if 16 grammes of oxygen occupy 11*2 litres what would 39*18 grammes measure. , 16 : 11*2 : : 39*18, 11*2 X 3q*t8 , or ^ = 27*43 litres of oxygen. i|6 The weight of a litre of any gas may also be obtained by the use of the crith, or weight of a litre. of hydrogen, which is *0896 gramme. If this be multi- plied by the ato 7 nic weight of any elementary gas, or half the 7 nolecular weight oi any co 77 ipound gas, the weight of a litre of the gas in question is obtained. The calculations are all supposed to be done on gases at normal temperature and pressure, and the present is a mere introductory sketch, full details of the in- fluence of change of the conditions when measuring being given elsewhere. {See Specific Gravity, Thermometer, and Barometer in the Author's Analyti- cal Chemistry, 9-17? cind 3-6.) CHAPTER III. SIMPLE BASYLOUS RADICALS. SOURCES, ISOLATION, AND CHARACTERS. The elements, or simple radicals, are divided into two classes : the metallic elements, and the metalloids. It may be remarked, at this point, that — METALLOIDS Are usually electro-negative in the compounds they form on uniting with metals or compound basylous radicals. This class includes : Arsenic* Boron Bromine Carbon Chlorine Fluorine Iodine Nitrogen Oxygen Phosphorus Silicon Sulphur Selenium METALS Are usually electro-positive in the compounds which they form on unit- ing ’ with metalloids, or compound acidulous radicals. The metals used in pharmacy are : — Aluminium Lead Antimony Lithium Barium Magnesium Bismuth Manganese Cadmium Mercury Calcium Nickel Cerium Platinum Chromium Potassium Cobalt Silver Copper Sodium Gold Strontium Hydrogen Tin Iron Zinc Following out the principle of the distinction between basylous and acidu- lous radicals, it is first necessary to consider the former class. We will therefore take the simple basylous radicals or metals seriatim, with special reference to their sources, isolation, and analytical detection, afterwards treat- ing of compound basylous radicals in a separate chapter, and finally devoting a special chapter to each of the metalloids and .their compounds with basylous radicals and with each other. All simple basylous radicals are solid, except mercury (and hydrogen, if regarded as a metal), and most solid metals possess the properties of: — I. Malleability, the capability of being spread out into plates, or leaves, or ‘ foil, under mechanical force. Gold-leaf offers the most striking ex- * Arsenic is a connecting link between metals and metalloids, possessing to some ex- tent the properties of both. For good reasons, it is recommended that the pharmaceutical student should regard arsenic as a metalloid, although in practical analysis this substance is detected and separated among the metals. Bismuth and antimony own similar properties, but for convenience they are classed among the metals. MALLEABILITY.— DUCTILITY.— FUSIBILITY. 27 ample of the tenuity to which a highly malleable metal may be ham- niered ; and silver, platinum, copper, and tin form illustrations of the delicate leaf or foil to which these metals may be rolled. But pressure or blows on any malleable metal increase the specific gravity, render- ing it harder, and inducing a tendency to brittleness. Such a condition would obviously unfit many of our best known and most useful metals for the uses to which they are constantly applied in the arts. By the simple process of annealing, however, any malleable metal may regain its original condition, as it likewise recovers its former specific gravity. Heating the metal to redness away from contact with the air (if it will bear such a heat without fusion), then cooling gradually or rapidly, according to the degree of softness required, constitute the whole pro- cess of annealing. 2. Ductility, that tenacity or power of resisting separating force which is exemplified in the art of wire-drawing. This consists in drawing metallic rods through a succession of cone-shaped perforations in a steel plate, each hole being a shade smaller than its predecessor, until the desired degree of fineness has been obtained. Under such treat- ment, the metal is apt to become brittle, but is at once restored to its original condition, as in the analogous cases of metals being passed through rolling mills or under the hammer, by the process of annealing. It having been found necessary in the arts to determine the order of tenacity of ductile metals, this is accomplished by noting the amount of weight demanded in order to break wires which have been drawn through the same orifice. The order is as follows : — Iron, Copper, Platinum, Silver, Gold, Zinc, Tin, Lead. 3. Fusibility, the degree of susceptibility to the melting power of heat pos- sessed by metals. This sensitiveness is exceedingly variable, and reaches from mercury, which is always fluid above - 39° Fahr., to cast iron, which requires 2786°; not to mention platinum, which is only partly fusible by the oxyhydrogen blowpipe. Iron, platinum, and some other metals, possess an additional property when in a partially melted condition, which, in the arts, greatly enhances their value. Before fluidity supervenes, they acquire an adhesive or viscous state, which admirably suits them to endure the blows of the hammer or the pres- sure of the rolling-mill ; to be puddled in the furnace, and welded to- gether either in or out of it. It is this speciality which enables us to unite separate pieces of iron or steel without the aid of solder, and to hammer or compress spongy platinum into a solid bar. -X Simple basylous radicals form two varieties of combinations : — 1. Those with acidulous radicals, called salts, as already explained. 2. Those alloys which are produced by the mutual combination of metals themselves. Although most metals may to some extent exist in a state of combination with each other (a state called alloy, and, when mercury is present, amalgam), yet the chemical affinity between them is often so feeble, and the restraint which binds them together so weak, that the synthesis is easily disturbed. But it has been observed that in proportion to the dissimilarity between the metals of an alloy or amalgam is the stability and permanence of the com- pound increased ; and yet in no case does that peculiar alteration of physical character, which specially marks chemical combination, occur to any great 28 SIMPLE BASYLOUS RADICALS. extent. A metal alloyed or amalgamated with another metal, retains most of its distinguishing features, and no such metamorphosis or transmutation occurs as we find in the combination of a metal with a gas, an acid, or an alkali. The alteration which usually occurs affects the metallic tenacity, colour, and degree of hardness, although alloys of metals possessing wholly opposite chemical characteristics, are remarkable for their exceeding frailty of mutual cohesion. Table of the Composition of the more Common Alloys. Brass ... Britannia Metal Bronze... Bell Metal Gun Metal Pewter... Speculum Metal Solder (soft) ... „ (hard) ... Type Metal White Metal ... Oreide ... Among these are potassium and sodium, which are distinguished by the peculiarity of each metal forming but one chloride. Their carbonates are soluble in water. Heat fails to expel the water contained in their alkaline and caustic hydrates ; they decompose water at all temperatures ; energetically combine with oxygen ; and they are soft, easily fusible, and volatile at high temperatures. Silver is only distantly related to the alkali-metals, as, for in- stance, in forming an alum, similar to that obtained from aluminium and* potash. Hydrogen, although a gaseous body, and always formerly treated in chemical works as a metalloid, is, for various reasons to be given hereafter, considered by us a monad metal. Cu(84'3) + Zn(5'2) -f Sn(io'6). Sn(25) -1- Sb(5o) -»-Bi(25). Cu(86) + Zn(i I'l) -1- 811(2-9). Cu(8o) + ZnU'G) + Sn(io-i). Cu(93) + Sn(7). Sn(86) + Sb(i4). Cu(5o) + Zn(2i) + Sn(29). Pb(i) + Sn(2). Cu(8) 4-Zn(8) + Sn(i). Pb(69) + Sb(T5-s) + Bi(i5-5). Cu(7-4) + Zn(y4) + Sn( 28 ' 4 ) + Sb( 56 ' 8 ). Cu(73) +Zn(i2-3) [with MgO(4-4)NH4Cl(2'5) KHC4H40g(6'5) and CaO(i'3) as fluxes]. Class I. MONADS. HYDROGEN (L/ydrogenitm) . Symbol, H. In the free state^Yi^. Atomic Weight, 1. Atomicity, Monad. Density, 1. Weight of 1 litre, at 0 ° C. aiid 760 imn.., *0896 gramme. One gramme, at 0 ° C. and 760 occupies 11*3 litres. This colourless, inodorous, and tasteless gas, is the lightest known body in nature ; and, as being the standard adopted among scientific men (both as regards its combination by weight and volume) to which all other bodies are referred, and with which they are compared, it deservedly commands prior study. By some chemists it has been described as a gaseous metal, under the names hydrogenium and hydrium, on account of alloys which have been apparently formed by it with palladium and other metals. This idea seems to have re- ceived confirmation from the fact that such metals, although known to have absorbed many hundred times their bulk of hydrogen, refused to part with any of it, either in vacuo or at a red heat. It is beyond doubt, also, that the chief relations of hydrogen are electro-positive ; and, looked at in this light, we prefer to treat the body as if its metallic properties had been definitely proved. HYDROGEN. 29 Hydrogen was alluded to by Paracelsus as early as the i6th century, al- though first isolated by Cavendish in 1766 ; an honour which is likewise claimed for Watt and Lavoisier. It is found in the vapours which emanate from certain volcanic fissures in Iceland ; it forms one-fourth of the compound called marsh-gas ; water contains it to the extent of one-ninth ; in smaller quantities it appears combined with numerous other substances ; and it is present in all vegetable and animal organisms, and in many minerals. The lightest body known in nature ('the oxygen of the air is sixteen times heavier), it might naturally be supposed that an inverted, open-mouthed jar would be in no danger of losing its contents. Yet the reverse is the truth, as we find that the law of diffusion, which is more or less characteristic of all gases, prompts the hydrogen in the jar to diffuse downwards, as well as in every other direction, so that in a very short period of time the vessel, once full of this gas, would be found occupied by ordinary atmospheric air. This law of diffusion, as already mentioned, proceeds in inverse proportion to the square root of the specific gravity of the gas. Hydrogen may be prepared as follows : — 1. By throwing potassium on water, when potassium hydrate is simul- taneously formed. Kg + 2H2O = 2KHO -F H3. This action is simply one of direct displacement, and is so violent that the heat produced inflames the hydrogen. 2. By passing the vapour of water over red-hot iron; forming ferroso-ferric oxide, and liberating hydrogen. Feg + 4H2O = Feg04 + 4 ^ 2 - 3. By the action of dilute sulphuric acid or hydrochloric acid upon iron or granulated zinc, sulphates of the metals being formed in the first case, and chlorides in the second : — Fcg + 2H2SO4 - 2FeS04 + 2^2* ^^2 + 4HCI = 2FeCl2 + 2H2. Zn2 + 2H2SO4 = 2ZnS04 + ^^2- '^^2 + 4HCI - 2Z11CI2 + 2H2. Granulated zinc is the preferable form in which to use this metal for the evolution of hydrogen. It is thus made : The ordinary zinc of commerce, reduced to moderately small fragments, is fused in an iron ladle over a brisk fire. As soon as the metal has become fluid, it is poured into a bucket of cold water, from a height of about a dozen feet, when each drop expands into a trumpet-shaped mass, which, exposing a considerable surface to chemical action, is readily dissolved when in contact with a suitable acid. 4. By the action of potassium or sodium hydrate upon zinc, aluminium, or tin, forming zincates, alummates^ or stannates : — Zn + 2KHO = KaZnOg + H2. 2AI2 + 6NaHO -F 3H2O = Na6Al40g + 6H2. 5. By the action of potassium or sodium hydrate upon oxalates, and upon many other organic salts : — K2C2O4 + 2KHO - 2K2COg -F Hg. Hydrogen is capable of liquefaction by submitting it to a pressure of 650 atmospheres in a tube cooled to - 220° Fahr. with the aid of solid carbonic anhydride. On suddenly releasing the pressure by opening a jet, the liquid hydrogen rushes out, forming a steel-blue spray of liquid,' which solidifies 30 SIMPLE BASYLOUS RADICALS. through the cold produced by its own evaporation, and falls as a hail of solid particles. This great discovery has been made by the aid of an ingenious apparatus devised by M. Pictet The gas is but sparingly soluble in water or alcohol, one hundred gallons of either only dissolving or absorbing two gallons. It is condensed in the substance of several metals, notably platinum (to the extent of 3 ’8 volumes), palladium (376 volumes), and iron (about two volumes). The late Professor Graham, who studied this phenomenon carefully, applied the term occlusion to this singular state of absorption. During his researches it came to light that the meteoric iron of Lenarto, when placed in a good vacuum, yielded 2-85 times its volume of gas, consisting of 85*68 per cent, of hydrogen, 4*46 of carbon monoxide, and 9*86 of nitrogen. When we reflect that spectrum analysis proves that hydrogen constitutes the chief element in the atmosphere of many of the fixed stars, and then gaze upon the fragment of such an aerolite as that of Lenarto, we can appreciate the words of Professor Graham, when he says that “ this meteorite may be looked upon as holding imprisoned within it, and bringing to us, the hydrogen of the stars.^’ When a light is applied to hydrogen gas, as it issues from a jet in contact with the atmosphere, it inflames, producing water ; but although thus proved to be combustible, it is not a supporter of combustion. The flame produced possesses intense heating power, notwithstanding its feeble illuminating pro- perties ; and should a stream of oxygen gas be impinged upon it, so that neither jet occurs in excess, the oxyhydrogen blast resulting, yields, with the exception of that generated by an electric current, the most concentrated and irresistible heat with which we are yet acquainted. The absorption of gases- by certain metals is strikingly exemplified by the following simple experiment ; — If a fragment of spongy platinum be exposed to a jet of hydrogen, it “ occludes’' the gas so rapidly that sufficient heat is generated to produce final inflamma- tion of the hydrogen. Seizing upon this circumstance enabled the inventor of the now almost obsolete hydrogen lamp to obtain an instantaneous light, long before lucifer matches had been popularized. The objection to this means of obtaining an immediate light lies in the fact that, if the hydrogen lamp is left unused, its little mass of spongy platinum becomes damp, through absorption of moisture from the air, so that its usefulness for a time is lost. Free hydrogen is feeble in its action on other substances, but in the nascent condition it is remarkably powerful. It will be understood that by the term nascent is meant the instant of its liberation from any body with which it may happen to be combined. In order to obtain the full benefit of this peculiar activity it is only necessary to expose the matter to be decomposed, in a state of solution, to the action of a mixture of zinc and sulphuric acid, or some other similar combination of ingredients from which hydrogen may be evolved. By such exposure bodies are, in chemical language, said to be “ reduced ” from a higher to an inferior state of oxidation, on account of the abstraction of their oxygen to form water. For example : — Ferric salts are reduced to fer- rous ; or nitric acid to ainmonia. Hydrogen possesses the property of entering into combination with all the non-metallic elements as follows : — HYDROGEN.— LITHIUM.— AMMONIUM. 31 Non-Metallic Compounds of Hydrogen. Monads Dyads Triads Tetrad Element. Symbol. Result of Combination. Chlorine . HCl Hydrochloric Acid. Bromine . . HBr Hydrobromic „ Iodine . . . HI Hydriodic „ Fluorine . . HFl Hydrofluoric „ Oxygen . . H^O Water. Sulphur . , . HgS Sulphuretted hydrogen. Selenium . . HgSe Seleniuretted „ Nitrogen . . NH3 Ammonia. Phosphorus . PH3 Phosphuretted hydrogen. Arsenic . . ASH3 Arseniuretted „ Antimony . SbH3 Antimoniuretted „ Marsh gas, and a long series \ of bodies called hydro- Carbon . . CH, . carbons, of which this compound is the starting - point. Hydrogen also combines with many metals and organic radicals to form combinations called “ hydrides.” But it should be recollected that the atom of this element found in the basylous parts of salts has quite a different duty to perform from that occupying the acidulous. It is the latter combination which yields the hydrides just referred to, whilst the basylous radical of acids is wholly due to the former. The only metallic hydride of interest to the pharmacist is cuprous hydride, CugHg. This is a yellow powder, when first obtained by precipitating cupric sulphate with hypophosphorous acid, but it quickly becomes reddish-brown. The precipitate occurs at about 160° F., but the product is decomposed if the heat be raised to 212°. It may be distin- guished from metallic copper, to which it bears a great resemblance, by dis- solving easily in dilute hydrochloric acid with effervescence, whilst copper does not give rise to any action whatever.' LITHIUM. Symbol, Li. Atomic Weight, 7. Specific Gravity, 0*59. Melting Point, 356° F. Lithium is found as lepidolite or petalite (aluminium and lithium silicate) ; but the best sources of this metal are certain mineral springs (discovered in Cornwall and brought into notice in 1864), in which it exists as chloride. In the metallic state lithium is a chemical curiosity, and oxidizes so readily that it requires to be kept from the air. It may be prepared from its chloride by electrolysis. This metal is harder than potassium, but softer than lead ; it is ductile, and is remarkable as being the lightest known solid. When heated in the air it burns, forming an oxide. {For detection and separation of Lithium see Author’s Analytical Chemistry, page 46.) AMMONIUM. S 3 rmhol, Am (NH^). Atomic Weight, 18. The existence of this metal in the free state is still a doubtful point. Some 4 32 SIMPLE BASYLOUS RADICALS. chemists say that it has been isolated, and takes the form of a very volatile deep blue liquid, decomposing rapidly at the ordinary temperature of the air, and only capable of existing in the almost entire absence of heat, and under very great pressure. It is quite certain, however, that it may be obtained by the action of sodium and mercury, with which it forms an amalgam when these metals are placed in contact with a concentrated solution of ammonium chloride (NH^Cl). Na2Hg+ 2NH4Cl = Hg(NH4)2 + 2NaCl. This amalgam rapidly splits up : — 2Hg(NH,) = Hg2 + 2NH3+H2. Combinations of ammonium with a volatile acid are entirely volatile ; with a fixed acid, such as phosphoric or horacic, the acid remains. This metal is monad in all its compounds. [For detection and separation of Ammonium, see Author's Analytical Chemistry, 48.) SODIUM {Natrium). Symbol, Na. Atomic Weight, 23. Specific Gravity, '972. Melting Point, 207° F. Sodium salts are almost universally distributed in nature. The chloride (NaCl) constitutes a large proportion of the residue of sea-water. The car- bonate (Na2C03) was, in former times, almost entirely obtained from the ashes of marine plants. It is now, however, prepared from the chloride, either by Leblanc’s process or by a new mode, called the ammonia pi'ocess, which has been devised by R. Wagner (see Carbonates). The metal is prepared by heating a mixture of sodium carbonate and charcoal, in the manner adopted for the preparation of potassium, the next metal to be described. In its general properties sodium resembles potassium ; but its combination with other bodies is attended with less violence, and the hydrogen it ev^olves when brought into contact with water, does not burst into flame unless the water be heated, or the sodium kept stationary. [For detection, separation, and estimation of Sodium, see Author's Analytical Chemistry, pages 47 and 176.) POTASSIUM {Kalium). Symbol, K. Atomic Weight, 39T. Specific Gravity, *865. Melting Point, 144° F. Compounds of potassium are found in the ashes of most plants, in many waters, and in combination with silicic acid in several minerals. Potassium may be obtained by calcining potassium hitartrate (thus converting it into a mixture of potassium carbonate and carbon), and heating the residue to whiteness in a suitable retort, having adapted to it a condenser containing mineral naphtha. The metal is collected in small globules, which, on exposure to the air, are almost instantaneously oxidized, the oxide (,K20) being formed. In contact with water, at any temperature, potassium becomes sufficiently hot to inflame the hydrogen, which it displaces as the gas escapes. By this displacement potassium hydrate is formed : — K2-f2H20-2KH0-i-H2. The flame of the escaping hydrogen is tinged purple or violet by a trace of potassium vaporized by the heat. With all colourless acids, potassium forms colourless salts, and always behaves as a monad. [For detection, separation, and estwiation of Potassium, see Author's Analytical Chemistry, pages 4 T and 17 S-) SODIUM. -POTASSIUM.— fM, 10|j SILVER {Arge7itiwi). Symbol, Ag. Atomic Wi 10*47. Melting Point, white heat. The Hartz mountains in Germany, KongsbergHk Norway the Andes of America appear to be the seats of the chief sil\wn5m^^rTb^ metal is found in the forms of sulphide, chloride, iodidfeJ^^S^Jorpy^E^^nd occasionally it occurs almost pure. The ore, having been powdered and mixed with common salt, is subjected to a low red heat in a suitable furnace, the result being that any sulphide of silver present is transformed into chloride. The whole is then transferred to a cylindrical vessel revolving on its axis, into which are likewise introduced water and scraps of iron, the arrangement and its contents being kept in motion until the silver chloride is reduced by the iron to metal. Mercury is now poured on the mass, and the trituration repeated, when the mercury unites with the silver, gold, and metallic copper, producing a fluid amalgam which is readily separated from the mud in the vessel by subsidence and washing. A strong linen cloth is presently brought into requisition, through which the amalgam is strained, the solid portion remaining being subjected to distillation, by which its mercury is volatilized and the impure silver left. Every specimen, nearly, of native lead sulphide contains silver ; but its extraction rarely pays for the expense. Silver is also obtained by roasting the ore with pyrites, which converts the mass into argentic sulphate, the heat being so regulated that the ferrous sul- phate, also produced, becomes decomposed towards the end of the process. Metallic copper is then introduced, which decomposes the argentic sulphate, when a deposition of metallic silver follows, leaving cupric sMphate in solu- tion ; thus yielding a product of great commercial value : — AggSO^ + Cu = Agg + C11SO4. Chemically pure silver may be prepared from any alloy containing it, such as a silver coin, by dissolving the article in dilute nitric acid aided by heat. The addition of hydrochloric acid will precipitate the silver in the form of chloride, leaving the other metals in solution. The argentic chloride having been collected and washed with boiling water, may now be reduced to the metallic state by any of the following processes : — I. By fusing it with a mixture of potassium with sodium carbonate : — _ 2AgCl + KNaCOg = Ag^ + KCl NaCl + CO2 + O, (This is the B.P. process.) By boiling with an alkaline solution of glucose. (Argentic chloride, by the action of potassium hydrate, yields argentic oxide, from which glucose reduces the metal.) By reducing the freshly precipitated chloride with zinc and very dilute sulphuric acid ; — qAgCl + Zug = 2ZnCl2 + 2Agg. Silver requires the power of a white heat in order to melt it ; and although, when in a state of fusion in contact with the air, it absorbs oxygen, this gas does not combine with it to form an oxide, but is entirely rejected by the metal during the process of cooling. Silver is not acted upon either by cold hydrochloric or sulphuric acids, but on being boiled with the latter it dissolves, forming argentic sulphate : — Agg -t- 2H2SO4 = Ag2S04 + SOg + 2HgO. The best solvent for silver is dilute nitric acid, in which it dissolves freely on the application of a gentle heat, and forms argentic nitrate. 3Agg + 8HNO3 = ^AgNOg -h 2NO 4- 4H2O. II III. D 34 SIMPLE BASYLOUS RADICALS. When silver is digested in pure strong nitric acid (sp. gr. 1*42), it dissolves only by the application of heat, but the presence of even a trace of nitrous acid causes immediate action. It combines directly with sulphur, chlorine, iodine, and bromine. By the action of sulphuretted hydrogen it is blackened : — Agg + HgS = AggS + Hg. Silver is monad in all its compounds, silver chloride being AgCl, sulphate AggSO^. [For detection, separation, and estimation of Silver, see Author's Analytical Chemistry, pages 27 and 165.) Class II. DYADS. Group i. consists of the three metals, calcium, strontium, and barium, which unite with oxygen to form oxides called “ alkaline earths.” Like the former class, they each form but one chloride, but their carbonates are wholly insoluble in water. Group 2. The resemblance between cadmium, zinc, and magnesium con- sists in the fact that they are volatile at high temperatures, burning when heated in the air ; that they each form only one oxide and one chloride ; and that they displace the hydrogen from dilute acids. Formerly, magnesium was regarded as one of the earth metals, but it is now held to evince a closer analogy to zinc. Group 3. Copper and mercury are powerless to decompose water at any temperature, but are themselves oxidized by nitric and strong sulphuric acids, and they each form two chlorides and two oxides. CALCIUM. Symbol, Ca. Atomic Weight, 40. Specific Gravity, I* 5778. Of all the alkaline-earthy metals, calcium is the most copiously distributed, entering into the composition of entire mountain ranges ; and yet it never occurs in a free state, but always in combination with other substances. Its compounds exist in the forms of carbonate, tungstate, sulphate, nitrate, sili- cate, arseniate, chloride, and fiuoride, in rocks and earths ; as carbonate and phosphate in animal bones ; as carbonate in the shells of crustaceas and tes- taceae ; and it exhibits its presence in the ash of nearly every plant, and is held in solution by all waters. The metal may be procured by the electrolysis of calcium chloride, or by the action of sodium vapour upon the same : — 2CaClg + 2Nag = Gag -f 4NaCl. As this metal rapidly oxidizes when in contact with air, especially if it be moist, preservation in mineral naphtha is necessary. In colour, ductility, malleability, and hardness, it resembles gold. Heated in the air on platinum- foil over a spirit-lamp, it oxidizes with a brilliant flash. Of its compounds with other metals comparatively little is at present known. It forms an amalgam with mercury, but as yet, in the arts, calcium has received no prac- tical application. Thrown on water or on acids it ignites. The common forms of calcium carbonate are limestone and marble, while its rarer and purer states are calc-spar and arragonite. [For detection, separation, and esthnation of Calcium, see Author's Analytical Chemistry, pages 45 and 173.) STRONTIUM. Symbol, Sr. Atomic Weight, 87'5. Specific Gravity, 2*5418. This metal takes its name from Strontian, in Argyleshire, where it was first observed in the form of carbonate in 1787 j and it has since been detected, to CA L CIUM.-S TR ONTIUM.-BA RIUM.—MA GNESIUM. 35 a limited extent, in a salt-spring at Eger, in sea-water, and in the mineral waters of Kaiser-Franzensbrunnen. The native carbonate {strontianite^ SrCOg) and the sulphate {ccelestin^ SrSO^) are the chief sources of strontium, which in some respects resembles calcium and barium. This metal resembles calcium in possessing a similar yellow colour ; but it oxidizes in the air with much greater rapidity, and it ignites when thrown upon water and on acids.. Strontium possesses no pharmaceutical interest, its use being almost altogether limited to pyrotechnical display. The strontium nitrate is invaluable for this purpose, owing to the brilliant crimson colour it may be made to communicate to flame. {For detection^ separation^ and estimation of Strontium, Analytical Chemistry, pages 44 and 1 74. ) BARIUM. Symbol, Ba. Atomic Weight, 137. Specific Gravity, 4. Melting Point, below redness. The metal barium, although as yet unapplied to any practical purpose in the arts or sciences, is peculiar on account of the great density of its com- pounds. It is from this circumstance that its name has been taken from the Greek word, heavy. Its chief sources are the native carbonate ( Withe- rite, BaCOg) and snlphate {barytes, or heavy spar, BaSO^). From the former (barium carbonate) the rarer barium salts are prepared ; whilst from the latter, a substitute for white-lead, used in oil painting, is derived. Never found uncombined, it is obtained by passing sodium vapour over fused barium chloride, or by the electrolysis of the latter : — aBaClg + aNag = Ba2 -f- 4NaCl. Barium is ductile, and may be hammered out into a sheet ; but as it oxidizes very rapidly in the air, these useful properties give it no practical utility. Heated in the air, it oxidizes with a dark red light, and with a greenish flame before the oxy-hydrogen blowpipe. {For detection, separation, and estimation of Bar iujn, see Author's Analytical Chemistry, pages 43 and 173.) MAGNESIUM. Symbol, Mg. Atomic Weight, 24. Specific Gravity, 1*7430. Melting Point, 752° F. Magnesium is usually extracted frpm dolomite (magnesium and calcium carbonate) or from its various silicates. It also occurs in springs in the form of E,psom salts (magnesium sulphate) in sea- water ; in the structure of animals and plants ; and in combination with acids derived from organic sources. Magnesia alba (magnesium carbonate) was formerly used in Rome as a medicine about the commencement of the i8th century; but it was Sir H. Davy who first obtained the pure metal, which may be eliminated by electrolysis, as follows. Introduce into the bowl of a common tobacco-pipe, a mixture of four parts magnesium chloride, three parts potassium chloride, with a little ammonium chloride. Heat the bowl over the flame of a spirit-lamp or Bun- sen’s burner, the negative pole being an iron wire passed up the pipe stem, and the positive pole a fragment of coke, which must touch the surface of the fused contents, when the metal will appear in the form of globules. For commercial purposes, magnesium is produced by heating together to bright redness, in a covered earthen crucible, a mixture of six parts magnesium chloride, one part fused sodium chloride, one part pulyerized calcium fluoride, and one part of sodium, when the metal collects in large globules. In ‘dry air magnesium oxidizes with difficulty, but a moist atmosphere quickly converts it into the oxide. Strongly heated, as when being held in the 36 SIMPLE BASVLOUS RADICALS. flame of a lamp or gas jet, it ignites, burns with an intense white light, and deposits magnesium oxide. The metal is rapidly soluble in very dilute hydrochloric and sulphuric acids, with the evolution of hydrogen ; but it is only slowly soluble in strong sulphuric acid. When thrown into strong hydrochloric acid it momentarily takes fire. In its behaviour it is invariably a dyad. It forms a solid amalgam with mercury, either when the two are heated together or when produced by electrolysis in the presence of the latter metal. The chief native magnesium silicates may be noted to be as follows : — Chrysolite . . . MggSiO^. Mica or Talc . . . 4MgSi03Si024H20. Meerschaum . . . 2MgSi03Si02. Soapstone is magnesium aluminium silicate, while augite and hornblende are magnesium and calcium silicates with a little iron. {For detection^ separation^ arid estimation of Magnesium, see Author’s Analytical Ckemistry, pages 45 and 174.) ' ZIFC. Symbol, Zn. Atomic Weight, 65. Specific Gravity, from 6’8 to 7*2. Melting Point, 773° F. Zinc is largely found in the forms of carbonate {calamine), sulphide {blende, or black jack), and oxide {red zmc-ore) ; and it appears in less abundance as aluminate, arseniate, phosphate, and sulphate ; but the most valuable of all the zinc ores is the calamine, or native carbonate, so named on account of the structural resemblance of the mineral to a reed. Although not usually a constituent of plants, this metal has been discovered in the ash of the Viola calairdnaria, a violet which flourishes in Rhenish Prussia on the debris of the calamine mines in that district. Zinc is extracted as follows : — The ore, after subjection to a preliminary calcination, is mixed with half its weight of powdered charcoal, anthracite, or coke, and heated in muffles furnished with a rectangular flue, when the mingled vapours of carbonic oxide and zinc pass off, and the latter, on condensing, drops from the opening in a liquid condition. As a secondary product in the smelting of lead ores, zinc is not disregarded. Provision is usually made for the condensation of the fumes, which are received upon' a slanting stone (called at Goslar, in the Hartz mountains, the zinc stool), from whence the metal is collected, melted in iron pots, and poured out on tables. The change effected on zinc ore in the furnace is as follows : — I . ZnCOg == ZnO + CO2, or zZnS + 302= zZnO + zSOg. 2. 4 ZnO + Cg = zZn2 + 2CO2. The first portions of the zinc which volatilize, are generally rendered impure by the presence of cadmium and arsenic. On this account they are occasion- ally rejected, or are subjected to special purification. When the metal is strongly heated it vaporizes, and the fumes burn in the air with a brilliant white flame, resulting in the formation of zinc oxide. Zinc is readily soluble in dilute sulphuric, hydrochloric, and nitric acids. It combines directly with chlorine, bromine, and iodine; in all its compounds behaving as a dyad. Cold strong sulphuric acid has little or no action upon zinc, but the dilute acid forms zinc sulphate with the evolution of hydrogen. Hydrogen is like- wise evolved when the metal is treated with hydrochloric acid, the result being zinc chloride. Tolerably strong nitric acid unites with it, and forms zinc nitrate, with the evolution of nitric oxide ; whilst very dilute nitric acid in forming zinc nitrate produces ammonia. This metal is soluble in potas- sium and sodium hydrates, with the evolution of hydrogen. ZINC.— C A DMIUM.— COPPER. 37 Zinc is brittle, and slowly tarnishes or oxidizes when exposed to the air ; if heated from 248° to 292° Fahrenheit, it becomes malleable, and and may be hammered or rolled without risk of disintegration, retaining this valu- able property on cooling. This is how the sheet-zinc of commerce, which IS now put to so many varied and important uses, is made. The so-called “ galvanized iron ” is simply sheet-iron upon which a coating of zinc has been deposited of sufficient thickness to prevent rusting for a long time. German silver is a compound consisting of nickel and zinc. {For detection, separation, and estimation op Zinc, see Author^ s Analytical Chemistry, pages 41 and 171.) CADMIUM. Symbol, Cd. Atomic Weight, 112. Specific Gravity, 8 60. Melting point, 500° F. Bishopstown in Renfrewshire has the distinction of producing the only pure native source of this metal at present known. It occurs there in the form of Sulphide, and passes under the name of Greenockite. In small quantities it is found also in the blende of Hungary and Nuissere, and in the zinc ores from Frieberg, Mendip, Silesia, in the smelting of which it is obtained as a secondary product of importance. Owing to its greater volatility, its vapour appears among the first results of distillation. The distillate is dissolved in warm hydrochloric acid, and the metal afterwards precipitated by the addition of sulphuretted hydrogen, which throws it down as a yellow sulphide, and yields a pigment highly esteemed for its rich golden 'colour and permanence. This sulphide, dissolved in hydrochloric acid and treated with metallic zinc, deposits the metal. ^ " ' 2CdCl2 + Zng = Cdg + 2ZnC\. It volatilizes at about 650° F. without odour, and is white with a blue tinge, flexible, malleable, lustrous, and ductile. Always dyad, it combines directly with chlorine, iodine, and bromine, and is dissolved with ease by hydrochloric and nitric acids, but with difficulty by sulphuric. Heated in contact with the air, it ignites, producing brown cadmium oxide. It forms a silvery alloy with platinum, and yellowish with copper. {For detection, separation, and estimation of Cadmium, see Author's Analytical Chemistry, pages 32 and 167.) COPPER (Cufntm). Symbol, Cu. Atomic Weight, 63*4. Specific Gravity, 8*96. Melting point, bright red heat. From the fact that-copper is found naturally in the metallic state, and is ductile and malleable immediately after fusion, we have no difficulty in arriv- ing at the reason why this metal should have be,en used by primitive man for the fashioning of agricultural implements, rude tools, and weapons of war, long before iron. Copper is abundantly distributed, and the following ores are those which exhibit its usual form : — eopper pyrites (cuprous sulphide with ferric sulphide, CugSFegSg), malachite (cupric carbonate with cupric hydrate, CUCO3CU2HO), cupric sulphide (CuS), and cupric sulphate (CUSO4). The metal is usually obtained either from the copper pyrites or from the cupric sulphide. These are roasted in the air till part of the sulphide is converted into oxide ; and when the mass is heated, without contact with the air, metallic copper and sulphurous anhydride result. 1. 2CuS -f- 202=^ zCuO -f- SOg. 2. 4CuO -f- 2CuS = 3CU2 4- 2SO2. In order to remove a little cuprous oxide which generally remains undecom- 38 SIMPLE BASVLOUS PAD/CALS. posed, the fused metal is stirred with a piece of green wood. Copper, although a dyad metal, possesses the property of becoming self-saturated, Cu", pro- ducing (Cug)'''. The former is the radical of cupric salts, the latter of cuprous. The cupric salts are by far the more important, none of the cuprous being either known in commerce or used in medicine. This metal resists the action of either dilute sulphuric or hydrochloric acids ; but strong sulphuric acid, aided by heat, converts it into cupric sulphate, with the evolution of sulphurous anhydride. It is acted upon by nitric acid whether strong or dilute, which attacks it readily, forming cupric nitrate, with the evolution of nitric oxide. When the acid is hot and strong, a little nitrogen is also formed ; and when cold and dilute, the evolved gas contains a little nitrous oxide. When heated in the air, copper oxidizes without inflaming. Our bronze coinage is an alloy into which 4 per cent, of tin and i per cent, of zinc with 95 per cent, of copper enter. Copper unites with a great number of other metals, such as gold, silver, cadmium, iron, lead, aluminium, antimony, and even with arsenic, forming with the last named, very definite, grey, brittle compounds. {For deteciion, separation^ and estimation of Copper^ see Author's Analytical Chemistryj/a^^j- 31 and 167.) MERCURY (Hydrargyrum). Symbol, Hg. Atomic Weight, 200. Specific Gravity, 13 59. Boiling Point, 652° F. Apart from the singularity of its appearance, mercury is deserving of special attention on account of the varied and important purposes to which it is applied both in pharmacy and in the arts. Known from the earliest times, cinnahar (mercuric sulphide) was employed as a pigment by the ancients ; calomel (mercurous chloride) was familiar to the alchemists ; and corrosive sublimate (mercuric choride) at an early period was common among the Arabians. Although often found in the form of globules distributed throughout the substance of its ores ; in combination with gold and silver, as amalgams ; as chloride, iodide, and rarely as selenide, — it is in the form of sulphide that we meet the source from which the bulk of the mercury of commerce is obtained. The chief ciimabar mines are those of Almaden in Spain, and Idria in Illyria ; but in Bavaria, Bohemia, Hungary, and some other parts of Europe the ore occurs sparingly ; whilst in China and Japan, Peru and California, it is much more extensively found. Cinnabar is deprived of its mercury by two methods, ?>., by roasting in the air, or by being heated with quicklime (calcium oxide). By the first process the following effect is produced : — 2 HgS + 2O2 = Hgg + 2SO2 When calcium oxide is used, calcium sulphide is formed, oxygen being evolved : — 2HgS + 2CaO = Hg2 -f- 2CaS + O2. By the action of metallic iron we can also obtain mercury from cinnabar : — 2HgS -f Fe2 = Hg2 + 2FeS. The boiling point of mercury being 662° F., in all the preceding processes it distils over, and condenses in chambers having an inclined floor, which enables the metal to run out and be collected. Its purification is accomplished by pressure through wash-leather and redistillation. In atomicity mercury is a dyad, although it has the property of self- MERC UR Y.—GOLD. 39 saturation so as to produce (Hgo)", the radical of mercurous salts, Hg" being the radical of mercuric compounds. Mercury is rapidly oxidized on exposure to the air, when at a temperature approaching 662° F., but is only slowly oxidized by moist air at the normal heat of the surrounding atmosphere. Hydrochloric and dilute sulphuric acids exert no action upon this metal ; but strong, boiling sulphuric acid converts it into sulphate, with the evolu- tion of sulphurous anhydride. Dilute nitric acid dissolves it, and a mixture of mercuric and mercurous nitrates results, unless the temperature of the acid has been low throughout the progress of the operation, in which case only the latter is obtained. The action of pure nitric acid of 1*42 specific gravity requires heat unless some nitrous acid be present. Mercury forms amalgams with many metals, notably zinc, lead, gold, silver, potassium and sodium. The latter compound is extensively used in organic research. Tin amalgam is used for ‘‘ silvering ’’ mirrors. {For detection^ separation, and estimation of Mercury, see Author's Analytical Chemistry, pages 28, 30, and 166.) Class III. TRIADS. The only metal of interest to us in this group is : — GOLD (Aurum). Symbol, Au. Atomic Weight, 1967 . Specific Gravity, 19 * 50 . Melting point {average'), 2435 ° F. {Pquillet, 2192°; Marveau, 2518°; Daniell, 2596°). If the eagerness with which any natural production is sought after by all conditions of civilized man be a correct index of its value, then indeed gold stands pre-eminent. But this beautiful and much- desired metal has special 'merits of its own, which would amply recommend it, even were it as cheap as iron. , Probably no substance amidst all our geological treasures is more impartially distributed over the globe than gold, inasmuch as, in some form or other, it is found in every country under the sun. In Europe our chief sources of supply are Transylvania and Hungary ; but it occurs in notable quantities in the sands of the Rhine, the Aar, and the Reuss ; it lurks amidst the recesses of the Alps, Monte Rosa, and Val d’ Aosta ; and to come nearer home, we are occasionally gratified by a glimpse of its glittering particles in the streams of Cornwall and amidst the rocky fastnesses of Scotland and Ireland. The Ural mountains, Siberia, the Altai and Cailas mountains, China, Ceylon, and the Eastern Archipelago, all yield a copious Asiatic tribute of gold ; Africa has its mines at Kordofan, between Darfour and Abyssinia ; the Ophir of Solomon is supposed to have been on the coast opposite the island of Madagascar; and we have learnt from Dr. Livingstone and other travellers, of rivers that teem with golden sand. In the New World we find gold abundant in Brazil, New Granada, and Chili; in Mexico, California, British Columbia, and Nova Scotia. And lastly, Australia and New Zealand produce the much-coveted metal in abundance. Gold is invariably found in the metallic state ; in the sands of rivers in the form of dust ; in auriferous quartz as grains ; and under the surface of the earth in the alluvial deposits formed by the disintegration of auriferous strata. Probably the purest samples yet obtained are those from Schabrowski in the Ural mountains, one of which was found to contain 98*96 per cent, of the pure metal. But our Australian gold does not compare unfavourably even with this remarkable assay, as it averages from 96 to 96*6 per cent. 40 SIMPLE BASYLOUS RADICALS. The extraction of this metal from the mineral substances mechanically associated with it is remarkably simple. It consists in washing with water to remove earth and clay, leaving the metal, either pure or alloyed, behind ; or by treating the bruised auriferous rock with mercury, thus forming an amalgam, which is afterwards purified and separated into its constituent parts by pressure through wash-leather, the removal of the mercury by distillation, and treatment with nitric acid to dissolve out the silver. Gold does not combine directly with sulphur, although it is tarnished by the presence of sulphuretted hydrogen. It is insoluble in all simple acids, but dissolves in nitro-hydrochloric acid, and in solutions of chloriae, iodine, and bromine. In its compounds it acts as a triad, but may by partial self-saturation act as a monad. The chloride pro- duced by its solution in the first-mentioned solvent is auric chloride (Au'^'CIg). Its oxide does not combine with oxy-acids to form salts. In the air, gold undergoes no change, not even when strongly heated ; but under the effect of a powerful current of electricity, thin leaves or minute wires are volatilized. Gold forms compounds with most metals ; the copper alloy is that used for coin, jewellery, etc. Gold solder is frequently partly silver as well as copper. {For detectioji., separation^ and estimation of Gold, see Authors Analytical Chemistry, pages 35 and i68.) Class IV. TETRADS. ALUMINIUM. Symbol, Al. Atomic Weight, 27*4. Specific Gravity, 2*56 to 2*67. Aluminium occurs in nature as oxide (Alg O3), and in many minerals as silicate. It is prepared by heating its chloride or fluoride with metallic sodium. AI2CI6 + sNag - AI2 + 6NaCl. This metal does not readily oxidize ; is but slowly attacked even by boiling nitric acid. Hydrochloric acid dissolves it readily, with the evolution of hydrogen. Al2 + 6HCl = Al2Clg-F3H2. It is not acted upon by dilute sulphuric acid, and scarcely at all by pure acetic acid. In solutions of alkaline hydrates it dissolves readily, producing aluminates and evolving hydrogen : — , AI2 + 2KHO -f 2H2O - K2AI2O4 -f 3H3 In no compound does the single atom, Al, exist, but always the double atom, Alg, which acts as a hexad. Great hopes were raised with respect to the application of aluminium in the arts, owing to its extreme lightness and the manner in which it resists oxidation. Deville was the first chemist who succeeded in obtaining . it in a pure metallic state. The so-called “ aluminium gold,” is nine-tenths copper and one-tenth aluminium, and is also known as aluminium bronze. {For detection, separation, and estimation of Aluminium, see .< 4 «//^i?r’/Analytical Chemistry, pages 39 and 172. ) MANGANESE. Symbol, Mn. Atomic Weight, 55. specific Gravity, 8. Manganese occurs in the ashes of plants and in several ores, of which pyrolusite (manganic dioxide, MnOg) is the chief. It is prepared by igniting this mineral, mixing the product with charcoal, and subjecting the combina- ALL UMLNUM.— MANGANESE.— IRON. 41 tion to intense heat. The metal so obtained is not readily fusible, and is quickly oxidized by exposure to the air. It is a tetrad in atomicity ; but two of its powers are generally latent, and thus it behaves as a dyad. The man- ganic salts are but little known, the manganous only being worthy of attention. Manganese is practically insoluble in cold strong sulphuric acid, but on heating it dissolves, evolving sulphurous anhydride. It is freely soluble in very dilute sulphuric and hydrochloric acids, with the evolution of hydrogen; and it is also readily attacked by nitric and acetic acids. Manganous salts are the only ones produced by the direct solution of the metal in acids. The material known as “ spiegel-eisen ” (mirror-iron) and employed in commerce as an addition to improve the quality of iron and steel, is an alloy of about four parts of iron to one of manganese. {For detectio 7 i, sepai'ationy and estimation of Manganese, see Ant/ior’s Analytical Chemistry, t>ages 40 and 1 7 1 . ) IKON {Ferrum). Symbol, Fe. Atomic Weight, 56. Specific Gravity, 779. If we consider the astonishing strides made in human industry, and to what an extent civilization has spread since the universal use of iron among culti- vated nations, we cannot fail to admit that although this metal may not be intrinsically the most valuable, it is by far. the most important. In the metallic state it is of very limited occurrence ; and with the exception of a trifling vein in the state of Connecticut, and isolated masses found on the surface in various parts of the world, supposed to be of meteoric origin, it has rarely been seen as such. The metal is contained in many ores, the most notable being the ferrous carbonate (FeCOg) or spathic ore ; the magnetic oxide (Feg04) i ferric oxide (FegOg) ; or hcematite; and the ferrous disul- phide (FeSg) or iron pyrites. The forms of the ferrous carbonate, “ black- band ” and ‘‘clayband’’ ironstones, are the ores from which iron is usually extracted in this country. These are first subjected to a preliminary roasting in a kiln or in heaps, to drive off water and carbonic acid gas, and then intro- duced into a blast furnace along with coke and limestone, where the ores are reduced at first to the metallic condition and afterwards the carbon present unites by cementation with the metal to form a “ carbide ” ; the silica and alumina contained in the ore uniting with the lime to form fusible slag. The blast of air used is heated to a temperature capable of melting lead, before it is allowed to enter the furnace ; and the operation proceeds night and day, fresh ingredients being poured in at the top of the furnace while the melted iron is run off at the bottom at convenient intervals into furrows prepared in a bed of sand, where it solidifies and is then known as pig hvti. In this form the metal contains proportions of carbon, phosphorus, and silicon, and is necessarily brittle and without a trace of malleability ; but by heating it in a reverberatory furnace in a blast of air, accompanied by continual movement (technically termed “ puddling ”), and subjecting the mass to the strokes of a steam hammer, the impurities are to a great extent removed; and although the iron becomes less fusible, it acquires that tenacity which confers malleability, and is known as wrought or bar iron. By heating bars of iron for several hours in charcoal, the metal combines with about one and a half per cent, of carbon, and is converted into steel. The process is termed cetnentation, and the product, ‘‘ blister steel.” This useful variety of iron may also be prepared directly from \he. pig by the Bessemer process, which consists in melting the metal, and forcing a blast of air through the fluid mass until all impurities are burnt out. At this stage just sufficient crude cast iron is added to yield the necessary carbon to convert the whole into steel, when the contents of the crucible are run into moulds. 42 SIMPLE BASVLOUS RADICALS. Steel is rendered hard for the manufacture of edged tools by heating it to about 470° F., and suddenly cooling; or elastic, by heating to 550° F., and quickly cooling as before. This process is called the “ tempering of steel.’' Iron alloys itself readily with other metals when they are heated with it. Iron is truly a tetrad, but it never acts as such. In the ferrous compounds it behaves as a dyad, and in the ferric as a hexad. These facts are explained by the following formulae : — Iron in the free state. Fe Fe = Fe.2. Ferrous chloride. Ferric chloride. Strong cold sulphuric acid has little or no action upon iron, but the dilute acid dissolves it, forming ferrous sulphate and liberating hydrogen. It is also soluble in hydrochloric acid, forming ferrous chloride and likewise evolving hydrogen. With tolerably strong nitric acid, or with a dilute acid by the aid of heat, ferric nitrate is produced, and nitric oxide evolved ; but with very dilute and cold nitric acid, ferrous nitrate is formed, with the produc- tion of nitrous oxide, or ammonium nitrate is yielded in solution, without the evolution of any gas ; — aFeg + 10HNO3 = 4FC2N03 f NH4NO3 4 - 3H2O. True theoretical nitric acid, entirely free from water, does not attack iron in the least and if the metal after such treatment be plunged into B.P. acid (1-42 sp. gr.) it will not even then be affected, but the, moment it is touched with a piece of copper the action will set in with great rapidity. This curious behaviour is called passivity. {See Nitric Acid, Chap. X.) {For detection, separation, and estimation of Iroji, see Autkods Analyticsil Chemistry, f 7, i$S, and iji.) ^Fe ^^Cl -^Cl~ Fe'Clg. CL Cl Cl^ Fe— Fe: Cl ^ Cl COBALT. Symbol, Co. Atomic Weight, 58*8. Specific Gravity, 8*54. Cobalt is one of the scarce metals, and has never been found in the metallic state, except as a component part of meteorites, in which it occurs sometimes to the extent of one per cent., associated with nickel and iron. The pure metal has a steel-grey colour, with an inclination towards red ; but in the polished form is white. Less easily melted than gold, it is subdued by the heat of the furnace sooner than iron, and, like the latter, is magnetic : a property which the strongest red heat cannot eradicate, although it is destroyed by the presence of a minute quantity of arsenic. Solution of cobaltous chloride is used at Sevres to counteract the yellow colour of the finer kinds of porcelain, a bright clear tint of any desired inten- sity being thus produced according to the proportion of the cobalt solution that may have been employed. Cobalt is found in similar ores to the metal nickel, and is extracted there- from in a precisely similar manner. (See Nickel.) / It is usually a dyad, and, when so, forms cobaltous salts. These salts, '-when anhydrous, are blue ; when hydrated, pink. Its behaviour with acids is similar to nickel. {For detection, separation, and estimation of Cobalt, see Authods Analytical Chemistry, pages and 170.) COBAL T.— NICKEL.— CERIUM.— TIN. 43 NICKEL. Symbol, Ni. Atomic Weight, 58*8. Specific Gravity, 8'80. This beautiful metal has much in common with cobalt and iron, and is con- stantly found in association with them; both in various ores and in meteorites. Several of its properties fitting it for an alloy, it is used in the proportion of 40 parts of nickel, 60 of zinc, and 100 parts of copper, for the production of the highly popular metal called Germaii silver., or Nickel silver. This alloy is exceedingly malleable, and takes a high polish. Among all the metals, nickel is the only one possessing a name of opprobrium, which arose from the cir- cumstance that in early days the ignorant German miners, having in vain tried to extort copper from its ore (the mono-arsenide, Nix\s) in disgust bestowed the epithet upon it of Kupfe^'-nickel , or false copper. This metal is found naturally in combination with arsenic and sulphur, and in order to get rid of these impurities the ore is roasted in a state of powder, at a moderate heat, by which preliminary operation the greater portion of its arsenic is volatilized, and the oxide of the metal remains. This is exposed to a white heat in a charcoal-lined crucible, the oxide, having been previously carefully mingled with powdered charcoal. In order to obtain the resulting metal in ingots, the shapeless masses are fused at the strongest heat of a forge fire. This metal is also magnetic ; but, unlike cobalt, it loses this property when heated to 662° F. It is usually a dyad; and the salts it forms when in this state, which are termed nickelous, are well-defined, and of a green colour. It dissolves when heated with hydrochloric or dilute sulphuric acid, with the evolution of hydrogen ; and it is rapidly attacked by nitric acid. (/v?r detection, separation, a?id estimation of Nickel, see Author's Analytical Chemistry, pages 42 and 171.) CERIUM. Symbol, Ce. Atomic Weight, 92. Specific Gravity, 5*5 @ 54° F. Cerium is found in the form of cerite, a silicate obtained from Sweden. The metal is never seen in an isolated condition except as a chemical curiosity, when it usually appears as a grey powder, soluble in dilute acids, and decom- posing water at a boiling heat with the evolution of hydrogen. Its only com- pound of interest to the pharmacist is cerous oxalate (Ce"C2043H20). {For detection and separation of Cerium, see Author's Analytical Chemistry, 38.) TIN (Slanmtm). Symbol, Sn. Atomic Weight, 118. Specific Gravity, 7’29. Melting Point, 230° F. Tin is derived from an ore popularly called tinstone (S11O2) by heating it with charcoal. aSnOg -f 2C2 = Sng -{- 4CO. If the product be again heated, the pure metal fuses first, a less fusible alloy remaining solid, from which the fluid metal may be decanted. The chief sources of supply are Devonshire and Cornwall, although the mines of Malacca and Banca rank high in importance ; and of late years the supplies from Aus- tralia have not only been considerable, but the tin from Melbourne occa- sionally contains so much gold that its extraction is profitable. This metal does not oxidize at the ordinary temperature of the air, but when strongly heated it ignites, and stannic acid is formed. As regards atomicity, tin is usually tetrad, but by self-saturation is capable of behaving as a dyad. The compounds in which it exists in the former state are stannic, those in which it exhibits the latter, statinous. With lead, tin forms the alloy called pewter; with lead and bismuth, Rose’s metal, an alloy which melts below 44 SIMPLE BASVLOUS RADICALS. 2I2°F. It is a component of bronze, bell metal, speculum metal, gun metal, Britannia metal, and “ coarse ” and “ fine ” solder. Tin is deposited on pins in the wet way and on tin plate ” by dipping the sheet-iron in the melted metal, for the purpose of lessening the corrosive power of liquids and the atmosphere on the brass and iron respectively. Tin is difficultly soluble in dilute sulphuric acid, but when heated with the strong acid it forms stannic sulphate, and evolves sulphurous anhydride. Nitric acid converts the metal into white insoluble metastannic acid. Dilute hydrochloric acid is devoid of action, but by boiling with the strong acid stannous chloride is formed, and hydrogen evolved. Nitro -hydrochloric acid produces a mixture of stannic and stannous chlorides. Tin does not readily form salts with oxy-acids. {For detection, separation, and estimation of Tin, see Author's Analytical Chemistry, 35 and 169.) ' PLATINUM. Symbol, Pt. Atomic Weight, 197*4:. Specific Gravity, 2T50. Melting Point, Oxy-hydrogen Uowpipe. Platinum enjoys the rem.arkable distinction of being at once the heaviest substance at present known ; the most refractory under the glow of the fiercest furnace ; the most defiant to the solvent power of all individual acids ; and the potent auxiliary of the laboratory, without the aid of which many of our most delicate and important investigations would be but imperfectly con- ducted. Like gold, it occurs in a metallic state in grains and little masses amidst the sand and debris of the Ural mountains, in various parts of Russia, in Brazil, Ceylon, and in the auriferous sands of some American rivers ; but it has not as yet been detected in any rock, not even in the serpentine forma- tion, although frequently discovered surrounded by such detritus as would lead to the inference that its matrix belonged to one of the earliest volcanic forma- tions. The metal is purified by solution in nitro-hydrochloric acid ; is pre- cipitated by ammonium chloride, and calcination completes this preliminary process. It now appears in the form of an incompact mass, called spongy platinum, which requires the intense heat of the oxy-hydrogen blowpipe to accomplish its liquefaction. This is managed as follows : — A little furnace is constructed out of two solid pieces of lime, the lower fragment having a cavity hollowed out to contain the melted metal, with a notch at one side through which the crude platinum is gradually introduced in small pieces, and from which the fluid may in due time be poured. A cover of lime with a conical perforation on the top for the admission of the blowpipe is then fitted close, and the arrangement firmly braced together with iron wire. The tap admitting the hydrogen is theri* turned and the gas lighted at the notch in the crucible, the oxygen being slowly and gradually supplied. When the furnace is hot enough the platinum is introduced, piece by piece, through the side orifice. With the exception of iridium and rhodium, all metallic and other substances originally in the platinum are expelled ; any sulphur, phosphorus, arsenic, and osmium there may be, are oxidized and driven off in vapour ; palladium and gold are volatilized ; and the iron and copper oxidize and dis- appear into the mass of the crucible. By this method about fifty pounds of platinum may be fused at one time. Previously to the application of the oxy-hydrogen blowpipe to this refractory metal, it was obtained in a solid and compact form from the spongy condition by pressure, heat, and hammering. The loose and incoherent metal was rubbed down in a wooden mortar, and worked up into a paste with water, before being subjected to pressure in a brass conical mould. It was then dried, heated to whiteness in a furnace, and hammered, after which it acquired sufficient malleability and ductility tp be rolled into plates or drawn out into wire. PLA TJNUM.—LEAD. 45 Platinum in the finely divided state has the property of absorbing gases without combining with them. Of oxygen it is capable of condensing about four hundred volumes. The variety of platinum thus employed is known as Platinum black, and is prepared by boiling platinic chloride with glucose and sodium carbonate, when it deposits, leaving a colourless solution. As already mentioned, the most powerful furnace heat fails to cause even incipient fusion ; and when subjected to the oxyhydrogen flame it does not oxidize. It remains perfectly insoluble in all simple acids ; but nitro-hydrochloric acid colli- quates it, platinic chloride (PtCl4) being formed. When potassium hydrate is fused in platinum vessels, these are acted upon, and a potassium platinate results ; for this reason, if alkalies are required to be fused, silver crucibles must be used. With several metals, — zinc and lead for example, — it forms alloys which are fusible by the heat of an ordinary furnace, as is likewise its compound with phosphorus. Although platinum is a tetrad, it occasionally acts as a dyad. {For detectio 7 t, separation, and estimation of Platinutn, see Atdhor’s Analytical Chemistry, pages 36 and 168.) LEAD {Plumbum). Symbol, Pb. Atomic Weight, 207. Specific Gravity, 11-45. Melting Point, 590° F. It is, perhaps, a fortunate circumstance that lead is a metal as abundant as it is useful, and that it is peculiar to no one part of the world. Yet, although fully twenty ores • containing this metal are on the catalogue of the mineral- ogist, practically our sources of supply are confined to a few, the chief of which are galena (plumbic sulphide, PbS), white lead, or ce 7 msite (plumbic carbonate, PbCOg), and anglesife (plumbic sulphate, PbS04). Lead is usually extracted from the first mentioned, which is roasted in the air, being thereby converted into a mixture of plumbic sulphate and plumbic oxide, sulphurous anhydride being evolved : — 3PbS + 5O2 - 2PbO + PbS 04 + 2SO2. The whole is then strongly heated away from contact with the air, when the undecomposed galetia acts upon both the oxide and the sulphate, the sole products being metallic lead and sulphurous anhydride : — 2PbO + PbS 04 + 2PbS = sPb + 3SO2. Another process for the extraction of lead from its ore, is to roast gale?ia until it is entirely converted into oxide, and then to reduce the result with charcoal : — 2PbO-hC2 = Pb2 + 2CO. Lead is rendered more fusible by adding arsenic, as is done in making shot, harder by being alloyed with antimony, as in type-metal, and more fusible by tin. In its pharmaceutical salts lead is always dyad, its chloride being PbCl2, its sulphate PbS04. When melted in contact with the air, this metal becomes covered with a crust of plumbic oxide (PbO). Lead is slowly oxidized by water when it contains fixed air. Boiling sulphuric acid converts it into sulphate, but it resists all action of cold hydrochloric and sulphuric acids. Aqua regia, however, converts it into chloride. Warm and dilute nitric acid dissolves the metal with ease, forming plumbic nitrate (Pb''2N03'), and evolving nitric oxide : — Pbg + 8HN03 = 3Pb2N03 + 2NO + 4H2O., The oxide is acted upon by acetic, nitric, and nearly all acids, forming plumbic salts. {For detection, separation, and estimation of Lead, see Author's Analvtical Chemistry, paii^cs 2 Za?td i 6 s.) SIMPLE BASYLOUS RADICALS. 46 Class V. PENTADS. BISMUTH. Symbol, Bi. Atomic Weight, 210. Specific Gravity, 9*90. Melting Point, 500° F. Bismuth does not take rank among those metals which are universally distributed throughout the geological formation of every country, yet it possesses three most remarkable properties which are well worthy of attention. Of all metals it is the most diamagnetic ; unlike other metals, when ex- posed to immense pressure, its density decreases (under 200,000 pounds the specific gravity falls from 9 ‘90 to 9*546) ; and after being melted it expands on resuming the solid condition. This metal reaches us chiefly from Saxony, where it occurs in veins permeating clay-slate and gneiss, from Siberia, from Cornwall, and Cumberland. As a sulphide (BigSg) it is more abundant than in the native metallic state. Its preparation is as follows • The ore having been roasted, this reaction occurs ; — 2Bi2Sg 4 9O2 = 2Bi203 + 6SO2. f This hismuthous oxide is now heated with charcoal, when metallic bismuth ^ and carbonic oxide result. 2 Bi 20 g -I- 3C2 = 2Bi2 + 6CO. Bismuth is a greyish metal with a pink tinge, which melts at 500° F. and volatilizes at a white heat. In dry air, at the ordinary temperature, it does not oxidize ; but when strongly heated it burns with a blue flame. It easily dissolves in nitric acid, with the evolution of nitric oxide. Heated with strong sulphuric acid, hismuthous sulphate is formed, with the evolution of sulphurous anhydride ; but it is altogether insoluble in dilute sulphuric acid, and nearly so in hydrochloric, even when heated. Its most remarkable alloy consists of one part of lead, one of tin, and two of bismuth, which melts at a little under the boiling point of water. The solder used in mending pewter requiring - to be very fusible (otherwise the pewter itself would melt) has Bismuth added to lower the melting point. Type-metal sometimes contains this metal, which is utilized as a material whose great expansion on cooling admits of the production of very fine casts. It is a triad /// all compounds con 7 iected with Pharmacy. {For detectio 7 i, separation^ and estimation of Bismuth^ see Author's Analytical Chemistry, tages 31 and 1 68.) ANTIMONY {Slihum). Symbol, Sb. Atomic Weight, 122. Specific Gra- vity, 670 to 6*86. Melting Point, 842° F. Antimony occurs naturally as sulphide, and is also found in combination with various metals. As antimony ochre., it usually takes the formula of Sb204 ; as grey atitimony, Sb2S3 ; and as antimony blende., or red antimony^ it presents a mixture of the first and second. The abundance of the grey (or black) ore abolishes any necessity for having recourse to any others, conse- quently their employment for the extraction of this metal is rare. Ores which are comparatively free from other metallic contamination are thus treated : — A portion is roasted until oxidized; mixed with the remainder, and again strongly heated. The Sb2S3 may be reduced in a different manner, by contact with metallic iron, or with an alkali and charcoal. Native antimonious sulphide, SbgSg, occurs in mechanical combination with quartz and limestone. It may be separated from these by fusion, the heavy metallic portion sinking by the BISMUTH.— ANTIMONY. 47 law of gravity, and abandoning the impurities, which remain on the surface of the molten mass. Arsenic being a contamination from which commercial antimony is rarely free, the use of the metal under consideration in medicine would doubtless be attended with the gravest results, were not some ready process available for its complete purification. The following method for the attainment of this object may be recommended: — Two parts of dry sodium carbonate, mixed with five parts of sodium nitrate (or potassium nitrate, the former being pre- ferable) and four parts of metallic antimony, are thrown into a red-hot crucible. The evolution of gas having ceased, the heat is increased until pressure with a spatula on the glowing mass proves that no cavities remain. Removed from the crucible whilst still soft, and having been reduced to powder on cooling, the result is rubbed in contact with boiling water, the surplus liquid being poured off from time to time. A smooth creamy mass having at length been produced, its freedom from alkaline matter is accom- plished by further washing, decantation, and purification on a filter. Thus obtained, the powder, fused at a red heat with potassium hydro-tartrate (cream of tartar), on subsequent lixiviation with water, yields the metal. Antimony is a brittle, silvery, and very brilliant substance, appearing in plates, or in rhombohedral crystals. The metal may be obtained in an amorphous state by electrolytic action. When fused it burns, forming anti- monious oxide ; but it does not oxidize at the ordinary temperature of the atmosphere. The oxide produced by combustion is nearly pure white. Should the metal at the commencement of its combustion emit a garlic-like odour, the presence of arsenic is indicated. Nitric acid oxidizes it, but fails to dissolve the product of its action, which, should the acid be very strong, becomes antimonic oxide, containing more or less antimonious oxide accord- ing as the acid used deviates from purity. Dilute sulphuric acid exerts no influence on this metal, although heating with a concentrated acid determines the production of a sulphate, with the evolution of sulphurous anhydride. Except when reduced to fine powder, boiling hydrochloric acid does not affect antimony. There are two classes of antimony salts, in one of which the metal behaves as a triad, and in the other as a pentad. The former are named antimonious salts, and are the only ones possessing pharmaceutical interest ; whilst the latter are termed antimo7iic salts. The maximum atomicity is the one by which we classify it, the lower being accounted for by the theory of self- saturation. Many metals form alloys with antimony, the following being the most useful and interesting — “ Britannia metal,” used for so many domestic articles. Type-metal, in which it is united with lead. Copper antmi07iiae has the approximate composition Cu 2 Sb 7 , probably a mixture of Cug^'Shg'" and Cu 3 "Sb 2 ”', in nearly equal proportions. Its colour is violet, which does not in the least resemble that of a mere mixture of the two elements, and it is likewise very brittle. Lead a7iti77i07iide is harder than lead alone. When antimony is present to the extent of about twenty per cent., the alloy is recognised as type-metal. The combination is denser {i.e., it possesses a greater specific gravity) than the calculation from the respective quantities of the two metals indicates. Silver a7tti77ionide is found native, and is precipitated from argentic nitrate by antimoniuretted hydrogen, evolved by the action of zinc and dilute sulphuric acid upon a solution containing an antimony salt. The full description of the formation of this body will be found under the head- ing Arsenic, among the Metalloids ; the striking resemblance between the 48 SIMPLE BASYLOUS RADICALS. reactions of antimony and those of that element being rendered evident by the adoption of such a course. {For detection., separation, and estimation of Antvnony, see Authors Analytical Chemistry, pages 34 and 169.) Class VI. HEXADS. CHROMIUM. Symbol, Cr. Atomic Weight, 52*2. Specific Gravity, 7*3. The Shetland Islands contribute the ore, from which the metal may be ex- tracted in considerable quantity. It is chrome iron ore (FeCrgO^). The metal, which, however, is of no commercial importance as yet, is obtained by igniting chromic oxide with charcoal at a white heat, or by reducing chromic chloride (CrgClg) with sodium or zinc. In chromic salts the hexad radical Crg""* exists, whilst in the higher oxides the single hexatomic atom Cr is alone present. Chromic salts are either green or violet in colour ; those containing chromic anhydride (CrOg) are yellow, orange, or red. Heated to redness in the air, it soon exhibits a yellowish-bluish tarnish like that seen upon steel under similar circumstances ; this gradually changes to a thin film of green oxide. It rapidly dissolves in hydrochloric acid, evolving hydrogen, and forming blue chromous chloride. At ordinary temperatures dilute sulphuric acid does not interfere with it ; but on the application of a gentle heat, an instantaneous and violent action occurs, leaving the remnant of the metal in a condition easily acted upon, even after washing, by the same acid in its weakest form. Nitric acid, in any degree of dilution or concentration, is quite powerless on chromium. {For detection, separation, and estimation of Chromium, see Author's Analytical Chemistry, pages 39 and 172.) Having thus reviewed the metals, it next becomes necessary to study the Metalloids, not only with regard to their individual properties, but as to their compounds inter se and with the metallic elements already considered. CHAPTER IV. FLUORINE AND CHLORINE. Chemical bodies have an official designation ; but they are described by various titles, either popular, hereditary, or scientific. These different names, meaning the same thing, are called synonyms, and have in the following pages been invariably attached. The synonym is not strictly the translation of the word, but the mode in which it is expressed other than by the term used in accordance with its accepted present nomenclature. FLUORINE. Symbol, F. Atomic Weight, 19. Atomicity, Monad. Although the existence of this body is quite certain, it has not yet been isolated, owing to its powerful action on all vessels of glass and porcelain as well as of silver and platinum. It combines directly with all metals to pro- duce fluorides, and has been stated to have been obtained as a gas something like chlorine by the action of perfectly dry iodine on argentic fluoride, but the experiment wants confirmation. HYDROG-EN FLUORIDE (Syn. Hydrofluoric Acid). Formula, HF. Mole- cular Weight, 20. ' Is prepared by heating together calcium fluoride and sulphuric acid in a leaden vessel : — CaFg + H2SO4 = 2HF + CaSO^, The real acid is a gas, which when passed into water dissolves and forms a commercial liquid acid, containing 37 per cent, of real HF. Both this solu- tion and the gas itself act with great avidity upon glass by combining with the silicic anhydride (silica) contained therein, and forming silicon tetrafluoride. It is therefore much used for etching the patterns on glass with which we are all familiar. In commerce the acid is occasionally stored in leaden bottles, but usually it is preserved in gutta percha. (See Silicon.) CALCIUM FLUORIDE (Syns. Derbyshire Spar. Fluor Spar. Blue John). Formula, CaFg. Molecular Weight, 78. Is found native in fine blue cubical crystals, but the colour is not always constant, varying through violet, yellow, rose, and even sometimes colourless. It is much used for glass etching. When employed for preparing the acid, leaden retorts and condensers must be used. Compounds of fluorine are not employed in medicine or pharmacy. {For detection and separation of Hydrofltioric Acid and Fluorides, see Author’s Analytical Chemistry, page 49.) E 50 FLUORINE AND CHLORINE. CHLORINE (Syn. (obsolete) Oxy-Muriatic Acid'). Symbol, CI2. Atomic Weight, 35 * 5 . Density, refei'red to Hydrogen^ 35 * 5 . Density, referred to Air, 2 * 46 . Weight of a litre, 3*17 grammes = 35*5 crithy^ Weight of 100 cubic inches, 76'3 grains at 60 ^ F. and 30 in. barom. Atomicity, Monad. This element was discovered by Scheele in 1774. It does not exist free in nature, but is found chiefly in combination with sodium as common salt, which is the great natural reservoir for chlorine. It is also found combined with magnesium, silver, lead, and many other substances. In the vegetable king- dom it is not abundant ; but chlorides are found in every secretion from ani- mals. When persons are suffering from pneumonia, however, the absence of chlorides from the urine is a marked and curious symptom. It is prepared : — 1. By pouring sulphuric acid upon a mixture of sodium chloride and man- ganic dioxide. The action, which occurs at once, without the application of heat, is usually represented as follows : — 2NaCl -f- MnOg + 2H2SO4 = Clg + Na2S04 + MnS04 + 2H2O. In reality the action is probably much more complicated. The sulphuric acid first acts on the sodium chloride to produce hydrochloric acid : — • 4NaCl + 2H2SO4 = 4HCI + 2Na2S04. The acid thus produced then acts upon the manganic dioxide to produce manganic tetrachloride : — 4HCI + MnOg = MnCl4 + 2H2O. On heating slightly, this is decomposed thus ; — MnCl4 = MnCl2 + CI 2 . The H2SO4 gives rise to a considerable amount of heat when it acts upon the NaCl, and the MnCl4 is therefore decomposed as soon as it is formed. 2. By heating hydrochloric acid with manganic dioxide : — Mn02 4HCI = MnCl2 + CI2 + 2H2O. This is the preferable manner of preparing chlorine on a small scale, because the action only occurs when heat is actually applied, and the process is there- fore well under control. When this process is used on a manufacturing scale, the MnOg may be re- covered by Weldods method, as follows. The solution of MnCl2 left in the retort is precipitated with lime, forming manganous oxide. MnCl2 + CaO = MnO + CaCl2. The precipitate is then mixed with some more lime, and air is blown through the whole, which causes the conversion of the MnO into Mn02- 3. By passing mixed air and hydrochloric acid gas over heated fire-bricks previously soaked in a solution of copper and dried. Cuprous chloride is formed first, which takes up chlorine and becomes cupric chloride.. CU2CI2 + 2HCI + O = 2CUCI2 + H2O. And then, by an increased heat, gives off the chlorine and re-forms cuprous chloride : — 2CUCI2 = CI2 + CU2CI2, which is ready for use again. This is known as Deacon^ s process, and gives chlorine containing the nitrogen of the air j but that is of no consequence for the manufacture of bleaching powder. • One litre of hydrogen weighs o’oSg6 gramme. A volume sometimes called a crith. A very small weight, literally a barleycorn. CHLORINE. 51 4. By heating magnesium chloride with manganese peroxide {^Macqute?i s process). 2MgCl2 + MnOa = 2MgO + MnCl2 + CI2 5. By heating hydrochloric acid with potassium dichromate. K 2 Cr 207 + 14HCI = 3CI2 + 2KCI + Cr2Clg + 7H2O. 6. By the electrolysis of hydrochloric acid. 2HCl = Cl2 + H2. 7. By fusing together ammonium chloride and ammonium nitrate. 2NH4CI + 4NH4NO3 = CI2 + 5N2 + 12H2O. When chlorine is required free, it must be collected by displacement ; that is, by passing the tube conveying the gas from the generating flask, to the bottom of a deep and dry bottle in which the chlorine gradually collects, displacing the air until the vessel is full. Thus obtained, it is observed to be a greenish-yellow gas possessing a pungent and irritating odour, and proving instantly fatal to animal life, even when diluted with sixty times its bulk of air. Should it be accidentally inhaled, the best-known antidote is ammonia gas. Chlorine is much heavier than air, and is exceedingly soluble in water, which at ordinary temperatures dissolves 2\ times its volume. This solution is known as chlorine water, and possesses the property of dissolving gold, of Uberating iodine and bromine from their salts, and of raising iron from the ferrous to the ferric state. When cooled to the freezing point, a solution of chlorine deposits crystals of chlorine hydrate (CI5H2O). It is possible to liquefy the gas by a pressure of four atmospheres, or about dqlbs. per square inch ; but no attempts to solidify it have hitherto been successf^ul. Chlorine has an energetic action on metals, with which it combines directly to form chlorides. Powdered antimony, iron, and also magnesium and sodium, take fire when placed in a vessel of the gas, and even gold leaf slowly combines to form AuClg. The metalloids are also in many cases readily attacked ; phos- phorus and sulphur both burning in an atmosphere of chlorine to form chlo- rides, while selenium, silicon, and boron unite with it when heated ; but it has no direct action upon either oxygen or carbon. Compounds rich in hydrogen all unite readily with chlorine, forming hydro- chloric acid, and setting carbon free if present. For example : {a) A piece of paper dipped in turpentine (CioH^g) takes fire in a bottle of dry chlorine : — CioHie-f 8Cl2 = Cio+i6HCl. {p) Olefiant gas (C2HJ explodes with chlorine when a spark is applied, thus : — C2H4 + 2CI2 = 4 ^^C 1 -f C2. Marsh gas (CH^,), however, does not liberate carbon ; but, when mixed with excess of chlorine and exposed to sunlight, yields chloroform and carbon tetrachloride : — 2CH4 + 7CI2 = CHCI3 + CCI4 -f 7HCI. From its power of thus attracting hydrogen, chlorine can displace that element from many compounds to a greater or less extent. An example of this is found in the manufacture of chloral (C2HCI3O) by passing chlorine into alco- hol (C2H5HO) C2H5HO -f 4CI2 = C2HCI3O + 5HCI. Chlorine acts as an indirect oxidizer by thus combining with hydrogen and liberating oxygen, and forms one of the most useful of disinfecting and deodorizing agents. It also performs the function of a bleacher of organic colouring matter, such as indigo and other vegetable dyes, when moisture is 52 FLUORINE AND CHLORINE. present., by reason of a similar indirect oxidation, or by entering into combina- tion with the pigment. For example: indigo (CgH^NO) is first oxidized to isatine (CgH^NOg), and then converted into chlor-isatine (CgH^ClNOg), thus : — CgH^NO + Cb + HoO - CgH^NOg + 2HCI. CgHgNOa + Cb - CgH^ClNOg + HCl. Liquor chlo 7 'i of the B.P. is prepared by heating manganese peroxide with hydrochloric acid and passing the gas first through a little water to wash it, and then into a larger bulk of distilled water. It is a yellowish-green liquid, smelling strongly of chlorine, and immediately discharging the colour of a dilute solution of sulphate of indigo. Specific gravity, i ‘003. By exposure to light, it rapidly changes to hydrochloric acid, at the same time liberating oxygen : — 2CI2 + 2H2O = 4HCI + O2. {For detection of free Chlorine and analysis of Chlorine wqter, see Authors Analytical Chemistry, page 49.) When equal volumes of chlorine and hydrogen are mingled together, with the application of an electric spark, they combine to form hydrochloric acid. CI2 + Hg -2 HCl. 2 vols. + 2 vols. — 4 vols. The reaction occurs so readily that even exposure to a ray of sunlight causes an explosion. METALLIC CHLORIDES. HYDROGEN CHLORIDE (Syns. Hydrochloric Acid. Muriatic Acid. Spirit of Salt). Formula, HCl. Molecular Weight, 36*5. Density, refer 7 'ed to Hydrogen., 18’25. Density, 7 ^ef erred to Air, 1*27. This body is really a gas, and is prepared by exploding equal volumes of chlorine and hydrogen in a tube over mercury. All the adjuncts must be perfectly dry for the success of the experiment, as the gas is very soluble in water, one gallon of which dissolves 460 of hydrochloric acid gas at an ordi- nary temperature. Although not hitherto solidified, it has been liquefied by a pressure of forty atmospheres. Theoretically, hydrochloric acid is produced whenever a substance containing hydrogen is brought into contact with free chlorine. For example, we may refer to the decomposition of chlorine water when exposed to sunlight, already shown ; or to the following reaction of chlorine upon sulphuretted hydrogen : — 2HgS -I- 2CI2 = 4HCI 4 - Sg 4 vols. + 4 vols. = 8 vols. The acidtwi hyd 7 'ochloricu 77 i of the B.P. is a solution of the gas in water to the extent of 3 1 '8 per cent. It is prepared by heating a mixture of sodium chloride and sulphuric acid, then passing the evolved gas into cold water : — 2NaCl + H2SO4 = 2 HCl + NagSO^. The sulphuric acid, after slight dilution, is poured upon the sodium chloride in a large flask, and, heat being applied, the gas is first passed through a three- necked Woulffs bottle containing four ounces of water, and then into a large ' bulk of distilled water kept perfectly cold. Thus prepared, it is an almost colourless and strongly acid liquid, emitting white fumes possessing a pungent odour. Specific gravity, i’i6. {lor analysis of B.P. Hyd 7 'ochloric Acid, see AuthoPs Analytical Chemistry, fage 82.) HYDROCHLORIC ACID.-CHLORIDES. 53 Acidum hydro chloriciim dilutum has a specific gravity of i’o^2, and contains io’5o per cent, of real acid. It is made by taking 8 fluid ounces of the strong acid, and adding water till the whole measures 26 J ounces at 60° Fahr. Commercial hydrochloric acid is produced largely in the manufacture of sodium sulphate used for making sodium carbonate by Leblanc’s process. (See Carbonates.) Usually it is of a yellowish colour, and stronger than the pure B.P. acid, as it is often found to contain 40 per cent, of HCl. It is frequently contaminated with free chlorine, ferric and stannic chlo- rides, sulphurous and sulphuric acids, and arsenious acid. These impurities are removed by heating with a little potassium chlorate and, when the action has concluded, by the addition of a little barium sulphide and distillation into pure water so soon as all traces of sulphuretted hydrogen have disappeared. The potassium chlorate produces chlorine, and changes the sulphurous into the less volatile sulphuric acid : — H2SO3 + CI3 + H3O = H2SO4 + 2 HCl, Whilst the sulphuretted hydrogen, afterwards developed, decomposes any volatile arsenious chloride which might have been formed. The common acid may be converted into a fairly pure acid by dilution with water and re- distillation. Hydrochloric acid acts upon metals with the exception of gold, platinum, silver, lead, mercury, and some others, forming chlorides^, with the evolution of hydrogen, thus : — Zug + 4HCI = 2ZnCl2 + 2H2. When pure and cold it is powerless against copper, and acts but slowly when heated and brought into contact with the finely powdered metal. All oxides (except those of Ag and Hg2) dissolve in this acid, producing a chloride and water, thus : — Cu0 + 2HCl = CuCl2 + H20, While upon peroxides, such as those of manganese or lead, it acts by forming chlorides and evolving chlorine, heat being usually required at the commence- ment. With barium peroxide, in the presence of a freezing mixture, however, it forms hydrogen peroxide or hydroxyl (see Oxygen) and barium chloride : — BaOg + 2HCI - BaCl2 + H2O2. With the exception of the argentic, mercurous, and plumbic salts, all chlo- rides are soluble in cold water, and the latter dissolves in the boiling liquid. Cuprous chloride is likewise only slightly soluble. Some chlorides of metal- loids, such as phosphoric chlorides, are at once decomposed by contact with water. PCI5 + 4H2O = H3PO4 + 5HCI. The antimonious and bismuthous chlorides are not so thoroughly decom- posed by water, having only part of their chlorine displaced by oxygen, and forming insoluble oxychlorides, which precipitate, hydrochloric acid being at the same time produced in solution. For example : — BiClg + H2O = BiOCl + 2 HCl. Magnesium, aluminium, and zinc chlorides ‘are not decomposed by simple contact with water, but only when their solutions are attempted to be evapor- ated to dryness. The chlorides of ammonium, zinc, iron, and antimony are volatilized by heat without decomposition. Potassium and sodium chlorides are also capable of volatilization, the former at a bright red, the latter at a white heat. {For deteciion, separation, and estimation of Chlorides, see Author's Analytical Cliemistry, pages Ap ), 51, 53, 156, 176, and 177.) 54 FLUORINE AND CHLORINE. AMMONIUM CHLOKIDE (Syn. Sal-am 7 noniac). Formula, NH^Cl. Molecular Weight, 53-5. This substance is prepared from the ammoniacal liquors of gas works, either by directly neutralizing with hydrochloric acid, or more commonly by first forming ammonium sulphate and subliming that salt with sodium chloride : — + zNaCl - 2NH4CI + Na2S04. The B.P. describes it as follows : — ‘Tn colourless, inodorous, translucent, fibrous masses ; tough, and difficult to powder ; soluble in water and in rectified spirit. When heated it volatilizes without decomposition and leaves no residue.’' As already noted in the chap- ter on theories, the vapour of this salt undergoes dissociation at a high tem- perature into HCl and NHg, which again unite on cooling. {For analysis and hyipurities, see Atithor's Analytical Chemistry, 82.) Ammonium chloride is used in analysis to prevent the precipitation of magnesium hydrate by ammoniuib hydrate or ammonium carbonate. When heated with an alkaline hydrate, ammonia gas is evolved. i^NH^Cl + CazHO - CaClg + 2NH3 + 2H2O. SODIUM CHLORIDE (Syns. Common Salt. Table Salt). Formula, NaCl. Molecular Weight, 58*5. Occurs native in mines as rock-salt^ and is also extracted from sea-water by evaporation and crystallization. Referring to this useful substance, the B.P. says it should be in small, white, crystalline grains or transparent cubic crys- tals ; free from moisture and having a purely saline taste. {For analysis and inipuritieSy see Authors Analytical Chemistry, 83.) Common salt is soluble in three parts of cold water, and boiling water fails to increase its solubility to any marked extent. It is not soluble in pure alcohol, and but slightly in ordinary spirit. When exposed to a sudden increase of temperature, it decrepitates ; the water mechanically imprisoned between its particles being rapidly converted into steam, and so creating an abrupt disruption of the crystals, accompanied by a loud crackling sound. When heated to bright redness it volatilizes in the most perceptible manner, and great caution is therefore required to keep the temperature low in the taking of the ash of substances, such as milk, in which it is intended to esti- mate the amount of salt. POTASSIUM CHLORIDE. Formula, KCl. Molecular Weight, 74*5. This substance is contained in sea and other mineral waters, and is ex- tracted by evaporation. It also occurs native. Although only slightly soluble in rectified spirit, it dissolves with greater readiness, and to a larger extent, in distilled water than sodium chloride. It is also somewhat more volatile than the latter body. , ARGENTIC CHLORIDE (Syns. Chloride of Silver. Horn Silver). Formula, AgCl. Molecular Weight, 143*5. Is formed as a curdy white precipitate when argentic nitrate is added to a solution of any chloride. It is readily soluble in ammonium hydrate, but resists the solvent effects of nitric acid ; it is also soluble in sodium hyposul- phite and potassium cyanide. Digested in potassium bromide, it yields argentic bromide, AgBr, and with potassium iodide it forms argentic iodide, CALCIUM AND BARIUM CHLORIDES. 55 Agl. , It is somewhat soluble in strong solutions of alkaline chlorides, especially in ammonium chloride. , CALCIUM CHLORIDE. Formula, CaClg. Molecular Weight, 111 . This substance, which on the manufacturing scale is a bye-product in the preparation of ammonia gas, is also produced by dissolving calcium carbonate in hydrochloric acid. CaCOg + 2HCI = CaCl2 + COg + H2O. According to the B.P., — It may be formed by neutralizing hydrochloric acid with carbonate of lime, adding a little solution of chlorinated lime and slaked lime, filtering and evaporating until a solid residue is left, then drying the salt at about 400° F. The reason for using chlorinated lime and slaked lime is that nearly all native calcium carbonate, even in a fairly pure form, as white marble, contains iron ; and when the mineral is treated with hydrochloric acid it passes into solution chiefly as ferrous chloride (FeClg). The chlorine given off by the chlorinated lime in contact with the acid solution {see Hypochlorites) changes the. ferrous into ferric chloride, and the calcium hydrate precipitates the iron as ferric hydrate, which being insoluble {see Hydrates), is easily removed, leaving a pure neutral solution of calcium chloride : — 4FeCl2 -f- Ca2C10 + 4Ca2HO -i- 2H2O = 5CaCl2 + 2Fe26HO. Calcium chloride is usually met with in Pharmacy in white agglutinated masses, dry but very deliquescent. It can however also be crystallized in prisms having the formula CaCl26H20. When dried in vacuo it becomes CaCl22H20j and when strongly heated it loses its water of crystallization, and fuses. The fused mass stirred until it cools, and thus aggregated into lumps, is used in analysis for absorbing moisture and drying gases, because it is very deliquescent and is capable of absorbing even more water than is necessary to convert it into a liquid. When crystallized and dissolved in water it reduces the temperature considerably, and is therefore employed in the production of extreme cold. The fused chloride must not be used for this purpose, as it develops instead of absorbing heat when placed in contact with water, because it combines with it and takes up water of crystallization. Calcium chloride will not develop chlorine in contact with acids, and must not be confounded with the substance commonly called chloride of lime {calx chlorata^ B.P.). {For analysis and impurities^ see Author’s Analytical Chemistry, 83.) BARIUM CHLORIDE (Syn. (obsolete) Muriate of Barytes). Formula, BaCl22H20. Molecular Weight, 244 . Is prepared by dissolving barium carbonate in hydrochloric acid : — BaCOg + 2HCI = BaCl2 + CO2 H2O. Or it may be made from barium sulphate by igniting it with coal to reduce it to sulphide : — BaS04 + 2C2 = BaS + 4CO, And then dissolving the barium sulphide in hydrochloric acid : — BaS + 2HCUBaCl2 + H2S. It forms crystals containing 2H2O, is soluble in water, nearly insoluble in alcohol, and its solution is used as a reagent for detecting and estimating sul- phuric acid, with which it forms a precipitate of barium sulphate : — BaCla 4 - H2SO4 = BaS04 + 2HCI. 56 FLUORINE AND CHLORINE. MAGNESIUM CHLORIDE. Formula, MgClg. Molecular Weight, 95. Is prepared in solution by dissolving magnesium carbonate in hydrochloric acid. This solution cannot be evaporated to dryness, as it deposits mag- nesium hydrate and the hydrochloric acid escapes ; but if ammonium chloride be added, it forms magnesium-ammonium chloride, and when this is dried the ammonium chloride alone is driven off, leaving pure magnesium chloride behind. It is one of the most deliquescent substances known, and is used for the preparation of the metal magnesium. / ZINC CHLORIDE. Formula, ZnCl 2 Molecular Weight, 136. Is prepared in an absolutely pure and anhydrous state by distilling perfectly dry zinc sulphate with calcium chloride. The B.P. salt, which contains some water of crystallization, is prepared by evaporating liquor zinci chloridi until it solidifies on cooling. It is employed as a caustic, and is described as being in colourless opaque rods or tablets, very deliquescent, and soluble in water, alcohol, and ether. Liquor zinci chloridi is prepared by dissolving zinc in hydrochloric acid. Zng + 4HCI == 2ZnCl2 + 2H2. Put I lb. of zinc into a porcelain basin, add by degrees 44 ounces of hydro- chloric acid diluted with 20 ounces of water, and gently warm it on a sand bath until gas is no longer evolved. Boil for half an hour, and filter into a gallon bottle, add chlorine water until the fluid acquires a permanent odour of chlorine, and then add zinc carbonate with agitation, until a brown sedi- ment appears. Filter and evaporate to a bulk of 2 pints. The chlorine water and zinc carbonate are used to remove iron and lead, which are contained in nearly all commercial samples of metallic zinc. The chlorine changes the iron from the ferrous to the ferric state, and the zinc carbonate precipitates the iron as ferric hydrate and the lead as peroxide. 2FeCl2 + PbCl2 + 2CI2 + 5ZnC03 + sHgO = 5ZnCl2 + Fe26HO -1- PbOg + sCOg. Zinc chloride constitutes Burnett’s disinfecting and deodorizing fluid. It is an acrid, strongly acid substance, and a powerful poison. Any alkaline carbonate (as chalk or washing soda) will act as an antidote. It precipitates albumen and gelatin. Zinc chloride has a burning taste, and can be sublimed with tolerable facility. On account of its great affinity for water it may be substituted for sulphuric acid for preparing ether. A strong solution cannot be filtered, as it dissolves paper. {For analysis and impurities^ see Authods Analytical Chemistry, page 83.) CUPRIC CHLORIDE. CUCI 2 and CUPROUS CHLORIDE. CU 2 CI 2 CuCl. Result from the solution of cuprtc oxide, CuO, and cuprous oxide, CU2O, in hydrochloric acid. The cupric salt is green, the cuprous colourless. Neither are of pharmaceutical interest; but cupric chloride is very useful for the separation of citrates from tartrates {see Citric Acid), and a perfectly neutral solution is therefore a handy laboratory reagent. The cuprous chloride solution is used in volumetric analysis of gases for absorbing carbonic oxide. CALOMEL. 57 MERCUROUS CHLORIDE (Syns. Calomel. Calomelas. Hydrai'gyri Sub- chloridum). Formula, HgCl or Hg 2 Cl 2 . Molecular Weight, 235-5 or 471. Is prepared by subliming together a mixture of mercuric sulphate, metallic mercury, and sodium chloride. The excess of mercury changes the mercuric sulphate to mercurous sulphate, thus : — 2 HgS 04 + Hgg = 2 Hg 2 S 04 , And the sodium chloride then produces mercurous chloride by double decomposition, thus : — Hg2S04 + 2NaCl = Hg2Cl2 + Na2S04 ; Or the reaction may be represented in one equation, thus : — HgSO^ + Hg + 2 NaCl = Hg2Cl2 + N a2S04. The mercuric sulphate is moistened, and rubbed with the mercury until globules are no longer visible. The sodium chloride is added, and the whole sublimed by a suitable apparatus into a chamber of such size that the calomel, instead of adhering to its sides as a crystalline crust, shall fall as a fine powder on its floor. This powder is washed with boiling water until the washings ' cease to be darkened by a drop of sulphide of ammonium, and finally dried at a heat not exceeding 212° Thus prepared, calomel is a dull white, heavy, and nearly tasteless powder, rendered yellowish by trituration in a mortar ; insoluble in water, spirit, or ether, and entirely volatile by heat. {For analysis and impurities, see Author's Analytical Chemistry, page 83.) When treated with either potassium, sodium, or calcium hydrate, it be comes black, owing to the formation of mercurous oxide. Hg2Cl2 + Ca2HO = CaCl2 + Hg20 + H2O. While with ammonium hydrate it yields a black variety of hydrargyrutn amitioniatum, called mercurous ammonium chloride : — Hg2Cl2 + 2NH4HO = NH2Hg2Cl + NH4CI + 2H2O. Lotio hydrargyri nigra is calomel treated with limewater, and -therefore contains mercurous oxide suspended in a very weak solution of calcium chloride. Owing to the cost of mercury, and the natural desire of the manufacturer to save expense, it sometimes happens that sufficient mercury is not added to cause all the mercuric sulphate to assume the mercurous state, and in this case the calomel is contaminated with mercuric chloride. This is a very dangerous thing, as will be seen when we consider that while we may give 5 grains of calomel for a dose, the outside dose of mercuric chloride is §• of a grain ; and every conscientious pharmacist should always examine parcels of calomel. The test given in the B.P. is to shake with ether, and see if anything dissolves \ but a more simple and inexpensive method is to place the suspected calomel on a filter, and wash it once or twice with boiling dis- tilled water. If mercuric chloride be present it will dissolve, and may be tested for in the filtrate with liquor potassce, with which it gives a yellow precipitate. Reducing agents, such as stannous chloride, cause mercurous chloride to be converted into metallic mercury. When subjected to the action of hydro- cyanic acid, calomel is decomposed into mercuric chloride and metallic mercury; the latter, in consequence of its finely-divided state, possessing a blackish colour. 58 FLUORINE AND CHLORINE. Mercurous chloride may also be produced by precipitating mercurous nitrate or sulphate with hydrochloric acid, or sodium and ammonium chlorides. Also by heating mercuric chloride with mercury, or reducing it by sulphurous acid. MERCURIC CHLORIDE (Syns. Corrosive Sublimate. Bichloride of Mercury, Hydrargvri Perchloridum). Formula, HgCl^. Molecular Weight, 271. Prepared by subliming mercuric sulphate with sodium chloride : — HgSO^ + 2NaCl = HgClg + Na^SO^. Mercuric sulphate and the sodium chloride are mixed with a little manganese peroxide, and the mixture is put into an apparatus adapted for sublimation, and sufficient heat applied to cause vapours of perchloride of mercury to rise into the less heated part of the apparatus, which has been arranged for their condensation. The mercuric chloride collects in heavy, colourless masses of prismatic crystals, possessing a highly acrid metallic taste ; more soluble in alcohol, and still more so in ether, than in water, and entirely volatile by heat. The use of adding the manganic dioxide is to produce a little free chlorine, and so to prevent the formation of calomel. {For analysis and wipurities, see Author's Analytical Clieniistry, 83.) When treated with potassium, sodium, or calcium hydrate, it yields a yellow precipitate of mercuric oxide. Reducing agents, such as stannous chloride, change mercuric chloride first to calomel and finally to metallic mercury. The precipitation of albuminous and fibrinous matters by this salt causes it to be employed as a preserver of animal textures, increasing their firmness, and entirely arresting the putrefactive process. In order that an aqueous solution of mercuric chloride may be obtained which is not liable to spon- taneous decomposition, the B.P. directs that an equal quantity of ammonium chloride be simultaneously dissolved in the water. If this direction be not attended to, mercurous chloride may be formed, together with hydrochloric acid and oxygen gas ; thus : — qHgCla + 2H3O = 2Hg2Cl2 + 4HCI + 03^. In the' presence of ammonium chloride, the tendency of the mercuric chloride to form double salts being satisfied, this decomposition is averted. Upon litmus paper which has been reddened by mercuric chloride, sodium chloride exerts an alkaline action, restoring its blue colour. AMMONIO MERCURIC CHLORIDE (Syns. Mercur-Aitimonium Chloride. White Precipit'ate). Formula, NH 2 HgCl. Molecular Weight, 251*5. Is produced when a solution of mercuric chloride is added to ammonium hydrate : — HgCl2 + 2NH4HO = (NH2Hg)Cl + NH4CI + 2H2O. In this reaction the dyad radical Hg" displaces H2' from the monad radical NH4, and produces a radical which is called mercur-ammonium (NHgHg), which acts as a monad, and forms salts similar in formula to those of am- monium. The mercury may also entirely displace the hydrogen of the NH^, giving rise to the radical called di-mercur-ammonium (NHg2), acting as a monad ; or a similar thing may take place with the double molecule of am- monium (N2H3), which may, by displacement of H2 by mercury, become WHITE PRECIPITATE. 59 mercur-di-ammonium (NgHgHg), acting as a dyad radical and also forming salts. Thus we have : — (NH,)C 1 . , ^ (NH2Hg)Cl. Ammonium Chloride. Mercur-ammonium Chloride. (NHg2)Cl (N,U,Ug)C\,. Di-mercur-ammonium Chloride. Mercur-di-ammonium Chloride. As to mercur-ammonium chloride^ which is called hydrargyrimi ammoniatu 7 n in the B.P., that authority instructs us to dissolve the mercuric chloride in water and to add this solution to the ammonium hydrate, constantly stirring ; to collect the precipitate on a filter, and wash it well with cold distilled water, and lastly, to dry the product at a temperature not exceeding 2 1 2°. Thus prepared, hydrargyrum ammoniatum is an opaque white powder, on which cold water, alcohol, and ether have no action, and entirely volatile by heat. {For analysis and impurities, see Author’s Analytical Chemistry, 84.) It is necessary to add the mercuric chloride to the ammonium hydrate, and wash, exactly as ordered, otherwise the colour of the substance would be rendered yellow, owing to the formation of hydrated di-mercur-ammonium chloride, (NHg2)ClH30, which is produced either by boiling water, or even by the prolonged action of cold water. The white precipitate of the B.T. does 7 iot fuse before volatilizing when heated. All parcels should be examined in this way, because it is not un- common to have the mercur-di-ammonium chloride (N2HgHg)Cl2 substituted for the proper B.P. article. This is the old fusible white precipitate^'' of the London Pharmacopoeia 1824, and is prepared by precipitating mixed solutions of mercuric chloride and ammonium chloride by sodium carbonate. It con- tains less mercury than the B.P. precipitate, and fuses befo 7 'e volatilizmg by heat. Other adulterations, such as white lead or chalk, are left as residues on volatilization. AURIC .CHLORIDE (Syns. Chloride of Gold. Terchloride of Gold). Formula, AuClg, and ^ STANNIC CHLORIDE (Syns. Tetrachloride of Tin. Tin Liquor. Formula, Sn^'Cl^. May be produced by the solution of the respective metals in nitrohydro- chloric acid. They are chiefly used for analytical purposes, the former is sometimes employed, either alone or in combination with potassium cyanide, for electro-plating. The last named (SnCl4) is valuable to dyers. ALUMINIUM CHLORIDE. Formula, AlaClg. Interesting on account of its peculiar method of production, and being used in making the metal. It is produced when chlorine is passed over a mixture of aluminium oxide and carbon heated to redness. AI2O3 + C3 -f 3CI2 - AI2CI6 + 3CO. The mixture of aluminium oxide and carbon, which must be very intimate, is made by mixing aluminium hydrate with oil and flour, and heating to redness. A solution of aluminium chloride forms the so-called Chloralu 77 il'' MANGANOUS and STANNOUS CHLORIDES. Formula, MnCl2 a 7 id SnCls- Can be obtained by boiling the metal or the hydrate with hydrochloric acid. The former may also be formed by treating any oxide of maganese with boiling hydrochloric acid. 6o FLUORINE AND CHLORINE. Stannous chloride constitutes one of the most useful tests for mercury and for gold. With the former it yields a grey, and with the latter a black pre- cip-itate. In each case the precipitate consists of the respective metals in a finely divided state. {For analysis and hnpurities, see Authors Analytical Chemistry, 84.) FERKOUS CHLORIDE (Syn. Formula, FeCl 2 . Molecular Weight, 127. Produced when iron is dissolved in hydrochloric acid : — Fe.2 + 4HCI = 2FeCl2 + 2H3. The greenish solution thus obtained, evaporated out of contact with the air, deposits greenish crystals of FeCl24H20. Exposed to the air, it decom- poses, changing partly to ferric chloride, and depositing a reddish-yellow ferric oxychloride. FERRIC CHLORIDE (Syn. Per chloride of Iron). Formula, Fe 2 Clg. Molecu- lar Weight, 325. Prepared in the anhydrous state by passing dry chlorine over iron filings heated to redness in a porcelain tube, terminated by a receiver in which the chloride collects. It is a red substance, appearing greenish by transmitted light, very volatile and deliquescent, and used occasionally in a solid state in pharmacy. The liquor fei'ri perchloridi fortior of the B.P. is an acid solution of this substance, which is prepared by dissolving iron wire in hydrochloric acid \ adding more hydrochloric acid, and a little nitric acid, and warming until the solution ceases to evolve red fumes, and becomes changed to a reddish- brown colour. {For analysis and impurities, see Author’s Analytical Chemistry, 84.) By this method we first produce ferrous chloride by the action of iron wire and hydrochloric acid : — 3Fc 2 + 1 2HCI = 6FeCl2 + 6H2. On heating this solution containing FeCl2 with more hydrochloric acid and nitric acid, the latter becomes reduced to nitric oxide, and gives up nascent oxygen, which instantly combines with the hydrogen of the hydrochloric acid, and so liberates six atoms of chlorine to change the 6FeCl2 into 3Fe2Clg (three molecules of ferric chloride) thus : 6FeClo + 6HC1 + 2HN03 = 3Fe2Clg + 2NO + 4H2O. Liquor ferri perchloridi is made by taking 5 fluid ounces of strong solution of perchloride of iron and 15 fluid ounces of distilled water, and mixing. It is important for medical reasons in making this liquor not to exceed the quantity of acid, as the solution is to be taken internally ; but for chemical reasons the acid is essential, because if too little HCl be used, a yellow deposit would form, very difficult to redissolve, and having the composition Fe2Clgi2Fe203. The substance thus produced is therefore an oxychloride of iron, and is only one of the large series of very interesting compounds of a similar nature. When liquor ferri perchloridi is digested with freshly precipitated ferric hydrate, the latter at once begins to dissolve, at first rapidly, but afterwards more slowly, until a point arrives at which the liquid becomes a jelly. This jelly is soluble in water, and is also an oxychloride containing from Fe2ClgioFe203 to FeoClgi2Fe203, according to the exact amount of ferric CHLORIDES. 6i hydrate dissolved. The solution of this jelly is not affected by boiling, dilution, or the addition of spirit; but it is instantly precipitated by the addition of a few drops of hydrochloric acid. By dialysis much of the crystalline ferric chloride may be removed from this compound, and the fluid remaining in the dialyzer is known as liquor ferri dialysati. {See Ferric Hydrate.) A mixture of liquor ferri perchloridi fo 7 'tior and rectified spirit constitutes tinctura ferri perchloridi., if the mixture be made in the proportion of three ot spirit to one of the liquor by measure. The addition of the spirit, far from being an improvement, renders the mixture liable to deposit on keeping. In fact, it invariably produces an insoluble oxychloride, after a time varying with the season, and consequently with the temperature. Ethyl chloride and some other products are also simultaneously formed. COBALTOUS CHLORIDE. Formula, CoCE, and COBALTIC CHLORIDE. Formula, COoClg. Neither are of any interest from a pharmaceutical point of view. Both may be formed from the corresponding oxide by dissolving in cold hydro- chloric acid. The former results from the action of this ,acid upon the metal also, and is red when hydrated but blue when anhydrous. NICKELOUS CHLORIDE. Formula, NiCl^. When hydrated this salt is green, but when obtained anhydrous by sublima- tion is golden yellow. It may be produced by the action of chlorine on the heated metal, or by dissolving nickel oxide or hydrate in hydrochloric acid. PLATINIC CHLORIDE (Syns. Perchloride of Platiniwi. Tetrachloride oj Platinum). Formula, PtCl^. Is formed by dissolving the metal in nitro-hydrochloric acid. It requires some time to effect complete solution, and the whole is then evaporated to dryness on the water-bath with the addition from time to time of a little more hydrochloric acid, till all traces of nitric acid are expelled. The salt is thus obtained as a yellowish mass soluble in water, alcohol, and ether. When heated it fuses ; and if a strong heat be applied it decomposes, leaving at first platinous chloride (PtCE), but afterwards nothing but metallic platinum remains. Platinic chloride is used for the quantitative estimation of potassium and ammonium, with which it forms insoluble double chlorides having the respective formulae of PtCl42KCl and PtCl42NH4Cl. {For analysis and impurities, see Authors Analytical Chemistry, 84.) PLUMBIC CHLORIDE (Syns. Magistery of Lead. Horn Lead). Formula, PbCl^ The precipitate produced when a soluble salt of lead is mixed with hydro- chloric acid. It is nearly insoluble in cold water, quite soluble in boiling water, and absolutely insoluble in alcohol. It may be prepared, though with difficulty, by boiling lead with very strong hydrochloric acid. 135 parts of cold water are required to dissolve it ; but only 30 parts of boiling water are required. ANTIMONIOUS CHLORIDE (Syn. Liquor Antimonii Chloridi. Butter of AntUnony). Formula, ShClg. May be prepared solid as a transparent, colourless, fatty-looking mass, 62 FLUORINE AND CHLORINE. which fumes slightly, and melts at i6o° F., by distilling the B.P. liquor miti- mo 7 iii chloridi^ until (the water and excess of acid having passed off) the product solidifies in the receiver. The B.P. liquor is produced by dissolving the black native sulphide of antimony in strong boiling hydrochloric acid ; cold acid being devoid of action. SbgSg + 6HC1 = 2SbCl3 + 3H2S. The sulphide dissolves with the evolution of sulphuretted hydrogen gas, and leaves a solution of antimonious chloride in excess of undecomposed hydrochloric acid. Liquor anthnoiiii clilo 7 'idi is a heavy liquid, usually of a yellowish-red colour, having a specific gravity of I'qy ; when it is poured into water it forms a white precipitate of oxychloride of antimony, which has been found to contain (SbClg)25Sb203 ; thus : — i2SbCl3 + 15H2O - (SbCl3)25Sb203 4- 30HCI. {^For analysis a^id impurities., see Author’s Analytical Chemistry, page 85.) This substance was formerly used in medicine, and called the powder of algaroth, but its only interest now arises from its production in the course of making the B.P. antimonii oxidum. This precipitate is entirely soluble in tartaric acid, which serves to distinguish it from the similar oxy salts produced by acid solutions of bismuth, when diluted with water. The colour of antimonious chloride is due, in most cases, to the presence of ferric chloride produced by the iron usually existing in the native anti- monious sulphide employed. Sometimes, however, in consequence of an idea that the strength of the colour is an indication of the quality, this is pur- posely increased in depth by the addition of ferric nitrate. BISMUTHOUS CHLORIDE, BiClg, and OXYCHLORIDE, BiOCl. The former is soluble in acidulated water, and the latter is produced as a white precipitate, on diluting a solution of the former extensively with water. The BiClg is formed by the solution of the metal in hydrochloric acid. Bismuth oxychloride is a heavy white powder which is sometimes termed bismuthyl chloride^ and is extensively used as a cosmetic under the name of blatic desperles. By ignition it is converted into the oxide. CHROMOUS CHLORIDE, CrCl2 ; CHROMIC CHLORIDE, CrgClg ; and PERCHROMIC CHLORIDE, CrClg. The latter is not known in the free state, but is probably united with chromic anhydride, CrOg, in chlorochromic anhydride, Cr02Cl2 or ^CrOj. CrCle = (Cr3ClA). The chromous chloride results from the action of chlorine upon chromic oxide (CrgOg) and carbon heated to redness. Chromic chloride is produced by the same means ; the chlorine, however, being passed over the mixture for a much longer time. It may be obtained in a hydrated form by dissolving chromic hydrate in hydrochloric acid, or by exposing the blue solutron of chromous chloride to the air. The hydrated Cr2Clg decomposes, like magnesium chloride, by evaporation, depositing CrgfiHO (chromic hydrate). CHLORINE WITH OXYGEN 63 A solution containing perchromic chloride may be obtained, by acting on plumbic chromate with hydrochloric acid, which possesses the power of dissolving gold. COMPOUNDS OF CHLORINE WITH OXYGEN. Chlorine forms a series of oxides which yield their corresponding acids by the addition of HgO, as follows : — Hypochlorons Anhydride, CI3O Chloric Oxide {undiscovered)^ ClgOg. Chlorous Anhydride, ClgOg Perchloric Oxide, or Chloric Peroxide, CI2O4 Chloric A 7 ihydride (undiscovered) , OI2O5 . . Perchloric Anhydride (undiscovered)^ OlgO^ . Hypochlorons Acid, HCIO. Chlorous Acid, HClOg. Chloric Acid, HCIO3. Perchloric Acid, HCIO4. HYPOCHLOROUS ANHYDRIDE. Formula, C\ 0 . Is a yellowish gas with an irritating odour recalling that of chlorine. It is condensable by cold to a blood-red liquid, and is prepared by passing perfectly dry chlorine over precipitated and dried mercuric oxide, in a tube cooled to the freezing point : — HgO-f-2Cl2=Cl20 + HgCl2. It is remarkable that the B.P. red mercuric oxide prepared from the nitrate will not thus act with chlorine. In contact with water it should form hypochlorous acid : — Cl20 + H20 = 2HC10. In practice, however, no such action occurs. HYDROGEN HYPOCHLORITE (Syn. Hypochlorous Ada). May be prepared by passing chlorine into water containing calcium car. bonate in suspension. CaCOg + HgO + 2CI2 = 2HCIO -f- CaCl2 + CO3. Also by passing air saturated with hydrochloric acid gas through a solution of potassium permanganate acidulated with hydrochloric acid and heated to 212° F., when HCIO distils over. (For characters and detection^ see Author’s Analytical Chemistry, page 50.) This acid, in solution, as we prepare it, is a yellowish liquid, possessing in a concentrated degree the odour as well as the bleaching and oxidizing pro- perties of chlorine. Treated with hydrochloric acid it is decomposed, forming chlorine and water : — HClO-f HCl^Clg + HgO. It combines with metals to produce a class of salts called “ hypochlorites,’ ’ in which CIO acts as a monad acidulous radical. Th^y are not employed in the pure state in Pharmacy, but occur mixed with chlorides under the names of calx chlorata and soda chlorata. 64 FLUORINE AND CHLORINE, METALLIC HYPOCHLORITES. SODA CHLORATA (Syns. Chlorinated Soda. Laharraquds Liquid). Formula, NaClNaClO. Is prepared in solution as liquor sodce chloratce by passing chlorine gas into cold solution of sodium carbonate : — Na^COg + CI2 = NaClNaClO + COg. The B.P. instructs that the chlorine, prepared by heating hydrochloric acid with manganese peroxide, shall be passed into such an amount of sodium carbonate in solution that an excess of the latter shall be left unsaturated. The carbonic anhydride liberated acts upon this excess and converts it into sodium, hydrocarbonate ; and therefore the liquor really contains 'sodium hypochlorite, sodium chloride, and sodium hydrocarbonate, thus : — 2Na2C03 + CI2 + H2O - NaClNaClO + 2NaHCOg. Thus prepared it is an alkaline colourless liquid, smelling of chlorine and having a specific gravity of i’io3. It decomposes slowly at ordinary tem- peratures and rapidly on boiling, forming a mixture of sodium chloride and chlorate. '{For analysis and impurities and volumetric estimation^ see Author's Analytical Chemistry, pages 85 and 158.) CALX CHLORATA Syns. Chlorinated Lime. Chloride of Lime. Bleaching Powder. Calcyl Chloride). Formula, CaCl2Ca2C10. Is prepared by passing chlorine gas over calcium hydrate. This most important industrial process is conducted by very carefully slaking the calcium oxide (which should be as free from magnesium and metals as possible, lest deliquescent magnesium chloride be formed, and the product be too much inclined to dampness), and rubbing it through a sieve until perfectly powdered. The powder is then spread out on shelves in a rectangular chamber, and the latter having been closed, chlorine gas is admitted at the top, and its passage continued as long as absorption takes place, and until a product has been formed which contains 33 per cent, of available chlorine. In winter this point is easily attained, but in summer it is not always possible, owing to the heat, which prevents full absorption. Commercial chloi'ide of lime is a dull white dampish powder smelling strongly of chlorine. It contains calcium hypochlorite, calcium chloride, calcium hydrate, and calcium carbonate, with sundry impurities. Water partially dis- solves it, taking up the hypochlorite, chloride, and a little of the calcium hydrate, and leaving the bulk of the latter, together with the carbonate, etc., insoluble. {For analysis and impurities., see Author's Analytical Chemistry, pages 85 and 158.) Both the soda and calx chlorata evolve hypochlorous acid under the in- fluence of very dilute acids, and even when simply in contact with the carbonic acid of the atmosphere. With the very slightest excess of any acid, such as sulphuric, howe/er, they do not evolve that substance, but are decom- posed, yielding chlorine : — CaCl2.Ca2C10 + 2H2SO^= 2CaSO^ + 2 CI 2 + 2 H 2 O. This occurs, more strictly speaking, as follows : — 1. CaCl2.Ca2C10 + 2H2S04= 2CaS04 + 2HCIO -f- 2HC]. 2. 2HCIO + 2HCU2CI2 + 2H2O, HYPOCHLORITES AND CHLORITES. 65 By the last reaction, it is evident, that in the presence of hydrochloric acid, chlorine is also evolved. CaCl2.Ca2C10 + 4HCI = 2CI2 + 2CaCl2 + 2H2O. The estimation of the amount of chlorine which any particular sample ot bleaching powder will evolve for industrial or other purposes is a matter of much importance. The chlorine thus estimated is called by the analyst available chlorine^ and it is always ascertained by volumetric analysis. {See Author's Analytical Chemistry, 158.) As it is impossible to demonstrate conclusively the existence of metallic chlorides in good chlorinated lime and soda, many chemists consider these products to be chlorides of the hypothetical radicals, — Calcyl (CaO) and sodyl (Na^O). Thus : — Sodyl Chloride, Na20Cl2. Calcyl Chloride, CaOCl2. These formulae may be accounted for, thus : — Na— CI2— O— Na. Cl— Ca— O— Cl. In the' sodium compound the group CI2 acts as a dyad, though it is usually a saturated molecule. If the calcium compound had the formula it is usually supposed to have, the calcium chloride could be dissolved by alcohol. As this cannot be done there seems no better explanation than to ascribe to the calx chlorata the above given composition. CHLOROUS ANHYDRIDE (Syn. Chlorous oxide'). Formula, CI2O3. Is a greenish yellow gas, only liquefiable by the most intense cold. It is prepared by heating a mixture of potassium chlorate with nitric and arsenious acids. The latter acid reduces the former to nitrous acid, which in its turn deoxidizes the chlorate. The action of the nitrous acid may be shown thus : — 2KCIO3 + 2HNO2 = CI2O3 + H2O + 2KNO3. HYDROGEN CHLORITE (Syn. Chlorous Acid). Formula, HCIO2. When chlorous anhydride dissolves in water this acid is formed, which combines with metals to form a class of salts called chlorites^ which are of no pharmaceutical interest. It possesses bleaching properties, is a greenish liquid^ and combines violently with alkaline hydrates. A remarkable fact about chlorous acid is that it is destitute of the power of decomposing a carbonate. PERCHLORIC OXIDE. Formula UgO^ =20102- A very heavy and exceedingly explosive yellow gas, produced by the action of strong sulphuric acid upon potassium chlorate : — 3KCIO3 + 2H2SO4 = KCIO4 + 2KHSO4 + CI2O4 + H2O. The least elevation of temperature, or the presence of any combustible or organic matter, instantly causes this gas to decompose, with a powerful ex- plosion, into chlorine and oxygen. It can be condensed by cold into a liquid ; and is the active agent in the well-known experiment of spontaneous combus- tion when a mixture of sugar and potassium chlorate is touched with strong sulphuric acid. It cannot be collected either^ over water or mercury, as it is decomposed by both. F 66 FLUORINE AND CHLORINE. By the action of the former perchloric oxide is decomposed into a mixture of chlorous and chloric acids : — CI2O4 + HgO = HClOg + HCIO3. ' HYDROGEN CHLORATE (Syn. Chloric Acid). Formula, HCIO3. May be prepared in solution by the action of very dilute sulphuric acid upon a chlorate. The best one to use for this purpose is barium chlorate, because the bye-product of barium sulphate, being insoluble, can be easily removed by filtration. Ba2C103 H2SO4 = 2HCIO3 + BaSO^. Thus prepared, and concentrated by evaporation in vacuo^ it is a thick liquid, with an irritating chlorine-like odour, and immediately decomposed by organic matters or by heat. It combines with metals to form a class of salts, called chlorates., having for their acidulous radicals the group CIO3, which acts as a monad. All chlorates are more or less soluble in water and decom- posed by strong sulphuric acid. Alkaline chlorates are prepared by passing chlorine into a solution of an alkaline hydrate, thus forming hypochlorite and chloride (already studied). 6KHO + 3CI; = 3KCIO + 3KCI + 3H2O. On boiling this solution, it decomposes, and forms a mixture of chloride and chlorate. The latter can be separated by fractional crystallization : — 3KCIO + 3KCI = 5KCI + KCIO3. Thus we see that the result of passing chlorine into a solution of an alkali, and heating, is the production of an ide and an ate in the proportion of five of the former to one of the latter. This is an important fact to keep in mind, because it applies equally to iodine and bromine, and will assist materially in writing out equations. {For detection and separation of Chlorates, see Author's Analytical Chemistry, page 50.) POTASSIUM CHLORATE (Syn. Chlorate of Potash). Formula, KCIO3. Molecular Weight, 122 5. Can be prepared as just described ; but such a process would be very ex- pensive, owing to the amount of potassium wasted as chloride. It has been found, however, that by substituting a proper proportion of slaked lime for -| of the potassium hydrate, all the former will become chloride while the latter only will form chlorate. By this process a great saving of potassium is effected ; and not only so, but as potassium hydrate is produced by potassium carbonate and slaked lime, it is only necessary to use 6 molecules instead of 5 of the latter, and then potassium carbonate can be employed. The B.P. process is therefore essentially to pass chlorine into a solution of potassium carbonate, mixed with slaked lime, until absorption ceases, boil the solution, filter, and crystallize. Viewed by the light of these explanations, an appa- rently very difficult equation becomes simple : — K2CO3 -I- 6Ca2HO + 6CI2 - 2KCIO3 -1- 5CaCl2 + CaC03 + fiHgO. In practice the lime and potassium carbonate are made into a paste with water, placed in a carboy, and chlorine passed through. The whole is then boiled with a good quantity of water, filtered, and crystallized. The completion of the action of the chlorine is determined by examining the colour of the pasty mass in the carboy. If it be pink (owing to the formation of a small quantity of an alkaline permanganate from the trace of manganese mechanically carried over with the current of chlorine) no further METALLIC CHLORATES PERCHLORATES.— EUCHLORINE. 67 absorption will take place. Potassium chlorate is in colourless rhomboidal crystalline plates, sparingly soluble in cold water and insoluble in alcohol. It is much employed, either alone or mixed with hydrochloric or sulphuric acid, as an oxidizing agent. When heated in contact with organic substances, it speedily converts them into their ultimate products of combustion, viz., car- bonic acid gas, water, and ammonia gas or nitrogen. In combination .with hydrochloric acid it is used in toxicological investigations, for the purpose of destroying, to a considerable extent, such substances as might interfere with the detection of poisons. It was formerly supposed that potassium chlorate, when medicinally administered, tended to oxidize all the impurities with which it might come in contact ; but it has been found that, like other saline bodies, it passes through the body with but little if any decomposition or alteration. {For analysis and impurities., see Aiithor’s Analytical Chemistry, page 85.) Potassium and all alkaline chlorates yield oxygen when heated, and leave a residue of chloride : — 2KC103 = 2KC1 + 302 . While, on the other hand, chlorates of earthy and heavy metals evolve oxygen and chlorine, leaving oxides : — 2 (Mg 2 C 103 ) = 2MgO -f 2CI2 5O2. When potassium chlorate is heated until it fuses thoroughly, and begins to thicken, and the source of heat is withdrawn, a residue is left, containing potassium perchlorate together with potassium chloride. . ' 2KCIO3 = KCIO4 -i- KCl + O2. A similar action takes place when potassium chlorate is treated with nitric acid j only in this case the bye-product is nitrate instead of chloride : — 6KCIO3 -f 4HNO3 = 2KCIO4 -f 4KNO3 + 4O2 + 2CI2 + 2H2O. The perchlorate obtained by either of these processes, being much less soluble in water than either of the bye-products, crystallizes out first. PERCHLORIC ACID. Formula, HCIO^. May be produced by distilling potassium perchlorate with sulphuric acid. It is a heavy colourless liquid, which, even when preserved in the dark, sud- denly decomposes with explosion after a week or two. It explodes at once with fearful violence on touching organic matter or carbon. POTASSIUM PERCHLORATE (Syn. Perchlorate of Potash). Formula, KCIO^. May be obtained mixed with potassium nitrate by dropping crystals of potassium chlorate (one or two only at a time) into hot nitric acid, and after- wards separating by fractional crystallization. Explosion in this process is avoided because, instead of forming perchloric oxide, the chlorine and oxygen are liberated as a 7 nixtu 7 'e, and not a compound.’ It is, like the chlorate, only slightly soluble in water. The perchlorates are not of pharmaceutical interest. {For detection of Perchlorates, see Author's Analytical Chemistry, 50.) EUCHLORINE. Formula, C1^206- This peculiar body, discovered by Sir Humphrey Davy, is a greenish-yellow gas, produced by the action of hydrochloric acid upon potassium chlorate. Its odour is characteristic, and it is a mixture of nine parts of chlorine and three of perchloric oxide : — (3C102 + 9C1) = C1i20,. 4KCIO3 -f 12HCI = -f 4KCI + 6H2O. CHAPTER V. BROMINE AND IODINE. BROMINE. BROMINE. Symbol, Br. Atomic Weight, 80. In the free state, Brg Molecular Weight, 160. Density of Vapour, referred to Air, 5’54. Density of Vapour, 7 'ef erred to Hyd 7 'ogen, 80. Atomicity, Monad. Exists in nature in certain saline springs, notably those near Kreuznach, in Germany. It is also found in sea water, in the state of magnesium bromide, and in the mother-liquors of kelp, along with iodine. {See Iodine.) The water of the spring is evaporated and crystallized, this process being repeated until all the alkaline chlorides and sulphates are removed. The mother-liquor, which contains the magnesium bromide, is evaporated, and distilled with manganic dioxide and sulphuric acid. The neck of the retort is plunged under cold water, and the bromine collects in drops at the bottom. MgBrg + MnOg + 2H2SO4 ^ Brg -f- MgS04 + MnS04 ^ 2H2O. The crude bromine thus obtained is finally rectified over calcium chloride. It is also prepared from the residual liquors of kelp, after removal of the iodine as cuprous iodide (^see Iodine), by evaporation and distillation as above described. Bromine is a dark brownish-red, very volatile liquid, with a strong and dis- agreeable odour. Its specific gravity is 2*966. It is soluble in water to the extent of about 31 in 1000, the solution thus obtained having a specific gravity of 1*024. This solution is of a slightly orange colour, is not nearly so rapidly decomposed by light as chlorine water, and when cooled to the freezing point it forms, like chlorine, a definite solid hydrate, Br5H20. It is more soluble in alcohol than in water, and very freely so in ether, chloroform, and carbon disulphide, its solutions in these 77 ie 7 istriia having a very characteristic yellowish-red tinge. Like chlorine, it acts as an indirect oxidant in contact with water ; but is weaker in its affinities to basy- lous radicals than that substance, although stronger than iodine. Thus, while free chlorine will replace both bromine and iodine from a metal, free bromine will only displace iodine. It is, therefore, intermediate, in all its properties, between those two metalloids. The following table will give an idea of the relative powers of Cl, Br, and I, which constitute a group by themselves, under the name of the Haloge 7 is. They are thus called because th^y can combine directly with bases, without forming acids. Atomic Weight. Character at Behaviour Ordinary OF Solution Temperature. IN Light'. Cl * 35‘5 • • . . Gaseous rapidly decomposed. Br . 80 . . . . . Liquid slowly ditto. I . 127 . . . . . Solid scarcely affected. METALLIC BROMIDES. 69 Bromine is slightly volatile at ordinary temperatures, giving red vapours having an exceedingly offensive odour; and heated to about 120° F., it boils, giving a vapour which has a density of 5*54 (referred to hydrogen, of 80) ; at 4° F., it is converted into a reddish crystalline solid. Free bromine combines with starch paste to form an orange-red compound called bromide of starch, which is not readily bleached by excess of chlorine. {For detection of Bromine^ see AzithoFs Analytical Chemistry, 51.) METALLIC BROMIDES. HYDROGEN BROMIDE (Syn. Hydrobroniic Acid). Formula, HBr. Mole- cular Weight, 81 . Is given off as a colourless gas, with a decided pungency, similar to that of hydrochloric acid, whenever sulphuric acid is heated with potassium bromide or any alkaline bromide. 2KBr + 2HBr + K2SO4. It cannot be prepared thus in practice, because it is at once decomposed by any excess of sulphuric acid, yielding sulphurous anhydride and free bromine : — H2SO4 + 2 HBr - Brg -1- SO2 + 2H2O. It is therefore prepared in solution (i) by passing sulphuretted hydrogen through bromine suspended in water : — 2 H 2 S -t- 2Br2 = 4HBr -f- ; or (2) by acting on phosphorous bromide with water, thus : — PBrg + 3H2O = sHBr -f H3PO3. This solution is very similar in appearance to ordinary aqueous HCl. Hydrogen will unite with bromine vapour directly, to form this acid, but not nearly so rapidly as in the case of chlorine, which acts by mere sunlight (as already mentioned), while, bromine requires the application of a decided source of heat, and immediate contact therewith : — Br2 Hg = 2 HBr. 2 vols. -f- 2 vols. = 4 vols. One gallon of bromine vapour thus requires one gallon of hydrogen to form two gallons of HBr. Bromides are derived by the displacement of hydrogen from hydrobromic acid by a basylous radical. They are mostly soluble in water, except the argentic, mercurous, and plumbic salts. {For detection., separation, and estimation of HBr and B 7 'omides, see Author’s Analytical Chemistry, 51, 53, 156, and 176.) AMMONIUM BROMIDE (Svx. Ammonii Bromidum). Formula, NH^Br. Molecular Weight, 98 . Sometimes prepared by the direct combination of ammonium hydrate and hydrobromic acid ; but more commonly by mixing solutions of ferrous bromide and ammonium carbonate. This latter precipitates ferrous carbonate, leaving the ammonium bromide in solution. FeBr2 -f- (NH 4 ) 2 C 03 = 2NH4Br + FeCOa. The B.P. describes it as being in colourless crystals, which become slightly 70 BROMINE AND IODINE. yellow by exposure to the air, and have a pungent saline taste. Ammonium bromide may be sublimed unchanged by the application of heat. It is readily soluble in water, and less soluble in spirit. {For analysis and estimation^ see Author’s Analytical Chemistry, 88 and 156.) POTASSIUM BROMIDE (Syn. Potassii Bromidutii). Formula, KBr. Mole- .cular Weight, 119. . Prepared by dissolving "bromine in heated solution of potassium hydrate, thus forming a mixture of potassium bromide and bromate : — 6KH0 + sBrg = sKBr + KBrOg + 3H2O. The solution having been evaporated to dryness, the residue is heated in a crucible with a little charcoal, to change the bromate into bromide : — KBrOg + Cg^KBr + sCO. Potassium bromide is usually met with in transparent, cubical crystals with no odour, but a pungent saline taste ; readily soluble in water, less soluble in spirit. Potassium bromide is fusible by heat, and may be volatilized at a tempera- ture not far removed from that necessary to vaporize potassium chloride. Like sodium chloride, heat causes it to decrepitate. {For analysis and impurities, see Authors Analytical Chemistry, 87.) ARGENTIC BROMIDE (Syn. Bromide 0/ Silver). Formula, AgBr. Mole- cular Weight, 188. The dirty-white precipitate produced by argentic nitrate, in a solution containing a bromide. Insoluble in dilute nitric acid, but slowly soluble in liquor ammonice. Treated with free chlorine it gives up its bromine, and becomes argentic chloride. Digested for some time with potassium iodide it becomes argentic iodide. FERROUS BROMIDE (Syn. Bromide of Iron). Formula, FeBrg. Molecular Weight, 216. May be produced by direct combination of iron wire and bromine, in the presence of water. (See Ferrous Iodide.) ^ COMPOUNDS OF BROMINE WITH OXYGEN. Only two of these compounds are known (i) Hypobromous Acid. HBrO. corresponding to hypochlorous acid (for detection, see Authors Analytical Chemistry, 51), and (2) : — HYDROGEN BROMATE (Syn. Bromic Add). Formula, HBrOg. This acid may be obtained by acting on barium bromate with very dilute sulphuric acid. It closely resembles chloric acid, and forms salts called bromates, produced, as already seen, along with the corresponding bromide by the action of alkalies upon bromine. If desired, the bromate may be separated from the bromide by fractional crystallization, the former being much less soluble in water than the latter. {For detection of bromates, see Author’s Analytical Chemistry, page 52.) MANUFACTURE OF IODINE. 71 IODINE, IODINE. Syml)ol, I. Atomic Weight, 127. Vapour Density, referred to Hydrogen., 127. Vapour Density, referred to Air, 8*71 In the free state, I 2 . Molecular Weight, 254. Atomicity, Monad. Exists in sea water, and is stored up in the substance of many marine plants and animals. Cod-liver oil contains a decided percentage of iodine, and so do sponges. It is also found in many minerals, notably in rock-salt, and in the native saltpetre from Chili. In practice, it is chiefly extracted from certain varieties of Ailgoe, the most highly iodized variety being the Fucus palmatus. The seaweed is collected on the shore, dried, and placed in pits surrounded by a low wall. In these it is set on fire, when all the vegetable matter burns off, and the ashes are found at the bottom as a fused mass, which on cooling sets into a cake, and is called kelp. There are two varieties of this ash ; viz,, drift seaweed kelp and cut sea- weed kelp, the former being the richer in iodine. The kelp is first digested in water in large vats, called chests, and the soluble parts having been thus extracted, the liquor is drawn off and evaporated in boilers. During this evaporation, sodium sulphate separates ; and the liquid, on cooling, also deposits crystals of potassium chloride. This process is repeated until no more crystals can be obtained, and the uncry stallizable mother-liquor is then used for the production of iodine. It is called the residual kelp liquor, and contains the iodine as sodium iodide, together with carbonates and sulphides. The residual liquor is first neutralized with sulphuric acid, which causes a copious evolution of gases (CO.2, H2S, and SO2); and it is then boiled and cooled, when some more sodium sulphate is deposited, mixed with sulphur. The clear liquor is now run off into a still, and having been mixed with excess of sulphuric acid and manganic dioxide, heat is applied, when the iodine distils over in magnificent violet-coloured vapours, and collects in the receiver, leaving sodium and manganous sulphates in the retort : — 2NaI -i- MnOg + 2112804= I2 -f Na2S04 -t- MnS04 + 2H2O. The following statement relative to the practical results of this importan industry may be accepted as a record of practical experience. One Ton of Drift Weed One Ton of Cut Weed Kelp yields : Kelp yields ; cwt. lbs. cwt. lbs. Iodine . . 0 12 . 0 •4 Potassium Chloride • 4 84 . • 3 56 Potassium Sulphate 2 84 . . • 3 56 Fished Salt* . 2 84 . • 3 56 Refuse Sulphur 0 28 . 0 56 This process with manganese and sulphuric acid, yields iodine contaminated with bromine, should that element be present in the kelp. It also produces chlorine from any of the chlorides in the liquor. The production of chlorine is often apt to cause a loss of iodine by form- ing iodic chloride, ICI3. It is, therefore, desirable to have a process by which the iodine can be separated from both these elements. This is attained by precipitating the purified residual liquor with a solution containing r part Trade name for other residual mixed salts. 72 BROMINE AND IODINE. cupric sulphate to 2*25 parts ferrous sulphate, when the iodine is precipitated as cuprous iodide, leaving the bromides and chlorides unaffected : — 2NaI + 2C11SO4 + 2FeS04 = 2CuI + NagSO^ + FegsSO^. The precipitated pure cuprous iodide is then collected, washed, and distilled with manganic dioxide and sulphuric acid, when perfectly pure iodine is obtained. After this separation, bromine may be obtained from the filtrate in very rich kelps. A similar process has been recommended in analysis for detecting a bromide in presence of an iodide, but it is not sufficiently delicate for that purpose. Some trace of iodine invariably remains in solution, which, in the hands of the inexperienced, is forthwith mistaken for bromine. Iodine is usually met with in laminar crystals, of a peculiar odour, black colour, and metallic lustre, which are entirely volatile by heat to a purple vapour. Its specific gravity is 4*948, and the density of its vapour is 8716 compared with air, and 127 compared with hydrogen. It is only soluble in water to the extent of i in 7000. It is more soluble in alcohol, and still more in ether, chloroform, benzene, and carbon disulphide, communicating a magnificent violet colour to these four last-named fluids. Its best ordinary solvent, as adopted in pharmacy, is a strong solution of potassium iodide ; 30 grains of which, dissolved in an ounce of water, will take up 20 grains of iodine. Its vapour, like that of chlorine, is very irritat- ing ; but if not in large quantities it may be inhaled without giving rise to any ill effects. The melting point 6f iodine is 236° F., and it volatilizes at 356° F. It colours the skin brown, or, if in small quantities, yellow ; but the stain may be instantly removed by ammonium hydrate. Iodine possesses an intimate relation to chlorine and bromine in all its compounds, but its affinities are much more feeble. Free chlorine or bromine can therefore liberate iodine from all its combinations with basylous radicals by substitution, thus : — 2KI-FCl2-2KCl-f-l2. 2KI + Br2 = 2KBr + I2. The combinations of iodine with oxygen and similar electro-negative elements are, on the other hand, more stable than those of chlorine and bromine. It combines directly with metals to form iodides, and when heatfed in the presence of water it can dissolve gold. It also acts, in the presence of water, as an indirect oxidizer, but more feebly than either chlorine or bromine. As its solution is not liable to rapid decomposition in contact with air and light, it is sometimes used in analysis in preference to these elements. {For detection and wipurities of free Iodine.^ see Author's Analytical Chemistry, 52 and 86.) METALLIC IODIDES. HYDROGfEN IODIDE (Syn. Hydriodic Acid). Formula, HI. Molecular Weight, 128. Like hydrochloric acid, this is truly a gas, very soluble in water. It is pro- duced in solution by adding an acid, such as sulphuric acid, to potassium iodide. It cannot, however, be isolated thus, as the sulphuric acid on heat- ing decomposes it and sets free iodine. Practically it is prepared in solution, — I. By passing sulphuretted hydrogen through iodine suspended in water, and filtering from the deposited sulphur 2H2S-f 2l2 = 4HI-tS2. METALLIC IODIDES. 73 2. By the action of water upon phosphorpus iodide : — PI3 + 3H2O-3HI + H3PO3, yielding hydriodic and phosphorous acids. This is usually done by packing a tube (closed at one end and furnished with a cork and delivery tube) with alternate layers of iodine, powdered glass moistened with water, and phos- phorus, the use of the glass being simply to moderate the action. 4KI -F 5I2 + P2 -h 8H2O = 14HI + 2K2HPO4. Strong solution of hydriodic acid distilled over at a temperature of 260° F. has a specific gravity of 1*7, and as it contains 57 per cent, real HI, has the formula (2HI1TH2O). Lately hydriodic and hydrobromic acids have been prepared sufficiently pure for pharmaceutical purposes by simply shaking up a strong solution of potassium iodide with the slightest possible excess of tartaric acid : — - KI -f H2C4H,Oe = m + KHC^H.Oe, and filtering out the precipitate of cream of tartar which forms. Iodides are salts which have iodine for their acidulous radical, acting as a monad. In two of its combinations, at least, namely ICI3 and I(C2H302)3, I acts as a triad ; but as neither of these compounds is of pharmaceutical importance, its atomicity may be taken as monad. Alkaline iodides are soluble, but many of those of heavy metals are insoluble, and are characterized by very brilliant colours. Insoluble iodides, as a rule, give up their iodine when -digested with potassium hydrate, forming potassium iodide. {For deteciion., separation, and estimation of Iodides, see Authods Analytical Chemistry, pages 52, 53, 156, 176, and 177.) AMMONIUM IODIDE. Formula, NHJ. Molecular Weight, 145. Seldom used in Pharmacy, it may be prepared by precipitating ferrous iodide with ammonium carbonate. It is very deliquescent, and crystallizes in cubes. Iodine must not be added to ammonium hydrate, for the reason already stated (see Iodide of Nitrogen). It becomes coloured by exposure to the air from the liberation of a little iodine ; but it may be restored to its original whiteness by a trace of a reducing agent, such as sulphuretted hydrogen or sulphurous anhydride. SODIUM IODIDE. Formula, Nal. Molecular Weight, 150. Prepared like potassium iodide, using sodium instead of potassium hydrate. It is rarely used in Pharmacy, probably on account of its unsightly and deliques- cent nature ; but in many cases its action is superior to that of potassium iodide, and it is employed by some high authorities in preference to that salt, as it exerts a less depressing influence. POTASSIUM IODIDE (Syn. Potassii lodiduni). Formula, KI. Molecular Weight, 166. Prepared by dissolving iodine in heated solution of potassium hydrate, which forms potassium iodide and iodate : — 6KHO + 3I2 = 5KI + KIO3 -f 3H2O ; and then evaporating to dryness, heating the residue with charcoal in a cru- cible, which changes the iodate into iodide, with evolution of carbonic oxide : — KI 03 -FC 3 -KI + 3C0. 74 BROMINE AND IODINE. Potassium iodide is commonly met with in colourless, generally opaque cubic crystals, readily soluble in water, and in a less degree in spirit. It usually has a feebly alkaline reaction, and should be soluble in six parts of rectified spirit by weight. It is commonly adulterated with chlorides, carbon- ates, or iodates. The explanation of the test for iodate with tartaric acid and starch paste will be found under Potassium Iodate. Potassium iodide is fusible by heat, and at a very high temperature it vola- tilizes unchanged. It is decomposed with the liberation of iodine by the fol- lowing among others : — Chlorine water. Nitrous Acid. Bromine Water. Calx a 7 id Soda Chlorata. Nitric Acid. Ammonium Nitrate. Sulphuric Acid (concentrated). Potassium Ferricyanide. {For analysis and impurities., see AtUhods Analytical , page 86.) CADMIUM IODIDE (Syn. Cadmii lodidittti). Formula, Cdl 2 . Molecular Weight, 366. Prepared by digesting iodine with metallic cadmium in the presence ot water : — Cd-Flg^Cdlg. The B.P. describes it as follows : — In flat micaceous crystals, white, of a pearly lustre, which melt when heated to about 6oo° F., forming an amber-coloured fluid. At a dull red heat, violet- coloured vapours are given off (iodine). It is anhydrous and permanent in the air, freely soluble in water and in rectified spirit. The solution reddens litmus paper. {For analysis and impurities, see Aidhods Analytical Chemistry, 86. ) CUPEOUS IODIDE. Formula, Cul. Molecular Weight, 190 5. Produced as a dirty-white precipitate on mixing solution of potassium iodide with a solution of i part cupric sulphate and 2'5 parts of ferrous sulphate. Neither chlorides nor bromides are affected by this reagent. {For the equation see Purification of Iodine.) Cuprous iodide may also be formed from iodine and finely-divided copper, by heating them together in such a manner that the iodine vapour may pass over. the metal at a red heat. By the action of potassium or sodium hydrate or carbonate upon it, cuprous oxide of a red colour is formed. MEECUEOUS IODIDE (Syn. Hydrargyti lodidum Viride). Formula, Hgglg or Hgl. Molecular Weight, 327. By rubbing together mercury and iodine in proper proportions, in the pre- sence of spirit, and drying in the dark. Hg -t- I = Hgl, or more correctly Hgg + I2 = HggIg 200 + 127 = 327. Thus prepared, it is a dark green powder, insoluble in water, which darkens in colour upon exposure to light. {For analysis and itnpurities, see Author's Analytical Chemistry, 86.) It is most essential that the slightest excess of iodine should be avoided, as that would form the much more active tnercuric iodide. This impurity is tested for by shaking up with ether, in which the mercurous iodide is insoluble. METALLIC IODIDES. 75 while the mercuric iodide is soluble. The pure mercurous iodide should not be so green as the B.P. preparation, but more yellowish. On heating, it splits up into mercury and mercuric iodide, thus : — 2Hg2l2=2Hgl2 + Hg2. The same decomposition is induced by simple exposure to light ; and this causes the chief objection to what would be otherwise a very excellent pre- paration for medicinal purposes. Mercurous iodide may also be produced by precipitating mercurous acetate with potassium iodide. The nitrate is apt to yield an impure product. Besides this and the mercuric iodide, two other iodides are stated to exist (Hg2l3 and Hgl^) ; but they do not appear to be unquestionably chemical compounds, and are of no importance to pharmacists. MERCURIC IODIDE (Syn. Hydrargyri lodidmn Rubrum). Formula, Hgl^. Molecular Weight, 454. Prepared by precipitating a solution of mercuric chloride with potassium iodide, carefully avoiding excess : — HgCl2 + 2ia = Hgl2 + 2KCI. 271 4- 332= 454 + (149). The equation shows that, to produce a proper effect, the ingredients must be in the proportion of 10 of mercuric chloride to i2j of potassium iodide, any excess of either, but especially of the latter, causing the precipitate to redissolve. In practice, the solutions are mixed boiling hot, and after the whole has cooled, the precipitate is filtered out, washed with cold water, and dried at 212°. Thus prepared, it is a crystalline .powder, of a vermilion colour, becoming yellow when heated over a lamp on a sheet of paper ; almost insoluble in water ; dissolves sparingly in alcohol, but freely in ether or mer- curic chloride, or potassium iodide. It is not soluble in boiling water. {For analysis and impm'ities^ see Author'' s Analytical Chemistry, page 87.) The property above mentioned of its turning yellow by heat, is extremely interesting. This is what is called a dimorphous body, 2>., it can crystallize in two forms. In the ordinary precipitated condition it is not crystalline ; it is then said to be amorphous (a, without ; i*-opOg + — 2Na2S20'g. Or by adding sulphur to a solution of sodium carbonate, and passing through it a stream of sulphurous anhydride : — NaaCOg + S + SOa + sHgO = Na^SgOs.sHgO + COg. Commercially it is prepared from the ^^soda waste ” and ‘‘^-as limef both of which contain calcium sulphide, by exposing it to the air so as to convert it into thiosulphate, and making a double decomposition with sodium carbonate, thus : — aCaSg + 3O2 = 2CaS203 + 382- CaS20g + Na2C03 = Na2S203 + CaCOg. The solution, filtered from the precipitated calcium carbonate, is evapo- rated and crystallized. The salt forms into large crystals, soluble in water, but not in alcohol. It is fusible by heat, and if melted in a clean flask at 212° F., the mouth being instantly closed with a cork, it will remain fluid ; but the moment that the cork is removed, and the surface of the liquid touched with a particle of anything solid, the whole flies into a mass of crystals. A white precipitate of Ag2S203.H20 (or Ag2H2S204), results from the addi- tion of thiosulphate to argentic nitrate, if the latter be kept in excess. By a gradual decomposition this becomes argentic sulphide, AggS, thus : — Ag2S203.H20 Ag2S + H2S04. The transformation is rendered visible by the insoluble product being black. If too much sodium thiosulphate be used, the white precipitate of hydrated argentic tliiosulphate, at first formed, will be redissolved. It is a curious chemical fact, that the addition of a little argentic chloride to a solution of sodium thiosulphate (itself very bitter), forms the sweetest known liquid, which is, however, extremely poisonous. Solution of sodium thiosulphate will not keep well, even in a stoppered bottle, as it deposits sulphur, and becomes sodium sulphate, so that the volu- metric solution should always be tested before being used. When added to a solution of iodine it decolorizes it, forming sodium iodide and tetrathionate, thus ; — 2Na2S203+ I2 =_ 2 NaI + NagS^Og. It is therefore used for estimating iodine. {See Author's Analytical Chemistry, 152.) HYDROG-EN DITHIONATE (Syn. Dlthiotiic Acid . Hyposulphuric Acid ) A Formula, HoSoOg. Is prepared by passing sulphurous anhydride through manganic peroxide COMPOUNDS OF SULPHUR WITH OXYGEN. 19 suspended in water, and kept cool, by which means manganous dithionate is formed ; — Mn02+2S02 = MnS20g. , This is then treated with barium hydrate : — MnS20g + Ba2H0 = Mn2HO + BaSgOg. I.astly, the barium dithionate is exactly decomposed by an equivalent quantity of dilute sulphuric acid, and the liberated dithionic acid concentrated in vacm till it has a density of 1*347. It is distinguished from sulphuric acid by thus forming a soluble salt with barium. HYDROGEN TRITHIONATE (Syn. Trithionic Add). Eormula, H2S3O6. Is liberated from its potassium salt by hydrofluosilicic acid, but gradually splits up into sulphur, sulphurous, and sulphuric acids. Potassium trithionate, KgSgOg, is formed by the action of sulphurous anhy- dride on potassium thiosulphate : — 2K2S2O3 + 3SO2 = 2K2S30g + S. HYDROGEN TETRATHIONATE (Syn. Tetrathionic Add). Formula, H2S40g. May be produced by the action of sulphurous anhydride on chlorine disul- phide, or isolated from its barium salt. Sodium tetrathionate, Na2S^Og, is produced when iodine acts on sodium thiosulphate in the volumetric analysis of iodine and available chlorine, by the B.P. processes. {See Author's Analyti., richer in ethene, acetylene, and kindred bodies). COMPOUNDS OF CARBON WITH OXYGEN, CARBONOUS OXIDE (Syns. Carhoriic Oxide. Carbon Monoxide). Formula, CO. Molecular Weight, 28. Density, refer^'ed to Hydrogen, 14. Density, referred to Air, *968. Is produced — 1. By the combustion of carbon in a limited supply of air. 2. By passing carbonic anhydride over red-hot charcoal : — C02-{-C=2C0. 2 vols. 4 vols. 3. By heating oxalic acid with sulphuric acid : — H2C2O4 + H2SO4 = H2SO4H2O + CO + CO2 ; and then absorbing the carbonic anhydride by passing the mixed gases through solution of calcium hydrate. 4. By heating crystallized potassium fe'rrocyanide with ten times its volume of strong sulphuric acid : — K.FeCgNfi.sH^O + 6H2SO4 + 3H2O - 6CO + 2K2SO, + FeSO^ + It is important not to continue the heating beyond the point sufficient to liquefy the contents of the retort, as the sulphuric acid is reduced to sulphu- rous anhydride, and carbonous oxide is no longer evolved. * The most valuable illuminating portions, f The largest constituent. I The most undesirable impurities. 140 CARBON. Carbonous oxide is an exceedingly poisonous gas, colourless, invisible, and scarcely soluble in water. It burns in the air with a blue, lambent flame, producing carbonic anhydride. It reduces at a red heat many metallic oxides, and it thus plays an impor- tant part in the preparation of metals, such as iron, the ores of which are heated in a furnace with coal. It is absorbed by potassium hydrate, producing potassium formate : — KHO + CO = KCHOg. But its best absorbent is solution of cuprous chloride, which is therefore the reagent employed for this purpose in gas analysis. Carbonous oxide acts as a dyad radical in displacing the hydrogen of compound radicals, such as ammonia, and is then called carbonyl. (^See Amides.) CAEBONIC ANHYDEIDE (Syns. Carbon Dioxide. Carbonic Acid Gas. Choke Da?np). Formula, COg. Molecular Weight, 44. Density, refer 7 'ed to Hydrogen, 22 . Density, referred to Air, 1*524. Is prepared — 1. By burning carbon in a full supply of oxygen. 2. By the action of an acid upon a carbonate : — CaCOg + 2HCI - CaCl2 + CO3 + H3O. It is given off in great abundance from volcanoes, and also in certain fissures in volcanic regions, notably the Grotto del Cane in Italy. It is the invariable product of the burning of vegetable and animal matters in the air, and is the choke damp which collects in mines after an explosion. Carbonic anhydride is colourless, incombustible, and much heavier than air. It is soluble in water, and also to some slight extent in alcohol ; and when prepared for use should be collected by displacement. (^See Chlorine.) Atmospheric pressure greatly increases vthe solubility of carbonic anhydride in water, of which the ordinary aerated waters are examples. Carbonic anhydride may be liquefied by a pressure of 36 atmospheres at 32° F., and the resulting fluid will solidify by the cold produced by its own evaporation as it issues from a small j et into a metallic cylinder. Liquid carbonic anhydride, mixed with ether, creates an intense degree of cold. The solution of carbonic anhydride in water is viewed as being carbonic acid, HgCOg ; but that body has not been isolated, owing to the great readiness with which it decomposes. Such solution possesses a sharp taste, and is acid to test-paper. It is the acid which gives rise to the class of salts called carbonates^ The carbonates of ammonium, sodium, and potassium* are soluble in water; that of lithium is sparingly so, and the remaining metallic carbonates are insoluble. All carbonates effervesce with acids, giving off carbonic anhydride, and when heated to dull redness become converted into oxides, except the carbo- nates of calcium, barium, and strontium, which require continued bright-red heat, and those of sodium and potassium, which are not decomposed by heat. Solutions of soluble carbonates precipitate most metals from their solutions, either in the form of carbonates, hydrocarbonates, or simple hydrates. The first variety of precipitate is produced in solutions of calcium, barium, stron- tium, silver, lead, and mercury ; the second, in solutions of magnesium, zinc, copper, ferrous iron, and bismuth; the third, in solutions of aluminium, ferric iron, chromium, and antimony. LITHIUM AND AMMONIUM CARBONATES. 141' METALLIC CARBONATES. LITHIUM CARBONATE (Syn. LithicB Carbonas). Formula, Li2C0g. Is produced by mixing strong solutions of lithium chloride (or sulphate) and ammonium carbonate : — 2LiCl + (NHOgCOg = LigCOg + aNH^Cl. In consequence of lithium carbonate being soluble to the extent of about I per cent, in water at 60° F., it cannot be procured in a very pure state by this method, as, if it is washed much, a considerable waste is incurred. It is therefore more advisable to begin by converting lithium sulphate into lithium acetate by double decomposition with barium acetate. The solution, after filtration and evaporation, yields lithium acetate in a solid condition ; and upon heating this until the residue is white, it is converted into carbonate. The B.P. thus describes the salt : — Charactei's and Tests. — In white powder or in minute crystalline grains, alkaline in reaction, soluble in 100 parts of cold water, insoluble in alcohol. It dissolves with eifervescence in hydrochloric acid. {For analysis, see Authors Analytical Clieniistry,/<7^£' 94,) A solution of this salt of per cent strength exhibits the reaction of an alkali. A hot saturated solution will deposit the anhydrous carbonate by slow evaporation. In some respects it resembles sodium hydrocarbonate. Dis- solved in water in the proportion of half a grain per ounce, and the solution saturated with carbonic anhydride at a pressure of about 100 pounds per square inch, the resulting solution is liquor lithice effeivesce 7 is, B.P. On account of the small atomic weight of lithium, a little of its carbonate will perform the same office as a much larger amount of sodium or potassium carbonate. This property and the ready solubility of the salt it forms with uric acid (lithium urate) are the reasons for the introduction of lithium salts into medicine. The B.P. thus describes the manufacture of liquor lithice effervescens : — Take of— Carbonate of Lithia . . . . . . 10 grains. Water i pint. Mix in a suitable apparatus, and pass into it as much pure washed car- bonic acid gas, obtained by the action of sulphuric acid on chalk, as can be introduced with a pressure of seven atmospheres. Keep the solution in bottles securely closed, to prevent the escape of the compressed gas. Characters and Tests. — Effervesces strongly when the containing vessel is opened, carbonic acid gas escaping. The liquid is clear and sparkling, and has an agreeable acidulous taste. Half a pint of it, evaporated to dryness, yields five grains of a white solid residue, answering to the tests for carbonate of lithia. AMMONIUM CARBONATE (Syns. Carbonate of Ammonia. Diammonium Carbonate). Formula, (NH4)2C03. Has not been isolated. The ordinary carbonates containing a larger per- centage of the carbonate radical. It is supposed to exist in spiritus ammonice aromaticus, being formed by the action of the ammonium hydrate on the official carbonate, thus : — N.HigCgOg - 1 - 2NH,H0 sCNHJ^COg + H^O. In practice, however, it contains a slight excess of ammonium hydrate, owing to some of the bicarbonate remaining in the retort. CARBON. 142 AMMONIUM-HYDROGEN CARBONATE (Syns. Bicarbonate of Ammonia. Acid Caf'bonate of Ammoiiia. Aimnonium Bicarbonate. ' Hydric A^jwio- nic Carbonate). Formula, NH4HCO3. Is prepared by saturating ammonium hydrate with carbonic anhydride. The ordinary carbonate of ammonia of the shops, when exposed to the air, is slowly converted into this salt, which has a less ammoniacal odour than the other compounds of ammonium and the carbonate radicals. It can be sepa- rated from the carbonate above described by treatment with alcohol of 90 per cent, strength, in which it is insoluble, while the ammonium carbonate dissolves. TETR-AMMONIUM CARBONATE (Syns. Sesqui- Carbonate of Ammo7iia. Ammonice Carbonas). Formula, N^H^gCgOg. Molecular Weight, 236. Commercial carbonate of ani7nonia consists essentially of this salt. It is prepared by heating together calcium carbonate and ammonium chloride or sulphate, until no more tetr-ammonium carbonate sublimes j when the follow- ing reaction probably takes place : — 3(NH4)2S04 + sCaCOg - N^HigCgOg + H3O + 2NH3 + sCaSO^. The salt is found sufficiently pure in coirimerce for all pharmaceutical pur- poses, and the manufacture on the small scale is troublesome. It is met with in translucent crystalline masses, with a strong ammoniacal odour and alkaline reaction ; soluble in cold water, more sparingly in spirit. It volatilizes entirely when heated, and is readily dissolved by acids with effervescence. [For analysis a 7 id impurities , see Authod s Analytical Chemistry, 94 ) 20 grains of I <- r ( gi'^-ins Citric Acid. Carbonate of Ammonia ) I 25 J grains Tartaric Acid. The formula N^H^gCgOg must be regarded as purely empirical, being really composed of one molecule of ammonium carbamate (NgHgCOg), and two of ammonium-hydrogen carbonate (NH^HCOg). The carbamate is regarded as derived from diammonium carbonate by the abstraction of the elements of water, which body is easily and quietly taken up again on exposing the car- bamate to its action. ^Tetr-ammonium carbonate does not dissolve in water without decomposition. If the powdered salt be stirred up with water, and the solution after a few seconds poured off, the residue will be tolerably pure ammonium-hydrogen carbonate. Carbamates may be viewed as being derived from an acid called carbamic, which has not been isolated. The formula of this acid is considered to be HNHgCOg, or,— CO I I which yields by displacement of H by ammonium, CO | The formula of ammonium carbarmate is therefore NH^NHgCOg, or empi- rically NgHgCOg, and the whole molecule of carbo7iate of a77i77io7iia is thus constituted : — NH4HCO3 NH4HCO3 N,Hg CO, Two molecules ammonium-hydrogen carbonate. One molecule ammonium carbamate. ^4^16^3Q8 The strong odour of the commercial carbonate is due chiefly to the presence of carbamate. TETR-'AMMONIUM AND SODIUM CARBONATES. H3 The affinities and analogies of ammonium carbonate are numerous. Through ammonium cyanate it has affinity with cyanates generally, and also with sulphocyanates. {See Cyanogen.) Thus substances between which there v/ere formerly supposed to be no noticeable resemblance, are now seen to be members of greatly similar (in some cases identical) series. In practice, the manufacture of tetr-ammonium carbonate is sometimes conducted by the dry distillation of any animal matter. If produced in this manner, it requires purification, which is carried out by re-subliming the im- pure salt with the charred material left in the retort after the evolution of vapour has entirely ceased. It is best to condense the sublimate in an earthen or glass receiver, but lead is sometimes employed. The chief pro- bable contaminations are ammonium sulphate, ammonium chloride, calcium hydrate, calcium chloride, lead, and rarely ammonium hyposulphite. By the evaporation of a solution of the commercial salt in liquor ajimionicB., the pure tetr-ammonium carbonate is procured, the crystals of which are transparent and prismatic. These decompose into ammonium-hydrogen car- bonate upon exposure to the air much more readily than the fibrous opalescent masses in which the salt exists in commerce. In consequence of ammonium carbamate being more volatile than ammonium carbonate it is dissipated before the latter; and therefore, after exposing commercial sesqui-carbonate to the air for some time, the residue receives the name of “ mild carbonate of ammonia,’’ and its vapour, which only comes off slowly, is very feebly alkaline to red litmus paper. The solution in dilute acids should be perfectly colourless, otherwise contamination with oily empyreumatic products is in- dicated. SODIUM CARBONATE (Syns. SodcB Carbonas. Subcarbonate of Soda. Soda. Disodic Carbonate'). Formula, Na 2 C 03 . Molecular Weight, 106. Formula, when crystallized, Na^COg.lOHgO. This highly important salt is found in nature in an impure state. It is of interest, not only in its pharmaceutical and chemical relations, but also in dyeing, glass-making, and many other branches of the industrial arts. The natural sources from which sodium carbonate may be procured by merely physical processes are : i. The “ soda lakes of Egypt and Hungary.” 2. The Icelandic hot springs, believed to be of volcanic origin. 3. Certain plants found near the sea-shore in Spain and some other countries, which yield the ash known as barilla. 4. As a substance found solid in various countries, and termed natron^ in which form it is contaminated with sodium sulphate and other salts of sodium. Sodium carbonate is also a constituent of kelp^ and crystallizes out during the evaporation of the solution, together with the other sodium salts. Almost the entirety of the enormous quantity of sodium carbonate at present consumed, is produced by a modification of Leblanc’s original process. There are three distinct steps. The first stage consists in decomposing sodium chloride (6 parts) by means of sulphuric acid (10 parts). The bye-product is hydrochloric acid, which must be condensed as before directed. {See Hydrochloric Acid.) The second stage consists in the conversion of 35 parts of sodium sulphate (formed in the last process) into sodium carbonate by the joint action of calcium carbonate (4 parts) and carbon, in the form of small coal or coke dust, at a high temperature. 1. H2S04-f2NaCl = Na^SO^-f 2HCI. 2. Na2S04-f2CaC03-f2C2 = NaaCOg -h CaO.CaS -f COg + 4CO. 144 CARBON. The third stage is the purification of the hard dark-coloured product (termed black ball soda), by pulverization, disintegration by means of steam, and lixiviation of the resulting mass with water. For the sake of economy it is customary not to attempt to dissolve the sodium carbonate in pure water, but to use a nearly saturated solution ob- tained from a previous treatment. Thus a much less quantity of water will have to be removed by evaporation. On applying heat until the dry salt, in consequence of frequent stirring, is obtained in the form of a coarse powder, a residue termed soda salt remains. But this is not generally pure enough to be redissolved and crystallized without further treatment. The usual course pursued in order to decompose and remove impurities consists in roasting four ^ parts with one part of sawdust. Thus the sodium sulphide contained in the ^ soda salt is converted by the elimination of sulphuretted hydrogen into sodium ^ oxide, which with the carbonic anhydride, produced by the combustion of the .1 sawdust, forms sodium carbonate. • \ Commercial soda, as it is commonly called, ordinarily occurs in crystals. \ These are formed by dissolving the purified soda salt in hot water, and ^ removing the solution after subsidence into crystallizing pans, constructed of such a shape that a large surface shall be exposed to the air. The formula ^ of the crystals is Na2C0g.ioH20. i SodcB Carbonas is usually met with in transparent colourless laminar crystals !■ of a rhombic shape, efflorescent, with a harslr alkaline taste and strong alkaline , , reaction. By heat they undergo aqueous fusion, and then dry up, losing l| 63 per cent, of their weight. {For analysis, see Author's Analytical Chemistry, 95.) 20 grains of ) / 97 grains Citric Acid, or Carbonate of Soda j I io'5 grains Tartaric Acid. If a sample be found impure, the most ready mode of purification is to make a hot saturated solution, and whilst it is cooling agitate constantly and quickly. By this means the sodium carbonate is obtained in a coarse crystal- line powder, whilst much of the contaminating salts remains in solution, and the greater part of those adherent to the crystals may be removed by shaking with cold water and pouring off the solution. SodcB carbonas exsiccata, B.P., is simply the crystals from which water (to the extent of 63 per cent.) has been removed by heat. Water at 212° F. dis- solves fully ij times its weight of the crystals, but only about 47 ’6 per cent, of this powder ; whilst at 60° F. it takes up 50 per cent, of the hydrated and 2 1 "8 per cent, of the anhydrous salt. The point of greatest solubility appears to be a little below 100° F. The desiccated salt forms several hydrates in contact with water, heat being in all cases rendered perceptible. The powder formed by the efflorescence of crystals of sodium carbonate in the air is Na2C0g.5H20. If the temperature be raised to about 100° F. this powder loses more water, being converted into Na2C0g.H20. These hydrates may also be formed by moistening the anhydrous salt with a little water : crystals having 7, 8, 9, and 15 HgO are also obtainable. j (For another process by which Na2Co3 is made, see Sodium.) ^ SODIUM HYDROGEN CARBONATE. Bicarbonate of Soda. Sodium ' Bicarbonate. Sodium Acid Carbonate. Hydric Sodic Carbonate. Formula, NaHCOg. Molecular Weight, 84. j This salt is manufactured on the large scale by passing a stream of carbonic 1 anhydride through a mixture of two parts of the crystallized and three of -j the anhydrous sodium carbonate. The carbonic anhydride is absorbed and ] BI- AND SESQUI- CARBONATE OF SODA. H5 sodium hydrogen carbonate is produced in the form of small crystalline par- ticles. The reaction is : — NaaCOg + CO2 + HgO = 2NaHC03. The employment of a proportion of anhydrous carbonate is necessary, because it is desired to obtain a remunerative product in a pulverulent form. If no other than the crystallized salt be employed, as the carbonic anhydride is passed, the mixture becomes liquid, and the hydrogen carbonate afterwards only partially deposits in transparent crystals, much of the product remaining in solution which cannot be evaporated without decomposition. In practice the passing of CO3 is continued until a little of the product dissolved in cold water ceases to give a red precipitate with* mercuric chloride, showing that the carbonate has been entirely converted. SodcE bicarbonas is met with in powder or small opaque irregular scales, white, of a saline not unpleasant taste. {For analysis, see Analytical G)a.Qmistxj , page 95.) 20 grains of ) [ 167 grains of Citric Acid, or Bicarbonate of Soda ) C grains Tartaric Acid. The salt constitutes the alkaline portion of several mineral waters. A mode of manufacture of great practical and theoretical interest is to take advantage of the double decomposition between solid tetr-ammonium carbonate and a solution of sodium chloride. A solution of the latter in three parts of water is stirred up with one part of the sesquicarbonate of arm 7 i 07 iia of commerce. After the mixture has been allowed to react for five or six hours, the sodium hydrogen-carbonate deposits in small particles. The following is the reaction : — HgO -f N^H^gCgOg + 2NaCl = 2NaHC03 -1- 2NH4CI -i- (NH^)2C03. Ammonium chloride and ammonium carbonate, being considerably more soluble than the sodium hydrogen-carbonate, remain in solution. The objec- tion to this mode of preparation is, that a variable quantity of sodium chloride is carried down, which cannot be entirely removed from the product without great loss. When the hydrogen carbonate is heated it begins to lose carbonic anhydride and water at (or even below) 160° F. At a red heat nothing remains but sodium carbonate in an anhydrous condition. When a solution is boiled for a long time, pure sodium carbonate is the only salt left in the liquid. At 60° F. the strongest solution of sodium hydrogen carbonate which can be made will contain i of the salt in 9I of water. The solubility of the salt in water at high temperatures (such as 120° to 2i2°F.) cannot be accurately determined because of the readiness with which it commences to decompose. TETRA-SODIUM CARBONATE (Syn. Sesquicarbonate of Soda). Formula, Na4H23C03. Occurs in the form of Ti'ona in Africa. It is undoubtedly a combination of the two preceding substances, formed as shown below : — Na 2 C 03 + 2 NaHC 03 = Na^H'23G03. The native salt contains 2H2O (as water of crystallization). That these two salts are chemically united, is proved with tolerable certainty by the fact that a 10 per cent, solution of magnesium sulphate does not lose its limpidity upon the addition of a saturated solution of tetra-sodium carbonate. Water at 60° F. takes up about 16 -8 per cent. 146 CARBON. POTASSIUM CARBONATE (Syns. Subcarbonate of Potash. Potassce Carbo 7 ias. Dipotassic Carbo?iate. Salts of Tartar). Fornmla, K 2 CO 3 . Molecular Weight, 138. Is not a natural product, but is readily procured, though in a very impure form, by calcining plants and vegetable substances. Upon lixiviating the ash, potassium carbonate, together with some potassium sulphate and potassium chloride, are separated in solution, whilst aluminous matter, silicic anhydride, calcium carbonate, and calcium phosphate, remain undissolved. On evapo- rating the solution, a residue commercially termed crude potash is obtained. In order to convert this into the tolerably pure form of potassium carbonate known pearlash, and mentioned in the B.P. as the source of the official salt, it is necessary to digest with an equal weight of water for about a week, and to evaporate the clear decanted liquid with constant stirring until crystalline grains are left. These may be washed with a nearly saturated solution of the pure salt, dried, and fused in iron pots. As it is easier to burn wood than the leaves and succulent portions of plants, wood ashes are the practical sources of potassium carbonate, especially since, even if the other portions could be economically burnt, the mineral residue would be so light as to be blown away should any wind prevail at the time of the combustion. For though the process is conducted in as sheltered spots as convenient, or in excavations purposely made, it is almost impossible to secure the entire absence of loss, even in the case of wood. The carbonate is derived from the malates, tartrates, oxalates, and other organic salts of potassium contained in plants. It has been observed that the yield of potassium carbonate depends greatly upon the woody or herbaceous nature of the vegetable substances used in its production ; the latter, in con- sequence of the liquid portion {t.e. the sap) containing the salts, being the most abundant source. The less compact portions of the same plant also yield more than the hard and close-textured. North America and Russia export a large quantity of potash and pearlash. Potassce carbonas is described in the B.P. as K0CO3 with about 16 per cent, of water of crystallization. Obtained from commercial pearlash, the product of lixiviation of wood ashes, by treating the pearlash with its own weight of distilled water, and evaporating the solution so formed to dryness, while it is kept briskly agitated. {For analysis, see Authods KiasXytxcdl Chemistry, page g^.) The B.P. describes the pure salt as follows : — Characters and Tests. — A white crystalline powder, alkaline and caustic to the taste, very deliquescent, readily soluble in water but insoluble in spirit, and effervescing with diluted hydrochloric acid. Loses about sixteen per cent, of its weight when exposed to a red heat. 20 grains ) ripiitraUze / grains Citric Acid, or Carbonate of Potash / ( 18 grains Tartaric Acid. A boiling saturated solution forms crystals of the formula K2CO3.2H0O, which are octahedra and extremely deliquescent. They only contain 4 per cent, more water than the B.P. pulverulent salt. Water at 60° F. dissolves about i'i8 times its weight of the dry carbonate. When a current of steam passes over the salt heated to incipient fusion, carbonic anhydride passes off, potassium hydrate remaining. The decomposition, however, is never complete. There are many other sources from which potassium carbonate in a pure condition may be procured : for example, when potassium oxalate or quadr- oxalate is heated the carbonate left is free from uncombined carbon, and all BI- AND SESQUl- CARBONATE OF POTASH. 147 but mere traces of salts. Potassium hydrogen tartrate also yields potassium carbonate when it is calcined. In this case, however, the residue contains free carbon, which on treatment with water remains insoluble, and may be filtered out. A very pure form of the carbonate may likewise be obtained by calcining potassium hydrogen carbonate in a silver crucible. POTASSIUM HYDROG-EN-CARBONATE (Syns. Potassm Bicarbonas. Mono- Potassic Carbonate. Potassium Acid Carbojiate). Formula, KHCO3. Molecular Weight, 100 . Is prepared by satiurating an aqueous solution of potassium carbonate with carbonic anhydride. Crystals separate after some days ; but the solution must not be evaporated at 212° F., as some amount of decomposition would then occur. When it is requisite to entirely prevent decomposition, 100° F. is the limit of maximum safety and rapidity. In consequence of the less ready combination of potas- sium carbonate than of sodium carbonate with carbonic anhydride, and of the desirability of procuring the hydrocarbonate in large crystals, the carbonate is dissolved in water, instead of being (as in the case of the sodium salt) treated in the solid state. The decomposition which takes place is : — K2CO3 + CO2 + H2O = 2 KHCO3. The characteristics of the salt are as subjoined : — Colourless right rhombic prisms, not deliquescent, of a saline feebly alkaline taste, not corrosive. Diluted hydrochloric acid causes strong effervescence. {For analysis., see Author's Analytical Chemistry, page 95.) 20 grains ) npntrnhVp / ^4 grains Citric Acid, or Bicarbonate of Potash / (15 grains Tartaric Acid. Only a very small quantity dissolves in boiling alcohol, and still less in cold. It behaves like sodium hydrogen-carbonate as regards magnesium sulphate. When subjected to a high temperature it undergoes the same decomposition as the corresponding sodium compound. It is neither deliquescent nor efflorescent, in the latter respect differing from the sodium carbonate. Water at 60° F. dissolves (approximately) 25 '5 per cent. This being less than the solubility 'of potassium carbonate in water, explains the fact that on passing carbonic anhydride into a saturated solution of that salt, crystals of the compound resulting from its action are deposited. It is a solvent of uric acid, hence it is used in medicine for that purpose (in lithiasis). With the salts of several metals it combines to give birth to double carbonates, such as the magnesium potassium-carbonate. It is a slight solvent of metallic iron when a solution is boiled in vessels of that metal. TETRA-POTASSIUM CARBONATE (Syn. Sesquicarbonate of Potash). Formula, K4H2.3CO3. The existence of this salt is not definitely determined. It is constituted like the sodium salt, and is said to separate on crystallizing a mixture of 79 of potassium carbonate and 100 of potassium hydrogen-carbonate. ARGENTIC CARBONATE. Formula, Ag2C03. When free from alkaline salts, this is a yellow powder, which blackens qn exposure to light. It constitutes the white precipitate produced on adding 148 CARBON. potassium carbonate to argentic nitrate. Ammonium hydrate takes it up with ease, and on heating to 480° F. leaves the pure metal ; but provided the temperature does not exceed 390° ^., argentic oxide remains. CALCIUM CARBONATE (Syns. Chalk. Calc-spar. Carbonate of Lwie. Limestone. Marble. Arragojiite'). Formula, CaCOg. Molecular Weight, 100 . Is the most abundant and valuable natural salt of calcium. It is secreted by many of the lower classes of animals to form their shell. It may be obtained in a condition absolutely free from contamination by dissolving marble or any similar variety of the salt in hydrochloric acid, and after throw- ing down the aluminium, iron, magnesium, and the phosphates of the same by means of calcium hydrate, and filtering, neutralizing the filtrate with ammonium carbonate. By this method a white powder is produced which requires drying at 400° to 500° F. When thrown down from cold solutions, calcium carbonate is amorphous, but on being kept under water it assumes the crystalline state. With hot solutions the precipitate is at once produced as minute crystals. The action upon neutral litmus paper is very feebly alkaline. When heated in hermetically sealed iron vessels it fuses, and a marble-like solid is found on opening the tube after cooling. It dissolves much more readily in water in presence either of ammoniacal salts or carbonic anhydride. The official forms are : — - 1. White marble {inarmor alburn^ B.P.) which is stated to be — Hard, white, crystalline native carbonate of lime, in masses. Used in producing carbonic acid gas, and should be the Carrara or statuary marble. 2. Chalk {creta., B.P.) which is — Native friable carbonate of lime. The native chalk may be employed to yield carbonic acid gas, but is less useful than marble because it does not act so regularly, and forms a frothy mixture j also a large bulk must be used because its specific gravity is much less. 3. Prepared Chalk {creta preparata, B.P.). Chalk, freed from most of its impurities by elutriation^ and afterwards dried in small masses, which are usually of a conical form. Elutriation {duo) is the process of purifying a substance insoluble in water, by washing and straining. It possesses the subjoined qualities. A white amorphous powder, effervescing with acids, and dissolving with only a slight residue in diluted hydrochloric acid. It is perfectly amorphous. 4. Precipitated chalk {calcis carbonas precipitata, B.P.) is directed to be prepared by mixing calcium chloride and sodium carbonate, collecting, wash- ing, and drying the precipitate. CaClg + NagCOg - CaCOg -f aNaCl. It is a white crystalline powder, insoluble in water, dissolving in hydro- chloric acid with effervescence. {For analysis, see Author's Analytical Chemistry, page 96.) There is a crystallized form of calcium carbonate known as hydrocalcite, containing 5H2O, and a compound sometimes denominated ‘‘calcium ortho- carbonate,” Ca^CO^. The latter is supposed to be derived from the acid H^C04, which is termed orthocarbonic. The ordinary and normal acid, HgCOg is, under this .theory, looked upon as metacarbonic acid ; chalk, with the other forms of normal calcium carbonate, is called calcium metacarbonate. CALCIUM, BARIUM, AND STRONTIUM CARBONATES. 149 The fact that this body, which is the result of heating chalk or marble in powder to low redness, produces a hydrate with the water, even though its formation be not attended by the evolution of great heat, seems to counte- nance the idea that it is composed of a mixture of carbonate and oxide ; in other words, is an oxy-carbonate, forming with water a hydrato-carbonate. The composition, in accordance with this view, would be : — CaCOg.CaO = Ca2C04. And the proportions of the hydrated salt of hydrato-carbonate ; — Ca2C04 + H20 - CaCOg.Ca2HO. CALCIUM HYDROGEN-CARBONATE (Syns. Bicarbonate of Lime. Calcium Acid Carbo 7 iate). Formula, CaH22C0g. The existence of this salt has been inferred for many years, but it has never been actually obtained. It is supposed to be formed when calcium carbonate is dissolved in water containing carbonic acid. It is of great importance from a pharmaceutical as well as interesting from a general standpoint. By boiling it redeposits the carbonate. Water fully charged with carbonic anhy- dride dissolves only *07 per cent, of calcium carbonate, hence it requires extremely dilute solutions of potassium hydro- (or sodium hydro-) carbonate and a soluble salt of calcium to give no visible reaction. Water charged as above has the capability of dissolving out calcium oxide from calcium silicate. Thus it disintegrates calcareous rocks, and when the solution comes in contact with solid bodies it deposits calcium carbonate of more or less purity, accord- ing to the nature and amount of the matters mechanically carried down. The presence of calcium in this form imparts to spring and river water the quality known as tempora 7 -y hardness, because it is removed by boiling. {See Water Analysis in Authors Analytical Chemistry, 187.) The calcium carbonate let fall on subjecting a solution of the hydro salt to the action of a high temperature, constitutes one of those troublesome and dangerous deposits — boiler incrustations. In the presence of ammonium chloride no precipitate is caused by boiling a solution of calcium hydrogen-carbonate. BARIUM and STRONTIUM CARBONATES. Formia», BaCOg and SrCOg. These bodies are sometimes employed as the sources of the other barium and strontium salts, but do not yield such pure products as the sulphates. In qualitative analysis, barium and strontium are precipitated as carbonates on adding ammonium carbonate to their solutions. When the hydrates are brought in contact with carbonic anhydride, or the oxides with water and the same, the result is the formation of barium and strontium carbonates. Advantage has been taken of the fact that oxalic acid in solution, added to a liquid containing salts of lime and baryta, precipitates the whole of the lime hnmedicttely, the baryta being only affected after some time. Witherite, dis- solved in water and hydrochloric acid is thus treated. About thirty grains of oxalic acid are sufficient for one pound. The lime precipitate having been eliminated, to the clear filtered solution caustic soda is added. After an houds rest, filter again and treat the liquid with a solution of sodium car- bonate. Collect and wash the precipitate in the usual manner. Barium carbonate is poisonous, and is occasionally used as a vermin de- stroyer. Strontium carbonate is quite innocuous except in large quantities in the presence of acids. The barium salt only is transformed into sulphates 150 CARBON. by cold alkaline sulphates in solution. Neither give up carbonic anhydride so readily as calcium by the influence of heat. Steam, at a red heat, con- verts them into oxides or hydrates. The native barium carbonate is witherite ; native strontium carbonate is strontianite. MAGNESIUM CARBONATE. Formula, MgCOg. Exists in nature as the minerals termed magnesite (tolerably pure), hydro- i 7 iagnesite (united with hydrate), and dolomite (combined with calcium carbon- ate). Unlike most other carbonates, it cannot be produced by precipitating a magnesium solution by an alkaline carbonate, as the oxy- or hydrato- car- bonate is more stable. If, however, the carbonic anhydride be passed into water, in which the magnesium hydrato-carbonate is kept suspended by brisk agitation, the hydrate is converted into carbonate, which may be separated in minute crystals by evaporation. Sodium caibonate heated with crystallized mag- nesium sulphate in a closed vessel gives the pure magnesium carbonate. Both the ordinary hydrato-carbonate and the pure carbonate dissolve more readily in aqueous carbonic acid than in water. MAGNESIUM HYDRATO-CARBONATE (MAGNESIUM OXY-CARBONATE) (Syns. MagnesicE Carbonas. Magnesice Garbonas Levis. Magnesia Alba). Formula, (MgC 03 )gMg 0 . 5 H 20 ; or., better, (MgC03)sMg2H04I^0. This is the official salt, prepared in two forms, both of which possess absolutely the same composition. Magnesice carbonas levis is produced from cold dilute solutions of magnesium sulphate and sodium carbonate, and magnesice carbonas from strong hot solutions of the same. The following is a representation of the reaction : 4MgS04 + 4Na2C03+5H20 = (MgC03)3Mg2H0.4H20 + 4Na2S04 + CO 2 . In order to secure the most ponderous product, it is requisite to evaporate the solutions after mixing them to perfect dryness, and then dissolve out the soluble portion with hot water. To obtain a result of the utmost lightness it has been advised to subject the moist precipitate, after washing, to a temperature not exceeding 30° F., whereby the water is frozen. On allowing the mass to melt, and then drying as usual, there results a product of even greater levity than the levis of the B.P. Both 77 iagnesice ca 7 'bo 7 ias and 77 iag 7 iesice carbonas levis are white powders the former amorphous and the latter in part crystalline. They are practically insoluble in water unless it contains much CO2 dissolved, and when heated give off carbonic anhydride and water, leaving the oxide without any change of colour. Both are soluble in acids with effervescence. ^For analysis, see Auihods Analytical Chemistry, 96.) The liquid known as fluid magnesia {liquor 77 iag 7 iesice ca 7 'bonatis, B.P.), and consisting of a solution of magnesium oxy-carbonate in water charged with carbonic anhydride, may be regarded as probably containing magnesium hydrogen-carbonate, MgH22C03. In default of the existence of this body, which is by no means certain, it undoubtedly is a solution of magnesium carbonate with excess of the carbonic gas. On exposure to light and air the excess of carbonic anhydride passes off and crystals of the carbonate are deposited, having the formula MgC035H20. ZINC CARBONATE (Syn. Cala 77 iine). Formula, ZnC 03 . Has not been thoroughly investigated. It may probably be procured by ZINC AND PLUMBIC CARBONATES. the same methods as magnesium carbonate. Is formed during the prepara- tion of the next salt, but immediately splits up. ZINC HYDRATO-CARBONATE (ZINC OXY-CARBONATE) (Syns. Wkife Zinc [incorrect]. Zinci Cardonas. Prepared Calai7une. Lapis Calaminarts). Formula, ZnC03.(Zn0)23H20 ; or, better, ZnC03(Zn2H0)2H20. Occurs native as zinc bloom, which, however, is not always pure white in colour. It is also prepared by precipitating a solution of zinc sulphate with sodium carbonate, as represented in the equation : — sZnSO^ + + sHgO = ZnC03(Zn2H0)2.H30 + 3Na2S04 4 - 2CO2. Zinci carbonas, B.P., is a white, tasteless, inodorous powder, insoluble in water ; soluble, with effervescence and without residue, in dilute acids. At 390° F., it evolves carbonic anhydride and water, zinc oxide remaining, which is yellow while hot but white on cooling. {For analysis and impurities^ see Author's Analytical Chemistry, pa^-e g 6 .) The impure native form, known 'as calamine, does not decompose under 570° F., and only slowly at that temperature. PLUMBIC CARBONATE (Svns. Ceritse. Cerusite. Carbonate of Lead). Formula, PbC03. Cannot be formed by acting upon a plumbic salt with an alkaline carbonate, the precipitate thus formed containing some hydrate, and being — PLUMBIC HYDRATO-CARBONATE (or OXY-CARBONATE) (Syn. White Lead). Formulae, 2 PbC 03 .Pb 2 H 0 , or 2PbCO3.PbO.H2O. It is rarely made in this manner j a more ready and valuable product being obtainable by less expensive methods. At one time this salt was extensively made by passing a current of carbonic anhydride through a solution of plumbic oxy-acetate. The neutral acetate remains in solution, the oxide dissolved being alone precipitated. This acetate on being digested with plumbic oxide, takes up a quantity of the latter, which may again be transformed into carbonate, a portion of plumbic acetate thus serving continuously as a means of causing plumbic oxide to enter into rapid combination with carbonic anhydride. Another mode is to expose sheets of lead to the simultaneous influence of carbonic anhydride, aqueous vapour, and acetic acid. The latter, of about half the strength of vinegar, is placed in small earthenware vessels in the midst of heaps of decaying matter, such as the exhausted bark used in tanning, which give off abundance of carbonic acid gas. Over these pots are laid the sheets of metal, so that both the carbonic and acetic vapours may have access to the same surface. The temperature of the tan should approximate to 145° F., and the fermentative decomposition which it undergoes will suffice to maintain the mass at about this degree. The B.P. description is : — ■ A soft heavy white powder, blackened by sulphuretted hydrogen, insoluble in water, soluble with effervescence in diluted acetic acid without leaving any residue. Heated to redness it becomes deep yellow being converted into plumbic oxide. . {For analysis., see Author's Analytical Chemistry, 97.) Sometimes lead shavings are used. In any case the white lead requires 152 CARBON. grinding. The pasty form used by gasfitters, is manufactured by simply rubbing about 14 parts with i part of linseed oil. Some samples of plumbic oxy- or hydrato- carbonate contain a rather larger proportion of carbonate than that we have given. CUPEIC CAEBONATE. Formula, CuCOg. Is not known. The carbonates existing in nature are : — 1. Malachite, dicupric oxy- (or “ortho”) carbonate : C1I2CO4 + H2O. 2. Azurite, tricupric oxy- (or ortho ”) carbonate : Cu3H2(C04)2. The formulae may be stated : — 1. CU2C04 4-H20 = CUCO3.CU2HO. 2. CU3H2(C04)2 = 2CUCO3.CU2HO. The former is that obtained on subjecting cupric sulphate to precipitation by an alkaline carbonate, and drying at a gentle heat. At 390° F. it leaves cupric oxide by the evolution of carbonic anhydride and moisture. The mineralogical and technical names for the first salt are, ARas ore., green car- bonate of copper., and mountain green. Of the second, Chessy copper., blue malachite, saurite, blue carbonate of copper, and blue verditer. MEECUEOUS CAEBONATE. Formula, Hg2C0.. Is of a black or yellow colour, and is produced by the double decomposi- tion between potassium carbonate and a soluble mercurous salt. Mercuric carbonate (HgCOg) cannot be formed from mercuric chloride, nor from mer- curic nitrate in the presence of a chloride, by hydrogen-carbonates or carbon- ates, but an oxycarbonate can be produced by the latter. In consequence of the oxychloride thrown down by hydrogen-carbonates being white in colour, whilst mercuric oxy-carbonate is dark red, it is thus possible to distinguish between soluble carbonates and hydrogen-carbonates. FEEEOTJS CAEBONATE (Syn. Carbonate of Iron). Formula, FeCOg. Molecular Weight, 116. This compound occurs in nature as spathic iron ore and clay iron-stone. It may be obtained in a pure condition by precipitating a solution of ferrous sulphate with ammonium carbonate. FeSO^ -F (NH4)2C03 = FeCOg -i- (NH4)2S04. In order to prevent as much as possible the decomposition which takes place during the operation of drying, the B.P. separates the precipitate by filtration, partially dries it by pressure in calico, and then mixes* it with sugar, by which means alteration is greatly retarded. Ferri carbonas saccharata is met with in small coherent lumps, of a grey colour, with a sweet, very feeble, chalybeate taste. It dissolves with efferves- cence in warm hydrochloric acid diluted with half its volume of water, and is converted into ferric oxide by heating in the air. {For analysis and estimatioti, see Authod s Analytical Chemistry , 96 and i59-) The highest (theoretically) attainable percentage is 46. In practice few samples contain the official proportion of carbonate. Out of twenty-five sam- ples examined a few years ago, only one contained a trifle over the amount, and two others were within a single per c6nt. of the same. Not more than one out of three samples will contain 37 per cent., which is reckoned an average purity. FERROUS AND BISMUTH CARBONATES. ^53 It is sometimes the practice to mix the ferrous sulphate with sugar before solution. To provide against the possibility of the action of dissolved air, it might be advisable to boil the ferrous sulphate with water for some time, and add a few drops of aqueous sulphurous acid, until the precipitate (if any) is entirely redissolved. If a few drops of sulphurous acid be also added to the tetr-ammonium carbonate solution, oxidation would still further be prevented. In spite of these precautions, it is impossible to entirely arrest oxidation. But by washing with water which has been boiled until the ebullition has become irregular and convulsive, and using the utmost despatch in mixing with the sugar, a product of 45 per cent, may practically be obtained. It oxidizes much more readily in moist than in dry aiif. The reddish-brown powder which passed by the name of subcarbonate (or carbonate) of iron some years back, was that now known as ferric oxy-hydrate. It results when ferrous carbonate- is dried with free exposure to the air and without admixture of sugar. The advantage ferrous carbonate is believed to possess over and beyond ferric oxy-hydrates and oxide is a more ready solubility in gastric juice. Ferrous carbonate is the active constituent of 7iiistura ferri composita., the well-known Griffith’s mixture ; and in consequence of the great rapidity of its oxidation when in solution, the ferrous sulphate is directed to be added at the last, and in crystals, the bottle being instantly corked. Practical phar- macists keep in readiness a concentrated emulsion with the omission of the iron, the ferrous sulphate and the requisite rosewater being added at the moment of dispensing. By this means an admirable result is gained. BISMUTH OXY-CARBONATE (or BISMUTHYL CARBONATE) (Syns. Bis7mithi CarboTias. Snbcarbofiate of Bis77mth). Formulae, Bi23C0^.2Bi203, or (Bi 0 ) 2 C 03 ; as m B.P. Bi 202 C 03 . This is the white precipitate produced by introducing a solution of bismutli ous nitrate into a solution of tetr-ammonium carbonate, collecting the precipi- tate, washing and drying at a temperature not exceeding 150° F. 4Bi3N03-f-3N^Hi6C308 - 2(Bi0)2C03 + i2NH^N03 + 7 CO 2 . The bismuthyl carbonate contains one molecule of H20,‘ which may be driven off by a heat of 212° F. In consequence of its containing this when allowed to dry spontaneously, the air-dried salt ought really to be represented by a much more complex formula than that given in the B.P. This complex form, however, need not be used in the equation, as its exact composition has not been definitely ascertained. Bis77iuthi carbo7ias is a white powder, blackened by sulphuretted hydrogen ; insoluble in water, but soluble with effervescence in nitric acid. Heated to redness, it turns yellow, forming bismuthous oxide. {For analysis, see AuthoT^s Analytical Chemistry, 97.) COMPOUNDS OF CARBON WITH THE HALOGENS. CARBON TETRACHLORIDE (Syn. Tet7'achloro77ietha7ie). Formula, CCl^. Is a colourless liquid boiling at i38'5° Fahr., and haYing a specific gravity of I '56. It may be formed by the action of excess of chlorine on methane in direct sunshine ; but it is more commonly prepared by passing chlorine and the vapour of carbon disulphide through a red-hot tube. When the vapour of the tetrachloride is passed through a red-hot tube, either by itself or mixed with hydrogen, a mobile liquid is obtained, having a gravity of 1*629, boiling at 211° Fahr., which is carbon dichloride, or tetrachloroethe 7 ie, CgCl^. 54 CARBON. It has been already seen, that when ethene is mixed with chlorine, ethene chloride, CgH^Clg, is formed ; and if this oily liquid be then exposed to sunshine in contact with excess of chlorine, we obtain a white solid, crys- talline and aromatic, insoluble in water, but soluble in alcohol and ether. This is the remaining chloride, viz., carbon trichloride, or hexchloroetham, CgClg. CARBON TETRABROMIDE (Syn. Tetrabromethane). Formula, CBr^^. CARBON TETRA-IODIDE (Syn. Tetf'a-iadomethane). * i . , CI 4 ,. Are both crystalline solid bodies, the former white and the latter red. The first produced by the action of bromine in the presence of antimonious bro- mide on carbon disulphide, and the second by heating carbon tetrachloride with aluminium iodide. Both form di- and tri- compounds analagous to the chlorides, but all solid. All these compounds are really haloid ethers, which will be fully described further on. CARBONYL CHLORIDE (Syns. Carbon Oxychloride. Phosgene Gas). Formula, COCI2. This is a pungent, suffocating gas, decomposable by water, and therefore having to be collected over mercury. It is condensable to a liquid at 32° Fahr., and is produced when chlorine and carbonous oxide are exposed to sunshine, or, more practically, by passing carbonous oxide through antimonic chloride. SbCls -}- CO = COCU SbClg. COMPOUNDS OF CARBON AND SULPHUR. CARBON DISULPHIDE. Formula, CS^. Molecular Weight, 76. This highly important solvent in the arts is prepared by passing the vapour of sulphur over red-hot charcoal. C3+2S2-2CS2. 4 vols. 4 vols. The crude product thus obtained has a very offensive odour, which was at one time considered natural, but has now been found to be owing to contami- nation with a variety of sulphur compounds. These are removed by agitation with mercuric chloride, or recently-reduced copper, and the purified product is then redistilled. As thus prepared it is a colourless mobile liquid, with a faint, but still somewhat disagreeable odour, boiling at 116° F., and having a specific gravity of i'2 7. It cannot be solidified, and its evaporation in vacuo produces extreme cold. It dissolves iodine, sulphur, phosphorus, camphor, fixed and volatile oils, and caoutchouc. It is miscible with alcohol and ether, and burns in the air with a blue flame, producing sulphurous and carbonic anhydrides. Besides its solvent powers, it is a most powerful reducing and sulphurizing agent, converting metallic oxides into sulphides, and reducing nitric acid, dichromates, and permanganates. It is much employed in the extraction of oils and fats, and in the vulcanizing of india-rubber. By exposing carbon disulphide to direct sunshine in sealed tubes for some time, a brown powder is deposited. This is carbon monosiilphide, CS, which is destitute of smell, and has a specific gravity of i *66, and inflames in contact with strong nitric acid. CHAPTER IX. . BORON, SILICON, SELENIUM,' AND TELLURIUM, BORON. 871111301, B. Atomic Weight, 11 . Is a metalloid resembling carbon in many respects, and, like it, existing both in the crystalline and amorphous condition. Amorphous boron is a greenish-grey powder, infusible, and burning with great rapidity in oxygen or in the air, to form boric anhydride ; while crystalline boron is somewhat similar in appearance to the diamond. The former is prepared by fusing boric anhydride with potassium ; and the latter by fusing the. same body with aluminium. Boron combines with oxygen to form boric anhydride, B2O3, which in turn produces boracic acid. HYDROGEN BORATE (Syns. Boracic Acid. Orthohoric Adi). Formula, H3BO3. Molecular Weight, 62 . Is prepared by making a strong solution of borax in boiling water, adding hydrochloric acid until an acid reaction, is obtained, and cooling, when the boric acid crystallizes out, and may be washed with cold water, and dissolved for use in rectified spirit. A solution of boracic acid so obtained is used in the B.P. as a test for the presence of turmeric in powdered rhubarb. When crystallized it is in colourless crystals, soluble in water and spirit, which when strongly. heated lose water and become converted into a glacial mass of boric anhydride. Besides this acid we have a metaboric acid, HBOg, forming metaborates ; and a tetraboracic acid is also presumed to exist, HgB^Og. Borates are frequently insoluble in water. {J^or detection and separation of Boracic Acid and Borates, see Authors Analytical Chemistry, page 59. ) BORAX (Syns. Sodium Dimetahorate. Biboi'ate of Soda. Tinkat). Empirical Formula, NagB^O^lOHgO : Rational Formula (NaB02)2B203.10H20. This peculiar salt, so useful in blowpipe analysis, is found native on the shores of saline lakes in Thibet, and was formerly much imported under the name of tinkal. A new source has also been discovered in South America ; beds of native calcium borate having been found in Iquique, in the vicinity of the deposits of sodium nitrate. It is now, however, chiefly imported from some recently-discovered beds in California, or prepared from the native boric acid found in volcanic regions. In certain parts of Italy, notably near Castel Nuovo, a great number of jets of steam rise from the earth. They are called suffioiii, and in condensing form small lakes called lagojii, in which the boric acid collects. • The exact manner in which a non-volatile acid gets into the 156 BORON, SILICON, SELENIUM, AND TELLURIUM. steam jets has not been definitely proved. Some suppose that it is mechani- cally carried up by the force of the jet, but the hypothesis of M. Dumas is probably much nearer the truth. He supposes that the boron exists in the jets as boron sulphide, and on coming into contact with watery vapour it is decomposed, thus : — BaSg-f-bHgO = 2H3BO3 + 3H2S. This is the more probable, seeing that the gas evolved from the suffio 7 ii, after contact with water, contains 4 per cent of sulphuretted hydrogen. The pro- cess of obtaining boric acid and the subsequent production of borax consists in making artificial reservoirs or lakes round a series of suffioni on the side of a hill, all communicating by means of wooden tubes. Water is then pumped' into the highest reservoir, and allowed to remain until by the action of the hot jet it is raised nearly to the boiling point, and . impregnated with about I per cent, of boric acid. It is then allowed to run into the next reservoir, where it is acted upon by a fresh jet, and still further charged ; until, by passing down the whole series of lakes, it becomes sufficiently concentrated. It is allowed to settle, and is finally evaporated to the crystallizing point in an immense fiat vessel of lead, aided by the natural heat from the suffio 7 ii. The acid having been separated and dried, is re-dissolved in water, neutralized with a proper quantity of sodium carbonate, and the borax thus produced is purified by recrystallization. According to the temperature and degree of concentration two varieties of borax may be obtained, viz. : — Prismatic Borax (official) . ». . . NagB^O^ioHgO. Octahedral Borax ...... Na2B^075H20. The former is slightly efflorescent, and has a specific gravity of i'7 ; while the latter absorbs moisture from the air, becoming opaque, and having a specific gravity of i‘8. As to the official variety, the B.P. says that it should be met with in trans- parent colourless crystals, sometimes slightly effloresced, with a weak alkaline reaction ; insoluble in rectified spirit, soluble in water. A hot saturated solu- tion, when acidulated with any of the mineral acids, lets fall, as it cools, a scaly crystalline deposit of boracic acid. Borax is also soluble in glycerin, and such a solution ( i in 6 by weight) is official as glyce 7 i 7 tu 77 i boracis, {For analysis, see Author’s Analytical Chemistry, 106.) SILICON (Syn. Silicitm). Symbol, Si. Atomic Weight, 28. Is a metalloid closely resembling carbon, and like that element is allotropic, and capable of assuming a crystalline, a graphitoidal, and an amorphous state. It exists very extensively in nature as sa 7 id (hence its name, from silex), and may be isolated by the action of metallic potassium on potassium silico- fluoride. HYDROGEN SILICO-FLUORIDE (Syns. Hydro-duosilicic Acid. Silico-Jiuo 7 -ic Acid). Formula, H 2 SiFg. When hydrofluoric acid is brought into contact with sand, glass, or any similar silicium compound, silicon fluoride is produced. This is a gaseous body, colourless, and having a density of 3*6 referred to air. It is the forma- HYDRO-FLUOSILICIC ACID.—SILICA. 157 tion of silicon fluoride whict causes the powerful action possessed by hydro- fluoric acid on glass : — S102 + 4HF = S1F4+2H20. On heating together fluor-spar, powdered glass, and sulphuric acid, and passing the evolved silicon fluoride into water, it decomposes, depositing silicic anhydride, and leaving hydrogen silico-fluoride in solution : — 3SiF4 + 2H20 = 2H2SiFg -f- SiOg. As thus produced silico-fluoric acid is a fuming liquid which evaporates spontaneously at 100° F. When neutralized with sodium hydrate, it yields sodium silico-fluoride (Na2SiFg), which is often used as a test for potassium, as it produces with soluble salts of that metal, a transparent gelatinous pre- cipitate, having the formula KoSiFg. SILICIC ANHYDRIDE (Syns. Silica. Anhydrous Silicic Acid). Formula, Si02. Molecular Weight, 60. Exists in nature as rock crystal^ quartz^ agate ^ opal., flint, sand, and many other similar minerals. Rock crystal is nearly quite pure crystalline silica, and in the amorphous state it may be prepared by passing hydrogen silico- fluoride into water, as already shown. It is then a white tasteless powder, unalterable by ordinary sources of heat, but capable of fusion by the oxy- hydrogen flame. After ignition it is insoluble in water and all acids except hydrofluoric. It combines with water to form a series of hydrates which act as acids, the chief one being silicic acid, having the formula ^[48104. These hydrates in turn produce a long series of silicates with metals, the formulae of which are too complicated to be discussed in a work like the present. The great mass of minerals which come under the notice of the analyst contain silica in some form, and its detection and estimation is of importance. To effect this, the mineral is reduced to a very fine powder, and intimately rubbed with three times its weight of a mixture of potassium and sodium carbonates previously dried with care. The whole is introduced into a silver or platinum crucible, and heated until tranquil fusion sets in. After maintaining the heat for a short time, the crucible and its contents are cooled and placed in a basin with a little water and a slight excess of hydrochloric acid, and boiled. When the mass has detached itself from the crucible the latter is removed, and the whole contents of the basin are evaporated to dryness, and maintained for half an hour at a temperature of 280° to 300° F. By this treatment the silica is rendered anhydrous and absolutely insoluble^ and it only remains to treat once more with very dilute hydrochloric acid, collect the insoluble silica on a filter, wash, dry, ignite, and weigh. On fusion with the mixture of car- bonates as above described a potassium sodium silicate is formed which is soluble in water. On treating this solution with hydrochloric acid the silicic acid is set free, partly as a gelatinous precipitate, but a considerable portion remains dissolved. The evaporation to dryness, and subsequent heating, causes the decomposition of the silicic acid, which gives up water, and leaves the silica in an insoluble condition fit for collection. Sodium Silicate is frequently prepared in the form of a strong solution which is known as soluble glass by fusing silica or sand with sodium carbonate and digesting in water, and is used for coating buildings, in order to prevent decay. It becomes totally insoluble by exposure to the air in contact with the stone, which is thereby covered by an impervious coating. Sodium silicate is also used to adulterate soaps. Glass is a mixture of noncrystalline and insoluble silicates of potassium. 158 BORON, SILICON, SELENIUM, AND TELLURIUM. sodium, calcium, magnesium, and lead, usually containing a large excess of silica. The following is the composition of some of the principal varieties of glass : — Flint Glass Silica, Sodium Carbonate, and Plumbic Oxide. Green Bottle Glass . . . Silica, Sodium Carbonate, and Iron. Plate Glass Silica, Potassium Carbonate, Calcium Oxide. f Silica, Potassium Carbonate, Calcium and Mag- Refractory Chemical Glass < nesium Oxides, with traces of Aluminium and (, Manganese. The materials, such as white sand, sodium carbonate, and red lead, are fused together in a crucible until perfectly bright and free from bubbles of escaping gas. The workman then dips in his tube, the article required is blown, and afterwards annealed by being allowed to cool gradually in an oven. Were,Ais latter process not perfectly carried out, glass would not bear the slightest change in temperature without flying to pieces. Porcelain and stoneware are essentially aluminium silicate : the former being very pure, and the latter containing iron, calcium, etc. Both are made by fashioning clay into the desired shape, and then baking in a furnace. The glaze is communicated by throwing into the fire sodium chloride, which volatilizes, and combines with the outer portion of the ware to form a glisten- ing coating of sodium silicate. [The difference between stoneware and porcelain appears to be this, that the vitreous change in the porcelain is carried farther than in stoneware, until it approaches a condition of glass ; while earthenware contrasts with both materials in respect to its more or less porous body and dry fracture, also in being absorbent. (John Sparkes.)] SELENIUM. Symbol, Se, Atomic Weight, 79*5. Atomicity, Dyad, Tetrad, or Hexad. This element, discovered by Berzelius in 1817 among the refuse materials of a sulphuric acid factory, is interesting to medical men and pharmacists, from the fact of its being a not uncommon impurity in some varieties of com- mercial bismuth, to which it communicates dangerous properties ; and cases have occurred where most unpleasant symptoms have followed the use of Liquor Bismuthi made from such samples. It is also found associated with sulphur in many ores, especially as a double selenide of copper and lead found in the Hartz Mountains. It is most easily prepared from the deposit found in the vitriol chambers of chemical works, where use is made of pyrites con- taining selenium. The deposit is treated with a mixture of nitric and sulphuric acids, and from this solution of selenious acid the selenium may be separated by diluting with four times its volume of water, and passing a current of sul- phurous anhydride. The precipitate produced is taken up by agitating the liquid with carbon disulphide, and the selenium is finally recovered from the solvent by evaporation. Like sulphur, selenium is allotropic, and is known both in the amorphous, vitreous, and crystalline states. In the amorphous condition it is in ductile red flakes, while in the vitreous state it is black and insoluble in carbon disulphide. The crystalline variety is prepared by heating the black modifi- cation to 204-8° F., and is bluish-grey. Selenium fuses and boils below a red heat, giving a vapour having the odour of putrid horseradish. It burns in the air with a blue flame, forming SeOg. It forms with oxygen a series of acids as follows : — Selenious Anhydride, SeOa- Is produced when selenium is burnt in the SELENIUM. — TELL URIUM. 159 air or boiled with nitric acid. It is a white deliquescent solid, soluble in water to form selenious acid, HgSeOg. By passing any reducing gas, such as sul- phurous anhydride or sulphuretted hydrogen, it is decomposed, yielding a red precipitate of amorphous selenium. Selenic Acid, H2Se04,. Corresponds to sulphuric acid ; but its anhydride has not been isolated. It is a syrupy liquid, evolving heat when mixed with water, and is prepared by passing sulphuretted hydrogen through plumbic seleniate ; which latter is formed by precipitating potassium seleniate (produced by fusing selenium with nitre) with plumbic nitrate. Selenium forms with hydrogen a compound, HgSe, called seleniuretted hydrogen, similar to sulphuretted hydrogen, but much more offensive and dangerous. Compounds of selenium exhibit the following reactions : — I. Heated with sodium carbonate on charcoal in the blowpipe flame, they evolve a peculiar odour of decaying horseradish ; and a red sublimate is pro- duced on a piece of cold porcelain held close to the charcoal. II. Soluble selenites yield a red precipitate of selenium with sulphurous acid, and a. yellow mixture of sulphur and selenium with sulphuretted hydro- gen, supposed formerly to be a definite sulphide. \ III. Soluble selenates give a white precipitate with barium chloride which is insojuble in dilute hydrochloric acid; but when heated with strong hydro- chloric acid it dissolves, with evolution of chlorine. TELLURIUM. Symbol, Te. Atomic Weight, 128. Is a very rare element, also found on one occasion in an impurity in com- mercial bismuth. It was discovered by Muller in 1782, and is a pinkish-white crystalline body, having a metallic appearance. Its compounds are very active irritant agents ; and even the minutest trace existing by accident in liquor bismuthi imparts a horrible garlic odour to the breath. It bums in the air with a blue flame, yielding Te02, dissolves in sulphuric acid to a purple-red solution, from which it again separates on the addition of water. It forms the following series of oxides : — Tellurous Oxide, Te02, forming Tellurous Acid, H2TeOg Telluric „ TeOg „ Telluric „ H2Te04 Tellurous Oxide is found native as tellurite^ and is fusible by heat, being a yellow glassy mass while hot, but changing to white on cooling. Telluric Acid is prepared like selenic acid, and when heated leaves telluric oxide as a yellow solid, insoluble in water and acids. CHAPTER X. NITROGEN. NITROGEN (Syn. Azote [French'])^ Symbol, N or Az \^French\ Atomic Weight, 14. Density, referred to Hydrogen, 14. Density, referred to Air, *972. Weight of a Litre, g 7 'a 7 ?imes C 7 'iths. This body, which was discovered by Scheele and Rutherford in 1772, and called by the latter 77 iephitic air, exists in the atmosphere, of which it con- stitutes four-fifths of the entire volume, the remaining fifth being oxygen, with a trace of carbonic anhydride, and some slight impurities. Ozone, the nature of which is still under investigation, must be included. It is called by foreign chemists azote, because it does not support life (from the Greek d [privative] not, tjm\, life); while by us it is named nitrogen, because it is the element which gives birth, as it were, to nitre. Nitrogen is easily prepared, in a tolerably pure condition, by burning out the oxygen from an enclosed space of air by means of phosphorus. A piece of common phosphorus is wiped dry, and placed in a small porcelain capsule, which is floated on the surface of water contained m a flat dish. A light is then applied, and a glass bell-jar is quickly covered over the whole. The phosphorus commences to burn inside the jar, producing copious white fumes of phosphoric anhydride (P2O5) by uniting with the oxygen. When all the oxygen has been consumed, the phosphorus ceases to burn, and the white fumes gradually disappear, because they dissolve in and com- bine with the water, to form meta-phosphoric acid ; and thus eventually nothing is left in the jar but a colourless gas, which is almost pure nitrogen. The steps of the process by which the oxygen is removed, may be thus represented : — .%No -1- 2P2 -f 5O0 = 2P205-f.^N2' a:N2 + 2P2O5 + 2H2O = 4HPO3 + a;N2. Nitrogen may also be isolated from the atmosphere by passing air slowly over red-hot copper, which absorbs the oxygen, and leaves the nitrogen ; thus : — C1I2 + O2 + ^^Ng = 2C11O -}- Another way of proceeding, is that usually employed in the volumetric analysis of air. A quantity of air is introduced into a graduated tube in- verted over a trough of mercury. The measure of air having been read off, a few drops of strong solution of potassium hydrate are introduced into the tube, which quickly absorb the carbonic acid gas. The volume is again read off, and a few drops of strong solution of pyrogallic acid are introduced, which combines with the potassium hydrate, forming potassium pyrogallate, a sub- stance possessing an extraordinary power of absorbing oxygen. When no further contraction of the gaseous contents of the tube is observ- able, the volume of pure nitrogen thus remaining is read off, and by a simple NITROGEN. .i6r calculation the respective volumes of the carbonic acid, oxygen, and nitrogen in the original volume of air are ascertained. By this and similar methods of analysis the atmosphere has been proved to be constituted as follows : — By Weight, By Volume. " Oxygen Nitrogen ...... Carbonic Anhydride. Aqueous Vapour . . . . Ammonia Gas and organic impurities . 23 . • 77 • i traces . 20*8 . 79-2 . traces 100 lOO'O It is certain that the air we breathe is not a chemical compound, but_ simply a mechanical mixture, because the oxygen and nitrogen do not exist in their proper combining proportions, or in any fixed arithmetical relations to these proportions. Moreover, when the two are attempted to be combined in proportions to form air, neither contraction nor development of heat takes place in any marked degree ; and indeed if the oxygen were not perfectly free, the air would not support the combustion of our fires* nor the respiration of animals. To prepare nitrogen in a state of absolute purity, ammonium nitrite is heated in a retort. It is thus completely decomposed into water and free nitrogen. The same result is obtained by heating together a mixture of potassium nitrite and ammonium chloride, thus : — KNO2 + NH4CI = Ng + KCl + 2H2O. It may also be obtained by passing a current of chlorine through a solution of ammonium hydrate. When the latter is strong, each bubble of chlorine leaves the liquid with a flash of light. Great care must be taken that the point of neutralization of the hydrate is not approached, as nitrogen chloride (an extremely explosive liquid) might then be formed. The reaction is : — 8NH4HO + 3CI2 = 6NH4CI + 8H2O + N2. Pure nitrogen is a colourless, tasteless, and inodorous gas ; entirely negative in all its properties ; neither combustible nor a supporter of combustion or of life. Capable of condensation to a liquid by combined intense cold and great pressure, and practically insoluble in water. 100 gallons of water at 60° F. only dissolve about one gallon and a half of nitrogen. In combination nitrogen exhibits an atomicity equal to Hg, and is therefore truly a pentad ; but in many cases part of the atomicity becomes latent, and it acts only as a triad. Examples may be seen in ammonium salts, and in arhmonia gas. {See Atomicity.) Nitrogen will not combine directly either with free oxygen or with free hydrogen, but will unite with the former when ozonized by the electric spark in presence of a strong alkali, and with the latter when presented in the nascent state. With magnesium and boron it will combine at a red heat, and also with carbon heated to redness, in presence of an alkali, to form a cyanide of the alkali. {See Cyanogen.) * If any one of the oxides of nitrogen were mixed with sufficient nitrogen for the mix- ture to have the percentage composition of air, the combination would not support com- bustion. M NITROGEN. 162 COMPOUND OF NITROGEN WITH HYDROGEN. AMMONIA. Formula, NH3. Molecular Weight, 17 . Density, referred to Air, * 5890 . Density, referred to Hydrogen, 8 ’ 5 . Weight of 1 Litre, *7633 gramme. • • Is a colourless gas, with a well-known pungent and irritating odour, which can be liquefied under a pressure of 6-5 atmospheres at a temperature of 62° Fahr., and even solidified by great cold and pressure. It is very soluble in water, which will absorb 700 times its own volume of the gas. It can be obtained, but with difficulty, by the direct combination of nitrogen and hydrogen, under the influence of a series of induction sparks produced by a powerful coil, and passing through the gaseous mixture from platinum-pointed wires : — Ng -t- 3H2 = 2NH3. • 2 vols. 6 vols. 4 yols. The molecule of ammonia gas therefore contains i volume N and 3 volumes H, condensing upon combination to 2 volumes. That is, i gallon of nitrogen and 3 gallons of hydrogen would produce 2 gallons only of NH3. Ammonia is practically produced : — 1. By the action of nascent hydrogen upon nitric acid or nitrates. This is seen when zinc, iron, tin, or cadmium are dissolved in very dilute nitric acid : — 4Zn + 9HNO3 = 4Z112NO3 + NH3 -f- 3H2O. Or better when a nitrate is acted on in solution by zinc or iron and dilute sulphuric acid. 2. By the action of zinc or aluminium and potassium or sodium hydrate upon a nitrate. The metal and alkali first yield nascent hydrogen : — 8KHO + 4Zn ^ 4 K 2 Zn 02 + 4H2* This acts upon the nitrate in presence of the water : — KNO3 + HgO -h 4H2 = KHO + NH3 + 3H2O. 3. By the decomposition of nitrogenous organic matters. {a) Such as cyanogen under the influence of water or alkalies. G) Such as albumen under the joint influence of oxidation and alkalies. {See Water Analysis in Author's Analytical Chemistry, 189.) 4. By heating ammonium chloride with calcium hydrate : — 2NH4CI + Ca2HO = CaClg + 2NH3 2H2O. A similar reaction will take place when any salt of ammonium is heated with an alkali. Ammonia in uniting with water or acids (which it does with great avidity) not only displaces hydrogen, but unites with the hydrogen so displaced to form the basylous radical ammonium (NH^). Nitrogen is truly a pentad in atomicity, but in ammonia two of the atomicities saturate each other, and so the nitrogen acts as a triad only. But it is always ready and eager to assume its proper state, and therefore when it is brought in contact with an acid it AMMONIA,— NITROUS OXIDE. 163 does so, and is thus saturated to its full extent, when a salt of ammonium is produced : — H H H 1 1 H 1 H— N— H + Cl = >N- V Cl 1 H NH3 -f HCl = NH4CI. This fact can be proved by simply holding near each other the stoppers from the hydrochloric acid and liquor a 7 nmoni(B bottles. Immediately this is done, a white smoke is tormed, consisting of solid ammonium chloride pro- duced by the combination of the two gases NH3 -f HCl. Ammonia gas is very soluble in water, forming ammonium hydrate : — NH3 HgO = NH4HO. On passing a series of sparks through a known volume of ammonia in a tube over mercury, the volume gradually increases until it doubles itself, and then the result is found to be free hydrogen and nitrogen, in the proportion of 3 vols. H and i vol. N. A similar reaction may be caused by passing am- monia through a red-hot tube. The hydrogen of ammonia may be displaced either by basylous or acidulous radicals ; in the former case an amine is produced, and in the latter an amide. These compounds are of the greatest interest, and will be found fully described in a future chapter. COMPOUNDS OF NITROGEN WITH OXYGEN. With oxygen nitrogen forms five compounds in regular series, thus : — Nitrous Oxide ....... NgO. • Nitric Oxide . ....... N2O3-2NO. Nitrous Anhydride ...... N2O3. Nitric Peroxide ....... No04^-2N02. Nitric Anhydride . . N2O5 NITROUS OXIDE (Syns. Laughing Gas. Nitrogen Mon-Oxide. Protoxide of Nitrogen) Formula, N 2 O. Molecular Weight, 44. Density, to Hydrogen^ 22*06. Weight of a Litre, 1*98 gi^amme. Prepared by simply heating ammonium nitrate, which is entirely decom posed into nitrous oxide and water : — NH4NO3 = N2O + 2H2O. The heat employed must be under 485° F. ; but at first a temperature of 350° F. will cause decomposition. The production of the gas is much facilitated by heating the crystals with a little water until perfect liquidity is effected, and then evaporating with con- stant stirring at a heat not exceeding 300° F. until the salt is converted into a fine white powder. Nitrogen mon-oxide may also be produced in a state of great purity by dissolving zinc in nitric acid largely diluted with water : — 2Zu 2 + 10HNO3 = NgO + 4Zn2N03 + 5H2O. In practice the zinc is shaken with i volume of nitric acid, i volume of sulphuric acid, and 50 volumes of water ; the gas is purified by passing through concentrated sulphuric acid. When nitrous oxide is prepared from ammonium nitrate, the latter should first be tested for ammonium chloride, as, should NITROGEN. 164 that substance be present, chlorine would be formed, which might cause fatal elfects when administering the gas as an anaesthetic. Traces of higher oxides may be removed by ferrous sulphate, and any acidulous impurity by sodium or potassium hydrate. Nitrous oxide is a colourless gas, with a sweet taste, soluble to a considerable extent in water* (100 gallons would dissolve nearly 80 gallons of the gas at an ordinary temperature). It is capable of liquefac- tion under a pressure of 30 atmospheres, when cooled to the freezing point of water. Liquid nitrous oxide on evaporating produces such intense cold that it will partially freeze itself, and become a white snow-like substance. The most important property of nitrous oxide is its power of producing when inhaled a kind of intoxication coupled with insensibility to pain : it is therefore much used in dentistry and minor surgical operations. It dissolves in the blood, which acquires for the time a peculiar tint; but with most persons its action is transient, and it does not leave any troublesome effects behind. Many bodies which burn in oxygen, also burn with considerable brilliancy in this, gas till all the oxygen has been removed. It will be found that after the experiment there will still remain a volume of free nitrogen equal to that of the nitrous oxide, proving that the volume of nitrogen required to form nitrous oxide is equal to the resulting oxide, viz., two volumes : — NgO = N2 -h O. 2 vols. 2 vols. I vol. The same fact may be proved by passing the gas through fed-hot tubes, or exploding it with hydrogen, which forms water, and sets free nitrogen : — N2O -F H .3 - N2 H2O. 2 vols. 2 vols. 2 vols. 2 VOls. Mixed with oxygen or air, nitrous oxide will not form red fumes ; but should it do so, it is then contaminated with the next compound, nitric oxide. NITRIC OXIDE (Syns. Nitrosyl. Nitrogen Dioxide. Binoxide of Nitrogen. Deutoxide of Nitrogen. Azotyl). Formulae, N 2 O 2 , or NO. Molecular Weight, 30. Density, referred to Hydrogen^ 15. Weight of 1 Litre, 1*34:4 gramme. This gas is usually produced when nitric acid acts so as to dissolve a metal, or to raise a body from a lower to a higher state of oxidation, as for instance iron from the ferrous to the ferric state. {^See Ferric Chloride and Ferric Sulphate.) Most commonly it is prepared from copper, since that metal dissolves easily in dilute nitric acid without the aid of heat, although it is usual to warm gently in order to quicken the action. The copper is placed in a flask, fitted with a funnel tube, extending to the bottom, and a delivery tube just passed through the cork. Sufficient water is added to nearly cover the copper, and half as much strong nitric acid is poured in by the funnel tube. At first the flask appears to be filled with red fumes, but soon the air becomes driven out, and a colourless gas is given off, which can be collected over water. This is the nitric oxide. It is a very dangerous gas to breathe, and should always be made in an open place or proper fume chamber. The moment it comes in contact with the air, it unites with the oxygen, and pro-*" duces red fumes, which consist chiefly of nitric peroxide : — 2NO + 02 = 2NO2. 4 vols. 2 vols. 4 vols. * A solution made under six or seven atmospheric pressures, is sometimes used as a stimu- lant. COMPOUNDS OF NITROGEN WITH OXYGEN, 165 When nitric oxide is passed over red-hot carbon, it is decomposed into carbonic anhydride and nitrogen ; — . 2NO -1- C = CO2 + Ng. 4 vols. 2 vols. 2 vols. When mixed with an equal volume of hydrogen, and a light or spark applied, combustion ensues, and water and free nitrogen are produced : — 2NO -i- 2H2 = Ng + 2H2O. 4 vols. 4 vols. 2 vols. When nitric oxide is mixed with sulphuretted hydrogen and passed over soda lime^ it is converted into ammonia gas. When produced in presence of a ferrous salt, it is absorbed, and combines with the salt to produce a dark coloured compound, which is instantly decomposed by heat, and slowly by exposure to the air. It contains two molecules of the iron salt and one NO, the compound with ferrous sulphate having the formula (FeS04)2N0. Nitric oxide is insoluble in water, but has lately been liquefied by extreme cold and pressure. It can act as a monad radical, and replace hydrogen. This is a common occurrence in organic chemistry. When it so behaves it is called nitrosyl. NITEOUS ANHYDEIDE (Syns. Nitrous Acid, Nitrogen Trioxide), Formula, NgOg. Molecular Weight, 76 . Is (at a temperature of 0° F.) a bluish liquid, emitting red fumes, prepared by mixing 4 vols. of nitric oxide and i vol. of oxygen together, in a glass tube surrounded by a strong freezing mixture capable of producing a temperature 20 degrees below the freezing point of water. , 2NO + O = N2O3. It is very unstable, and when brought into contact with water is decom- posed into nitric acid and nitric oxide : — 3N2O3 + H2O = 2HNO3 + 4NO. In this case, therefore, practice does not bear out the theory, which would be that nitrous anhydride should combine with water to form nitrous acid, thus : — N2O3 + H2O = 2HNO2. •But although we cannot really isolate and preserve pure nitrous acid, ^et such an acid must exist, as there is a definite class of salts called nitrites, which have for their acidulous radical NO2, behaving as a monad. An impure substance, called nitrous acid^ is prepared by acting on starch or arsenious acid with nitric acid. The commercial nitrous acid thus prepared is a solu- tion of nitrous anhydride in nitric acid, which is decomposed by dilution with water, in a similar manner to pure anhydride. The action of nitric acid upon arsenious acid may be thus shown AS2O3 + 2HNO3 ^ AsgOg + N2O3 -f HgO. AMMONIUM Nitrite of Am 7 nonia). Formula, NH4NO2. Already referred to under nitrogen, where its production is shown from ammonium chloride and potassium nitrite. POTASSIUM NITEITE. Formula, KNOg. Prepared by heating potassium nitrate until oxygen ceases to be evolved, and then boiling out with alcohol, and crystallizing from the alcoholic solution. NITROGEN 1 66 ARGENTIC NITRITE (Syn. Nitrite of Silver'). , Formula, AgNOg. A white precipitate produced by potassium nitrite in a solution of argentic nitrate, and sometimes contained in fused argentic nitrate {lunar caustic)^ being formed by the heat employed. When dried and ignited, it leaves a residue of pure metallic silver, and this reaction has been the means of proving the molecular weight of nitrous acid. 154 parts by weight of argentic nitrite yield 108 parts, or one atomic weight, of silver. The loss is therefore 46 parts of N and O ; and substituting one part of hydrogen for the 108 of silver left, we have the molecular weight of nitrous acid fixed at 47, which agrees with the formula HNO2. CUPRIC NITRITE (Syn. ^ Formula, Cu(N 02)2- Forms a solution of a peculiar apple-green colour, which when once seen is almost unmistakable. When a mixture of aqueous solutions of cupric sulphate and plumbic nitrite (the result of heating lead with plumbic nitrate) is made, cupric nitrite is produced in solution, which is converted by the 'absorption of oxygen into cupric nitrate. POTASSIUM COBALTOUS NITRITE. Formula, (Co20)4N02.6KN02. A yellow crystalline precipitate, produced when excess of potassium nitrite is added to a solution of cobaltous chloride, slightly acidulated with acetic acid. Quite insoluble in cold, but soluble in hot water. This substance is important, as it serves as a means of separating cobalt from nickel. Nitrites are also produced by the oxidation of ammonia gas, and often occur in the drinking waters of our cities and villages. Such water is looked upon with suspicion, as the nitrites might arise from oxidized sewage matter. {For detection of Nitrites^ see Author's Analytical Chemistry, 61.) NITRIC PEROXIDE (Syn. Hyponitric Acid). Formula, N2O4 = 2NO2. This oxide constitutes the chief portion of the red fumes formed when nitric oxide comes in contact with the air. It is also given off when plumbic nitrate is heated to redness : — 2Pb2NOg = 2PbO + 2N2O4 + O2. It can be condensed by great cold, first to a liquid and then to a solid state, while the oxygen passes off. It is also produced in the manufacture of hydrai'gyri oxidum rubrutn., during the heating of the mercuric nitrate with metallic mercury in the last stage of the process : — Hg2N03 4 -Hg = 2Hg0 + 2N02. In combination with a little water, it forms both nitrous and fiitric acids : — 2NO2 + H2O = HNOg-fHNOa. With excess of water the nitrous acid is itself decomposed into nitric acid and nitric oxide. In common with all the other oxides of nitrogen already studied, this body, although perfectly unaffected by a red heat, is decomposed into nitrogen and oxygen by the electric spark at 86° F. j but the action is not perfect, owing to a partial recombination taking place. In the same manner nitrous oxide is decomposed by the spark, two distinct actions taking place, thus : — 1. N2O = N3 + O. 2. 4N2O = No04-)-3N3. COMPOUNDS OF NITROGEN WITH OXYGEN 167 With nitric oxide the spark quickly produces the following simultaneous decompositions : — 1. 2N2O2 = N2O + N2O3. 2. 2N2O2 = N2O4 + N2. , • After a long continuance of sparks, the whole is decomposed into N2 and O2 with a little N2O4. These are the researches of M. Berthelot, who also states that nitrous oxide supports flame more readily than nitric oxide, because at a red heat the former body entirely breaks up into its elements, while at the same temperature the latter body also produces nitric peroxide. The group NO2 is a monad radical, and, like NO, is capable of replacing hydrogen in many compounds. It is called, when acting thus, nitryl^ and an immense number of substitutmi products in organic chemistry are thus pro- duced, such as nitrocellulose, nitrobenzene, and nitroglycerin, which are fully considered later on. NITRIC ANHYDRIDE (Syn. Anhydrous Nitric Acid). Formula, N2O5. Molecular Weight, 108 . Prepared by decomposing perfectly dry argentic nitrate with chlorine gas, and collecting the brilliant white crystals which are formed, in a receiver im- mersed in a freezing mixture. qAgNOg + 2CI2 = 4AgCl + 2N2O5 + Og. It combines with water, causing a great evolution of heat and forming nitric acid. It melts at 86° F., and decomposes when heated to about 113° F. It cannot always be preserved, even at the ordinary temperature and in closed vessels. Except after becoming moist, it possesses no acid properties ; but it combines with water with great avidity, to form : — HYDROGEN NITRATE (Syns. Nitric Acid. Spirits of Nitre. Aqua Forth). Formula, HNO3. Molecular Weight, 63. This acid is not found in the free state ; but is always prepared by distilling sodium nitrate or potassium nitrate with sulphuric acid, thus : — NaN03 + H2SO4 - HNO3 + NaHSO^. KN03 4-H2S04 -HNO3 + KHSO4. Using this proportion of sulphuric acid with sodium nitrate, the action takes place freely at a low temperature, and sodium hydrogen-sulphate is produced. If a fresh portion of sodium nitrate be added, and the heat ^eatly raised, a second reaction will set in, and nitric acid will be again given off ; the neutral sodium sulphate being produced : — NaN03 + NaHS04 - HNO3 + Na2S04. The latter process, however, tends to produce an acid containing nitric per- oxide, owing to the high temperature required partially decomposing the nitric acid formed. * , The B.P. thus describes nitric acid : — A colourless liquid, having a specific gravity of \'\2. When exposed to the air, it emits an acrid, corrosive vapour. If it be poured over copper, dense red vapours are immediately formed (nitric peroxide gas) ; but if the acid be mixed with an equal volume of water, and then added to the copper, it gives off a colourless gas (nitric oxide), which acquires an orange-red colour as it mixes with the air (nitric peroxide). The boiling-point of the acid is 250° F. It contains 70 per cent, of HNO3. {Fo 7 ' analysis and impurities^ see Authors Analytical Chemistry, page 10 1.) i6S NITROGEN. The B.P. aci 4 um nitricum dihitum is thus prepared : — Dilute 6 fluid ounces of nitric acid with 24 fluid ounces of water, then add more water, so that at a temperature of 60° it shall measure 31 fluid ounces. The resulting dilute acid has a specific gravity of I'loi. It contains 17 ’44 per cent, of HNO3. It is possible to produce a fuming nitric acid much stronger than the B.P. Absolute nitric acid has a specific gravity of 1*52. It is not commercially obtainable, the strongest being the 93 per cent, acid, which has the specific gravity, i'5. The “single” aqua forth contains from 30 to 35 per cent, of N2O5, and the “double strength” about 50 per cent, by weight. It has been found that the B.P. acid, being a definite hydrate, having the true formula, 2HNO3 + 3H2O, is much less liable to decomposition and the development of nitric peroxide by exposure to light, than the strong acids, besides being more certain and uniform in its action on metals. For instance, iron is violently attacked by the B.P. acid of i’42 specific gravity, indeed so violently that in making liquor ferri pernitratis we are specially warned to dilute the acid to moderate the action ; and yet iron is not the least affected by immersion in fuming HNO3 of i‘52 specific gravity, but exhibits what is called passivity, refusing even to dissolve when subse- quently immersed in B.P.- acid, until it has been touched by a metal strongly electro-negative, such as platinum. Even the B.P. acid acts unwillingly on silver and mercury, unless aided by dilution and a gentle heat, As regards the action of nitric acid on metals generally, it may be said that it dissolves them all with the exception of gold and platinum, on which it has no action ; and tin and antimony, with which it forms insoluble compounds (stannic and antimonic oxides). Tin will, however, dissolve in very dilute cold nitric acid, as will also zinc and iron, with the production both of nitrous oxide and of ammonia, in greater or. less quantity. The formation of ammonia from zinc and nitric acid may be thus represented : — aZng-f 9HNO3 = 4Zn2N03 - 1 - 3H2O -}- NHg. Nitric acid stains the skin yellow. This stain, the colour of which re- sembles that caused by iodine and bromine, can be readily distinguished from others by not altering when the part tinted is warmed, and being intensified into orange upon treatment with an alkaline hydrate. By the action of po- tassium permanganate the yellow stain is converted into a dark-brown colour. On dissolving this in a warm and weak solution of oxalic acid, or in sul- phurous acid, which decomposes and decolorizes it with even greater facility, all traces of the yellow coloration will be found to have disappeared. NITEO-HYDROCHLORIC ACID. When nitric and hydrochloric acids are mixed together, they react on each other, producing free chlorine and nitrosyl chloride, thus : — HNO3 3HCI = NOCl 4 - CI2 + 2H2O. The liquid obtained in this manner is called aqua regia., and is used for dis- solving metals, such as gold and platinum, wliich resist the action of all other acids. The acidum nitro-hydrochloricuni dilutum, B.P., is prepared by mixing 3 fluid ounces of nitric acid, and 4 fluid ounces of hydrochloric acid, letting the mixture stand for 24 hours and then adding 25 ounces of distilled water. It is a colourless acid liquid. Specific gravity, 1*07. {For ajialy sis, see Author’s Analytical Chemistry, page loi.) The acid may be distinguished from the dilute nitric and hydrochloric acids of the B.P., by the following tests : — It gives a precipitate with argentic nitrate insoluble in nitric acid, and at AMMONIUM, SODIUM, POTASSIUM NITRATES. 169 the same time it will convert ferrous sulphate to the ferric state, and cause an immediate blue colour when added to a mixture of potassium iodide and starch paste. The dilute nitric • acid, on the one hand, will not precipitate silver, while, on the other, the dilute hydrochloric acid will not liberate iodine, nor raise iron to the ferric 'state. METALLIC NITRATES. All nitrates are soluble in water, especially when slightly acidulated with nitric acid. The nitrates of the alkalies are only decomposed by a very high temperature ; but most of the nitrates of the heavy metals, such as copper, mercury, and lead, when heated, are readily decomposed, leaving a residue of oxide. Argentic nitrate, however, when heated leaves metallic silver. {For detection of Nitrdtes, see Author's Analytical Chemistry, pages 62, 63.) AMMONIUM NITRATE (Syn. Nitrate of Ammonia). Formula, NH^NO.. Molecular Weight, 80. Prepared by neutralizing nitric acid by ammonium carbonate, and crys- tallizing. It is used for making laughing gas, and is also employed in freezing mixtures, as it absorbs while dissolving an immense amount of heat, and so produces intense cold. Made from the official carbonate, the action is, — N4H16C3O8 + 4HNO3 = 4NH4NO3 + 3CO2 + 2 H2O. The B.P. orders the evaporation of the solution until crystals are obtained, and keeping these fused at a temperature not exceeding 320° until the vapour of water is no longer emitted. Thus made, it is a white deliquescent salt, in confused crystalline masses, having a bitter acrid taste. Soluble in less than its own weight of water, and sparingly soluble in rectified spirit. It fuses at a temperature of 320° F., and at 350° to 450° it is entirely resolved into nitrous oxide gas, N^O, and the vai^our of water. SODIUM NITRATE Nitrate of Soda. Cubic Nitre. Chili Saltpetre). Formula, NaNOg. Molecular Weight, 85. Is found native in immense quantities in Peru and Chili, and is purified from the chlorides and sulphates which it contains by recrystallization. It is deliquescent, and therefore unfit for the preparation of gunpowder. Its chief uses are for making potassium nitrate, for mixing with manures as a top dressing for land, and for making nitric acid. It is used in analysis as an oxidizing agent. A mixture of 4 parts of sodium nitrate and i part of sodium carbonate, when fused with the ores of chromium or manganese, converts them into soluble chromates or manganates ; so enabling them to be easily estimated. The same mixture, fused with arsenious acid, converts it into sodium arseniate ; with sulphides sulphates are formed, and indeed, it will act on any mineral capable of oxidation. The crystals are not perfect cubes. POTASSIUM NITRATE (Syns. Nitre. Saltpetre. Nitrate of Potash). Formula, KNO3. Molecular Weight, 101. Is found native in certain soils in India, in which it is doubtless produced by the oxidation of the nitrogenous portion of the decaying vegetable matters on the surface of the soil, such action being assisted by the powerful tropical 70 NITROGEN. heat, coupled with the moisture present in the air. Native saltpetre is much contaminated with calcium nitrate, and is purified by dissolving in water and adding potassium carbonate. The calcium carbonate formed having been allowed to subside, the clear liquor is drawn off and crystallized. Purified nitre is in white crystalline masses, or fragments of striated six- sided prisms, colourless, of a peculiar saline taste. Thrown on the fire, it de- flagrates ; heated, it fuses, gives off oxygen, and becomes potassium nitrite. Nitre may also be prepared, on a large scale, by mixing sodium nitrate with potassium chloride, and crystallizing several times to purify the product : — NaNOg + KCl = KNO3 + NaCl. The nitre, being much less soluble than the sodium chloride, crystallizes out first, and is thus separated. In France and some continental countries, artificial nitre beds were formerly made by mixing and exposing to the air heaps of decaying vegetable matters and lime. The heaps were watered from time to time with urine, until a quantity of calcium nitrate had been formed, which was then treated with potassium carbonate, to produce nitre. The crystals found on the surface of B.P. extracta are of two kinds in general. If cubes, they are usually potassium chloride ; but if needle-like, they probably consist of potassium nitrate. Potassium nitrate is not very deliquescent, and can therefore be used for making gunpowder. This is a mixture of nitre, sulphur, and charcoal, in certain proportions. As all true gases are transparent, the opaque smoke given off when gun- powder is exploded must contain a solid substance, which is believed to be potassium sulphate, K2SO4 \ and the gases also formed are carbonic anhy- dride (CO3), nitrogen, carbonous oxide (CO), and occasionally a little sul- phurous' anhydride (SOg). The nitre, sulphur, and charcoal vary in amount in different countries, and also according to the character desired in the gun- powder itself ; but a useful quality may be produced by mixing together 80 parts of the first, of the second, and 12 J parts of the last. The residue after combustion usually consists of potassium sulphate and carbonate. ARGrENTIC NITRATE (Syns. Nitrate of Silver. Lunar Caustic. Lapis Infernalis). Formula, AgNOg. Molecular Weight, 170 . Is prepared by dissolving silver, by the aid of a gentle heat, in dilute nitric acid, evaporating, and crystallizing : — 3Ag2-f8HN03 = fiAgNOg-f 2NO-f 4H3O. It is usually met with in tabular crystals, the primary form of which is the right rhombic prism, soluble in distilled water and in rectified spirit. It is also made into cylindrical pencils for the purpose of a cautery. A small fragment heated on charcoal with the blowpipe, first melts and then deflagrates, leaving behind a dull white metallic coating (metallic silver). [For analysis and impuritieSy see Author’s Analytical Chemistry , page loi.) As commercial silver (such as would be at hand to make nitrate) contains copper, it is necessary to know how to separate the one from the other. This maybe done in a variety of ways. I. The silver coin, or other alloy, may be dissolved in nitric acid, and the silver precipitated as chloride with sodium chloride. The precipitate, having been allowed to subside, is washed free from the copper by boiling with water, and decantation. It is then reduced to metallic silver, which is once more to be dissolved in dilute nitric acid, and crystallized. The reduction of , the chloride may be effected, — METALLIC NITRATES. {a) By acidulating with sulphuric acid, and stirring with a zinc rod free from lead. {E) By fusing in a crucible with a mixture of potassium and sodium carbonate. 2 .^ The coin may be dissolved in nitric acid, the green solution thus obtained evaporated to dryness, and heated over the flame until red fumes cease to be evolved. By this means the more readily decomposed cupric nitrate is converted into insoluble oxide, while the argentic nitrate is left undecomposed. ' A very common adulteration of argentic nitrate is potassium nitrate, which is added during crystallization. This, if anything, increases the brilliant appearance of the crystals, and cannot be detected by the eye. If a solution be made with distilled water, and all the silver having been precipitated by hydrochloric acid, and filtered out, the filtrate be evaporated to dryness, a residue will remain if nitre was present, which cannot occur with pure argentic nitrate. It is easy to prove the residue to contain potas- sium by qualitative analysis. Solution of argentic nitrate is useful for detecting the following : — Hydrates, precipitate, brown ■ AgaO. Chromates, do. red .... . Ag2Cr04- Phosphates, do. yellow ■ AgjPO^. Arsenites, do. yellow • AgjAsOs. Arseniates, do. reddish . AggAsOj. Chlorides, do. curdy white . AgCl. Bromides, do. dirty curdy white . AgBr. Iodides, do. curdy yellow • Agl. Cyanides, do. curdy white • AgCy. Ferrocyanides, do. white .... . Ag^FeCyj. Ferricyanides, do. orange red . ' . • AgeFejCyij. Solution of argentic nitrate is therefore used extensively in the estimation of several of these radicals. {See Volumetric Analysis in Author's Analytical Chemistry.) ARGENT-AMMONIUM NITRATE (Syn. Amtnonio Nitrate of Silver). Formulae, 2 NH 4 (NIl 2 Ag) 22 N 03 , or 2 NH 3 .AgN 03 . When a strong solution of argentic nitrate saturated with ammonium hydrate, and perfectly clear, undergoes spontaneous evaporation, this com- pound is obtained in the form of crystals. It is useful in analysis for pro- ducing precipitates with free arsenious and phosphoric acids, which, otherwise, would not give rise to their neutral argentic salts in the presence of the nitric acid which would be formed from ordinary argentic nitrate. The usual reagent, employed as ammonia nitrate of silver, is prepared by adding very dilute solution of ammonium hydrate to a strong solution of argentic nitrate, until the precipitate at first produced is nearly redissolved, and then filtering. CALCIUM NITRATE (Syns. Nitrate of Lime. Baldwin! s Phosphorus). Formula, Ca 2 N 03 . Is used in the preparation of potassium nitrate. It occurs as a white or greyish efflorescence in caverns formed in calcareous rocks. The destruction of the plaster and necessity for frequent renewal of the whitewash upon the inner side of walls, is due to the formation of this highly deliquescent salt. If it be desired in a pure state, the most advisable method to obtain it, is to 17 : NITROGEN. dissolve calcium oxide, hydrate, or carbonate in nitric acid. It can be procured in crystals by careful evaporation, and exposing the concentrated solution to a current of dry air. ' Heat causes these crystals to fuse, and finally to become a dry powder, which, after being raised to low redness and exposed to light for a short time, is luminous in the dark ; hence it receives its second synonym, from the name of its discoverer (Baldwin) and the word phosphorus (a light-bearer). By a long-continued high temperature it is totally decomposed into calcium oxide. STRONTIUM NITRATE (Syn. Nitrate of Stro?itia). Formula, -Sr2N03. May be procured from strontium sulphide (or the native carbonate, strontianite') by solution in nitric acid. It is only employed in pyrotechny, and (rarely) for producing the oxide. For the former purpose it must be rendered perfectly dry, as it is naturally a deliquescent salt. It is well adapted for exhibiting the flame reactions of the metal, being easily volatilized in contact with deoxidants at a high temperature. BARIUM NITRATE (Syn. Nitrate of Baryta). Formula, Ba2N03. Prepared by dissolving barium carbonate in nitric acid largely diluted with water, and crystallizing. This salt is used, instead of barium chloride, as a reagent for precipitating sulphuric acid when in the presence of silver or nitric acid. It is comparatively slightly soluble in water. CUPRIC NITRATE (Syn. Niti'ate of Copper). Formula, CU2NO3. Obtained by dissolving copper or its oxide in dilute nitric acid. It crystallizes in pale blue prisms, having amounts of water of crystallization varying from 3H2O to bHgO, according to the temperature at which it is crystallized. It is decomposed by heat, leaving cupric oxide. MERCUROUS NITRATE. Formula, Hg22N03.H20. Prepared by digesting excess of mercury vVith cold dilute nitric acid. It crystallizes in colourless, efflorescent, crystalline plates. It is not perfectly soluble in water, owing to its tendency to form basic salts ; but a drop of nitric acid added ensures a clear solution. It is used in analysis, as being the only common soluble salt of mercury in the mercurous state. When heated it gives off NO2, and leaves hydrargyri oxidum rubi'um, HgO. It is not in the B.P., but is produced in making the red oxide. {See Mercuric Oxide.) MERCURIC NITRATE. Formula, Hg2N03. Molecular Weight, 324 . Prepared by dissolving mercury in nitric acid of about half B.P. strength. 3Hg + 8 HN 03 = 3 Hg 2 N 03 + 2 N 0 + 4H20. The solution is effected in the cold, but it is afterwards boiled to expel the excess of nitric oxide, and to ensure the formation of mercuric nitrate. Liquor hydrargyri nitratis is a colourless and strongly acid solution of mercuric nitrate. Specific gravity, 2 ’246. {For analysis^ see Author’s Analytical Chemistry, 102.) Unguentum hydrargyri nitratis also contains mercuric nitrate, being formed by causing lard and olive oil to be heated with a strongly acid solu- tion of that salt till the whole froths up. MERCURIC, FERRIC, COB ALTO US NITRATES. 173 The frothing is caused by the liberation of carbonous and nitric oxides owing to the action of the NOg on the oleine of the fats, a portion of which is changed to elaidine, a fat isomeric with oleine, though differing in its properties. A red oil is formed at the same time, which colours the oint- ment ; and it is a question whether a basic nitrate of a yellow colour, and having the formula Hgg04.4N0g, be not frequently produced if the acid evaporate tod rapidly, although a large excess of acid is purposely used to prevent reduction as much as possible. Steel knives should never be used with this ointment. There are several bodies which are regarded as mercuric oxynitrates. The mercuric tri-oxynitrate has the formula, HggNgOy or HggNgOg^, which may be written (Hg20)g6N03 or 3Hg0.3Hg(N0g)2. The mercuric tetr-oxynitrate is found to possess the empirical composition, HggN208 or HggN^Ojg, which is rationally regarded as 4Hg0.2Hg(N0g)2- The salt approximating most to the pure oxide is hexa-mercuric oxynitrate, HggN20n, otherwise 5 Hg 0 .Hg(N 03 ) 2 . All three may be readily obtained from mercuric nitrate : the first by / evaporating a solution of that body rapidly ; the second results from agitating the salt obtained with cold water, and the third by boiling the last-mentioned product with water. Mercuric tri-oxynitrate, which may also be termed in accordance with its first formula di-mercuric oxynitrate, may be procured in white crystals, which are sometimes transparent, but readily become opaque. Mercuric tetr-oxynitrate (tri-mercuric oxynitrate) is a yellow powder, and hexa-mercuric oxynitrate is “ brick-red ” in colour. These formulae may be remembered with ease (if the simplest are supposed to be correct), by the fact that the first contains one molecule, the second two, and *the third five molecules of mercuric oxide united to one of mercuric nitrate. FERRIC NITRATE (Syns. Pernitrate of Iron. Nitrate of Iron. Nitrate of Peroxide of Iron). Formula, FogGNOg. This body is readily produced by the solution of metallic iron in diluted nitric acid, the reaction being : — ' Fe2 + 8HNOg = FegGNOg -l- 2NO + qHgO. Liquor Ferri Periiitratis, B.P., is a clear reddish-brown solution, having a specific gravity of I'loy. It is made by simply steeping iron wire in very dilute cold nitric acid until dissolved. The object of using the acid cold, is to avoid fumes during the operation. {For analysis, see Author's Analytical Chemistry, page 102.) Ferric nitrate may also be prepared by acting upon ferric oxide (or hydrate) with nitric acid. It may be obtained in crystals, which are sometimes almost pure white, but at other times possess a bluish tint, by adding strong nitric acid to a concentrated solution of the salt. By rapidly evaporating watery ferric nitrate, a basic or oxy-salt is formed, and the same result takes place when ferric hydrate is added. The oxynitrates are soluble in water. COBALTOUS NITRATE (Syn. Nitrate of Cohalt). Formula, Co2NOg. Is readily formed from the hydrate or oxide by solution in nitric acid. It is commonly employed as an ink termed sympathetic, which, from being pale pink and almost invisible when cold, becomes a deep blue on warming. It is valuable in analysis as a blowpipe test, as it imparts a strong blue colour to aluminium oxide when a very small quantity is placed upon a solid suspected to contain aluminium, and heated before the blowpipe. It also tints zinc 174 NITROGEN oxide under similar circumstances, but in this case the colour is green. If a blowpipe bead of borax, or microcosmic salt, be moistened with this (or any other cobalt salt), it yields on reheating a clear, blue, glassy substance. BISMUTHOUS NITRATE (Syn. Nitrate of Bismuth). Formula, BiSNOg. Prepared by dissolving bismuth in slightly diluted nitric acid* by the aid of heat : — Bis + SHNOg = 2Bi3N0g + 2N0 + 4H20. When the solution thus obtained is poured into water, a precipitate ot bismuthous oxynitrate is produced. BISMUTHOUS OXYNITRATE (Syns. Bismuthyl Nitrate. Bismuthi Suhnitras). Formula, BiONOgH^O. Prepared by pouring a solution of bismuthous nitrate into water. BisNOg + HgO = BiONOg + 2HNOg. In practice, however, the nitrate is not completely decomposed, a portion remaining dissolved by the nitric acid produced : — SBisNOg + SHjO = 4 (Bi 0 N 0 g.H 20 ) + Bi3N0g + 8HN0g. The B.P. bismuthi subnitras is a heavy white powder in minute crystalline scales, blackened by sulphuretted hydrogen (forming bismuthous sulphide), insoluble in water, but soluble in nitric acid mixed with half its volume of distilled water, forming a solution which, poured into water, gives a white pre- cipitate (characteristic precipitate of BiONOg). It is turned yellow by heat or by boiling with an alkaline hydrate, being converted into the oxide. {^For analysis, see Author's Analytical Chemistry, page 102. ) As even the so-called purified metallic bismuth often contains arsenic, it is advisable to get rid of that dangerous body. This is done by crystallizing the nitrate, and using the crystals only for making oxynitrate. When the bismuth is dissolved in nitric acid, the arsenic contained in it is changed into arsenic acid, which, being very soluble, remains in solution when the bismuthous nitrate is crystallized out. This is the usual commercial process, as only the exact quantity of water requires to be added, and so much filtration, &c., is saved. Theoretically, bismuthous oxynitrate is viewed as being a nitrate of the monad basylous radical bismuthyl, BiO. PLUMBIC NITRATE (Syns. Nitrate of Lead. Plumb i Nitras). Formula, Pb2N0g. May be prepared : — 1. By dissolving litharge in dilute nitric acid. PbO + 2HNO3 = PbaNOg -h H2O. 2. By boiling red lead with dilute nitric acid, filtering, and crystallizing. PbgO^ + qHNOg = 2Pb2N0g + Pb02 + 2H20. 3. By dissolving lead in dilute nitric acid by the aid of heat. Pbg + 8HNO3 ^ 3Pt>2NOg + 2NO + 4H2O. It is met with in colourless octahedral crystals, which are nearly opaque, permanent in the air, of a sweetish astringent taste, and soluble both in water and alcohol. Heated, it evolves N2O4, and leaves plumbic oxide. {For analysis, see Author's Analytical Chemistry, 103O NITROGEA WITH HALOGENS AND CARBON. 175 COMPOUNDS OF NITROGEN WITH THE HALOGENS. NITROGEN CHLORIDE (Syn. Chloride of Nitrogen). Formula, NCI3. Obtained by the action of an excess of chlorine upon ammonia gas, or am- monium hydrate, or an ammoniacal salt. Also by the action of the last-named upon hypochlorous acid. 4NH^Hd + 3CI2 - NCI3 + sNH^Cl 4 - 4H2O. In the last case, the action would be : — NH 4 CI + 3 HCIO = NC\^ + UC\ + 3U^0. Nitrogen chloride is a fearfully explosive, oily, yellow liquid, which must be prepared in a small leaden cup, and with every part of the apparatus perfectly free from grease. It has a peculiar sharp odour, is volatile, and is instantly decomposed by turpentine, phosphorus, and oily bodies, also by heat. If exploded in an iron or glass vessel, it reduces it to fragments. NITROGEN BROMIDE. Formula, NBrg. ' Formed from nitrogen chloride and potassium bromide. Is a thick, reddish- brown, very volatile liquid, resembling the chloride as regards odour, and readiness of decomposition with phosphorus ; and, like that body, being only of theoretical interest. NITROGEN IODIDE. Formula, NI3. Is produced when finely-powdered iodine is dropped into ammonium hydrate. A brown liquid is produced, consisting of a solution of iodine in hydrogen iodide, and the nitrogen iodide is deposited as ,a black powder, which, when dry, explodes violently even when touched by a feather, and often without apparent cause. The real composition of this powder has been variously stated to be NHI2 and NHI3.NH3; but it is probably not a constant com- pound, which accounts for the conflicting analyses which have been given. COMPOUNDS OF NITROGEN WITH CARBON. Many of these are exceedingly complicated, and will be treated of hereafter ; but the following are to be studied at this stage : — CYANOGEN. Formula, i?i the free state, (CN)2. Molecular Weight, in the f7'ee state, 52 . Density, refeiTed to Hydrogen, 25’ 5. Density, referred to Air, 1 * 81 . A chemico-historical interest attaches to cyanogen, as it was the first com- pound radical whose existence was definitely ascertained. Its isolation was due to Gay-Lussac, about thirty years after Scheele’s original discovery in 1782. It is a colourless gas, with a decided odour similar to that of bitter almonds. It can be liquefied by a pressure of 3*6 atmospheres at 45° F., and can be solidified by a temperature of 90 degrees below 0 ° F. It burns with a peach- blossom coloured flame, producing nitrogen and carbonic anhydride, thus : — (CN )2 ^ 2O2 ^ 2CO2 N2. 2 vols. 4 vols. 4 vols. 2 vols. That is, one gallon of cyanogen mixed with two gallons of oxygen, and exploded, would yield two gallons of CO2 and one gallon of nitrogen. 176 NITROGEN. It is prepared by heating mercuric or argentic cyanide. These substances are decomposed by heat, evolving cyanogen, and leaving the metal, which, in the case of mercury, sublimes with a little unaltered cyanide : — 2Hg(CN)2= Hg2 + 2(CN)2. Cyanogen, although truly CN, is usually represented by the symbol Cy, be- cause it behaves in every respect like an element, and to use such a symbol saves complication of the formula. For instance, it is easier to write Cyg, and remember that it stands for 6 times CN, than to write always CgNg. In future, therefore, Cy will stand for CN. METALLIC CYANIDES. HYDROGEN CYANIDE (Syns. Hydrocyanic Acid. Prussic Acid). Formula, HCy. Molecular Weight, 27. Exists ready formed in the juice of the bitter cassava, and is also formed when bitter almonds are rubbed with water, and when the leaves of the Prunus laurocerasits are distilled with water. It may be simply prepared by. mixing a solution of potassium cyanide with a slight excess of tartaric acid, when potassium acid tartrate deposits, and hydrocyanic acid remains in solution : — KCy + H2C4H4O6 = HCy + KHC4H4O6. Procured in this way, the acid is not quite pure ; but the process is useful to the pharmacist on an emergency, as yielding in a few minutes an acid of nearly the requisite strength. This may be extemporized by using 100 grains of tar- taric acid, 44 grains of potassium cyanide, and 2 fluid ounces of water. Shake violently, set aside to settle, and then draw off the clear liquid. The proper B.P. way of preparing the acid is, by distilling potassium ferrocyanide with sulphuric acid very largely diluted with water. The action is as follows {x re- presenting an indefinitely large quantity of water) : — * 2K4peCyg + 6H2SO4 + = 6HCy + 6KHSO4 + K2Fe2Cyg + XH2O. It is important that the acid should be very dilute, because tolerably strong sulphuric acid will entirely decompose potassium ferrocyanide, forming ferrous, potassium, and ammonium sulphates (the latter from the nitrogen of the CN), and evolving carbonous oxide, thus : — K4FeCyg + 6H2S04 + 6H20 = 2K2SO4 + FeSO^-f- 3(NH4)2S04-f- 6CO. To practically make the B.P. acidum hydrocyanicum dilutum, place 2\ ounces of potassium ferrocyanide, dissolved in 14 ounces of water and acidu- lated with an ounce of sulphuric acid, into a retort connected with a well- cooled condenser, the beak of which dips under the surface of 8 ounces of water placed in a receiver, also kept cool. Distil the whole slowly, until 17 ounces in all have collected in the receiver. Lastly, dilute the acid thus pro- duced until it shows a strength of 2 per cent, of real HCN, i.e. until 100 grains (no minims) of it precipitated with excess of argentic nitrate, and the preci- pitate collected, washed, dried, and weighed, shall show ten grains of dry argentic cyanide; or until 270 grains of it, rendered alkaline by the addition of solution of sodium hydrate, require 1000 grain-measures of the volumetric solution of argentic nitrate to be added before a permanent precipitate begins to form. {See Author's Analytical Chemistry, 156.) * The substance KoFejCye is a double ferrocyanide of iron and potassium, called, after its discoverer, Everett's salt. {See Ferrocyanides.) HYDROCYANIC ACID. 77 Thus made, the acid is a colourless liquid with a peculiar odour. Specific gravity o’ 99 7. It only slightly and transiently reddens litmus paper. Treated with a minute quantity of a mixed solution of ferrous and ferric sulphates, afterwards with potassium hydrate, and finally acidulated with hydrochloric acid, it forms Prussian blue. Scheele's prussic acid is stronger than the B.P., and contains 5 per cent, real hydrogen cyanide. {For analysis., see Author's Analytical Chemistry, 103.) Hydrocyanic acid decomposes slowly when kept in the dark, but very rapidly in the light. In the case of the dilute acid of the B.P., this decomposition is attended with the formation of ammonium formate : — HCN + 2H2O = NH4CHO2 ; a deposit of a peculiar brown substance being thrown down at the same time. Pure hydrogen cyanide is prepared by passing chlorine over dry mercuric cyanide. It is a colourless and volatile liquid, boiling at 79° Fahr., and soli- difying when cooled to 0° Fahr. It dissolves in water and alcohol in all proportions. In a state of vapour it yields, when exploded with excess of oxygen, carbonic anhydride, nitrogen, and water, thus : — 2HCN + 5O - 2CO2 + H2O + N2. 4 vols. 5 vols. 4 vols. 2 vols. Or, reducing the whole to the simplest ratio, 2 gallons of vapour require 2J gallons of oxygen, and yield 2 gallons CO2 + i gallon nitrogen. The remain- ing half-gallon of oxygen forming water with the hydrogen of the acid. By the action of hydrochloric or sulphuric acid, hydrocyanic acid is decomposed into formic acid and ammonia, but minute traces of either of them tend to preserve the dilute acid from decomposition. On the other hand, by heating ammonium formate to 392° Fahr., we obtain hydrocyanic acid and water. Cyanogen combines with metals to form cyanides, of which it is the acidu- lous radical, acting as a monad. Cyanides give reactions similar to hydrocyanic acid. They are all decom- posed by heating with water. In the case of alkaline cyanides, ammonia and formate of the alkalies are produced : — KCN + 2H2O = KCHO2 + NH3. But with those of heavy metals, carbonic anhydride, carbonous oxide, and ammonia are given off, and the metal is deposited with a little carbon. Alkaline cyanides heated in the air first yield cyanates : — KCN + O = KCNO, and then give off nitrogen and carbonic anhydride, leaving carbonates of the 2KCNO + 03 = K2CO3 + N2 + CO2. {For detection of Hydrocyanic Acid and separation of Cyanides, see Author's Analytical Chemistry, 63, 64, a 7 id 65.) An immense number of cyanides of organic basylous radicals exist, and they are a most interesting class of bodies. At present, however, we will only touch on a few metallic cyanides, merely noting that the organic salts above referred to are sometimes called azoparaffins, or nitrils, being viewed in the former case as compounds derived from hydrocarbons by the displacement of three atoms of hydrogen by one of nitrogen, or in the latter as compounds of nitrogen with triad radicals. Thus, hydrogen cyanide, HCN, may be called : — Azomethane CHN (from methane CHJ. or Methenvl Nitril (CH)'"N"' ; from the triad Methenyl (CH)'". N 178 NITROGEN. POTASSIUM CYANIDE. Formula, KCN = KCy. Prepared, — 1. directly by synthesis, by passing nitrogen over a mixture of potassium hydrate and charcoal heated to redness. ' 2. By heating potassium ferrocyanide to redness in a closed vessel, forming a carbide of iron, and evolving nitrogen : — K^FeCgNg or K^FeCyg = 4KCy + FeCg + Ng. 3. By fusing potassium ferrocyanide with potassium carbonate, forming potassium cyanate and iron, evolving carbonic anhydride : — aK^FeCyg + 2K2CO3 = loKCy + 2KCyO + + 2CO2. This is the commercial process, and yields a sufficiently pure product for the purposes to which this salt is applied in the arts. Potassium cyanide is usually seen in opaque, white, broken, flat lumps. It is alkaline to test-paper, very poisonous, and smells strongly of prussic acid. It is commonly very deliques- cent, and is used in photography for dissolving the unaltered argentic iodide or bromide from the plates, and so fixing the portrait by removing all sub- stances capable of being acted upon by light. MERCURIC CYANIDE. Formula, HgCyg. Is prepared by boiling potassium ferrocyanide with mercuric sulphate, and filtering hot. The salt crystallizes from this solution in white prisms resembling mercuric chloride in appearance, and is soluble n water and alcohol. Its solution is not precipitable by alkalies. ARGENTIC CYANIDE. Formula, AgCy. Is precipitated when argentic nitrate is added to hydrocyanic acid. It is a curdy-white substance, readily blackened by exposure to the light, and soluble both in ammonium hydrate and in strong boiling nitric acid. In presence of an excess of potassium or sodium hydrate it is converted into a soluble double cyanide, which explains the fact, that, in the volumetric test for the strength ot hydrocyanic acid above mentioned, when the silver solution is first added to the cyanide, no precipitate is produced, owing to the formation of a soluble double cyanide of silver and sodium : — 2NaCy-f AgNOg = AgCy.NaCy -r NaNOg. On continuing to add the silver, a time arrives when, the double compound having been fully formed, it is in turn decomposed by excess of silver, and a white cloud of argentic cyanide is produced : — AgCy.NaCy -f AgNOg = 2AgCy -F NaNOg. At the moment, therefore, when the precipitate appears, sufficient silver has been added to combine with one half of the cyanogen present in the sample^ as is shown by the formula, ‘AgCy.NaCy. This reaction is taken advantage of to determine volumetrically the strength of a sample of hydrocyanic acid. {See Author's Analytical Chemistry, 156.) The other cyanides are not of pharmaceutical importance. Besides the simple cyanides, the radical cyanogen has a great tendency to form double salts, containing two metals, and not only so, but to combine with a portion of the heavy metal, and form a new radical, itself capable of METALLIC FERROCYANIDES. 179 uniting with hydrogen to form an acid, which can in its turn produce salts. Thus, ferrous cyanide and potassium hydrate yield potassium ferrocyanide : — 3FeCy2 + 4KHO = K^FeCyg + 2Fe2HO. Here part of the Fe combines with the cyanogen to form a new acidulous radical called ferrocyanogen, FeCyg, which acts as a tetrad, and unites with four atoms of the monad potassium to form a definite salt (potassium ferro- cyanide). METALLIC FERROCYANIDES. HYDROGEN FERROCYANIDE (Syn. Hydro-Ferrocyanic Acid). Formula, H4FeCyg. Prepared by mixing potassium ferrocyanide with an acid, such as hydro- chloric or tartaric. As thus produced, in solution, it rapidly decomposes in contact with the air, forming hydrocyanic acid and Prussian blue. POTASSIUM FERROCYANIDE (Syn. Yellow Prussiate of Potash). Formula, K4FeCyg = K4FeCgNg. This salt, which is 7iot poisonous^ is prepared on the industrial scale by fusing hoofs, horns, hair, and other nitrogenous organic matters, in a closed iron pot with potassium carbonate and iron filings. The action is one of pure synthesis, f.d, these nitrogenous bodies produce the nitrogen and carbon, which combine with the potassium and form potassium. cyanide. On treating the mass with hot water, the cyanide is attacked by the oxide or sulphide of iron (the latter produced from the reduction of the sulphates existing in the crude pearlash used and in the animal matters), and converted into ferrocyanide. The boil- ing with water while still in the iron pot is an important and indispensable stage of the process. After filtering from the animal charcoal also produced, the solution yields crystals, having the formula, K4FeCyg3H20. They are large yellow crystals, permanent in the air, if not exposed to too direct light, soluble in four part's of cold and two parts of boiling water, and insoluble in alcohol. Heated in a closed vessel, they yield potassium cyanide and ferrous * carbide; and in an open vessel potassium cyanate is also formed. A new process for making potassium ferrocyanide consists in shaking up carbon disulphide with ammonium sulphide, which forms ammonium thiocar- bonate. CS2 + (NH,),S = (NHJ^CS,. This product, heated with potassium sulphide, yields potassium thiocyanate : — 2(NH4)2CS3 + KgS = 2KCNS 2NH4HS + 3H2S. Lastly, by drying the thiocyanate, and heating it with iron, we obtain — 6KCNS + 3Fe2 = K4FeCgNg + sFeS + K2S. ' This process is not yet carried out on any very large scale. Exposed for a long time to the air and strong light, potassium ferrocyanide decomposes on the surface, giving off prussic acid and becoming coated with Prussian blue. By mixing potassium ferrocyanide with soluble salts of other metals their ferrocyanides are produced by double decomposition. These reactions are very valuable in analysis, because nearly all the ferrocyanides of heavy metals form insoluble and highly characteristic precipitates. The following is a list of some of the chief precipitates thus formed : — i8o NITROGEN. Reactions of Potassium Ferrocyanide. Name of ^[ETAL. . Copper . Iron (ferrous) Iron (ferric) Lead Magnesium Mercury . Silver Zinc • Colour of Precipitate with Potassium Ferrocyanide. Reddish-brown (chocolate). White, instantly changing to pale blue. Dark blue. White. No effect in a fairly dilute condition. White. White, gelatinous, soluble in ammonium hydrate. Ditto ditto. These effects are only produced in slightly acid or perfectly neutral solu- tions. The two precipitates with iron deserve a special notice. POTASSIUM FERROUS FERROCYANIDE. Formula, KaFeFeCyg = KoFesCjg. Produced when a solution of potassium ferrocyanide is mixed with a ferrous salt : — K^FeCyg + FeSO^ = KgFegCyg K^SO^. It is also a bye-product in the manufacture of hydrocyanic acid. In itself it is white, but it instantly turns blue in contact with the air. It is insoluble in hydrochloric acid but destroyed by alkalies. FERRIC FERROCYANIDE (Syn. Prussian Blue). Formula, (Fe2)23FeCyg. Produced by adding a solution of potassium ferrocyanide to that of a ferric salt : — 3K4peCyg + 2Fe2Clg = (Fe2)23FeCyg -f- 12KCI. It is not soluble in hydrochloric acid; but alkalies turn it brown, ferric hydrate being deposited, and ferrocyanide of the alkalies re-formed : — (Fe2)23FeCyg-t-T2KHO = 3(K4FeCyg) + 2 Fe 26 HO. It is upon the formation of Prussian blue that Scheele's test for hydrocyanic acid, by first adding potassium hydrate then a mixture of a ferrous and a ferric salt, and finally acidulating with hydrochloric acid, is based. The explanation of the test is as follows (according to Gerhardt’s view) : — 1. The hydrocyanic acid and the potassium hydrate form potassium cyanide. 2. The addition of the ferrous salt produces ferrous cyanide. 3. This reacting with the excels of alkali forms potassium ferrocyanide. 4. On the addition of the ferric salt, it is at first precipitated by the excess of alkali, as ferric hydrate, which on acidulation dissolves to ferric chloride, forming ferric ferrocyanide (Prussian blue) : — 1. ' 6 HCy-f- 6 KHO - fiKCy + fiHgO. 2. 6KCy + 3FeCl2 = 3FeCy2 + 6KCl. 3. 3FeCy2 + 4KHO = K^FeCyg + 2Fe2HO. 4. 3K4FeCyg + 2Fe2Clg = (Fe2)23FeCyg + 12KCI. Or the whole may be shown in one equation, thus, which is quite •sufficient : — i8KCy + 3FeCl2 + 2Fe2Clg = (Fe2)23FeCyg -h 18KCI. {^For detection of Ferrocyanides, see Author's Analytical Chemistry, page 66.) METALLIC FERRICYANIDES. 8i METALLIC FERRICYANIDES. • FERRICYANOGEN. Fornmla, Fe^Cyig. This is a radical similar to the last studied, but differing from it inasmuch as the cyanogen is combined with ferric instead of ferrous iron, and the whole radical acts as a hexad in forming salts with metals. HYDROGEN FERRICYANIDE (Syn. Hydroferricyanic Acid), Pommla, EgFegCyig- Cannot be prepared like hydrogen ferrocyanide, but may be by the action of sulphuretted hydrogen on plumbic ferricyanide. POTASSIUM FERRICYANIDE (Syn. Red Prussiate of Potash), Formula, EgFegCyig- Prepared by passing chlorine gas through a dilute and cold solution of potassium ferrocyanide, forming at the same time potassium chloride : — 2K^^FeCyg + CI3 = KgFe2Cy^2 + 2KCI. , Although not shown in the equation, there is no doubt that the chlorine also assists to convert the iron in the radical from the ferrous to the ferric state, as during the process a ferric compound is precipitated ; and the finish is indicated when this ceases to form. Potassium ferricyanide crystallized from this solution is in ruby-red prismatic crystals, soluble in 4 parts of water, forming a dark greenish-yellow solution. Excess of chlorine decomposes •them, as also do reducing agents such as HgS, etc. Solutions of ferricyanide for use in analysis should be freshly made, as by exposure to the light it decomposes, being reconverted into ferrocyanide with a deposit of Prussian blue. Potassium ferricyanide is much employed in analysis, owing to its forming insoluble ferricyanides on adding it to solutions of many heavy metals. The following is a list of the most characteristic : — Reactions of Potassium Ferricyanide. Name of Metal. Colour of Precipitate with Potassium Ferricyanide. Iron (Ferrous) Iron (Ferric) Lead . Mercurous . Mercuric Stannous Stannic Silver . Dark blue (Turnbull’s). . No precipitate. Ditto. . Brownish red. . No effect. . White, soluble in HCl. . No effect. . Orange. By the above table it is evident that potassium ferricyanide is very useful in distinguishing between various states of the same metal : — iron, for example, with which it gives a dark-blue precipitate when the salt used is ferrous, and no effect when it is ferric. ' FERROUS FERRICYANIDE (Syn. TurjibulLs Blue). Formula, FOgFeoCyin. Produced between potassium ferricyanide and a ferrous salt : — KgFegCyio + aFeSO^ = Fe3Fe2Cyi2+ 3K2SO4. This precipitate is insoluble in hydrochloric acid, but when treated with i 82 NITROGEN. potassium hydrate, or any similar alkali, it is decolorized, and deposits ferroso-ferric hydrate, forming a ferrocyanide of the alkali used in solution : — FegFegCyia + 8KHO = 2 K 4 FeCye + FegSHO. [Tor detection of Ferricyanides^ see Author’s Analytical Chemistry, 66.) METALLIC NITROPRUSSIDES. These are a class of bodies obtained by the action of nitric acid on ferro- cyanides and ferricyanides having the general formula M 2 (NO)FeCy 5 . They may be viewed as derived from a half molecule of a ferricyanide, MgFeCyg, by the displacement of one molecule of the metallic cyanide, MCy, by nitric oxide (jutrosyl) the latter being formed by the reducing action exercised by the ferrocyanide on the nitric acid. SODIUM NITROPRUSSIDE. Formula, NA2(N0)FeCy5.2H20. Prepared by heating five parts nitric acid and two parts potassium ferro- cyanide with a little water, until a portion taken from the basin gives a slate- coloured, instead of a blue, precipitate with ferrous sulphate. The liquid having been allowed to cool (to deposit KNOg) is filtered and neutralized with sodium carbonate, and lastly, the whole having been again filtered, is crystal- lized. The ruby-red crystals of sodium nitroprusside are then carefully picked out, redissolved in water, and crystallized. The solution of this salt in water is employed to detect the presence of traces of alkaline sulphides, in the presence of which it becomes of a fine violet colour. METALLIC CYANATES. Cyanogen can also unite with oxygen to form a class of compounds called cyanates. They may be viewed as nitrogen with two of its atomicities satu- rated by (CO)" and the third by a basylous radical, thus : — Potassium Cyanate K' — N'">(CO)" or as cyanogen in combination with an oxygenated radical of the hydroxyl type, thus : — Potassium Cyanate (CN)' (OK)'. In point of fact, these two modifications actually exist, and have been named respectively isocyanates and tiormal cyatiafes. The cyanates are of no use in pharmacy ; but the following are interesting owing to their relation to urea. (See Amides.) HYDROGEN CYANATE (Syn. Cyatiic Add). Formula, HCNO. Is an exceedingly irritating colourless liquid, with a smell something between sulphurous anhydride and glacial acetic acid. It cannot be kept, as it sud- denly changes of its own accord into a solid white body called cyatnelide, which is, however, identical in composition. Cyanic acid cannot be obtained by liberation from its salts by the action of a mineral acid, as it is immediately decomposed on touching water into ammonium hydrogen-carbonate : — HCNO + 2H2O = NH^HCOg. Cyanuric acid, HgCgNgOg, is a polymer of cyanic acid, from which the latter may be produced by heating to a very high temperature, thus : — HsCgNgOg = 3HCNO. METALLIC CVANATES, THIOCYANATES. 183 Cyanuric acid is prepared by heating urea till it melts. Ammonia is given off, and the acid is left as an amorphous mass, which when purified forms efflorescent crystals feebly soluble in water, containing 2H2O of crystallization. It is soluble without change in the strongest sulphuric or nitric acids. AMMONIUM CYANATE. Formula, (NHJCNO. Is produced by synthesis from its elements by — 1. Making potassium cyanide by passing nitrogen over a mixture of carbon and potassium carbonate heated to redness. 2. Converting the potassium cyanide into potassium cyanate by fusing with an oxidizing agent such as red lead or manganic peroxide, and extracting the cyanate by boiling alcohol. 3. Mixing the alcoholic solution of potassium cyanate with ammonium sulphate, when double decomposition ensues, and the potassium sulphate, being insoluble in alcohol, is filtered out and the solution evaporated in vacuo. Ammonium cyanate, if heated, immediately undergoes a molecular change, and is converted into urea. {See Amides.) Thus we see one of those remark- able synthetical methods by which so-called organic matter is obtained from purely inorganic constituents. For detection of Cyanic and Cyanuric Acids, see Author’s Analytical Chemistry, page 65.) METALLIC THIOCYANATES. By the substitution 01 sulphur for oxygen in a cyanate, a class 01 salts called thiocyanates (formerly sulphocyanates) are produced, thus : — Cyanic Acid. . HCNO, forms Thiocyanic Acid . . HCNS. Potassium Cyanate, KCNO, „ Potassium Thiocyanate . KCNS. HYDEOGEN THIOCYANATE (Syn. Sulphocyanic Acid). Formula, HCNS. Is prepared by treating plumbic sulphocyanate suspended in water with sulphuretted hydrogen. By boiling or exposure to the air, it suffers a very complex decomposition. AMMONIUM THIOCYANATE (Syn. AmtJionium Sulphocyanate) . Formula, NH^CNS. May be obtained by the action ot excess ot ammonium hydrate on carbon disulphide, or by boiling ammonium cyanide with sulphur. It is also produced in the sulphur test for hydrocyanic acid as follows : — A drop oi yellow ammoniurnA sulphydrate is exposed to the vapour of, or added to a solution of, hydrocyanic acid, and the whole evaporated to dryness at a very gentle heat, with the addition of a drop of ammonium hydrate. A residue is thus obtained' which strikes a blood-red colour with ferric chloride, not dischargeable by hydro- chloric acid, but at once bleached by solution of mercuric chloride. This colour is due to the formation of ammonium thiocyanate (which takes place when an alkaline sulphide, containing excess of sulphur, is brought into con- tact with cyanogen) thus : — 2HCy + (NH4)2S + S2 = 2NH4CyS + HgS, and subsequent production of red ferric thiocyanate. 84 NITROGEN. POTASSIUM THIOCYANATE (Syn. Sulphocyanate of Potassium). Formula, KCNS. Is prepared by fusing dried potassium ferrocyanide with half its weight of sulphur in an iron pot, forming a mixture of potassium and ferrous thiocyanates : — K^FeCgNg + sSg = 4KCNS + FeaCNS. These salts having been dissolved out by water, the ferrous thiocyanate is decomposed by the careful addition of potassium carbonate : — Fe2CNS + K 2 C 03 = 2KCNS + FeC 03 , and the whole is then crystallized. A more expensive but better process is, to add the potassium carbonate to the fused mass, and then extract with and crystallize from alcohol. The crystals thus obtained are prismatic and anhydrous, but very deli- quescent, and bitter to the taste. They are soluble in water and alcohol, and melt at a very gentle heat to a colourless liquid. When potassium thiocyanate is treated with chlorine a curious yellow insoluble body is formed, which, although at one time believed to be the radical thiocyanogen in the free state, is now called persulphocyanogen, and has a formula of H3CNS or (C3N3HS3). The only use of potassium thiocyanate is as a reagent for the detection of ferric salts. The argentic and plumbic thiocyanates are insoluble in water. FERRIC THIOCYANATE. Formula, FegGCNS. Is the cause of the red colour which is produced when any ferric salt is brought into contact with a soluble thiocyanate. It must be carefully distin- guished from the similar colours by acetates, meconates, and carbolates, being known by its not being discharged by dilute hydrochloric acid, but being at once bleached by solution of mercuric chloride. {For detection of Thiocyanates, see Author's Analytical Chemistry, page 65.) COMPOUNDS OF CYANOGEN WITH THE HALOGENS. Cyanogen unites with chlorine to produce two polymeric compounds analogous to cyanic and cyanuric acids. They are CNCl and C3N3CI3 ; the first is a gas at ordinary temperatures very pungent and soluble in water which is prepared by passing chlorine over mercuric cyanide in the dark. The second is a solid crystallizing in needles produced by exposing to sun- light a mixture of chlorine and anhydrous hydrocyanic acid. In contact with water it forms cyanuric and hydrochloric acids. Bromine and iodine form similar compounds, which are pungent volatile solids. \ V CHAPTER XL PHOSPHOR US. PHOSPHORUS. Symbol, P, Atomic Weight, 31. Specific Gravity, 1-89. In the Free State, P 4 = 2 volumes. Molecular Weight, 124. Vapour Density, referred to Hydrogen^ 62*9. This element exists chiefly in the bones of animals, in guano, and in the minerals called apatite^ phosphorite, and coprolites, of which latter there are extensive deposits in Cambridgeshire. It is also present in nearly all the tissues of the human frame, especially the brain and nerve substance, and in animal excreta. It was discovered by Brandt, in 1669, and was prepared by slowly evaporating urine down to the consistence of honey, distilling, and purifying, with elaborate precautions. Dr. Kraft and Kunckell both made it ; but it was first presented in the solid form by Ambrose Godfrey Hanckwitz, chemical assistant of the Hon. Robert Boyle. Eventually it was isolated from bones, which consist of two distinct portions, animal and mineral. The first is called ossein, or cartilage, and is isolated by steeping the bones for some time in hydrochloric acid, which dissolves out the mineral part, and leaves the ossein as a stiff gelatinous mass, which retains the form of the original bone. The mineral portion is called hone earth, and is obtained by calcining the bones in contact with the air, until all the animal portion has burned off, leaving a nearly white ash. The relative proportions in well- selected ox bones are 30 per cent, of cartilage, and 70 per cent, of bone earth. To obtain phosphorus, 3 parts of the bone earth (consisting chiefly of trical- cium phosphate, Ca32P04, and calcium carbonate) are digested with 2 parts of sulphuric acid diluted with about 17 parts of water. This yields a solution of monocalcium hydrogen phosphate and a deposit of calcium sulphate, thus : — ^ Ca32P04+ 2H2SO4 = CaH42P04 + 2CaS04. ' The clear solution, having been run off and concentrated to a syrup, is mixed with powdered charcoal and sand. This is transferred .to an iron vessel, in which it is heated to a dull red heat. During the heating, th- hydrogen and a portion of the oxygen of the monocalcium hydrogen rAos- phate pass off in the form of water, and a very intimate mixture of ralcium metaphosphate with sand and charcoal is left : — CaH^2P04 = Ca2P03+ 2H2O. The whole is removed to an earthenware retort connected with a copper tube which dips into water, and distilled at a high red lieat. The charcoal combines with the oxygen to form carbonous oxide and so passes off ; while the silicic anhydride of the sand unites with the calcium to form calcium silicate, which remains in the retort \ and the phosphorus distils over through PHOSPHORUS. 1 86 the copper tube into the water, at the bottom of which it collects in yellow drops : — 2Ca2POg + 2Si02 + 5C2 = 2CaSi03 + 2P2 + loCO. The crude phosphorus thus obtained is transferred to a basin containing water, and having been heated until it melts, a little potassium dichromate and sulphuric acid are stirred in. An oxidation of the impurities then takes place, and the floating matters having been skimmed off, the melted phos- phorus is cast into sticks by passing it through glass tubes under water. Phosphorus is described in the B.P. as being a semi-transparent, colourless, waxlike solid, which emits white vapours when exposed to the air. Specific gravity i "89. It is soft and flexible at common temperatures, melts at 110°, ignites in the air at a temperature a little above its melting-point, burning with a luminous flame and producing dense white fumes. Insoluble in water, but soluble in ether and in boiling oil of turpentine. Phosphorus ought always to be kept under water, because it takes fire when exposed to the air. The flame cannot be extinguished by water ; and in case of accident the only course to pursue is to cover the burning mass with wet sand. Besides the menstrua already mentioned, phosphorus is soluble in benzene, carbon disulphide, and fixed and essential oils. When taken from the water, wiped gently, and placed upon a dry surface, it emits a bluish-white light, and gives off fumes, which are chiefly phosphorous anhydride mixed with a little phosphoric anhydride. If a light be applied it will burn and form copious, dense, white fumes, consisting entirely of phosphoric anhydride. The phos- phorus fumes emitted in contact with the air are extremely dangerous, and cause necrosis of the bones, chiefly attacking the jaw and smaller ankle-bones ; many lucifer-match makers die miserably from this cause. When mixed with potassium chlorate or nitrate, or any peroxide, such as Mn02 or Pb02, phos- phorus takes fire on being rubbed. It is on this principle that the action of the ordinary lucifer match is based. Phosphorus is an allotropic body, and besides the common form can exist as : — Red., or a 77 iorphoiis phosphorus. This modification is commercially import- ant, and is prepared by heating the common article in a closed vessel, from which the air is entirely excluded, to a temperature of not less than 465° F., and not exceeding 485° F., for about 36 hours. In practice the phosphorus is simply placed in an iron vessel, completely closed, and furnished with a tube dipping under mercury (to act as a safety-valve, allowing the outward passage of expanded gases, but not the inward passage of air). When first heated, the contents of the vessel take fire; but the oxygen of the air being quickly exhausted, the combustion ceases, and the conversion of the remain- ing phosphorus goes on quickly. Red phosphorus is not soluble in carbon \ disulphide, nor in any of the other solvents which attack the ordinary variety ; ^speither does it emit fumes, nor take fire spontaneously in the air. Indeed it wi -11 not inflame until heated to 500° F. It becomes luminous at 392° F., anWwhen exposed to the air it is slowly converted into a liquid which is found be a mixture of phosphorus and phosphoric acids, and smells of ozone. \ It is of tl^ red phosphorus that the well-known ruby and safety matches are made. In th^Jatter it is mixed with glue and manganic dioxide, and spread upon the box, v^ile the match is dipped only in potassium chlorate, glue, and antimonious s\dphide. It is thus impossible to inflame the match on anything but the box itself. Two new preparations of, phosphorus have been introduced into the B.P. : — I. Oleimi PhosphoratitmPpyf^da.Q.di by heating 4 ounces of almond oil to PHOSPHORUS,— PHOSPHURETTED HYDROGEN. 1 87 300° then filtering and dissolving 12 grains of phosphorus in it at a tempera- ture of 180° Fah. The product is a clear but slightly coloured oil ; phosphorescent in the dark. The object of heating is to remove any water from the oil and at the same time precipitate albuminous matters. It has been stated that this oil is apt to become thick and viscid when thus prepared. 2. Pilula Phosphori, made by. rubbing phosphorus with balsam of tolu under water at a temperature of 140° Fah., and then adding yellow wax. The great point in the successful manufacture of this mass, is to mix when the wax is just soft and not actually fluid. It has been objected to as being very insoluble in the stomach, and the addition of a little sugar has been advised when intended for immediate consumption. COMPOUNDS OF PHOSPHORUS WITH HYDROGEN. Phosphorus forms at least the three following compounds with hydrogen, with the first of which only the pharmacist is likely to meet : — Gaseous Hydrogen Phosphide ...... PH^. Liquid „ „ P2H4. Solid „ „ P4H2. HYDROGEN PHOSPHIDE (Syns. PhosphiLretted Hydrogeii. Phosphine).^ Formula, PH 3 . Molecular Weight, 34. ref erred to Hydrogen, 17'5 {theory = 17). Is evolved when phosphorus is boiled with an alkaline hydrate in solution : — . 3KHO + 2P2 + 3H2O - 3KPH2O2 + PH3. As thus prepared, it is usually contaminated with free hydrogen, produced by the action of excess of alkali on the potassium hypophosphite formed in the above reaction : — KPH2O2 + 2KHO = K3PO4+2H2. This may be avoided by the use of calcium, instead of potassium (or sodium) hydrate. In practice little balls of slaked lime, each containing in its centre a small fragment of phosphorus, are heated in water. As thus pre- pared, phosphuretted hydrogen is spontaneously inflammable in the air, and each bubble of the gas as it rises to the surface takes fire and forms beautiful rings of phosphoric acid in the form of a white smoke, which become larger and larger as they rise towards the ceiling, until they are finally dissipated : — PH3 + 2O2 ='H3P04. It has been ascertained that the spontaneous inflammability of phos- y'' phuretted hydrogen is due to the presence of traces of the vapour of and that the pure gas is not of itself inflammable in the air. The pure r/on- inflammable gas may be prepared by the action of phosphorus on al^bholic solution of potassium hydrate. H Phosphuretted hydrogen is a natural product of the putrefactiopf' of organic substances containing phosphorus, and is supposed to contribu^ to the cause of the appearance, so common in marshy districts, known 2 i^,'Will-d-the- Wisp. It is also evolved when a phosphite, or hypophosphite, is .heated to redness. On account of the fact mentioned in Chapter I. ^ -that the atom of phos- phorus only occupies half the volume required by the^ theory therein explained, it follows that one molecule of phosphuretted hydrogen (two volumes) con- PHOSPHORUS. i8S tains three volumes of hydrogen and half a volume phosphorus. As, however, we cannot talk of half an atom, we are obliged to say that two molecules (four volumes) of PHg contain one atom (one volume) of phosphorus, and six atoms (six volumes) of hydrogen. Phosphuretted hydrogen is colourless, possesses a disgusting odour, and is very slightly soluble in water. It is also poisonous, and is very eagerly absorbed by arterial blood, from which it abstracts oxygen. The odour produced in water under which phosphorus has been kept, with access of light, is due in some measure to the slow production of this gas. COMPOUNDS OF PHOSPHORUS WITH THE HALOGENS. Phosphorus combines immediately with bromine, iodine, and chlorine, to form bromide, iodide, and chloride of phosphorus. It can do so in two pro- portions, as follows (the preparation of the chlorides being taken as typical of that of the bromides) : — PHOSPHOROUS CHLORIDE. Formula, PCI3. Prepared by slowly passing phosphorus vapour over mercurous chloride. In this compound two of the atoms of phosphorus are self-saturated, and it acts as a triad. It is an offensive liquid having a specific gravity of 1*45 and fuming in the air. In contact with water it sinks to the bottom and is slowly decomposed, forming phosphorous and hydrochloric acids : — PCI3 -f 3H2O - H3PO3 + 3HCI. PHOSPHORIC CHLORIDE. Formula, PCI5. In this compound (which is a white crystalline solid) the phosphorus exer- cises its full (pentad) atomicity. It is prepared by passing a rapid stream of chlorine over red phosphorus. Treated with excess of water, it yields phos- phoric and hydrochloric acids : — PCI5 + 4H2O = H3PO4 + 5HCI. When the quantity of water is limited, or it is simply exposed to moist air, it produces phosphoric oxychloride : — PCI5 + H2O = POCI3 + 2HCI. PHOSPHOROUS OXYCHLORIDE. Formula, POCI3. Is a colourless liquid, having a specific gravity of 17, and boiling at 230°^ Fah. It has a pungent odour, and is readily decomposed by excess of water* into hydrochloric and phosphoric acid. In practice it is prepared by distilling phosphoric chloride with oxalic acid or phosphoric anhydride. The compounds of bromine with phosphorus resemble the above in pre- paration and pioperties. Iodine forms tw) compounds, Pig and PI3, both solid and produced by sim- ply dissolving phosjJi/irus and iodine in a suitable menstruum, such as carbon disulphide, and cooling qll crystals form. In contact with water, phosphorous and hydriodic acids are produced. The great use of phosphorous iodide is in the making of haloid ethers. (See Chap. XVII.) PHOSPHORUS WITH OXYGEN. 189 COMPOUNDS OF PHOSPHORUS WITH OXYGEN. With oxygen, phosphorus forms two oxides, viz., — 1. Phosphorous anhydride, in which it exhibits triad atomicity. 2. Phosphoric anhydride, when it acts as a pentad. These anhydrides give rise, with water, to acids, and there is also an acid (hypophosphorous) known, without a corresponding anhydride, thus : — Phosphorous Anhydride Oxides. Phosphoric Anhydride . • P9O5. Hypophosphorous Acid Acids. . . . H3P0, = (HPHA). Phosphorous Acid . ■ • H3P03 = (H3PHO3). Phosphoric Acid . . . . H 3 P. 04 . HYDROGEN HYPOPHOSPHITE (Syn. Hypophosphorous Acid). Formula, HPHgOg. May be prepared by decomposing solution of baric hypophosphite with the exactly equivalent weight of sulphuric acid : — Ba2PH202 + HgSO^ = 2HPH2O2 + BaSO^. It is a colourless liquid, which, on exposure to the air, is resolved into a* mixture of phosphorous and phosphoric acids : — 4HPH2O2 + 3O2 = 2H3PO, + 2H3PO3. It forms a class of salts called hypophosphites, which are coming into use in pharmacy, having been originally introduced as constituents in ParrisEs Chemical Food. They are, with the exception of the silver salt, all soluble in water, and most of them dissolve in alcohol. {For detection of Hypophosphites, see Author's Analytical Chemistry, 67 .) SODIUM HYPOPHOSPHITE. Formula, NaPH202. Molecular Weight, 88. Prepared by treating calcium hypophosphite with sodium carbonate, filtering the solution, evaporating and granulating at the heat of a steam bath (230° Fah.) Ca2PH202 + Na 2 C 03 = 2NaPH202 + CaC 03 . It is, when thus made, a white granular salt, having a bitter nauseous taste. It is deliquescent, very soluble in water and in spirit, but insoluble in ether. At a red heat it ignites, emitting spontaneously inflammable phosphuretted hydrogen. {For analysis, see Author's Analytical Chemistryj/a^^ I03*) / POTASSIUM HYPOPHOSPHITE. Formula, KPH 2 O 2 . Molecular Weight,* 104. May be prepared as the calcium salt, but using potassium hyarate, and converting the excess of the latter into carbonate, by adding potassium hydro- carbonate, and finally evaporating to dryness, then treating' with alcohol, which only dissolves the potassium hypophosphite ; but the tendency of the excess of potassium hydrate to decompose the hypophosphite, as already shown (page 187) renders its preparation from calcium hypophosphite by double de- composition with potassium carbonate more desirable. It resembles sodium hypophosphite in its properties. • PHOSPHORUS. I go CALCIUM HYPOPHOSPHITE. Formula, Ca 2 PH 202 . Molecular Weight, 170. Is prepared by gently heating phosphorus with water and calcium hydrate, phosphuretted hydrogen being evolved : — 3 Ca 2 HO + 6H2O + 4P2 = 3Ca2PH202+ 2PH3. In practice it is obtained by heating phosphorus with calcium hydrate and water until phosphuretted hydrogen gas ceases to be evolved, then filtering the liquid, separating uncombined lime with carbonic acid gas, and evapor- ating the remaining solution until the salt separates in a crystalline condition. ' It is met with as a white crystalline salt, with a pearly lustre and a bitter nauseous taste. Insoluble in rectified spirit. Soluble in six parts of cold water, and only slightly more soluble in hot water. The crystals do not lose weight when heated to 300°. Heated to redness, they ignite, evolving spon- taneously inflammable phosphuretted hydrogen, and leaving a reddish-coloured residue of calcium pyrophosphate. (Por analysis, see Atiihor's Analytical Chemistry, 104.) BARIUM HYPOPHOSPHITE. Formula, Ba 2 PH 202 . Molecular Weight, 267. Prepared like the calcium salt, taking barium hydrate instead of calcium hydrate. It is used .in pharmacy for preparing quinine and magnesium hypo- phosphites by double decomposition with their sulphates. PHOSPHOROUS ANHYDRIDE. Formula, P 2 O 3 . Molecular Weight, 110. Referred to under Phosphorus as being spontaneously generated on its contact with the air. When prepared by burning phosphorus in a limited supply of air, it is a white mass, with a slight odour of garlic. Thrown into water it gives a hissing noise, and forms phosphorous acid : — ^2^3'^ 3 ^ 2 ^ “ 2H3PO3. HYDROGEN PHOSPHITE (Syn. Phosphorous Acid). Formula, H3PO3. Molecular Weight, 82. May be prepared by exploding phosphuretted hydrogen with oxygen 2PH3 + 3O2 = 2H3PO3. 4 vols. + 6 vols. That is to say, in the simplest ratio, two gallons of phosphuretted hydrogen require three gallons of oxygen. It also results from the action of phosphorous chloride upon water. (SeeVCl^.) . It is usually found as a syrupy fluid. It acts as a reducing agent even upon Wch a comparatively stable compound as sulphurous acid : — 3H3PO3 + H2SO3 = 3H3PO, + H2S. Hea"t€$d, it is converted into phosphoric acid and phosphuretted, hydrogen. It forms^ith metals a class of salts called phosphites, of no great pharma- ceutical intei^st. {For detection of Phosphites, see Author’s Analytical Chemistry, 68.) PHOSPHORIC ANHYDRIDE. Formula, PgOg. Molecular Weight, 142. Produced by burning phosphorus in a glass globe, having a free supply of dry air, when it collects like a mass of snow at the bottom of the globe. PHOSPHORIC ACID, B.P. 191 It deliquesces in the air, and eagerly unites with water, producing heat, and forming metaphosphoric acid: Theoretically it unites with water to form three varieties of phosphoric acid, although in practice the meta acid is the one always formed by direct union (in the cold). These three varieties are as follows ; — PA + H3O = H^PA = 2HPO3 PA + ^Hp-H.PA . • PA + 3H2O = HgPA = 2H3PO, Metaphosphoric Acid. Pyrophosphoric Acid. Orthophosphoric Acid. HYDROG-EN PHOSPHATE (Syns. Orthophosphoric Acid.' Acidtcm Phosphori- CU 7 U, B.P.). Fornmla, H 3 PO 4 . Molecular Weight, 98. Prepared by boiling phosphorus in very dilute nitric acid. The action is one of direct oxidation, nitric oxide being evolved : — 3P2 + 10HNO3 + 4H2O = -6H3P04 + loNO. The B.P. directs the.operation to be made in a retort furnished with a con- denser at a gentle heat till the phosphorus is dissolved, returning the con- densed nitric acid and water to the retort from time to time. The liquid is then transferred to a porcelain dish and evaporated until it is reduced to four fluid ounces ; next it is removed to a platinum vessel, and the evaporation continued until orange-coloured vapours are no longer formed. The strong syrupy acid thus obtained is diluted to the proper strength, viz. : — 13*8 per cent. H3PO4 {-■ 10 per cent. PgOg). It is noticeable that at the end of the preparation the acid is found, not in the receiver, but in the retort. This is because phosphoric acid is not volatile, and the action is simply one of boiling, instead of distillation. The object of using a receiver is to condense the water and nitric acid which may boil off, so that they may be returned from time to time to the retort, to keep up uniform and continued action without loss of material. The acid, when trans- ferred from the retort, always contains H3PO3, which is only finally changed during concentration in a porcelain dish. The process ought, therefore, to be represented in two steps, thus : — ' 2HNO3 + P2 + 2H2O = 2H3PO3 + 2NO. 3H3PO3 + 2HNOs = 3H3PO4 -h 2NO + H2O. Acidum phosphoricum, B.P., is a colourless liquid, with a sour taste and strongly acid reaction. Specific gravity, i'o8. With ammonio-nitrate of silver it gives a canary-yellow precipitate, soluble in ammonium hydrate and in diluted nitric acid. Evaporated, it leaves a residue, which melts at a low red heat, and upon cooling exhibits a glassy appearance (metaphosphoric acid). {For analysis and impurities, see Author's Analytical Chemistry, page 104.) "When phosphoric acid is evaporated to dryness, it first loses one molecule of water, and at 430° F. becomes pyrophosphoric acid : — 2H3PO4-H2O - H4P2O7. This residue, if further heated to redness, again loses water, and is converted into metaphosphoric acid : — H4P2O7-H2O - 2HPO3. The intermediate step is difficult to obtain. In forming the class of salts called' orthophosphates, PO4 acts as a triad radical. 192 PHOSPHORUS. HYDRO&EN PYROPHOSPHATE (Syn. Pyrophosphoric Acid). Formula, H4P2O7. Is a soft substance of a glassy nature, which may be prepared, although not quite pure, by evaporating phosphoric acid, and heating to 430° F. until, on dissolving a portion in a little cold water, it ceases to give a yellow pre- cipitate with argentic nitrate. Another method is to heat disodium hydro- phosphate until it is entirely converted into sodium pyrophosphate : — aNa^HPO^ = Na^PgO^ + HgO. The residue thus obtained, if digested with a salt of lead, forms plumbic pyrophosphate, which may then be suspended in water, and treated with sulphuretted hydrogen : — PbgPgOy 2H2S = H4P2O7 + 2PbS. It forms salts called pyrophosphates^ having the radical P2O7 acting as a tetrad. By boiling with water it is converted into ortho-, and, by heating to redness, into 7 ?ieta- phosphoric acid. {For detection of Pyrophosphates, see Authors Analytical Chemistry, 68 ) HYDROGEN METAPHOSPHATE (Syns. Metaphosphoric Acid. Glacial Phosphoric Acid). Formula, HPO3. A hard glassy substance which dissolves thoroughly, but not rapidly, in water. It is prepared by evaporating the B.P. acid, and heating the residue to redness. By continued boiling with water it recombines, yielding the B.P. acid. It forms a class of salts called metaphosphates, in which PO3 acts as a monad. {For detection of Metaphosphates, see Author's Analytical Chemistry, page 68.) The three varieties of phosphoric acid may be thus distinguished : — Phosphoric Acids. With Argent-ammonium Nitrate. With Albumen, Orthophosphoric Acid . Pyrophosphoric Acid . . Metaphosphoric Acid Gives a yellow precipitate. Gives a white precipitate. Gives a white precipitate. No effect. No effect. Is coagulated. Orthophosphates are very complex in the possible variety of their formulae, because with the triad radical both monad and dyad bases may form hydrogen ^'Salts. For example, in theory, with sodium we might have : — Na3P04 Trisodium Phosphate. Na'jHPO^ Disodium Hydrogen-phosphate. NaHoP04 Monosodium Hydrogen-phosphate. With calcium we might have : — Ca32P04 .... Tricalcium Phosphate (basic). Ca2Ho2P04 = 2CaHP04 . Dicalcium Hydrogen-phosphate (neutral). CaH42P04 .... Monocalcium Hydrogen-phosphate (acid). COMPOUNDS OF PHOSPHORUS WITH OXYGEN. 193 DIAMMONIUM HYDROGEN-PHOSPHATE (Syn. PJwsphate of Ammonia). Formula, (NH^)oHP 04 . Molecular Weight, 132. , May be formed by mixing phosphoric acid with a slight excess of ammonium hydrate. It may also be directly prepared from bone ash by a similar process to that employed for disodium hydrogen phosphate, using ammonium carbonate instead of sodium carbonate. It is in transparent colourless prisms, soluble in water, but insoluble in spirit. When heated, it evolves ammonia gas, and leaves a residue of glacial phosphoric acid. (For analysis, see Author's AmdyticaA Chemistry, page 104.) DISODIUM HYDROGEN-PHOSPHATE (Syns. Tribasic Phosphate of Soda. SodcePhosphas, B.P.) Formula, Na 2 HP 04 . 12 H 20 . Molecular Weight, 358. Is prepared by digesting bone earth in sulphuric acid, forming monocal- cium hydrogen-phosphate in solution, and depositing calcium sulphate : — Ca32P04 + 2H2SO4 = CaH42P04+ 2CaS04. The pasty mass is then treated with water, and the removal of the calcium sulphate ensured by filtration and concentration. The clear solution of monocalcium hydrogen-phosphate thus obtained is treated with sodium carbonate, which causes a precipitate of dicalcium hydrogen-phosphate, and leaves disodium hydrogen-phosphate in solution : — CaH42P04 + Na2C03 = Na2HP04 -f- CaHP04 + CO2 + H2O. The deposited phosphate is by no means absolutely constant, but often contains tricalcium phosphate. Sodce Phosphas, B.P.., is in transparent, colourless, rhombic prisms, termin- ated by four converging planes, efflorescent, tasting like common salt ; it is soluble in water, its solution having a faintly alkaline reaction. When this salt is heated to redness it yields sodium pyrophosphate : — ■ 2Na2HP04 = Na4P207 H2O. By boiling with water, that salt may be again changed to the original disodium hydrogen-phosphate. {For analysis, see Author's Analytical Chemistry, ^a^e 104.) AMMONIUM and SODIUM HYDROGEN-PHOSPHATE (Syn. Microcosmic Salt). Formula, Na(NH 4 )HP 044 H 20 . Formed by dissolving seven parts of disodium hydrogen-phosphate and one part of ammonium chloride in two parts of boiling water, and crystallizing. This salt is used extensively in blowpipe analysis, because on heating, it evolves ammonia and water, leaving pure sodium metaphosphate. Thus pro- duced, it has the power of dissolving metallic oxides, many of which cause it to assume very characteristic colours. To perform such experiments, a little of the salt is placed in a loop of platinum wire, and heated with the bbw-pipe till a clear bead is obtained. The bead is then touched with the powder to be 'analyzed, and again ignited, first in the inner, and then in the outer flame ; and examined after each heating, when the following effects, among others, may be observed. o 194 PHOSPHORUS. Blowpipe Reactions of Microcosmic Salt. Colour of Bead. In the Inner Flame. In the Outer Flame. Blue .... Amethyst . . Red ... . Green. . . . Cobalt only .... Copper Chromium .... Cobalt and Copper. Manganese. Iron. Chromium. Silica floats about in the bead in undissolved particles, and silver produces an opalescent appearance. AMMONIUM MAGNESIUM-PHOSPHATE. Formula, MgNH^PO^. A white crystalline precipitate produced between magnesium sulphate and a soluble phosphate in the presence of ammonium hydrate, ammonium chloride having been previously added to prevent the precipitation of magne- sium hydrate ; — MgSO^ + NH^HO + NagHPO^ = MgNH^PO^ + Na^SO^ + HgO. It is slightly soluble in cold water, and forms very slowly in dilute solutions. Its production is much accelerated by stirring with a glass rod ; and after collection it must be washed with water containing ammonium hydrate, in which it is almost insoluble. By strong ignition it is converted into magnesium pyrophosphate (Mg^P^O,). It is in this form that phosphoric acid is usually- precipitated and weighed. 222 parts of MggPgOy = 142 parts P0O5, or 234 parts soluble phosphate of limef or 310 parts ‘‘ bone eai'th rendered solublel^ (See Gravimetric- Quantitative Analysis^ in Authors Analytical Chemistry, I 79 -) TRICALCIUM PHOSPHATE (Syns. Tribasic Phosphate of Calcium. Calcis Fhosphas, B.P.) Formula, Ca 32 P 04 . Molecular Weight, 310. Is prepared by dissolving bone ash in hydrochloric acid, monocalcium hydrogen-phosphate and calcium chloride being formed : — Ca32P04-f-4HCl = CaH42P04-f-2CaCl2; and then filtering from insoluble matters and reprecipitating with ammonium hydrate. • CaH42P04 -I- 2CaCl2 +.4NH4HO = Ca32P04 + 4NH4CI -f 4H2O. The precipitate is then washed and dried at 212° Fah. Calcis phosphas, B.P., is a light, white, amorphous powder, insoluble in water, but soluble without effervescence in diluted nitric acid. The solution continues clear when an excess of acetate of soda is added to it, because this phosphate is soluble in all ordinary acids, and even in acetic acid, in which the phosphates of aluminium and iron are insoluble. It is unaltered by heat, and is the form in which phosphorus is found in bone ash. (For analysis, see Author's Analytical Chemistry, page 105.) COMPOUNDS OF PHOSPHORUS WITH OXYGEN 195 DICALCIUM HYDEOGEN-PHOSPHATE. Formula, Ca 2 H 22 P 04 , or CaHPO^. This is the truly neutral, or simplest, combination of calcium and phosphoric acid. It is deposited as a gelatinous precipitate when disodium hydrogen- phosphate is added to an acid solution of calcium chloride, and also in the last stage of the B.P. manufacture of sodce phosphas. MONOCALCIUM HYDEOGEN PHOSPHATE (Syn. Superphosphate of Lime). Formula, CaH 42 P 04 . Molecular Weight, 234. Is produced whenever tricalcium phosphate is acted upon by an acid capa- ble of effecting its solution. This phosphate is the chief active principle of artificial manures ; and it is on the amount of this constituent that their main value depends for fertilizing purposes. It is known in trade as soluble phos- phate., or superphosphate, of lime. The estimation of the amount of soluble phosphate in a manure is an important operation. {See Gravwietric Qiiantiiative Analysis, in Aul/ioPs Analytical Chemistry, I 79 -) TEIFEEEOUS PHOSPHATE (Syns. Ferri Phosphas. Tribasic Phosphate of Iro 7 i). Formula, Fe 32 P 04 . Prepared by precipitating ferrous sulphate with disodium hydrogen-phos- phate in the presence of sodium acetate, washing the precipitate, and drying it at 120° F. : — 3FeS04 + 2Na2HP04-i- 2NaC2H302 = Fe32P04 + 3Na2S04 + 2 HC 2 H 3 O 2 . The sodium acetate is added to ensure the formation of triferrous phosphate, by combining with the excess of SO4 and liberating instead acetic acid, in which it is insoluble. If it were not employed, ferrous hydrogen-phosphate would be formed, thus : — 3FeS04+3Na2HP04 - 3FeHP04 + 3Na2S04. On adding the acetate, this hydrogen-phosphate is all converted into triferrous phosphate. 3FeHP04 + 2NaC2H302 = Fe32P04 - 1 ^ Na2HP04 + 2 HC 2 H 3 O 2 . Ferri phosphas, B.P., is met with as a slate-blue amorphous powder, insoluble in water and acetic acid, but soluble in hydrochloric acid. It is reprecipitable from its solution by the addition of excess of an alkaline hydrate or acetate. The addition, however, of a little citric or tartaric acid prevents its reprecipi- tation by ammonium hydrate. By heat it is changed into ferric phosphate in contact with the air. When first precipitated, triferrous phosphate is white, but turns to a slate- blue on contact with the air ; and as usually sold it is therefore really a com- plex compound, having the formula (Fe32P04)2(FeP04)2Fe203i6H20. It has also been stated, that if the iron salt be added to the disodium hydrogen- phosphate, instead of vice versa, the production of ferrous hydrogen-phosphate cannot be prevented. {For analysis, see Author's Analytical Chemistry, page 105.) 196 PHOSPHORUS. FEERIC PHOSPHATE (Syn. Perphosphate of Iron). Formula, FePO^ Molecular Weight, 151. Is produced as a white precipitate on mixing the solution of a soluble phosphate with ferric chloride in the presence of ammonium acetate. This reaction enables us to separate small quantities of phosphoric acid from all other metals. BISMUTHOUS PHOSPHATE. Formula, BiPO^. Molecular Weight, 303. Is a white precipitate formed when solution of bismuthous nitrate is added to a soluble phosphate. It is insoluble in nitric acid, and is used frequently for the separation of phosphoric acid from other metals. It fails in accuracy, however, in the presence of much aluminium and iron. AMMONIUM PHOSPHO-MOLYBDATE. Is formed as a yellow precipitate when solution of ammonium molybdate in nitric acid is added to a soluble phosphate. This is the most accurate process for the separation of phosphoric acid from all metals. It is performed in practice as follows : — the sample is dissolved in nitric acid, a large excess of ammonium molybdate dissolved in nitric acid is added, and the whole is allowed to stand for twelve hours in a warm place. The precipitated ammo- nium phospho-molybdate is collected, washed with water containing a little of the precipitant, and then dissolved in ammonium hydrate.. The solution thus obtained is then ready for treatment with the ordinary process. {See Gravi 77 ietric QuaTititatwe ATialysis m Author's Analytical Chemistry, 179.) This process is not effectual in the presence of arsenic or silicic acid. The following is the composition of ammonium phospho-molybdate dried at 212° F., as given by Muntzinger. , Phosphoric Acid 3*962 Ammonium Oxide . . . . . . 3*577 Molybdic Acid 92*461 . 100*000 COMPOUNDS OF PHOSPHORUS WITH SULPHUR. By heating amorphous phosphorus with sulphur, a very rapid and violent reaction takes place ; and, according to the quantities of each element used, \ the following series of compounds can be made : — Hemisulphide P4S. Monosulphide . P»S. Sesquisulphide . PIS3. Trisulphide P2S3. Pentasulphide , . . . . . . PgSs- Dodecasulphide . PgSig. None are of interest in medicine or pharmacy. CHAPTER XII. ARSENIC, ARSENIC (Syn. Arseniatm). Symbol, As. Atomic Weight, 75. In the Free State, AS 4 , = 2 volumes. Molecular weight, 300. Vapour Density, referred to Hydrogen, 153 at 860° C ; referred to Air, 10*6. This metalloid is one of the most extensively distributed substances in nature, although usually in small quantities. It is found native in silver and tin ores, also in the form of the yellow sulphide called orpiment (AsgSg) and the red sulphide called realgar (AsgSg). Its most abundant source, is the mineral commonly called arsenical iron pyrites (ferric sulpharsenide, Fe2'''S2''As2, or 2FeSAs), from which it may be obtained by sublimation, out of contact with the air. On a small scale it may.be produced by heating arsenious anhydride with a mixture of dried sodium carbonate and potassium cyanide in a dry test-tube the mouth of which is lightly closed by the thumb, when arsenic will form as a mirror inside the tube. Arsenic is a solid, crystallizing in octahedra, and volatilizing at 356° F., without previously fusing. It has a brilliant metallic lustre, which, however, rapidly tarnishes in the air ; and its vapour is of a yellowish tinge, and possesses a peculiar, garlic-like, odour. When heated in the air, it rapidly absorbs oxygen 'and deposits a crystalline sublimate of arsenious anhydride. It combines directly with chlorine, bromine, and iodine ; and so energetic is the action, that powdered arsenic introduced into chlorine gas suddenly in- flames, producing thick white fumes of arsenious chloride. Metallic arsenic is sometimes used in veterinary medicine, and is very poisonous, but not so much so as arsenious anhydride. {Fot" detection of Arsenic in cases of poisoning, see Author’s Analytical Cliemistry, page 144 ; for the genei'al reactions and separation, see page 33.) HYDROGEN ARSENIDE (Syns. Arseniuretted Hydrogen. Arsenamim). Formula, AsHg. Molecular Weight, 78. Dimity, ref ert'ed to Hydrogen,Z^. Density, referred to Air, 2’695. Is a very poisonous, colourless gas, with a strong garlic odour, which is produced whenever an easily-reducible compound of arsenic (such as arsenious anhydride) is brought into contact with nascent hydrogen, generated by a mixture of zinc and dilute sulphuric or hydrochloric acid. Taking the above- mentioned substance, the reaction would be : — AS2O3 + 6H2 = zAsHg + 3H2O. Mixed with excess of oxygen, and an electric spark passed, it explodes, forming arsenious anhydride and water. 2ASH3 + 3O2 = AS2O3 + 3H2O. 4 vols. 6 vols. 198 ARSENIC. The fact that arsenic in the state of vapour only occupies half the space of an atom of hydrogen, shows that two volumes (one molecule) of arseniuretted hydrogen must contain three volumes of hydrogen and half a volume of arsenic. When a light is applied to the gas as it issues from a jet, it takes fire, and burns with a long, narrow, greenish flame, producing copious fumes of arsenious anhydride. Arseniuretted hydrogen is decomposable by heat ; and when a current of it is passed through a tube heated to dull redness, a dark ring of metallic arsenic is deposited inside the tube. When compounds containing antimony are brought into contact with zinc and dilute sulphuric acid, a very similar gas is produced, called antimoniuretted hydrogen (SbHg). In general behaviour, this latter gas is extremely like arseniuretted hydrogen, except that it is inodorous, and its flame has a bluish tint. These two gases may be readily distinguished by passing them into solution of argenic nitrate, when the arseniuretted hydrogen will become decomposed, forming arsenious acid, which will remain in solution ; while the chief product of the decomposition of the antimoniuretted hydrogen will be argentic antimonide, which will deposit. In the case of arseniuretted hydrogen, the reaction is : — 6AgNOg + 3H2O + AsHg = 6HNO3 + HgAsOg + sAgg. With the antimoniuretted hydrogen, the following decomposition occurs : — sAgNOs + SbHg’ - sHNOg + AggSb. Another very marked distinction consists in the fact, that while arseniuretted hydrogen is evolved on adding arsenical solution to a heated mixture of zinc and solution of potassium hydrate, it is not possible to produce antimoniu- retted hydrogen in that way. This is sometimes attributed to the fact that the antimony compounds are thrown down in an insoluble form by the action of the alkali, and so it is prevented from combining with the nascent hydrogen ; but the true explanation is doubtless to be found in the much greater sta- bility possessed by the oxides of antimony over those of arsenic. When arseniuretted hydrogen is passed into a solution of a cupric salt, it deposits cupric arsenide : — 6CUSO4 + 4AsHg = 6H2SO4 -f- 2CugAs2. It acts generally as a reducing agent; and when passed into a mercuric solution it produces the corresponding mercurous salt, and deposits metallic arsenic : — 6HgCl2 + zAsHg = 3Hg2Cl2 + 6HC1 + As2. In addition to the gaseous compound just described, a solid hydride of arsenic has been prepared, to which the formula As^Hg has been assigned. The remaining metallic arsenides are of no great interest to pharmacists. ARSENIOUS ANHYDRIDE (Syns. Anhydrous Arsenious Acid. ^ Acidiim Arseniosiim. White Arsejiic). Formula, As20g. Molecular Weight, 198. Vapour Density, referred to Hydrogen, 188. Theory, 198. Vapour Density, refe 7 'red to Air, 13. ’ Specific Gravity, 3*6 to 3*7. Is obtained during the roasting of arsenical iron pyrites, and other ores containing arsenic. The metal volatilizes, combines with the oxygen of the air, and deposits as arsenious anhydride in long tubes, or in chambers, provided for the purpose. The deposit consists of the anhydride in a very finely- divided state, called by the workmen flour of arsenic. This is submitted to ANHYDROUS ARSENIOUS ACID. 199 resublimation, and the sublimate received in cylinders, where it collects in masses, which are broken up and sold as vitreous arsenic. These lumps gradually lose their glassy appearance, and become like masses of porcelain, but usually retain here and there streaks of the vitreous arsenious anhydride which has not suffered alteration. Vitreous arsenious anhydride is amorphous ; but when it becomes opaque and porcelaih-like, it changes to the crystalline form, and is then found to crystallize in octahedra, and when sublimed in a small tube it deposits as a white ring of opaque crystals having that form. The specific gravity of the vitreous anhydride is *3 7 8 and of the crystalline, 3*68. The former variety is also soluble in 25 parts of cold water, while the latter requires 80 parts of the same menstruum. Both are insoluble in ether, and only slightly soluble in alcohol ; but while the former dissolves better in strong than in dilute spirit, the case is just reversed with the latter. Arsenious anhydride is called (but erroneously) acidum arseniosum in the B.P., and is thus described by that authority : — Occurs as a heavy white powder, or in sublimed masses which usually present a stratified appearance, caused by the existence of separate layers differing from each other in degrees of opacity. When slowly sublimed in a glass tube, it forms minute brilliant and transparent octahedral crystals. It is sparingly soluble in water, and its solution gives with ammonio-nitrate of silver a canary- yellow precipitate insoluble in water, but readily dissolved by ammonia and by nitric acid. Sprinkled on a red-hot coal, it emits an alliaceous odour. It is entirely volatilized at a temperature not exceeding 400° F. {For analysis^ see AtithoFs Analytical Chemistry, io5-) Arsenious anhydride is an exceedingly powerful poison, the antidotes to which are calcium hydrate, magnesium oxide, and ferric hydrate, the latter being by far the best. All three act by forming insoluble arsenites, the ferric arsenite being the least easily dissolved. (^For particulars of the conditions^ for using ferric hydrate, see Ferric Arsenite.) An aqueous solution of arsenious anhydride, in consequence partly of its sparing solubility in cold water, displays only a slightly acid behaviour towards litmus paper, and does not possess any marked taste. If it be heated with black flux., or a mixture of potassium cyanide and sodium hydrocarbonate, or simply powdered charcoal, arsenic is evolved, and condenses on the cool part of the vessel as a metallic coating. When cupr-ammonium sulphate is added to the solution, green cupric arsenite falls. {For other tests ^ see Arseninretted Hydrogen.) When copper is boiled with strong hydrochloric acid, arsenious anhydride, and water, a deposit of cupric arsenide is formed upon the metal ; and it is on this fact that RemcFs test depends for its success. The deposit is decomposed by heating in an open tube, when it gives rise to a sublimate of minute octahedra of arsenious anhydride. The addition of a mineral acid, especially hydrochloric, augments greatly the solubility of arsenious anhydride in water. When a solution of the vitreous variety is made in boiling dilute hydrochloric acid, and allowed to crystallize in the dark, the production of the crystals is observed to take place accompanied by a small flash of light. This effect is more visible if the crystallization be hastened by shaking the vessel. Arsenious anhydride is also very soluble in solutions of alkaline carbonates, and both these facts are taken advantage of in the following B.P. preparations : — I. Liquor Arsejiici Hy dr ochloricus. Prepared by boiling 80. grains of arsenious anhydride in four ounces of water with 2 drachms of hydrochloric acid, and making up to i pint with water. 200 ARSENIC. Thus made, Liquor Arsenic! Hydrochloricus is a colourless liquid, having an acid reaction. Specific gravity, i ’oop. When arsenious anhydride is boiled with water and hydrochloric acid in anything like the proportions recommended above, no combination occurs. The only mode of causing the two bodies to unite, is to distil them without diluting the acid in the least. 2. Liquor Arsenicalis (Syn. Fowler's Solution). Prepared by placing 8o grains of arsenious acid and carbonate of potash respectively in a flask with ten ounces of the water, and applying heat until a clear solution is obtained. Allow this to cool. Then add 5 fluid drachms of compound tincture of lavender, and as much distilled water as will make the bulk one pint. The result is a reddish liquid, alkaline to test-paper, and having the odour of lavender. Specific gravity, I’ooq. Made as thus directed, liquor arsenicalis is simply a solution of arsenious anhydride in potassium carbonate. If, however, the solution were stronger and the boiling continued longer, a compound could be formed, having the formula 2KH2ASO3.AS2O3. Arsenious anhydride is estimated according to the B.P. by means of volu- metric solutmt of iodme. This solution acts as an indirect oxidizer, converting it into arsenic acid, the following reaction occurring : — ASgOg + 5H2O -f- 2I2 = 2H3ASO4 + 4HI. Thus it is plain that one molecular weight of arsenious acid represents four atomic weights of iodine. {See Volumetric Quantitative Analysis^ in Author’s Analytical Chemistry, 157,) Arsenious anhydride is supposed to form arsenious acid, HgAsOg, in con- tact with water ; but the acid has not been isolated. Displacement of its hydrogen by basylous radicals produces a class of salts called arsenites, of which there are several varieties, as in tlie case of phos- phites and phosphates. Thus we have (M, being any monad metal) : — ■ Arsenites ........ Mg'AsOg'". Pyroarsenites . . ... . . . AsgOg'^ Metarsenites ....... M'As02'. The different salts known as arsenites are, however, insufficiently defined to render it convenient to establish the distinction which is theoretically desirable. Ammonium arsenite in solution is entirely decomposed by evapo- ration, the acid being deposited in a pure condition, and ammonium hydrate being evolved. Potassium and sodium arsenites are alkaline in reaction whatever may be the amount of the arsenious anhydride they contain. Calcium, strontium, and barium oxides form soluble salts on boiling with arsenious anhydride (in excess) and water. On acting upon the solutions thus produced with the hydrates of the same metals, hydrato- (or oxy-) salts are produced, soluble like the hydrates in salts of ammonium, and also in acids. Silver, magnesium, and dyad, triad, tetrad, pentad, and hexad metals form insoluble arsenites, all of which may be procured by precipitation, except when ammonium salts, free hydrochloric acid, and in some cases free acetic acid, are present. {Eor detection of Arsenites, see Author’s Analytical Chemistry, 71.) CUPRIC ARSENITE (Syn. Scheelds Green). Formula, CuHAsOg or CU32ASO3. One or other of these two bodies is precipitated — I. When an alkaline arsenite is mixed with a cupric solution: — K2HASO3 + CuSO^ = CuHAsOg + K0SO4. COMPOUNDS OF ARSENIC. 201 2. When solution of pure arsenious acid is treated with cuprammonium sulphate free from excess of ammonia. This reaction is best performed by adding a little cupric sulphate to the suspected solution of arsenious acid, and then dropping in very dilute ammonium hydrate with great care until the precipitate forms. The second of the two greens is the brighter in colour, and both are soluble in the least excess of acid or alkali. A solution in excess of potassium hydrate alters rapidly, depositing cuprous hydrate, and leaving potassium arse 7 iiate in solution, the arsenious acid oxidizing itself at the expense of the cupric salt. A modification of Scheele’s green, commonly termed Schweinfurth, mitis, or imperial green, and when not so pure, Brunswick green, is prepared by boil- ing verdigris with arsenious acid and water. It is truly a cupric acetometar- senite, and is much employed for colouring wall papers, to the detriment of the health of persons inhabiting the rooms so ornamented. This poisonous effect is doubtless owing to minute particles detaching themselves from the paper and floating in the air. The dangers of arsenical wall papers are un- doubted, although perhaps somewhat exaggerated in the minds of many. FERRIC OXYARSENITE. Formula Indefinite. Is most probably the compound the formation of which renders ferric hydrate the most valuable antidote to arsenical poisoning. For this purpose fourteen parts of ferric hydrate must be employed to one part of the arsenious anhydride supposed to be present. Arsenious anhydride does not combine with the ferric hydrate unless freshly prepared ; and it is therefore always advisable to produce it at the instant of administration. Because of the purgative power of magnesium salts tending to work off the insoluble ferric oxyarsenite, it is best to precipitate the ferric hydrate with magnesium oxide {??iagnesia, B.F.) or magnesium oxycarbonate which has been heated until a portion only is converted into oxide. Sodium or potassium hydrates or carbonates may also be used ; but ammonium hydrate must not be employed, because of the marked solubility of the ferric oxyarsenite in ammoniacal salts. A quarter of an ounce of magnesium oxide (or three times the quantity of ordinary washing soda in crystals) will take two or three times its amount of the official liqitor ferri perchloridi fortioi% and will render innocuous a dozen grains or more of the arsenious anhydride. ARSENIC ANHYDRIDE (Syns. Anhydrous Arsenic Acid. Pentoxide oj . Arsenic'). Formula, AsgOg. Molecular Weight, 230. Is prepared, — 1. By strongly heating the arsenic acid. 2. By heating arsenious oxide with nitric acid, and decomposing the arsenic acid formed at a high temperature. 3. By evaporating to dryness, and heating the residue of a solution of arsenious oxide through which chlorine gas has been passed. The reaction in the last case, would be : — 1. AS2O3 + 5H2O + 2CI3 = 2H3ASO4 + 4HCI. 2. 2H3ASO4 = AS2O5 -f- 3H2O. A Strong red heat splits up arsenic anhydride into arsenious anhydride and oxygen, the former at the same time volatilizing. Thus no residue is left. 202 ARSENIC HYDROGEN ARSENIATE (Syn. Arsenic Acid). Eormnla, HgAsO^. Molecular Weight, 142. May be prepared 1 . By dissolving arsenious anhydride in nitric acid, evaporating to dryness, and moistening with a little more nitric acid, in order to ensure complete con- version. The reaction would be : — AsgOg + 2H2O + 2HNO3 = 2H3ASO4 + NgOg. 2. By passing chlorine into a solution of arsenious anhydride, when the decomposition represented under arsenic anhydride occurs. 3. When a solution of iodine acts upon arsenious anhydride, likewise in solution, the action being : — AsgOg + sHgO + 2I2 = 2H3ASO4 + 4HI. 4. When hydrochloric and nitric acids are unitedly made to oxidize arseni- ous anhydride, the hydrochloric acid converting it into arsenious chloride, and the nitric acid transforming the greater part of this into arsenic acid. The two stejDS will be : — 1. AS2O3 + 6HCI = 2ASCI3 + 3H2O. 2. 2ASCI3 + 5H2O + 2HNO3 = 2H3ASO4 + N2O3 + 6HC1. The solutions obtained in the above modes deposit, at the ordinary atmo- spheric temperature, crystals containing one molecule of water of crystallization, which are very deliquescent, and consist of prismatic and transparent plates. If these be fused at 212° F. they yield the true acid, HgAsO^. At about 300° F. this acid gives off half an equivalent of water, and yields pyroarsenic acid, thus : — 2H3ASO4 = H4AS2O7 + H2O. Unlike the tri-hydrated acid, the solution of this acid (pyroarsenic) in water is attended with considerable development of heat. At 403° F. pyroarsenic acid yields a salt-like mass of HAsOg (metarsenic acid). Arsenic acid is strongly corrosive, and attacks the cuticle, producing blisters. It is employed in dyeing to set free chlorine from calcyl chloride. A mixture of arsenic acid and gum is painted in patterns upon a coloured article, and when this is immersed in what is termed “the chloride of lime vat,” the chlorine set free by the acid bleaches the part of the material which has been thus treated. Arsenic acid and arseniates are less powerful as destroyers of life than the arsenites and arsenious acid. Although arsenic acid resembles phosphoric acid in many particulars, it differs from it in the ease with which the products of the action of heat upon it (arsenic anhydride, metarsenic acid, and pyro- arsenic acid) take up water, re-forming the true or ortho-acid. Pure arsenic acid in solution acts upon iron and zinc exactly like dilute sulphuric acid, liberating hydrogen, but in the presence of an acid it is advisable to employ an alkaline acetate, so that the only free acid may be acetic, in which arseniates dq not as a rule dissolve. An example of this is seen in the manufacture of ferri arsenias, B.P. < Afsgniates require the addition of hydrochloric acid to their solutions, pre- vious to forming a precipitate with sulphuretted hydrogen ; and the gas must be passed for a long time, as precipitation does not occur until the whole is first reduced to the arsenious condition. A great analogy obtains between arseniates and phosphates, and also be- tween arsenic and phosphoric anhydrides, both of which may be used to pro- duce many anhydrides of “ organic ” acids, owing to, their powerful affinity for water. The crystallizable salts of the two radicals are isomorphous. COMPOUNDS OF ARSENIC. 203 Thus there are two salts of sodium containing, respectively, twelve and seven molecules of water of crystallization. These are — Disodium Orthophosphates : — Na2HP04.i2H20, and NagHPO^.yHgO. With which are comparable — Disodium Orthoarseniates : — Na2HAs04.i2H20, and Na2HAs04-7H20. Both of the 12H2O salts form prismatic crystals, the arrangement of the seven-molecule salt being rhombic. All neutral arseniates give a brick-red precipitate with argentic nitrate, which serves to distinguish them from either arsenites or phosphates. {For detection and separation of Arseniates, see Author's Analytical Chemistry, 72.) DIAMMONIUM HYDBOGEN-ARSENIATE (Syn. Arseniafe of Atfwiojiium'). Formula, (NH 4 ) 2 HAs 04 . Is produced by adding ammonium hydrate to arsenic acid to slight alkaline reaction : — H 3 As 04 -F 2 NH 4 H 0 = (NH 4 ) 2 HAs 04 -f- 2 H 20 . The solution cannot be evaporated by heat without decomposition and production of monammonium hydrogen-arseniate, NH4H2ASO4, so sponta- neous deposition of crystals must be allowed to take place by simply exposing the solution to the air in a warm place. These crystals themselves decom- pose by exposure to the air, becoming efflorescent and evolving ammonia gas. The solution of diammonium hydrogen-arseniate may be often used with advantage in analysis, instead of the corresponding disodium hydrogen- phosphate, as a precipitant for magnesium. When evaporated to dryness and heated, it entirely decomposes into a set of volatile products, viz., nitrogen, ammonia gas, arsenic, and water. DISODIUM HYDROGEN-ARSENIATE (Syn. SodcB Arsenias). Formula, Na 2 HAs 04 . Molecular Weight, 186. Is prepared by fusing together arsenious anhydride, sodium carbonate, and sodium nitrate, forming sodium pyroarseniate : — AS 2 O 3 + Na2C03 + 2NaN03 = Na4As20y + N 2 O 3 -f COg, and then pouring out while fused on a slab, and when cool boiling the residue with water : — Na4As207 H- 15H2O = 2 (Na 3 HAs 047 H 20 ) (the offlcial crystallized salt). SodcB Arsenias, B.P., is in colourless transparent prisms soluble in water, the solution being alkaline. Heated to 300° it loses 40-38 per cent, of its weight. {For analysis, see Author's Analytical Chemistry, io 5 -) The Pharmacopceial crystallized salt, though nominally containing 7H2O, is sometimes liable to be contaminated with a salt of 1 2 equivalents of water of crystallization, and consequently suffers a considerable deterioration in strength. Roughly speaking, the percentage of As would be reduced by the entire substitution of the latter for the former from 24 to 18-5. The difference in the amount of water in Na2HAs04.i2H20 and Na2HAs04.7H20 is that 204 ARSENIC. between 5373 and 4o’39 per cent. For this reason the official solution of disodium arseniate {liquor sodce. arseniatis) consists of four grains of the anhydrous NagHAsO^ dissolved in an ounce of distilled water. The heat of 300° F. employed to dehydrate the crystals does not convert the residual salt into pyroarseniate, a temperature of 390° to 400° F. being required to effect this change. TRIARGENTIC ARSENIATE (Syn. Arseniate of Silver). Formula, Ag3As04. . Is the chocolate precipitate produced by all soluble arseniates in argentic nitrate solution, or by the free acid in solutions of argent-ammonium nitrate, also during the volumetric estimation of disodium arseniate. It dissolves in excess of ammonium hydrate, and in acetic and nitric acids, whilst hydro- chloric acid converts it into chloride. It is distinguished from argentic arsenite by its colour and by not leaving metallic silver when heated. CALCIUM HYDROGEN- ARSENIATE. Formula, CaHAsO^, and BARIUM HYDROGEN-ARSENIATE. Formula, BaHAsO^. Are the white precipitates produced on adding calcium and barium chlorides respectively to disodium arseniate, the- formation of which constitutes two of the B.P. tests for that body. As produced in this manner, they frequently contain more or less of the trimetallic salts. The former is found native, being contained in the minerals pharmacolite and haidingerite. MAGNESIUM AMMONIUM ARSENIATE (Syn. Ammonia Arseniate of Magnesia). Formula, MgNH^AsO^. Is formed in magnesian solutions by a mixture of a soluble arseniate and 'ammonium hydrate. Like magnesium ammonium phosphate, it is a white crystalline precipitate almost insoluble in a weak solution of ammonium hydrate, but dissolving in pure water slightly. When precipitated it contains Mg(NH4)As04.6H20, but by drying at 212° F. the formula becomes 2Mg(NH4)As04.H30 (molecular weight, 380). ' ZINC ARSENIATE. Formula, Z1I32ASO4. A white precipitate formed on adding zinc sulphate to disodium arseniate, according to the reaction stated in the B.P. The decomposition is rather complex, being : — 4Na2HAs04 -f 4ZnS04 = Zn32As04 -f- ZnH 42 As 04 -i- 4Na2S04. The latter salt is soluble, the former being that which falls as the pre- cipitate. In the presence of a little ammonium or sodium hydrate, the whole is converted into the trimetallic salt, thus : — 2Na2HAs04 -f- 3ZnS04 -f 2NaH0 = Zu32As04 -f- 3Na2S04 -f 2H0O. TRICUPRIC ARSENIATE (Syn. Arseniate of Copper). Formula, CU32ASO4. A green precipitate falling from a solution of cupric sulphate or cupr- ammonium sulphate upon the addition of a soluble arseniate. The reaction with the first salt and the ordinary disodium arseniate is the same as that with the latter body and zinc sulphate. In the case of the addition of cupr- ammonium sulphate no acid salt is formed, but if enough be added all the arseniate falls. There are six minerals in which cupric arseniate is contained, eiichroite and olivenite being the most important. COMPOUNDS OF ARSENIC. 205 TEIFERROUS ARSENIATE (Syn. Ferri Arsenias). Formula, Fe 32 AsO^. Results from mixing a solution 'of ferrous sulphate with sodium acetate and disodium arseniate, washing the precipitate, and drying at a temperature not exceeding 100° Fahr. The reaction is : — 3FeS04 + 2Na2HAs04 + 2NaC2H303 = Feg2As04 + 2HC2H3O2 + 3Na2S04. In consequence of the loss of arseniate which would occur if a similar reaction to that represented under zinc arseniate were allowed to take place (viz., the formation of a soluble ferrous hydrogen-arseniate), sodium acetate is added to prevent such an action. It does this by giving up its sodium to the spare molecule of SO4, and thus liberating acetic acid, in which the triferrous arseniate is not soluble. It has been stated that the addition of the acetate prevents the formation of free sulphuric acid, but such a reaction could never take place in the presence of a neutral arseniate. The real fact is doubtless, that it prevents the production of ferrous hydrogen-arseniate (FeHAsO^?). Ferri Arse 7 iias is a tasteless amorphous powder of a green colour, insoluble in water, but readily dissolved by hydrochloric acid. Boiled with an excess of sodium hydrate, it is converted into ferroso-ferric hydrate, and sodium arseniate passes into solution. When first precipitated, the salt is white ; but by exposure to the air it becomes greenish, owing to the formation of ferric oxyarseniate. {For analysis, see Author's Analytical Chemistry, 106.) COMPOUNDS OF ARSENIC WITH THE HALOGENS. ARSENIOUS CHLORIDE. Formula, AsClg. Is produced (accompanied by a flash of light) when powdered arsenic is dropped into chlorine, and is usually prepared by distilling arsenious anhydride wjth strong hydrochloric acid. It is a colourless, volatile, and very poisonous liquid, which, in contact with water, forms arsenious and hydrochloric acids. ARSENIOUS IODIDE. Formula, Aslg. Is a deep-red crystalline solid, produced by heating iodine with arsenic. A bromide and fluoride also exist, which are fluid. COMPOUNDS OF ARSENIC WITH SULPHUR. Arsenic unites with sulphur in three proportions, viz : — ARSENIC DISULPHIDE (Syns. Realgar. Red Sulphide of Arsenic. Red Orpiment). Formula, AsgSg. This body exists in nature as crystalline prismatic masses of a red or orange colour, in many parts of Europe (Switzerland, Bohemia, etc.) and in North America. It burns with a blue flame, producing sulphurous anhydride and arsenious anhydride. When used for painting on distempered walls, it is said to evolve arsenical fumes. It may be prepared by heating arsenious anhy- dride or metallic arsenic with sulphur, in atomic proportions (75 of As and 32 of S). 2o6 ARSENIC. When a salt analogous to ammonium sulphydrate is digested with arsenic disulphide, hyposulpharsenites are produced. The most easily prepared is : — AMMONIUM HYPOSULPHARSENITE. Formula, NH^AsS^. Which deposits in brown grains on keeping a neutral solution containing arsenic disulphide dissolved in ammonium sulphydrate in a closed vessel. None of these salts are of pharmaceutical interest. ARSENIOUS SULPHIDE (Syns. Yellow Sulphide of Arsenic. Kinfs Yellow. Auripig 7 nentum. Orpiment). Formula, AsgSg. Is the precipitate formed by sulphuretted hydrogen in arsenious solutions. In nature it is found in translucent, yellow, cleavable prisms. It may be fused and volatilized at a high temperature without decomposition. The native article often contains more arsenic than the formula would indicate, and it is therefore a dangerous preparation which is rarely used. It is insoluble in boiling solution of hydrogen-potassium tartrate and in hydrochloric acid. When treated with cold potassium (or sodium) hydrate, an analogous decomposition occurs, as when antimonious sulphide is boiled with either of these substances, namely : — 4AS2S3 + loNaHO = 6Na(AsS2) + 2Na2HAs03 + 4H2O. (Sodium meta- sulpharsenite.) On adding an acid, however, the precipitate is pure arsenious sulphide, no sulphuretted hydrogen being evolved. 6Na(AsS2) + 2Na2HAs03 + loHCl = 4AS2S3 + loNaCl + 6H2O. AMMONIUM SULPHARSENITE. Formula, (NH4)3AsS3. Is the body formed in the qualitative analysis of metals of the second group, when the precipitate caused by sulphuretted hydrogen is digested in ammonium sulphide. When sulphuretted hydrogen is passed into a solution containing arsenic acid or an arseniate., a precipitate does not form sometimes till after the lapse of some hours. This precipitate when formed is yellow, and answers when analyzed to the formula of AS2S5. By treatment with carbon disulphide, however (or any other suitable solvent), an amount of sulphur is dissolved out, and AS2S3 is left. We therefore consider that the AS2S5 is not a truly definite arsenic sulphide, but only a mixture of arsenious sulphide and free sulphur. CHAPTER XIIL HYDROCARBONS AND THEIR DERIVATIVES. Formerly the substances which are treated of in this and the succeeding chapters were viewed as being the products of some mysterious influence called “ vital force, and their study was therefore separated from that of the elements, and classed as organic chemistry. In 1828, however, Wohler succeeded in making urea by simply heating ammonium cyanate ; and subsequently it was discovered that potassium cyanide could be made by passing nitrogen over carbon and potassium hydrate heated to redness. This step gained, the ab- solute synthesis of urea from its elements, without the aid of “ vital force,” was quickly accomplished. Again, by passing the electric spark between carbon points in an atmosphere of hydrogen, acetylene, CgHg, was obtained : — Cg + Hg = C2H2. By acting on this compound with nascent hydrogen, we can get ethene, C2H2 + H2 = C2H,. When ethene is placed in contact with strong sulphuric acid, it forms ethyl sulphuric acid : — C2H4 + H2SO4 = C2H5HSO4. Lastly, by acting on ethyl sulphuric acid with water, ordinary alcohol is formed : — C2H5HSO4 + H2O - C2H5HO + H2SO4. Thus we have another body hitherto only produced by fermentation, and the very existence of which was supposed to be due to vital force, made directly from purely inorganic constituents. In thus doing away with the term organic body, the student must note that the true organized bodies, such as animal and vegetable tissues, still remain a distinct group unproduceable without the aid of the vital force. A marked property of many of these bodies is, that they are isomeric with each other, i.e., having a similar percentage composition, but differing in pro- perties. Isomeric bodies (lo-os, equal j /^epos, part) may be in turn classified as follows : — T. Truly isomeric: this name is given to bodies which, differing only in physical properties, undergo exactly similar decompositions when submitted to the action of other bodies or of heat. Examples : the volatile oils of lemon and of turpentine. 2. Metameric bodies (/xcra, beyond ; a changed condition) are those which, while they are alike in percentage composition and molecular weight, yet undergo different decompositions by the action of reagents. 2o8 HYDROCARBONS AND THEIR DERIVATIVES. 3. Polymeric "bodies are those which, although differing in molecular weight, have an analogous percentage composition. This is most characteristic of a certain series of hydrocarbons which are all polymeric (ttoXv's, many ; ix 4 po<;, part) with methene, CHg. In order to see the beautiful regularity and simplicity of the compounds of carbon and hydrogen, we must first glance at, — I. Homologous and Isologous Series of Hydrocarbons. It has been already shown (see page 136) that the atom of carbon can form an endless variety of compounds, commencing with CH^ and increasing by a constant addition of CHg, and that such a series is called homologous, and each series is represented by a typical formula. The ordinary saturated series, having the formula C,,H2n+2, can lose a molecule of hydrogen, and so give birth to another series having the formula C^IIgn. This giving up of hydrogen may be carried on through many more degrees ; but the following table shows the chief series thus constituted. The nomenclature is obtained by uniting a prefix of “ meth, eth,’' etc., which indicates the number of carbon atoms, and an affix of ‘‘ ane, ene, ine,” etc., which indicates the series, thus : — Typical Formula. -ane. CnHon+a -ene. -ine. Cnll 2 n -2 -one. C11II211 - 4 -nne. C11H2U- Meth- ... c . .. CH, . .. CH, . . . . — ... — Eth- ... , Cj . .. . .. C,H, , C3H3 . .. — ... — Prop- . . . C3 . .. C3H3 . •• C3H3 . C3H, . .. CgH. ... — But- ... C4 • .. .. .. QH3 . .. C4H3 . .. QH, ... QH3 Pent- ... C5 . .. . .. C3H13 . .. C3H3 . .. C3H3 ... C5H, Hex-^ ... C3 . •• CeHi, . - C3H32 . •• QHjq. - C3H3 ... CeHe so on by the etc. . . etc. . . etc. . . . etc. ... etc. Greek numerals. por example, the formula of ethane being wanted, we consider that eth - Cg and a?te — } therefore Cg and H twice two, viz. four, and two added = Hg : ergo the formula of ethane is CgHg. By diligently studying and mas- tering this nomenclature, the formulation of any body is made perfectly simple. Running down the table, we have the homologous series, differing by CHg \ and running across, we have the isologous series, differing by Hg. All members of these series are hydrocarbons of even atomicity, derived from saturated molecules by the abstraction of one or more molecules of hydrogen (pairs of hydrogen atoms). They are all capable of existing in the free state, and are known by special names, such as paraffins, olefines, etc., as hereafter described. II. Unsaturated Hydrocarbon Radicals (hasylous). Each saturated hydrocarbon, moreover, besides possessing the power of giving up Hg to form other hydrocarbons capable of free existence, can also part with single atoms of H, thus producing compounds of uneven atomicity, which do not exist in the free state without duplication, and behave as hasylous radicals. These radicals are named by adding yl to the name of the even hydrocarbon from which they are derived, except the monad series in which the final ane is converted into_y/. Taking a table of the full possible hydrocarbons thus obtainable, with the prefixes and affixes as above, we have : — HYDROCARBONS.— TYPICAL FORMULA. 209 CQ {2; o PC| < o o p w 0 p p 1 o p <1 o M P H « s, 1?^. §•? fl 'u u fl rt c^ (U -2 o d ^ 5=1 0 1^ 1 I 2 g ?-i (D O) U s o oi CL) >% >^ eg S £ P 9 (1) 3 -G ?H ^ c2 .S g S o ^ *5 -73 s ^ >» !5J3 .-t^ G o V o G tl 8 ^ >> p The radicals all behave like metals, and form salts by displacement of the hydrogen of acids. Their chlorides, bromides, or iodides are called haloid ethers, their oxides simple ethers, their hydrates alcohols, their salts with 210 HYDROCARBONS AND THEIR DERIVATIVES. oxygenated acids, compound ethers, and their hydrides are the corresponding hydrocarbons. For example, taking the monad radical ethyl, we have — Haloid ether . . . ethyl iodide. Simple ether . . . (C2H5)2'0, ethyl oxide {ether ^ B.P.). Alcohol .... CgHgHO, co 7 nmon alcohol. Compound ether . . C,^^.C^^O<^.,ethyl acetate {acetic etJw^Y*. Vi). Hydride .... CgHg.H, ethane. These basylous radicals can also displace more or less completely the hydrogen of ammonia to form amines ; Example, — ( (C2H5)' Ethyla 7 ?ime, NH2(C2Hg)', or N < H i H When the hydrogen of ammonia is entirely displaced by a triad radical, the resulting compound is called a nitril. The cya 7 iides of the monad series may be viewed as being the nitrils of the triad radical i 7 ri 77 iediately above m mwiber of carbo 7 is, thus : — Methyl cyanide, (CH3)'CN - (C3H3)"'N, ethe 7 iyl nitril. Ethyl cyanide (C2H5)'CN = profenyl nitril. It is by this means that we can pass from any one series to that immediately above it in complexity of carbon. The basylous radicals can unite with metals to form saturated compounds, capable of free existence, and called organo-metallic bodies ; Example, — Zinc ethyl .... (C2H5)2'Zn". Lastly, they can replace part or the whole of the hydrogen of phosphuretted, arseniuretted, and antimoniuretted hydrogen, to form bodies called respec- . tively phosphines, arsines, and stibines, thus— Triethyl Phosphine, P'"(C2H5)3'. Triethyl Stibine, Sb'"(C2H5)3'. ' JII. Oxygenated Hydrocarbon Radicals {acid). Each of the above-mentioned monad basylous radicals can exchange two atoms of their hydrogen for one of oxygen, ,and so give birth to a correspond- ing oxygenated radical, which is also a monad. These latter have been called acid radicals., but somewhat unfortunately, because it is apt to cause confusion with the ordinary acidulous radicals, with which they have no identity; and the term oxygenated radical is therefore better. The new radicals thus formed are terminated in yl ; and they are called, not after the name of the basylous radical from which they are derived, but by prefixing a portion of the name of the acid to which they give birth, as will shortly be shown. Examples of such radicals are found in the following : — Methyl (CH3)' gives birth to {OSAO)' formyl. Ethyl (C2H3)' Propyl (C3H7)' Butyl (QH,)' Pentyl (C.U,,)' (C2H3O)' acetyl. (CoHf-O)' propionyl. (C4H7O)' butyryl. (C5H9O)' valeryl. Dyad basylous radicals can suffer two successive steps of oxidation, and thus produce two oxygenated radicals. For example, — Ethene CoH^ by the ist oxidation forms C2H0O, gly colly 1 . „ C2H4 „ find „ „ CoOo, oxalyl. OXYGENATED HYDROCARBONS.— PARAFFINS. 2II The resulting oxygenated radicals are in this case dyads, following the atomicity of the basylous radicals from which they spring. The haloid salts of the oxygenated radicals are called acid halides,' their hydrides are termed aldehyds, their oxides, anhydrides or anhydrous acids, and their hydrates are called acids. Thus we have : — Acetyl Chloride C0H3O.CI, acetic chlor-arihydride. Acetyl Hydride CgHgO.H, acetic aldehyd. Acetyl Oxide (C2H30)2'0'', acetic anhydride {anhydrous acetic acid). , Acetyl Hydrate C2H3O.HO, acetic acid (usually written HC2H3O2). Like the corresponding basylous radicals, the oxygenated ones under con- sideration can displace the hydrogen of ammonia; but in this case the resulting compound is called an amide. Example : — ( C2H3O)' ) N < H y aceta 7 nide. (h I Lastly, the oxygenated radical can combine with the basylous radical imme- diately helow it in number of carbon atoms, to form a ketone. Example : — CH3.C2H3O, acetone. IV. Hydrocarbons on the Type CnH2n+2 or, Parafldns. The members of this series are called paraffins, because many of them are found in the illuminating oils sold as petroleum or paraffin. These oils are chiefly obtained from North America, where they rise from the earth like ordinary water springs, and are considered to be produced by the slow decay of vegetable substances deeply imbedded in the earth. Certain varieties of cannel coal and a peculiar mineral obtained at Boghead, in Scotland, yield paraffin oil by destructive distillation. The series is a long one, commencing with methane or marsh gas, CH^, already described at page 138, and increasing in complexity by a regular addition of CHg. The lower members are : — Methane . . . . ‘ . . . . . CH^. Ethane ......... C2Hg. Propane .......... C3Hg. Butane C^H^q. All of which are gaseous at ordinary temperatures. Next we have a series commencing with pentane, CgH^g, and ending with C^^Hgg, which are liquids boiling at points varying from 90° to 500° F., while in some of the heavier American oils we meet with still more complex paraffins boiling above 600° F. and solid at ordinary temperatures. All these paraffins, when subjected to the action of monad metalloids, give up the whole or a part of their hydrogen in exchange for the metalloid, form- ing salts of new radicals ; thus marsh gas, CH^, can Xq successive steps be changed by the action of chlorine (in sunlight) into : — CH3CI CH2CL CHCC CCI4 . Methyl Chloride. Methene Chloride. Methenyl Chloride. Carbon Tetrachloride. The paraffins may be produced artificially by heating metallic zinc and 212 HYDROCARBONS AND THEIR DERIVATIVES. water in a sealed tube with the iodides of their corresponding basylous radicals. Example : ethyl iodide, thus treated, yields ethane. 2C2H5I + 2H2O + Zng = 2C2Hg + Znig + Zn2HO. The following is a full list of the paraffins actually discovered : — Name. Formula. Boiling Point, Fah. Name. Formula. Boiling Poi^T, Fah. Methane . . Ethan . . Propane . . Butane . . Pentane . . Hexane . . Heptane . . Octane . . CH, C3H8 C5H1, CeHu CsHis 33-8° 1 00 ’4° 158-0° 210-2° 255-2° Nonane . . Decane . . Undecane . Dodecane . Tridecane . Tetradecane. Pentadecane Hexdecane . ^10^22 ^11^24 ^12^26 C13H28 ^14^30 ^5^32 ^16^34 298-4° 334*4° 363-2° 395*6° 424-4° 464-0° 5°S-6° 532'4° The more volatile liquid compounds of the paraffin series are now exten- sively used for lighting purposes. They are known in commerce as petro- leum spirit, gazoline, or benzoline, and give off highly inflammable vapours at the ordinary temperature. They require to be burned in special lamps, while their sale is restricted by Act of Parliament to certain hours of the day. The less volatile, which will not take fire on the application of a lighted match, and burn continuously at a temperature below 100° F., may be burned in lamps of ordinary construction and retailed at all hours of the day. The more viscid members of the series are greatly used as lubricating oils, while the solid ones constitute what is known as paraffin wax. The paraffins are distinguished by their great chemical indifference i^parum affinis). /Being saturated Hydrocarbons, they are incapable of uniting directly with monatomic elements or radicals, and are not sensibly affected by cold sulphuric acid. 'Nitric acid does not affect the lower paraffins ; and their nitryl compounds, called nitroparaffins, have to be formed by indirect means. The higher members, however, are attacked and form nitro compounds. y. Hydrocarbons on the Type These hydrocarbons are termed olefines. The series probably commences with methene, CH2, as yet, however, unisolated, and proceeds up as far as melene, CgoHgQ, which is, at ordinary temperatures, a solid. The most in- teresting compound of this class (because it is a leading constituent of coal gas) is ethene {olefiant gas) C2H4, already mentioned at page' 138; and its pro- duction by the subtraction of the elements of water from alcohol is character- istic of the whole series, the members of which may be obtained by a similar process from the hydrate of the monad basylous radical having a similar number of carbon atoms. All the olefines themselves act as dyad basylous radicals. I The olefines are prepared, — I. By the decomposition of paraffins at the moment of their liberation HYDROCARBONS.— OLEFINES. 213 from- their compounds by the action of zinc or sodium. Thus, by heating ethyl iodide with zinc, we form tetrane : — 2C2H5l + Zn = C^R^q + Zt)!^. but at the moment of liberation the tetrane breaks up into ethane and ethene, thus : — 2C2H5l + Zn = C2Hg + C2H4, + Znl2. 2. By the abstraction of water from the alcohol of the corresponding monad radical. Thus, ethyl alcohol, heated with strong sulphuric acid, forms ethene : — C2H5HO + H2SO4 = C2H4 + H2SO4.H2O. 3. By heating a haloid ether (preferably a bromide) of the corresponding monad radical with alcoholic potassium hydrate. Thus, ethyl bromide, so treated, yields ethene : — C2H5Br + KHO = C2H4 + KBr + H2O. Many other methods are known, which may be found in larger manuals. The members of this series all unite directly with chlorine, bromine, and iodine, forming haloid ether's. Example : — C2H/ + CI2 = C2H,Cl2; which haloid ethers, treated with argentic acetate, give rise to diatomic acetic ethers : — ~ zAgBr + C2H4-2C2H302 j and these ethers, distilled with a caustic alkali, yield diatomic alcohols or glycols : — C2H4.2C2H3O2+2KHO = C2H4.2HO + 2KC2H3O2. Some olefines are capable of uniting with concentrated sulphuric acid when briskly shaken up with it, forming acid ethers which contain the corresponding monad alcohol radical to the olefines employed ; thus ethene is absorbed by sulphuric acid, forming ethyl-sulphuric acid : — C2H4 + H2SO4 - C2H5.HSO4. These acid ethers distilled with water re-form sulphuric acid and the monatomic alcohol analogous to the olefine. Thus : — C2H5HS04-I-H20 = C2H5HO + H2SO4. Ethene List of the Normal Olefines : — Name. Formula. or ethylene . . C2H4 Boiling Point, F. Gaseous. Propene „ propylene . C3H3 . • Tetrene „ butylene . C4H8 . 33 - 8 ° Pentene „ amylene • . 95 'o Hexene „ hexylene CgHi2 149-0 Heptene „ oenanthylene . . C7H14 . . 204-8 Octene „ caprylene 248-0 Nonene „ nonylene . 284-0 Decene ,, paramylene . CioH.20 320-0 Hexdecene „ cetene C16H32 527-0 Cerotene • • • . C27H54 . Solid, melts at 135' Melene „ melissene • CgoHgQ „ » 144' 214 HYDROCARBONS AND THEIR DERIVATIVES. VI. Hydrocarbons on the Type CnHgn.g (Acetylene Series). These hydrocarbons may, as a rule, be prepared by heating the dibromides of the olefines with alcoholic potash. The decomposition takes place in two stages, a monobrominated olefine being first formed, and then deprived by the further action of the potash of the elements of hydrobromic acid, thus : — C2H4Br2 + KHO = CgHgBr + KBr + HoO. CgHsBr + KHO == + KBr + HgO. Many of the radicals of this series, when treated with an ammoniacal solution of argentic or cuprous chloride, yield salts in the form of crystalline precipi- tates. On heating these compounds with hydrochloric acid the original hydrocarbons are reproduced. This reaction affords a convenient method of separating acetylene and allylene from other gases. Shaken up with hydrobromic or hydriodic acid, they take up one or two molecules of these acids, forming compounds isomeric but not identical in composition with the analogous olefine compounds. The following constitute the members of this series so far as at present discovered. List of the Acetylene Series: — Name. Formula. Boiling Point, F. Ethine or acetylene . . . . — Propine „ a allylene . C3H, . . — /3 „ . C3H, . . — Crotonylene . . . . 64*5° Pentine „ avalerylene . • C3H8 . . 122 . C5H8 . . 113 Hexine „ hexylene . • CeH,„ . . 176 Diallyl . • CeH,„ . . 138 Heptine . C7H13 225 Octine . . CgH,, . . . 271 Decine „ decenylene . C10H13 . . 329 Rutylene . * ^ 10^18 302 Pentadecine „ benylene . C15H28 437 Hexdecine „ cetenylene C^gHgo 536 ACETYLENE, or ETHINE. Formula, C2H2. This hydrocarbon, one of the constituents of coal gas, has been described at page 138. ALLYLENE, or PROPINE. Formula, C3H4. Prepared by the action of sodium ethylate on bromopropene. It is a colourless, strong-smelling gas, burning with a smoky flame. With mercurous salts it forms a grey, with silver salts a white, and with cuprous a yellow precipitate. CROTONYLENE. Formula, C^Hg. Formed, as described in the general reaction, by the abstraction of BrH from monobromobutene ; also by distilling erythrite, C4 H;iq 04, with formic acid. Crotonylene is liquid below 59° F., boils at about 64°, and distils over between 64° and 75°. It has a powerful and somewhat alliaceous odour, and burns with a bright but smoky flame. HYDROCARBONS.— AROMATIC SERIES. 215 VII. Hydrocarbons on the Type CuH 2 n- 6 - This is called the Aromatic Series, and the typical compound with which it commences is — BENZENE (Syns. Benzol. Phenylhydride). Formula, CgHg. This body may be prepared by the action of heat upon acetylene : — ' 3 CgHg = CgHg, or by heating benzoic acid with calcium hydrate : — HC7Hg02 + Ca2H0 - CgHg + CaCOg + H2O. In practice it is prepared by fractional distillation from caabtar, being found in the portion distilling below 180° F. Benzene is a colourless and highly refractive’ liquid,- boiling at 177° F. It is very inflammable, and has been used aS' a cheap solvent for fats, resins, sulphur, and phosphorus. It is insoluble in water, but miscible with alcohol and ether, and has a specific gravity of *899 at 32° F, It is much employed for the manufacture of — NITKO-BENZENE (Syns. Nitrobenzol. Oil of Myrhane). Formula, CgH5N02- When purified benzene is treated with a mixture of fuming nitric acid and a little sulphuric acid, the nitro-benzene separates as a yellow oil, having a strong odour of bitter almonds. If the acids be allowed to act too long, or the mixture get too hot, a dinitro-benzene, CgH^(N02)o, would be produced, which crystallizes in long yellow needles. Nitro-benzene is much sold as artificial essence of hitter almonds., and is even used to adulterate the real oil. This adulteration is readily detected by the property which it possesses of becoming changed into aniline by the action of reducing agents. The best test to employ is nascent hydrogen, evolved from a mixture of zinc and dilute sulphuric acid. The resulting reaction is as follows — CgH^NOa + 3H2 - CgH^N + 2H2O. In practice the oil is dissolved in a little alcohol, and added to a tube containing zinc and dilute sulphuric acid. After standing for some time, a fragment of potassium chlorate is added, which immediately develops a beautiful mauve colour, caused by the oxidation of the aniline. Many chemists prefer to use a little solution of chlorinated lime, to develop the colour, instead of potassium chlorate. This is a process which every student should try for himself upon oil of myrbane, because much of its success depends on the degree of dilution of the sulphuric acid and upon the quantity of potassium chlorate employed — matters best learnt by experience. The quantitative estimation is somewhat uncertain;, but the following pro- cess yields at least nine-tenths of the adulteration in a state fit for weighing. 100 grains of essence of bitter almonds are agitated in a wide-mouthed flask with 300 to 400 grain-measures of saturated solution of sodium hydrogen- sulphite, and then the whole treated with a little ether. The solution is quickly filtered, evaporated to dryness, and the residue of nitro-benzene is weighed. The whole members of the aromatic group and their derivatives are of the greatest interest as being of late years chiefly extracted from coal tar, and utilized in almost innumerable ways, although till but recently either entirely unknown or considered to be waste products. From modifications of this group by substitution of various radicals for portions of the hydrogen of its members, we have carbolic, benzoic, cinnamic, and other acids ; aniline and similar dyes, nitrobenzene, turpentine, resins, and the great bulk of our essential oils. 2I6 HYDROCARBONS AND THEIR DERIVATIVES. A most curious fact is, that all the members of the aromatic group may be viewed as derived from the great typical hydrocarbon benzene, by substitution of various radicals for portions of its molecule. Thus, the next member, toluene, CyHg, may be viewed as being really methyl -benzene, CgH5(CH3). It is unfortunately impossible, within the limits set to the present edition, to go thoroughly into these relations ; but one more example may be given to show how turpentine, C^oH^g, may be theoretically connected with benzene, and to give an idea of the immense depth of research which has been brought to bear upon the aromatic group. Turpentine is first viewed as cymene hydride, HgC^oHj^. In turn cymene, (CjoHj^), is itself regarded as being methyl-propyl-benzene (CgH4.CH3.C3H7), that is, benzene, CgHg, in which two hydrogens have been respectively replaced by the monad radicals methyl and propyl. The constitution of these compounds may.be thus represented, — H H 1 1 H H 1 1 H H 1 1 1 1 c—c 1 1 C=C 1 1 C=C / \ / \ ^ / \ C C--H H— C C— (CHsX (C3H7)'-C C-(CH W // w // w // c— c 1 1 C— c 1 1 c— c 1 1 1 1 H H 1 1 H H 1 1 H H Toluene, or Cymene, or Benzene, Methyl-benzene, Methyl-propyl-benzene, CeH,. CyHg. ^ 10 ^ 14 * It is easy to see that bodies so constituted may have an immense amount of isomerism, as indeed they have ; but the study of them is quite beyond the scope of the present work : it must suffice to give a glance only at those members of the series of actual interest in pharmacy or medicine. CYMENE. Formula, C10H14. Is known in two. metameric varieties, ^ one of which is found among the lighter oils separable from coal tar by fractional distillation, while the other exists in the oil of Cicuta virosa. This modification may also be obtained from oil of cu 7 uin (cumic aldehyd, CioH^jO), by the action of alcoholic potash. CINNAMEIN. Formula, CgHg. Is a colourless oil existing in storax, and easily obtainable by distilling the storax with water and an alkali to fix the cinnamic acid. By heating in a sealed tube to 400° F,, it is converted into a white solid called metacinnamein. NAPHTHALENE. Formula, 'c^oHg. Is a white, solid separable from coal tar by fractional distillation, which is interesting as being the source of artificial benzoic acid. {See Benzoic Acid. ) ANTHRACENE. Formula, C14H10. ■ Is found in commerce as a yellow softish mass distilled from coal tar. It is used for lubricating delicate machinery, and also as a source of alizarin, a red colouring matter used in dyeing, and formerly only obtainable from madder. HYDROCARBONS.— ANTHRACENE,— TERPENES. 2T7 In explaining this reaction it should be noted that all the hydrocarbons of the series possess the power of forming by oxidation peculiar bodies called quinones^ in which Hg is displaced by the group Og acting as a dyad, exactly as Hgg has already been seen to act in mercurous ammonium chloride. They are neutral bodies, and by the action of nascent hydrogen yield hydroquino 7 ies ; that is, where the place of has been taken by (HO)3 in the hydrocarbon. Examples of this may be seen by comparing : — CeHe QH,(0,r CeH,(HO),' Benzene. Quinone. Hydroquinone. If therefore anthracene be heated with potassium dichromate and sulphuric acid, we obtain anthraquinone CuH,„ + 03 = Ci,H3(02)" + H,0. From this body, by heating with bromine, we obtain a substitution product called dibrom-anthraquinone : — Ci 4H8(02)" + 2Br2 - Ci,HgBr202+ 2HBr. This product, fused with potassium hydrate at 350° F., yields the potassium compound of alizarin : — Ci^HgBrgCOgr + qKHO = Ci4H6(KO)2'(02r + 2KBr + On dissolving the product in water and acidulating, the crude alizarin is precipitated and purified by sublimation. Alizarin is therefore anthraquinone in which an additional group of H2 has been displaced by (HO)2 thus : — Ci4H6(HO),'(02)". VIII. Terpenes. General Formula, CioHjg. ^ An immense number of these bodies are isomeric with each other, and exist in many volatile oils. They are prone to oxidation, and therefore the essential oils of commerce usually are partially altered, and when distilled carefully or refrigerated they are found to consist of — 1. An elceopten, which is the more volatile and unchanged portion, remain- ing perfectly fluid, and usually isomeric with oil of turpentine, CigH^g. 2. Astearopten, which is the portion frequently crystallizing out, which has undergone alteration by oxidation or contact with moisture. The body is frequently isomeric with common camphor. Oleum terehinthinse is the volatile oil distilled from the natural crude turpen- tine, an oleo-resin obtained from the pine tribe of coniferous plants. It is de- scribed by the B.P. as being limpid, colourless, with a strong peculiar odour and pungent bitter taste. The natural turpentine which exudes from the tree, when submitted to distillation, yields a distillate of common oil of turpentine, the residue in the retort being the well-known article resin (resma, B.P.). If this common oil be distilled with potassium carbonate m vaciw, the pure oleum terebinthinse, known in commerce as rectified spirit of turpe 7 itine., is obtained. When thus purified, it consists of one of two isomeric hydrocar- bons, according to the source of the original oleo-resin. The English oil, dis- tilled from American turpentine, is called chemically a 7 %straterebe 7 ithe 7 ie ; and the French oil, from Emus 77 iariti 77 ia, is termed te/'ebenthe 7 ie. Both' of these terpenes have the formula, CioH^g, together with a specific gravity of ’864 and boil at 320° F. The former, however, exhibits a dextro- and the latter a laevo- gyrate action on polarized light. Turpentine oils undergo a great variety of decom- position by the action of heat and reagents. A paper steeped in the ordinary oil and then introduced into chlorine, absorbs the latter so violently as to burst into flame. By passing dry hydrochloric acid gas into oleum terebinthinae 2i8 HYDROCARBONS AND THEIR DERIVATIVES. a crystalline compound called terebenthene hydrochlorate, CjoHigHCl, is obtained, and was formerly sold as artificial camphor. When ordinary turpen- tine oil is exposed to the action of water, it unites with it and deposits crystals of terpin hydrate, C|oHig3H20. By drying at 212° F. these lose water, and are converted into terpin, CioHig2H20. In addition to these hydrates the following are known, viz., terpentin hydrate, CioHigH20, and terpinol, (^10^16)2^2^- Oil of turpentine is insoluble in water, but miscible with strong alcohol, carbon disulphide, and ether. It is a good solvent of oils, resins, phosphorus, sulphur, and many other substances. It is employed in the ^laboratory for taking the specific gravity of sugar and similar bodies which" are soluble in water but insoluble in turpentine. It is powerfully acted on by nitric acid, potassium permanganate, and the other leading oxidants. CAMPHOR (SvNS. Camphoric Aldehyd. Camphoryl Hydride) Formula, CioHigO. Is the type of the oxidized hydrocarbons {stearoptens) of the essential oils, and as such is best studied here. Camphor is obtained from the bark and wood of the Lauriis Camphora., or Camphora officinarwn., from which it derives its name. The Chinese mode of extraction is to boil the wood, cut into pieces of suitable size, in a vessel having a conical clay condenser inverted over it. The camphor sublimes into this clay vessel, which is lined with rice straw to l^revent contamination of the sublimate by earthy matters. The crude camphor imported from China is grey ; that introduced from Japan (sometimes termed Dutch camphor) is pink. It invariably undergoes a second sublimation after it is brought to Europe before being used, and is then white, translucent, tough, and crystalline ; has a powerful penetrating odour, and a pungent taste followed by a sensation of cold ; floats on water \ volatilizes slowly at ordinary temperatures ; is slightly soluble in water, but readily soluble in rectified spirit and in ether ; sublimes entirely when heated, and burns in the air with a smoky flame. It is only slightly volatile at temperatures below 347° F., but above that degree it melts, and commences to boil at 400° F. It is soluble in water to the extent of one-tenth per cent. When an attempt is made to reduce it to powder, it does not succeed without the addition of some strong spirit. The temperature at which its specific gravity is taken affects the result greatly, causing it to vary from *9862 to '9958. When fragments of camphor are placed on water they assume a state of rapid movement. These movements are supposed by some to be attributable to the vapour evolved by the camphor preventing contact with the water; but it seems hardly probable that this would have sufficient power to move such large fragments as are thus caused to revolve. The fact, however, that a minute quantity of oil arrests the motion seems to lend some countenance to this opinion, as the vapour of camphor would be soluble in oil. The specific gravity of camphor at the freezing point has been found to be higher than that of water. At the degree of the greatest density of water (39*2° F.) it is also incapable of floating on that liquid, pro- vided it has been made damp. An alcoholic solution is precipitated by water, and this is sometimes the method adopted for preparing an aqueous solution, as the camphor thus (in consequence of its finely-divided state) dissolves in the water much more readily than if introduced in the ordinary manner. A stable liquid preparation may be made by adding a concentrated alcoholic solution of camphor to proof spirit in requisite proportions. Ether, acetic acid, essential and fixed oils, liquid acids, chloroform, and HYDROCARBONS.—CAMPHOR, 219 carbon disulphide are all good solvents of camphor. An alcoholic solution will take up much n)ore mercuric chloride than alcohol alone. By the action of potassium permanganate or nitric acid, camphoric acid, CioHig04, is formed. Camphor, though frequently represented as an aldehyd, does not strictly speaking belong to that class of bodies, as it does not combine with hydrogen- sodium sulphite, nor does it form the corresponding alcohol (camphol) by the action of nascent hydrogen, these two reactions being regarded as essentially, characteristic of true aldehyds. Unlike many similar bodies, it does not yield a resinous substance on oxidation either by nitric acid or the atmosphere. When distilled with phosphoric anhydride, it yields cymene. There is a sub- stance termed “ artificial camphor,” which is occasionally substituted for, or used to adulterate, true camphor. It is produced by the action of hydro- chloric acid on turpentine, melts at 240° F., and boils at 330° F. It is readily distinguished by inflaming it, then blowing out the flame, when the vapours which come off for a few seconds will have the odour of turpentine. By passing the products of its combustion into a solution of argentic nitrate, a precipitate of argentic chloride will result, to which the usual confirmatory tests may be applied. The gases formed by the burning of ordinary camphor will cause no precipitate. The artificial variety burns with a greenish colour, while the natural product gives a white flame. Both flames evolve carbon, and the vapours produced are consequently thick and sooty. Ordinary cam- phor is dextro-rotatory as regards polarized light. Some official volatile oils, viz. oleiwi 7 'osmarini and oleum lavandidce^ contain a substance possessing the same chemical properties as camphor, but are inactive in the polariscope. A Isevo-rotatory variety exists in the essential oil of feverfew. Ngai ca 7 nphor \\2 lS for its chief source the Blumea balsamifera, D.C. It is isomeric with Borneo camphor, but differs in some physical characteristics. Oleum anethi^ obtained from the fruit of Aiietlmm g 7 'aveolens by distillation with water. It is described as pale yellow, with a pungent, acrid, but sweetish taste. It varies in specific gravity from *88 to *95, according to its age, and boils at about 375° F. Oleum anisi, obtained as above from Pimpinella anisum or Illicium aiiisatum (star-anise). According to the B.P. it is, — ' Colourless or pale yellow ; with the odour of anise, and a warm sweetish taste. Concretes at 50°. It consists of a terpene, C^o^i6’ ^ stearopten, C40H42O, which latter causes the concretion when cooled. Its specific gravity is from *97 to '99, and it absorbs oxygen by exposure, losing its property of concretion by cold. The stearopten is usually called anise camphor ; and when acted on by anti- monious chloride it thickens to a reddish matter, which deposits a white substance called anisoin on boiling with water. By oxidation with potassium dichromate and sulphuric acid, oil of anise yields a mixture of acetic and anisic acid (CgHgOg). Oleum anthei 7 iidis^ distilled as above from the flower heads of A 7 ithe 77 iis 7 iobilis. It is described by the B.P. as being, — Pale blue or greenish-blue, but gradually becoming yellow ; with the peculiar odour and aromatic taste of the flowers. Great beauty characterizes the blue colour of the oil of chamomile when recently distilled. It contains a terpene, C^oHig, and also angelic aldehyd, CjHgO, which by heating with potassium hydrate yields potassium angelate : — CsHgO-hKHO'^ KC5H7O2 + H2. Oleu 77 t cajepiiti is distilled from the leaves of Melaleuca 77 imor. It is im ported from Singapore, and is described by the B.P. as being, — 230 HYDROCARBONS AND THEIR DERIVATIVES. Very mobile, transparent, of a fine pale bluish-green colour. It has a strong agreeable odour, and a warm aromatic taste, and leaves a sensation of coldness in the mouth. The specific gravity of cajeput oil is about *926. It consists chiefly of the monohydrate of a terpene called cajeputene, and its formula may therefore be taken as CjoHigHgO. It leaves on distillation a green resin soluble in ether. Oleum carui is distilled from the fruit of Carum Carui, and is described in the B.P. as being colourless or 'pale yellow, odour aromatic, and taste spicy. It is a mixture of a true terpene (carvene, C^oH^g) and an oxidized portion (carvol, CioHj^O). The latter may be separated from the former by agitation with ammonium sulphide,’ in which it dissolves, forming carvol sulphydrate (Ci„Hi,0)2H,S. Oleum caryophylh is distilled from the un expanded flower-buds of Caryophyllus aromaticus. According to the B.P. it is : — Colourless when recent, but gradually becoming red-brown, having the odour of cloves and a pungent spicy taste. Sinks in water. Chemically, this oil consists of a terpene, with eugenic acid, HCioH|^02, and a stearopten called eugenin, probably isomeric with the acid. On dis- tilling the oil with water the latter body may be observed to crystallize from the aqueous solution, while the eugenic acid may be separated as .potassium hydrogen-eugenate, KH2C10HJ1O2 + Aq, by agitation with weak warm solution of potassium hydrate and crystallizing. Oleujn cinnamo 7 ni. [See Cinnamic Aldehyd.) Oleum copaibce is distilled from the peculiar oleo-resm obtained from Copaifera multijtiga. It is described in the B.P. as being colourless or pale yellow, with the odour and taste of copaiva. It consists chiefly of a terpene polymeric with turpentine oil, and therefore has the formula of CgoHgg. When the oleo-resin itself {co 7 nmonly called balsam of copaiba) is examined, it is found to vary much in its constitution according to its source, for accord- ing to Fliickiger, balsam from Maracaibo rotates a polarized ray to the right, and that from Maranha exhibits a left-handed polarization. It contains the volatile oil above described, and also two resins, — one (in quantities varying up to 60 per cent.) called copaivic acid, and another in small quantities (usually 2 per cent.), which is not acidulous. Copaivic acid, HCgoHggOg, is the por- tion of the copaiba which causes it to harden when mixed with magnesium or calcium oxides. The copaiba contains a little moisture ; and in the pre- sence of this, the oxides, being converted into hydrates, attack the resinous copaivic acid, forming magnesium or calcium copaivates, which crystallize and take up the oily portion, and the whole then forms a solid mass. This property is utilized in making copaiba into pills. An equal weight of official . 77 iag 7 iesice ca 7 'bo 7 ias is usually employed, as, owing to its already con- taining hydrate, it acts more rapidly than the oxide. If time be not an object, however, the same effect may be ultimately produced by a much less quantity of magnesium oxide. The balsam from Maracaibo has been recently found to contain a new resin called metacopaivic acid, H2C22H32O4. Oleu 77 i cubebce., which is distilled from the dried unripe fruit of Cubeba officmalis^ consists of a hydrocarbon, cubebeTie (C25H24), holding in solution a stearopten called cubeb camphor, C25H24.H2O. The specific gravity of cubeb oil is -92. It thickens by exposure, and rotates polarized light to the left. Oleum coriaTidri^ which is distilled from the fruit of CQria 7 idru 77 i sativu 77 i^ is supposed to consist of a hydrated terpene, CigHjg.HgO. That this is so, is supported by the fact, that when distilled over phosphoric anhydride it yields camphene, CioH^g. Its specific gravity is about *87, and when treated with iodine a violent explosion takes place. HYDROCARBONS.— OLEA. 221 Oleum juniperi is distilled from the unripe fruit of Juniperus communis. It is described in the B.P. as being colourless or pale greenish-yellow, of a sweetish odour, and warm aromatic taste. It consists of a terpene, CioH;^g, possessing the power of uniting with water, and depositing in a hydrated form Oleum lavandulce., distilled from the flowers of Lavandula 'vera., is described in the B.P. as being colourless or pale yellow, with the odour of lavender and a hot, bitter, aromatic taste. It consists of a fluid portion containing two hydrocarbons, one of which at least is a true terpene, C^oH^g. The stearopten portion is similar to common camphor. Oleu 7 n Ihnonis is expressed or distilled from the rind of Citrus Limonis. Characters. — Colour, pale yellow ; odour, agreeable ; taste, warm and bitter. It is a mixture of two hydrocarbons, both CioH;^g, but differing in their action on polarized light. It is slightly soluble in water, and more so in alcohol, one part dissolving in seven parts of rectified spirit. By exposure it oxidizes, and deposits a substance called citroptene, to which, however, no exact formula has been affixed. Oleum menthce piperitce and oleum menthce. viridis, obtained by distillation from the respective fresh flowering herbs, are neither truly isomeric with ter- pene. The former contains a liquid portion called menthene, CioH;^g and a solid stearopten which is a hydrated variety of the same body, The latter oil would seem to answer chiefly to the hydrated menthene. Oleum myristicce is distilled from the kernels of the fruit of My^istica officinalis. It is described as colourless or straw-yellow, having the odour of nutmegs. It contains a liquid hydrocarbon, and deposits by oxidation a stearopten called myristicin. Oleum myristicce expressum is not a volatile oil, but a fatty body consisting of myristin {glyceryl myristate^ C3H53C;i4H2702). Care must be taken to keep distinct the two ideas of myristicin and fnyristm. OleiLm pimentce^ distilled from the dried unripe berries of Eugenia Pimenta, is, according to the B.P., colourless, or slightly reddish when recent, but becoming brown by age, having the odour and taste of pimento. Sinks in water. It is similar in composition to oil of cloves. Oleum rosmarini., distilled from the flowering tops of Rosmarinus officmalis., is stated in the B.P. to be colourless, with the odour of rosemary and a warm aromatic taste. It has a specific gravity of '90 usually, and consists of two terpen es, forming by oxidation a stearopten similar to camphor. Oleum sabince, distilled from Juniperus sabina^ consists of a terpene, C^oH^g, closely resembling those of oleu 7 n terebinthince. Oleum rutce., distilled from Ruta graveolens^ is a pale-yellow oil, containing a terpene, C^QH^g, together with euodic aldehyd, C11H22O. Gutta percha, the concrete juice of Isonatidra gutta ; and Caoutchouc., the well-known indiarubber of comrfierce, consist of a terpene, caoutchin, C^oH^g, and another hydrocarbon, called isoprene, CgHg ; and in addition, the former contains another polymeric oil, called heveene. When heated, both substances ^ melt, and then lose their elastic properties. They are soluble in turpentine, carbon disulphide, and benzol, and the latter combines easily with sulphur, forming, when the sulphur is present in small quantity, vulcanized rubber, and when in larger proportion, vulcanite. Gutta percha is an excellent insulator for covering electric apparatus, because, besides being a perfect non-conductor, it is not permeable by moisture. CHAPTER XIV. THE ALCOHOLS. The numerous compound basylous radicals produced by the various degrees of self-saturation of carbon atoms, and their combinations with hydrogen when so self-saturated, possess the power of forming hydrates by uniting with one or more molecules of the acidulous radical hydroxyl, in an exactly similar manner to the metals the hydrates of which we have already described. These hydrates are called alcohols from the fact of ordinary alcohol being the first of the series which was investigated and described. The whole of these organic hydrates are characterized by certain reactions which they exhibit in common, and more especially by possessing the power of forming neutral compounds with acids, the action being always accompanied by the elimination of water, formed by the union of the displaceable hydrogen of the acid with the hydroxyl contained in the alcohol. In formulating the alcohols, it is only necessary to remember the atomicity of the radical which gives them birth, and to add the proper number of molecules of HO; thus, the monad radical ethyl, CgH^, will have for its' alcohol C.2H5HO (common alcohol) which is called a monatomic alcohol. The dyad radical ethene, C2H4, will in turn form C2H42HO, known as a diatomic alcohol, or glycol, while the triad radical propenyl, C3H5, will produce C3H53HO, thus yielding a triatomic alcohol (glycerin). These classes have now to be discussed seriatim. I. MONATOMIC ALCOHOLS OF THE SERIES CnH^n+iHO. ' This series commences with methyl hydrate, CH3HO, and ends with melissyl hydrate, CgoHgiHO, as shown by the following table Name. Eormula. Boiling Point. Melting Point. Whence Obtained. Methyl hydrate or Methylic alcohol CH3.HO i5i°F. ... Destructive distilla- tion of wood Ethyl ,, Ethylic ? J C2H5.HO 173° Fermentation of sugar Propyl 5 ? ,, Propylic C3H7.HO 206° „ grape husks Butyl 5 > ,, Butylic C4H9.HO 233° „ beet root Pentyl 1 ? ,, Amy lie CsHn.HO 270° ... ,, potatoes Hexyl ,, ,, Caproic QH43.HO 309° ,, grape husks Heptyl ,, CEnanthic C7H45.HO 343 ° Distillation of castor oil with KHO Octyl ,, Caprilic CsH^-.HO 356° F ermentation of grape husks Nonyl ,, Nonylic C9H19.HO 392° See general processes Decyl ,, Rutic C10H21.HO 414° Oil of rue Dodecyl ,, Laurie C12H25.HO Whale oil Hexdecyl 5 ) ,, Cetylic )> f'lelhs* klO I22°F. Spermaceti Ceryl ,, Cerylic C27H55.HO 174° Chinese wax Melissyl ,, Melissic 11 C30H51.HO ... 185° Beeswax ALCOHOLS.— PRIMARY, SECONDARY, TERTIARY. 223 As soon as we pass the first two members, viz., methyl and ethyl, we may have several isomeric modifications of each alcohol, in addition to the true normal compound. These modifications are explained and classified by Kolbe as follows : Methyl alcohol, CH3HO, is called a carbinol, and every other alcohol is simply also a more complex carbinol formed by the displace- ment of H in the original carbinol by some radical of the series CnHon+i- By this view, starting with the primary carbinol, we have : — Carbinol CH3.HO = CH3HO primary Methyl alcohol Methyl carbinol CH2.CH3.HO = C0H5HO „ Ethyl „ Ethyl carbinol CH3.C2H5.HO = C3H7HO „ Propyl „ If, however, Hg be displaced from carbinol by two molecules of a radical, the result is a secondary alcohol, which differs from the primary alcohol in boiling point and in the products of its oxidation. Thus : — Dimethyl carbinol CH.(CH3)2HO = C3H7HO Propyl alcohol(secondary) Ethyl-methyl carbinol CH.CH3.C2H5HO = C4H9HO Butyl alcohol ' „ Finally, we may proceed farther, and have a tertiary modification, in which the whole H3 of the carbinol has been displaced by equivalent values of other radicals of the same series. For example : — Trimethyl carbinol C.(CH3)3HO = C4H9. HO Butyl alcohol (tertiary) Dimethyl-ethylcarbinolC.(CH3)2.C2H5.HO = C5H44HO Pentyl alcohol „ So that taking, for instance, butyl alcohol, we have three isomers, viz. : — C4H9.HO, normal Butyl alcohol CH3.C3H7.HO boiling at 233° F., (or Propyl carbinol.) C4H9. HO, secondary „ „ CH.CH3.C2H5.HO „ „ 207° F., (or Methyl ethyl carbinol.) C4H9. HO, tertiary „ „ C.CH3.CH3.CH3.HO „ 179° F., (or Trimethyl carbinol.) Ordinary primary, alcohols, when subjected to oxidation, form firstly an aldehyd, and secondly an acid, having the same member of carbon atoms as the alcohol, but secondary alcohols yield a ketone, instead of an aldehyd, and afterwards (by extreme oxidation only) an acid having a less iiumber of carbon atoms than the alcohol. Tertiary alcohols yield neither aldehyd nor ketone by oxidation, but one or more acids of the acetic type. It is only in the primary alcohols that we have much interest, and we will therefore chiefly refer to them ; but before considering each individually, the following general methods of making any alcohol of the series C,,H2n_4.HO should be understood. 1. By acting on the corresponding paraffin with chlorine, we obtain a corre- sponding haloid ether. This is then mixed with argentic acetate, forming the acetate of the required basylous radical, which, when distilled with potassium hydrate, yields the alcohol. Example : — CH4 -t- Clo = CH3.CI +HC1. CH3.CI 4- AgCoH302 = CH3.C2H3O. 4- AgCl. CH3.C2H3O24- KHO = CH3HO ^KCgHsOg. 2. From the corresponding olefine with sulphuric acid, and then distilling with water : — C2H4 4-H2SO4 = C2H5H.SO4. . C2H5H.SO44- H2O = C2H5HO 4- H2SO4. 3. From the corresponding haloid ether by simply acting with potassium hydrate, or better with argentic oxide in the presence of water, thus : — 2C2H5I 4- Ag20 + H.O = 2C2H5HO 4- 2AgI. 224 THE ALCOHOLS. 4. Any alcohol may also be prepared from that immediately below it in the series by taking advantage of the isomerism of cyanides and nitrils already referred to under cyanides. Thus, starting with methyl alcohol, we prepare methyl iodide, from this we then form methyl cyanide by the action of potassium cyanide. By now digesting methyl cyanide with sodium hydrate we obtain sodium acetate, which, by distillation with potassium formate, yields acetic aldehyd. Lastly, by acting on the aldehyd with nascent hydrogen, we obtain ethyl alcohol. CH3HO + HI = CH3I +H2O. CH3I + KCN = CH3.CN +KI. CH3.CN +NaH 0 + 2H20 = NaC2H302 + NH3 + H20. NaC2H302+ KCHO2 = C0H3O.H +KNaC03. C2H3O.H + H2 = C2H5.HO. ' The various decompositions which alcohols suffer in forming haloid, simple or compound ethers, aldehyds, acids, etc., will be fully considered under their respective headings in future chapters. METHYL HYDRATE (Syns. Methylic Alcohol. Carbinol. Wood Spirit. Wood Naphtha. Pyroxylic Spirit. Pyroligneous Spirit). Formula, CH 3 HO. Molecular Weight, 32. Specific Gravity at 59° F. '814r. « Was discovered by Taylor in 1812, and is one of the products of the destructive distillation of wood. It can also be obtained from some essential oils, and similar , vegetable constituents. It may be made by direct synthesis from inorganic materials, by mixing methyl hydride (marsh gas, CH^) with chlorine, and exposing the mixture to sunlight. This yields methyl chloride, CH3CI, which is converted into methyl hydrate by heating for some days to 212° F. with potassium hydrate. In the manufacture of wood spirit, the wood is enclosed in retorts, and subjected to heat. At the end of the distillation a very complex distillate is obtained, containing about one hundredth part of wood spirit. The lighter portions of the distillate are poured off, mixed with calcium oxide, and redistilled at steam heat ; which process is repeated until a sufficiently pure product has been obtained. If it be desirable to produce a still . purer spirit, the last distillate is mixed with calcium chloride, when a considerable amount of heat is generated, and a combination is formed having the formula CaCl2.CH3HO, which is not de- composed at steam heat. The whole is redistilled below 212°. The impurities pass over, leaving the compound already referred to in the retort. The residual liquor is mixed with water, which causes the separation of the pure methyl hydrate, when it is once more rectified over calcium oxide. Methyl hydrate is a colourless apd very mobile liquid, burning in the air with a flame which is rather paler than that of ordinary “alcohol.” It possesses a characteristic odour, has a specific gravity of 798 at 68° F., and boils at 15 1° F. It may be preserved without change in contact with the air, but in the presence of an oxidizing agent, such as platinum black, it is converted into its acid (formic) HCHO2; which by boiling with potassium carbonate, yields potassium formate. When treated by processes similar to those already described as applicable to ordinary “ alcohol,” it yields chloroform and bromoform, but not iodoform. A mixture of 90 per cent, of ordinary “spirit of wine ” and 10 per cent, of wood spirit, constitutes commercial methylated spirit, used in the arts and in the laboratory, but which, being totally unsuited for internal administration, is not liable to duty. As, however, it is sometimes said to be substituted by the unprincipled, either in part or wholly, for “ spirit of wine ” in medicinal preparations, its detection becomes a matter of importance. Author's Analytical Chemistry, page 195.) ALCOHOL.— FERMENTA TION. 225 ETHYL HYDRATE (Syns. Alcohol. Ethylic Alcohol. Spirit of Wine, Vinic \_absolute\ Alcohol). Formula, C2H5HO. Molecular Weight, 46 . Is obtained from wine and other fermented liquors, and from these it may- be separated by distillation at steam heat, and concentrated by frequent redistillation. Alcohol is always produced when sugar or any vegetable sub- stances containing saccharine matters are subjected to the process known as fermentation. There are several varieties of fermentation, each of which takes place in a specific manner, producing a characteristic result, and is induced either by certain nitrogenous bodies, or by the presence of minute living organisms, chiefly vegetable. The class produced by simple chemical means are sometimes called “ false fermentations,’' while those induced by the presence of organisms receive the name of true fermentations." Among the former may be noted : — The saccharine fermentation, which is the change of starch into dextrin, and of dextrin into sugar, by the action of a nitrogenous substance, called diastase. This change is the one which takes place during the germination of seeds when planted in the ground, and also in the artificially-produced germination of barley, known as malting. The barley is steeped in water, and then spread on a floor, in a house specially constructed for the purpose, in which a proper temperature is maintained, coupled with the free access of air, and the exclusion of light to a considerable extent. Under these con- ditions the grain swells, and the action of the diastase commences ; the starchy matter of the barley takes up the elements of water, and is converted into dextrin and sugar by a simple re-arrangement of its constituents, thus : — sCgHjQOs -f- H2O = 2C(5 Hjq 05 -f- CgHjgO^. (Starch.) (Water.) (Dextrin.) (Glucose.) When the action is judged to have proceeded sufficiently, it is stopped by transferring the malt to a kiln, in which it is subjected to heat. The pro- duction of malt in this way is the first step in the commercial manufacture of alcohol. The chief remaining false fermentations are : — 1. The production of volatile oil of bitter almonds by the action of a ferment called emulsin upon the amygdalin of bitter almonds, thus : — C2oH27NOn + 2H2O = C7H5OH + HCN ^ + aCgHigOg. • (Amygdalin.) (Water.) (Oil of Bitter (Hydrocyanic (Glucose.) Almonds.) Acid.) Emulsin is sometimes termed synaptase. 2. The production of volatile oil of mustard by the action of myrosin upon the potassium myronate of black mustard seed, thus : — K2C20H38S4N2O19 = 2C3H5CNS + 2(KHS03) + + HgO. (Potassium Myronate.) (Volatile oil (Hydrogen- (Glucose.) of Mustard.) Potassium Sulphite.) 3. The change of tannic acid into gallic, by the action of a ferment which has not yet been isolated, but which exists in the galls and becomes active when they are steeped in water and exposed to warmth, thus : — ^27^22^17 4H2O = 3H3C7H3O5 + CgHj20g. (Tannic Acid.) (Gallic Acid.) 4. The action, when starchy matters are chewed in contact with the saliva of the mouth, which is due to the presence of a ferment called ptyalin. _ 5. The action which is exerted by the pancreas, and which aids in the digestion of fatty matters taken in our food, which is determined by a ferment called pancreatiu. Q 226 THE ALCOHOLS. 6. The digestion, in the stomach, of fleshy matters, by means of a ferment called pepsin. The chief of the “ true fermentations,” is that which is employed in the manufacture of alcohol, and consists of the conversion of sugar into alcohol, in the presence of yeast. This ferment, when examined under the microscope, is found to consist of an immense mass of cells continually increasing in number. They are gene- rally held by observers of the present day to be of vegetable origin, and to constitute the yeast-plant, or Torula cerevisice. When a solution containing the special variety of sugar called glucose is mixed with yeast, and maintained at a temperature of 6 5° to 85° F., the action immediately commences, and the sugar becomes converted almost entirely into carbonic acid gas and alcohol, thus : — CgHigOg = 2C2H5HO + 2CO0. (Cfucose.) (AlcoLl.) Besides these bodies, small quantities of other matters are produced, and M. Pasteur gives the following as the exact result of the fermentation of 105-36 grammes of pure glucose : — Alcohol . . . . . . . .51*11 Carbonic Anhydride' . . . . .49-42 Succinic Acid . . . . . . . *67 Glycerin ........ 3*16 Cellulose, and other matters of the yeast-plant . i *oo 105-36 In the ordinary commercial fermentations, when malt is used instead of sugar, the formation of alcohol is accompanied by the production of many other substances, and notably of amyl hydrate. The remaining “ true fermentations ” are : 1. Acetic fermentation ; which is the change of alcohol into acetic acid, and takes place when fermenting liquors are freely exposed to the air. 2. Lactic fermentation; which is the change of organic matters into lactic acid by the action of a ferment, and most easily originates in milk. Alcohol is met with commercially in one or other of the following forms I. Spiritus Rectificatus. Rectified Spirit of Wine, or (simply) Rectified Spirit. Is prepared commercially by a process which has three distinct steps. 1. The prepa 7 'ation of the mash. — The flour of grain of various kinds, and frequently crushed potatoes, is mixed with a little malt obtained as already explained. The whole is then soaked with warm water, and beaten to a mash in a suitable apparatus. When thoroughly reduced to a pulp, it is allowed to stand for some hours, and by the action of the diastase in the malt, the saccharine fermentation sets in, and the whole becomes a translucent fluid, with a sweet taste. 2. The fermentation of the mash. — The liquid obtained in the last process is mixed with yeast, and allowed to ferment until the sugar has been sufficiently changed into alcohol, which is known by its decrease in specific gravity, called by distillers its degree of atteiiuation. 3. The distillation of the fermented mash. — The attenuated liquor is intro- duced into a still, where it is heated, and a very dilute alcohol is obtained, which is then concentrated by a redistillation , in a special apparatus. This process is called rectification, and is continued until the spirit is of the desired strength. SPIRITUS RECTIFICATUS.—SPIRITUS TENUIOR. 227 Rectified Spirit^ B.P., contains 84 per cent, of alcohol, and is colourless, transparent, very mobile and inflammable, of a peculiar pleasant odour, and a strong spirituous burning taste. Burns with a blue flame, without smoke. Specific gravity, o’838. Remains clear when diluted with distilled water (absence of. oily and resinous matters). Odour and taste purely alcoholic (freedom from aldehyd and amyl hydrate). Four fluid ounces, with thirty grain-measures of the volumetric solution of argentic nitrate, exposed for twenty-four hours to bright light, and then decanted from the black powder which has formed, undergo no further change when again exposed to light with more of the test (presence of a trace only of aldehyd and amyl hydrate, the B.P. allowing an amount of these impurities equivalent to 2\ grains of argentic nitrate per pint of spirit, as it would be impossible to obtain com- mercial alcohol entirely pure). II. Spiritus Teniiior (Syn. Proof Spirit). Is a mixture of rectified spirit and water, containing 49*25 per cent, by weight of alcohol, or 56*85 per cent, by volume, at 60° F. It is prepared by mixing five pints of rectified spirit with three pints of pure water, and its specific gravity should be *920. When the water and spirit are mixed, a reduction in volume of the whole takes place ; so that if 1 00 volumes of rectified spirit be mixed with sixty volumes of water, the resulting proof spirit would only measure 156 volumes. In applying to alcohol the dilution test (for oils and resinous matters), or in making proof spirit, the mixture must be allowed to stand for some time before an opinion is formed of the presence or absence of these bodies. The reason for this delay is, that distilled water almost invariably contains air, which, though soluble in water, is almost insoluble in dilute spirit. On the addition of the latter, therefore, it is expelled from solution in the form of small bubbles, which by reflecting the light in every direction, impart to the solution an opalescent appearance. Proof spirit owes its name to the fact that it is the excise unit, according to which the duty is charged ; and in former times, before the invention of hydrometers, the excise officers used to put spirit to the proof by moistening a little gunpowder with the sample, and applying a light \ when, if the spirit were stronger than proof., the gunpowder would take fire. In calculating the strength of spirit, the legal instrument for use in this country is Sykes’ hydrometer, which is floated in the spirit, and a reading being taken, together with the temperature of the spirit, a set of tables (sold with the instrument), is referred to, and the strength of the spirit, over or under proof, is ascer- tained. As 'this hydrometer becomes unavailable for mixtures containing a large percentage of sugar, endeavours are being made to encourage the dis- covery of a process by which it may be possible to determine the amount of alcohol in any mixture, no matter how composed, by one single operation. Proof spirit being considered as unity, it is evident that spirit of wine, B.P., which requires to be diluted with water in the proportion to make 100 volumes up to 156, is itself 56 degrees over proof. In the same way, a spirit which requires that water should be added until 100 volumes measure 130 before it is reduced to proof strength, would be 30 degrees over proof. III. Absolute Alcohol is prepared by keeping one pint of rectified spirit in contact with ounce of dry potassium carbonate in a stoppered bottle for two days, and then distilling over 10 ounces of freshly-burned quicklime at a temperature not exceeding 200° F. The first ij fluid ounce which comes over should be rejected. Thus prepared, ethyl hydrate is a colourless, volatile, and mobile liquid. 22S THE ALCOHOLS. having a specific gravity of 795, which should show perfect freedom from water by not turning anhydrous cupric sulphate blue. It registers (according to the Inland Revenue calculation) 74 per cent, over proof by Sykes’ hydrometer. Alcohol is a powerful preserver of animal and vegetable substances, and is therefore used as an antiseptic. It is employed in analysis as a solvent, and also as a precipitant of many substances from a watery solution. Precipitates which are slightly soluble in water are frequently washed with dilute alcohol, and it is also employed to some extent as a reducing agent A solution of potassium chromate, for example^ when heated with hydrochloric acid and a few drops of alcohol, becomes reduced to chromic chloride. When the vapour of alcohol is passed through a, red-hot tube, it deposits carbon and evolves carbonic acid gas and steam, together with a complex mixture of hydrocarbons. It burns in the air, producing carbonic anhydride and water. In contact with a heated spiral of platinum wire, or a little platinum-black, the vapour of alcohol undergoes a slow and imperfect combustion, yielding very irritating vapours containing carbonic, acetic, and formic acids, together with aldehyd, acetyl, and water. Pleated with soda-lime, it evolves hydrogen and forms acetates of the metals sodium and calcium. Strong nitric acid oxidizes it rapidly with a violent evolution of gas and production of beat. Excess of alcohol, heated at a proper temperature with strong sulphuric acid, yields ethyl oxide (ether), but if the acid be in excess, and the temperature high, ethylene (olefiant gas) is produced instead. The metals potassium and sodium decompose alcohol, evolving hydrogen, and forming potassium or sodium ethylate. This body is also formed in alcoholic solutions of potassium hydrate ; but when such solutions are exposed to' the air for a long time, they eventually decompose, and form a resinous matter and potassium acetate. When alcohol is mixed with water, considerable heat is evolved, and the resulting dilute spirit has a different specific gravity from that which would be expected by calculation. Owing to the great difficulty of preserving it, pure alcohol has only a very limited number of applications. BUTYL HYDRATE (Syns. Propyl Carhiml. Tdryl Hydraie). Formtila, C4H9HO, or CH2.C3Hy.HO. Is of interest because frequently contained in the fusel oil which is used to prepare pha.rmaceutical valerianates. It can be procured from the majority of samples of the commercial fusel oil by fractional distillation, the portion coming over between 220° and 240° E. being chiefly butyl hydrate. AMYL HYDRATE (Syns. Amylic Alcohol. Isopentyl Hydrate. Isohictyl CarbmoL Oil of Gram). Formula, CgH^^HO, or CH.(CH3)2.C2H4.H0. Is produced in an impure form {as fusel oil) during the fermentation of potatoes, and when the spirit is distilled it passes over with the last portions of the distillate, which are milky. It may be purified by digestion with calcium hydrate and hot water, recti- fying over calcium chloride at a temperature not far from 270° F., rejecting that which comes over below 265° or above 275° F. It is contained in ordinary spirit derived from farinaceous sources (especially from raw grain and potatoes), and is dangerous to health when present to any considerable extent in spirits intended for drinking purposes, a small quantity causing giddiness, nausea, and other unpleasant symptoms. A few drops of the pure AMVLIC, CETYL, CEROTIC, MELYL, ALCOHOLS. 229 amyl hydrate will produce all the effects of a large quantity of spirit, leaving the partaker in a most deplorable condition.- Fusel oil is a colourless liquid, with a penetrating and oppressive odour and a burning taste. When pure, its specific gravity is *818, and its boiling point 270° F., or 5° lower than that of the normal alcohol. Sparingly soluble in water, but soluble in all proportions in alcohol, ether, and essential oils. Exposed to the air in contact with platinum-black, it is slowly oxidized, yielding isovaleric acid. When ignited it produces a white flame. Phosphorus and sulphur are slightly soluble in amylic alcohol. By heating with potassium dichromate and sulphuric acid, valerianic aldehyd, acid and amyl valerianate are formed. When a mixture of potassium and calcium hydrate is treated with amyl hydrate, at 428° F. in closed vessels, potassium valerianate is produced and hydrogen liberated. In ordinary amyl hydrate there are said to be two modifications, one of which does not affect polarized light, whilst the other causes right-handed rotation. HEXDECYL HYDRATE (Syns. Ce/yl Akokdh Ethal). Formula, CigH33.H0. Prepared from spermaceti* B.P.), a crystalline fatty body found in the head of the sperm whale. In cetaceum the radical CigH33 takes the ^ place which in most fa*ts is occupied by glyceryl, C3H5 ; and spermaceti is therefore nearly pure cetyl palmitate, CigH33.CigH3^02, sometimes termed cetine. The spermaceti is saponified with caustic potash, and the cetyl alcohol formed is dissolved out by alcohol and afterwards purified by crystal- lizations from ether. Hexdecyl hydrate is a tasteless, odourless, white crystal- line mass. It melts at about 122° F. It dissolves freely in alcohol, but is insoluble in water. It distils at a high temperature and without decompo- sition. Heated with potash and lime, it is converted into palmitic acid, with evolution of hydrogen.- CERYL HYDRATE (Syns. Ceroti'c Alcohol. Qerotine). Formula, C2-H55.HO. This alcohol is obtained from Chinese wax, which is chiefly composed of ceryl cerotate. It is prepared by saponification much in the same manner as cetyl alcohol. It is a wax-like substance, melting at 2 06 6° F. It distils at a high temperature with partial decomposition. When heated with a mixture of potash and lime, it gives off hydrogen, and is converted into cerotic acid. MYRICYL HYDRATE (Syns. Melyl or Melissyl Alcohol). Formula, This is the highest member of the C„H2n+;^HO series at present known. It contains over 82 per cent, of carbon, whereas methyl alcohol, the lowest of the series, contains only 40 per cent. It is obtained by saponification from myricine (the portion of beeswax insoluble in boiling alcohol, and which consists of myricyl palmitate), the process being the same as that employed for cetyl and ceryl alcohol. Thus prepared, myricyl alcohol is a crystalline substance having a silky lustre. It melts at about 185° F. When heated it sublimes with partial decomposition. Heated with potash lime it is converted into potassium melissate with evolu- tion of hydrogen. 230 THE ALCOHOLS. II. MONATOMIC ALCOHOLS OF THE SERIES C^H^^.^HO. Only one alcohol of this series has been obtained, namely, allyl alcohol. The substance known as vinyl alcohol was long placed in this series ; but recent researches have shown it to consist of crotonic aldehyd. ALLYL ALCOHOL. Formula, CgH.'.HO. Prepared indirectly from glycerin by submitting it to the action of diphosphorous tetriodide, when allyl iodide is obtained : — ■ 2C3H5"'(H0)3 + P,l4 = 2C3H,'.I + 2H3PO3 + I3. The allyl iodide is then decomposed by silver oxalate, when allyl oxalate is formed : — 2C3H5 .1 + Ag 2 C 204 = (C3Hg)2 C2O4 + 2AgI. The allyl oxalate is next submitted to the action of ammonia, when oxamide and allyl hydrate are produced : — (C 3 H 5 ) 2 C 204 + 2 NH 3 = C202N2H,+ 2C3H/H0. Allyl alcohol is a colourless liquid having a burning taste and a mustard- like spirituous smell. It burns with a bright flame and is miscible in all proportions with water, alcohol, and ether. Boiling point, 2i7’5° F. Allyl alcohol is a primary alcohol, and in all ordinary reactions behaves like ethyl alcohol. By the action of platinum black or a mixture of sulphuric acid and bichromate of potash, allyl alcohol is transformed first into acroleiine and then into acrylic acid. Strong H2SO4 converts it into allyl sulphuric acid, CgH^'HSO,. HI. DIATOMIC ALCOHOLS, OR GLYCOLS, (C,H,J"2H0. The glycols are derived from the saturated hydrocarbons by the sub- stitution of 2HO' for 2H. Like the monatomic alcohols, they furnish ethers, aldehyds, and acids ; but while the former can only yield one each of these derivatives, the glycols, being diatomic, generally yield two of each and pass through two successive steps of etherification, dehydrogenation, and oxidation. The glycols are formed by the following general processes : — An olefine is combined with bromine, and the dibromide formed is treated with silver acetate, and thus .converted into a glycol diacetate. The diacetate is now acted on by potassium hydrate, when it yields potassium acetate and the ♦ required glycol. The glycols are colourless, inodorous, viscid liquids having a sweetish taste; freely soluble in water and alcohol. When subjected to the action of oxidizing agents they give up two or four atoms of hydrogen in exchange for oxygen and yield two distinct acids. METHYLENE HYDRATE (Syn. Methylene Alcohol). Fornmla, CH 22 HO. Is not at present known, though ethylene hydrate, the next member of the series, is easily obtained. ETHYLENE HYDRATE (Syns. Glycol Ethyl Glycol Ethylene Alcohol). Formula, C2H^2H0. Is procured by treating ethylene acetate with potassium or barium hydrate. C 2 H^ 2 C 2 H 302 + 2KH0 = C2H^2H0-f-2KC2H302. DIATOMIC AND TRI ATOMIC ALCOHOLS, 231 The ethylene acetate is the result of acting upon ethylene bromide, pro- duced by direct combination of ethylene (olefiant gas) and bromine with potassium or argentic acetate. It is of interest as yielding oxalic acid by oxidation. Glycol, as it is usually termed, is a syrupy, colourless liquid, soluble in water and alcohol, but only dissolving in a relatively large amount of ether. It boils at 387° F., and has a specific gravity of i’i25. It dissolves many bodies which are soluble in alcohol. When diluted with water, and the solution brought in contact with platinum-black, glycollic acid, a body intermediate between glycol and oxalic acid, is formed, having the formula C2H2O.2HO. Heated with potassium hydrate to 480° F., hydrogen is eliminated and potassium oxalate produced. C2H42HO + 2KHO = K2C2O4 + 4H2. PROPYLENE HYDRATE (Syns. Hydrate of Tritylene. Propylene Alcohol. Trityl Glycol). Formula, C3Hg.2H0. Is not of pharmaceutical interest except as the source of derivation of lactic acid. Prepared like ethylene hydrate. TETRYLENE, or BUTYLENE HYDRATE (Syns. Tetrylene or Butylene Alcohol, Butyl or Tetryl Glycol). Formula, C4Hg.2H0. Owes its interest to the fact that it yields succinic acid by oxidation. It may be produced by acting upon tetrylene acetate., with potassium hydrate, as in the preparation of glycol. IV. TRIATOMIC ALCOHOLS OF THE SERIES C,H2n-i.3HO. These hydrates may be regarded as derived from a triple molecule of water, HgOg, by substitution of a., trivalent alcohol radical for three atoms of hydrogen. The triatomic alcohols are able to exchange part or the whole of their hydroxyl for a halogen element or acid radical, thus glycerin forms three hydrochloric ethers : — ' ist. C3Hg'"Cl(HO)2, 2nd. C3Hg'"Cl2(HO), and 3rd. C3H5'"Cl3, which are known as chlorhydrins, and are obtained by the direct action of hydrochloric acid upon glycerin. There are only two triatomic alcohols known, namely, propenyl hydrate or glycerin, and pentenyl or amyl glycerin. GLYCERYL HYDRATE (Syns. Glycerin. Propenyl Alcohol. Glyceric Alcohol). Formula, CgH-.SHO. This important body is a bye-product in the preparation of the fatty acids for the purpose of making soap and candles, and also in the pharmaceutical preparation of lead plaster. It exists free in palm oil and some other varieties of vegetable oils, whence it can be dissolved out by agitation with hot water, and (as has been already shown under Alcoholic Fermentation) is formed in the production of wine and beer. Formerly glycei'ui was entirely obtained by the saponification of olive oil 'with plumbic oxide; but its great liability to contain lead when thus prepared has caused the almost total discontinuance of this process. If it be desirable to procure a small quantity for experimental or other purposes, plumbic oxide and olive oil are heated together until the B.P. lead plaster is formed, and the aqueous liquor is purified from lead by means of a 232 THE ALCOHOLS. stream of sulphuretted hydrogen gas ; the liquid after filtration is then very gently evaporated to a syrup. The process which is most generally employed at the present time, is one depending upon the dissociation of the acids and the glycerin of fats by the action of steam at about 580° F. The distillate which results consists of an aqueous solution of glycerin with the fatty acids floating upon its surface. The lower layer is drawn off by a tap near the bottom of the condenser and receiver combined, and the greater part of the water is removed by evaporation. When thus prepared, and its specific gravity rendered as high as possible by evaporation, glycerin is a clear, colourless fluid, oily to the touch, without odour, and of a sweet taste. It cannot be crystallized, and is soluble in water in all proportions, neutral to test-paper, decomposes almost entirely on being heated, and when abso- lutely free from water exhibits a specific gravity of i’2 6 at 60° F. although the commercial article rarely exceeds i'25. Glycerin dissolves as readily in alcohol and chloroform as in water, but ether entirely fails to xtake it up. Iodine is soluble to a large extent in glycerin, forming an orange solution, but no chemical action takes place. Glycerin forms salts with hydrates somewhat resembling saccharates, but less readily decomposed. For example, calcium, barium, and strontium saccharates are decomposed by carbonic anhydride, but the glycerin compounds of these metals are not. Potassium and sodium hydrates, and all salts having a great affinity for water, and consequently deliquescent, dissolve in glycerin. But this is not the only class of salts which it dissolves, for it takes up sodium sulphate, which has so little affinity for water as to be positively efflorescent ; also zinc and potassium sulphates, potassium and sodium chlorides, sodium carbonate, and others. The solubility of plumbic oxide in glycerin explains the fact that, when obtained by the action of plumbic oxide on olive oil, it always contains lead in solution. Insolubility in water, as a rule, also implies insolubility in glycerin ; but many exceptions exist. If mixed with potassium hydrate, no precipitate is formed when an excess of the mixture is added to a solution of cupric sulphate. Some alkaloids and their salts are taken up entirely by glycerin ; others dissolve if heated, but separate out on cooling. If then the mass be rubbed while cooling, an emulsion is formed. All carbonaceous acids are taken up by this remarkable solvent. The solutions of carbolic, gallic, and tannic acids in glycerin are official. The B.P. also contains a solution of borax, and a mucilaginous starch mixture in this liquid. Glycerin may be recognised by the following characteristics : — 1. Its specific gravity. 2. Its powerlessness to rotate polarized light. 3. It should be easily and entirely soluble in chloroform, otherwise it con- tains glucose. 4. Sodium hydrate, when heated with it, produces no brown colour (absence of glucose). 5. By heating with strong sulphuric acid, extremely acrid and irritating vapours are evolved, which are called acrolein^ C3H4O. These vapours are especially irritating to the eyes, and cause a copious flow of tears. Zinc chloride, phosphoric anhydride, or acid potassium sulphate, may be substituted for the sulphuric acid. If an aqueous solution of glycerin be employed, it must be rendered as strong as possible by evaporation, to ensure the success of this test. . The action of nitric acid upon glycerin produces, according to dilution and temperature, either nitro-glycerin or a mixture of glyceric and oxalic acids. It precipitates gold from auric chloride. NITRO-GL VCERIN.—MANNITE. 233 The salts of glyceryl formed from glycerin are generally called by special names derived from that of the acid which may be contained in them, by substituting in or ine for ic. Thus, glyceryl mon-acetate, C3H5.C3H3O2.2HO, is termed mon-acetin, glyceryl tri-palmitate, tri-palmitin. In cases in which all of the hydroxyl of the glyceryl hydrate is not displaced, the whole of the name of the acid except the last syllable is prefixed to the word hydrin : thus, mon-acetin would be mon-acet- hydrin. Usually, however, it is the hydrochloric derivatives to which this class of appellations is applied, because of the inconvenience of a word bearing so near a resemblance to chlorine as chlorin. NITRO-GLYCERIN. Formula, C 3 H 5 (N 02 ) 303 . A terribly explosive agent, obtained from glycerin by the action of a mixture of strong nitric and sulphuric acids in substituting nitryl for hydrogen. It it a heavy, oily liquid, and explodes violently by percussion. Dy 7 iamite^ litho-fracteiir^ and other blasting compounds, all depend for their activity on the presence of nitro-glycerin, usually finely divided by being mixed with sand, etc. V. HEXATOMIC ALCOHOLS. In this class of substances are included three of the natural sugars, mannite, dulcite, and sorbite, and the compounds known as saccharoses. The glucoses and the amyloses are also included as derivatives, they however demand a special chapter to themselves. MANNITYL HYDRATE (Syns. Mafmiie. Mannitic Alcohol). Formula, CgHg.eHO. This body exists to the extent of 60 to 80 per cent, in manna^ B.P., from which it may be extracted by alcohol. The natural sources are officially stated to be the Fraxiniis Of'nus and F. rotundifolia ; and from these it is obtained by making incisions in the stems of trees. cultivated for the purpose, chiefly in Sicily. The following official plants also contain mannite to a . greater or less extent, Acofiitiwt Napellus^ Ptmica Gra 7 iatum., and Ca 7 iella alba. It may be obtained artificially by subjecting glucose (CgH;^20g) to the action of nascent hydrogen (evolved from sodium amalgam and water), when the decomposition shown below occurs ; — C6Hi206-hNa2 + 2H20 = CgHg.dHO + 2NaHO. Manna is met with in commerce in stalactiform pieces from one to six inches in length, and one or two inches in width, uneven, porous, and friable, curved on one side, of a yellowish-white colour, with a faintly nauseous odour and a sweetish taste. It consists principally of mannite, together with common sugar and extractive matter. The mannite, which forms from 60 to 80 per cent, of the manna, may be extracted by means of boiling rectified spirit, from which it will afterwards separate on cooling in colourless, shining crystals. It requires five parts of cold water for its solution, and this does not undergo vinous fermentation in contact with yeast. Several recrystallizations from alcohol are required to produce it in a pure state. Unlike most sugars, mannite may be very readily crystallized from its aqueous solution, and without uniting with any water. The alcohol best adapted for dissolving mannite is that of 60 per cent., in which it dissolves to the extent of i‘25 per cent, in the cold, but much more extensively when 234 THE ALCOHOLS. heated. It does not dissolve in ether, but water takes up about 15*6 per cent, at the normal temperature. It is optically -inactive, but its adulterations and substitutions rotate a polarized beam of light. Mannite melts at 330° F. By oxidation it yields mannitic acid, CgH^gO^, and mannitose, CgHigOg. With nitric acid it yields saccharic acid, and ultimately oxalic acid. Heated with organic acids it forms compound ethers which are termed mannitanides. It does not form a precipitate when heated with cupric tartrate and potassium hydrate in excess, nor does it turn brown when boiled with the latter alone. Mannite is formed when sugar undergoes the mucous fermentation (which takes place by the action of a nitrogenous ferment in the presence of air), and may be obtained from the evaporated solution by extraction with hot alcohol. Ergot of rye (ergota, B.B.) sometimes contains mannite, as also some algce and fimgi, VI. ALCOHOLS OF THE AROMATIC SERIES.— PHENOLS. The displacement of more or less hydrogen from benzene by hydroxyl yields a series of alcohols called phenols. They differ from ordinary alcohols by having a somewhat acidulous nature and forming comparatively very stable compounds with metals. They may be prepared by heating the aromatic oxy-acids with calcium * oxide, when carbonic anhydride is given off and the phenol distils over. Thus salicylic acid so treated yields phenyl hydrate (carbolic acid). C^HgOg^ CgHg.H0 + C02 Of all organic series the aromatic is the most interesting ; but we are limited by our scheme to the consideration of those members employed in medicine or pharmacy. PHENYL HYDRATE (Syns. Phenol. Carbolic Acid. Phenic Acid. Coal Tar Creasote). Formula,’ CgHgHO. Is a constituent of casloreum, B.P., and may be obtained by heating salicylic acid ; but in practice it is procured from coal tar by distilling until a solid substance (anthracene) begins to come over. The product is then placed in another retort, and the distillate passing over between 360° F. and 390° F. is mixed with a solution of potassium hydrate containing some undissolved potassium hydrate in powder, when the oily liquid immediately becomes solid. It is then dissolved in hot water, and after some time the lower liquid is drawn off by any convenient means. Hydrochloric acid is next added until the liquid becomes neutral ; and the supernatant fluid, having been drawn off, is agitated with water, and, after digestion with calcium chloride for the purpose of absorbing the water, is subjected to several distillations. On cooling the final distillate to -18° F., pure phenyl hydrate crystallizes out. Phenyl hydrate fuses at 93° to 95° F., forming a colourless oily fluid. The crystals of the pure acid absorb moisture readily from the air, a very slight quantity causing their deliquescence from colourless needles to a liquid similar to that formed by the application of heat. Calcium chloride removes the moisture, consequently giving rise to an instantaneous resolidification. Though termed an acid, it does not affect litmus like other members of the acid class. It is a powerful antiseptic. When pure, it is met with in colour- less acicular crystals, which at a temperature of 95° become an oily liquid having a strong odour and taste, resembling those of creasote, which it also resembles in many of its characters and properties. Its specific gravity is CATABOLIC ACID.—CREASOTE. 235 1-065; boiling point, 370° F. It is only slightly soluble in water, but is freely soluble in alcohol, ether, and glycerin ; coagulates albumen and does not affect the plane of polarization of a ray of polarized light. A slip of deal dipped into it and afterwards into hydrochloric acid, and then allowed to dry in the air, acquires a greenish-blue colour. Concentrated sulphuric acid converts it into phenyl hydrogen-sulphate (sulpho-carbolic acid, C6H5HSO4). By passing ammonia gas into a solution of phenyl hydrate, and heating the result in a closed tube, a small quantity of aniline (phenylamine, CgHj.HgN) is formed : — CgHgHO -H NH3 ^ CgH-.H^N -f H^O A solution of potassium hydrate does not dissolve it in proportion to its strength, and unlike all true acids (except hydrocyanic), it does not decom- pose carbonates. None of the combinations are of pharmaceutical interest, except those produced by the action of ammonia gas, sulphuric acid, and nitric acid. If it be acted upon by ammonium hydrate and chlorinated lime, it gives rise to a blue liquid, which wood, or true creasote does not produce. From the latter it also differs by its capability of ready solidifica- tion ; true creasote not becoming solid at -49° F. Phenyl hydrate does not become solid after being melted, whereas if creasote be heated to 212° F. and maintained at that temperature for some hours, a solid residue remains. The following are some other points of distinction Phenyl Hydrate. Inactive towards polarized light. Commercial glycerin dissolves it. It precipitates nitro-cellulose from an ethereal solution in a gela- tinous form. Alcohol and ferric chloride yield a brown colour. Ferric chloride and a little am- monium hydrate produce a violet colour. Creasote. Dextro-rotatory. Does not dissolve it. Does not cause any effect when added to the same solution (known as collodiiwi, B.P.). Alcohol and ferric chloride yield a green coloration. Ferric chloride and ammonium hydrate give rise to a green coloration fading to brown. Creasote consists chiefly of creasol (CgHiQ02), a volatile liquid of a pleasant odour, which differs from phenyl hydrate in reducing the metal from argentic nitrate, and forming an almost insoluble crystallizable salt with ammonium hydrate. Creasol must not be confounded with cresyl hydrate (C7H7HO), a volatile liquid which is isomeric with the next substance we are about to consider. The radical contained in creasol being monad renders it almost impossible to regard that body as an “ alcohol,” because all alcohols possessing a monad radical contain a single atom of oxygen only. Phenyl hydrate being a dangerous poison can only be employed medi- cinally in very small doses. Should it accidentally happen that an excessive quantity has been taken, fixed oils will serve to mitigate the effect ; olive, almond, and castor oils being the most useful. The following are the qualities of true wood creasote : — A liquid, colourless or with a yellowish tinge, and a strong empyreumatic odour. It is sparingly dissolved by water, but freely by alcohol, ether, and glacial acetic acid. Specific gravity, 1-071. It coagulates albumen. A slip of deal dipped into it, and afterwards into hydrochloric acid, acquires on exposure for a short time to the air a greenish-blue colour. Dropped on white filtering paper, and exposed to a heat of 212°, it leaves no translucent 236 THE ALCOHOLS. stain. It turns the plane of polarization of a ray of polarized light to the right It is not solidified by the cold produced by a mixture of hydrochloric acid and sulphate of soda. BENZYL HYDEATE (Syns. Benzylic Alcohol. Benzoic Alcohol. Toluylic Alcohol). Formula, C7H7HO. Is of inconsiderable importance to pharmacists, but gives birth to two highly interesting products by oxidation. These are benzoic aldebyd (essential oil of bitter almonds) and benzoic acid, the basis of benzoates. The hydrate itself is made by decomposing benzoic aldehyd by means of a solution of potassium hydrate in alcohol, when the following rather remarkable reaction occurs : — 2C7H5O.H + KHO = C7H7.HO + KC7H5O2. When balsam of Peru {balsamu 7 n Peruvianu 7 u., B.P.) is warmed with potassium hydrate in aqueous solution, an oil rises to the surface. If this be separated, and distilled in an atmosphere of carbonic anhydride at the lowest possible temperature, the distillate contains benzyl hydrate. CINNYL HYDEATE (Syns. Cmnamic Alcohol. Storax Alcohol. Sfyro 7 ie Pe 7 'uvin). Formula, C9H9HO. Is prepared by distilling balsam of Peru with water, boiling the residue with sodium carbonate solution (forming styracin) and redistilling the insoluble portion with potassium hydrate. If salt be added to the liquid passing over, a solid body gradually forms on the surface, which is cinnyl hydrate. When pure, this body is composed of smooth needle -like crystals, possessing an odour of hyacinths. The crystals, when first formed, are extremely small; but when the solution is allowed to stand they gradually increase in size. CAMPHYL HYDEATE, or CAMPHOL (Syns. Bov 7 ieol. Bor 7 ieo CaTtiphor. Ca 77 iphyl Alcohol). Formula, CioH„HO. This body is a “ concrete volatile oil ” obtained from the D 7 yobala 7 iops aro 77 tatica of Borneo. It is one of the several substances passing under the denomination of camphors, but is not that in general use. Like other alcohols it yields ethers (salts) by the action of acids, water being eliminated. Camphol may be obtained from common (or China) camphor by heating it with an alcoholic solution of potassium hydrate in a sealed tube. The re- action is at some times less complex than at others, the following equation representing the most simple : — 2C10H16O + 4KHO = 2C10H18O + 2K2O + O2. Camphol melts at 388° F., and can be sublimed without decomposition at about 420° F. It is capable of conversion into ordinary camphor by the action of nitric acid, and is distinguished from the latter by not becoming liquid when treated with hydrochloric acid. CHAPTER XV. CARBO-HYDRA TES. These bodies are of ternary composition, containing carbon, hydrogen, and oxygen. They form a group by themselves, being easily converted into each other by the’ addition or subtraction of the elements of water. Properly they are derivatives of, and should be classified with, the alcohols of hexad radicals ; but for convenience we have placed them separately. Their connection, however, with hexad alcohols may thus be theorized : — 1. The hexad alcohol, by subtraction of hydrogen, may be supposed to yield an aldehyd : — CeHgfiHO + O =- CeHiaOg + (Mannite.) (Glucose.) 2. The aldehyd, by subtraction of water from two or more molecules, may yield a polyglucosic alcohol : — ^^ 6 ^ 12^6 “ ^ 2 ^ - C12H22O11. (Glucose.) (Saccharose.) 3. A polyglucosic alcohol, by further loss of water, may yield an oxygen- ether. ' ^12^22^111 “ ^2^ = ^CgHioOg. (Saccharose.) (Starch.) It is a fact worth noting, that in all these bodies the carbon exists combined with just sufiicient hydrogen and oxygen to always form a definite number of molecules of water. They are divided into three isomeric classes, corresponding with the above- mentioned reactions, as follows.* * Those marked 4- are c Isevo-rotary. Amyloses, (CeHioOj). Cellulose. Starch. + Dextrin. - Inulin. Glycogen. Gums. o-rotary to polarized light, Saccharoses, (C12H22O11). + Cane sugar. + Milk sugar. + Maltose. + Melitose. + Melezitose. + Trebalose. + Mycose. 4- Parasaccharose. while those marked — are Glucoses, (C6H12O6). + Grape sugar. - Fruit sugar. Mannitose. ■f Galactose. Inosite. Sorbin. Eucalin. 238 CARBO-HYDRA TES. I. AMYLOSES, Or Carbo-hydrates, of the General Formula CgH^^Og. CELLULOSE (Syns. Cellulin. Lignin). Formula, CgH^oOg. • Is the material of which the walls of the cells of plants are composed. The best-known forms of cellulose are cotton and linen, and its reactions may be learned by acting on either of these substances. It is official as gossypiu?fi, B.P., which is the carded hairs of the testa of the cotton plant. Cellulose is insoluble in water and also in dilute acids and alkalies, its best solvent being a deep-blue liquid obtained by dissolving cupric oxycarbonate in ammonium hydrate. When thus in solution it is re-precipitable by a slight excess of acid, in the form of white flakes which are not affected by tincture of iodine. The woody fibre of plants is an impure form of cellulose, containing usually more hydrogen, together with a little nitrogen. When cellulose is stirred into cold strong sulphuric acid, it is converted into a soluble gum similar to dexUHn, and by diluting and boiling this solution glucose is produced. Vegetable Parchment (Syn. Fapyrin), used in dialysis, has a composition analogous to cellulose, and is prepared by passing unsized paper through tolerably strong sulphuric acid, and then washing, first with pure water and afterwards with water containing a little ammonium hydrate. The estimation of woody fibre is a matter which is important in the analysis of vegetable matters. It is conducted by boiling a weighed portion of the article, first in dilute sulphuric acid and then, after filtration and thorough washing, once more boiling the insoluble portion in dilute solution of potassium hydrate. The whole, haying been filtered, is finally washed with boiling water, dried at 2 1 2°, and weighed. Nitro-cellulose (Syns. Pyroxylin. Gun Cotton). When cellulose is treated with nitric acid, a substitution of nitryl takes place for one or more atoms of hydrogen, and one of the three following varieties of nitro-cellulose is produced : — Mononitro-cellulose., CgHg(N 03)05. ' Dinitro-cellulose., or Pyroxylin^ B.P., C6H8(N02)205i Trinitro-cellulose.^ or Gun Cotton, CgH7(N02)305. In practice the nitric acid is mixed with sulphuric acid, because it is found to cause the former acid to act more quickly ; but it does not affect the real reaction, of which the following may be taken as a type, choosing dinitro- cellulose as the one most interesting to pharmacists and medical men : — CeHi„Os + 2 HNO 3 = C,H 8 (N 02)305 + 2 H, 0 . •The following table shows the characteristics of each of the three varieties : — Mononitro-cellulose. Not soluble in a mixture of alcohol and ether ; soluble in acetic acid. (Not very inflammable.) ' Dinitro-cellulose. Soluble in the former; insoluble in the latter. (Tolerably inflammable.) Trinitro-cellulose. Soluble in both. (Very inflammable.) The following are the instructions as to making and testing pyroxylin, B.P. (which is dinitro-cellulose). Take of Cotton I ounce. Sulphuric Acid ) Nitric Acid / 5 ounces. CELLULOSE.— STARCH, 239 Mix the acids in a porcelain mortar, immerse the cotton in the mixture, and stir it for three minutes with a glass rod, until it is thoroughly wetted by the acids. Transfer the cotton to a vessel containing water, stir it well with a glass rod, decant the liquid, pour more water upon the mass, agitate again, and repeat the affusion, agitation, and decantation, until the washing ceases to give a precipitate with chloride of barium. Drain the product on filtering paper, and dry in a water bath. Tesfs . — Readily soluble in a mixture of ether and rectified spirit ; leaves no residue when exploded by heat. The vapours set free when it explodes (which it does at 300° R), liberate iodine from potassium iodide, thus rendering paper soaked in that substance and starch paste, blue * they also show an acid reaction with litmus. When I ounce of pyroxylin is dissolved in a mixture of 36 fluid ounces ot ether and 12 fluid ounces of alcohol, collodium, B.P., is produced. It is a colourless highly-inflammable liquid with ethereal odour, which dries rapidly upon exposure to the air, and leaves a thin transparent film, insoluble in water or rectified spirit. STARCH (Syn. A??iylum). Formula, CgHioOg. Is a white granular body stored up in the stems, roots, and seeds of plants, and is the most abundant proximate principle found in the vegetable kingdom. It is separated from the plant tissues by steeping them for some time in water rendered just alkaline with sodium hydrate, and then rubbing the softened mass on a sieve under a slow stream of water. The fibre and glutinous matters remain on the sieve, while the starch passes through with the water, from which it is recovered by settlement, and finally drying at an exceedingly low heat. The ordinary patent starch used in laundries is usually prepared from rice by the above process, and then coloured slightly blue with indigo, and dried in lumps. Pure starch is a white powder with a peculiarly slippery feel between the fingers, and insoluble in cold water, alcohol, ether, and other common solvents. When examined under a microscope with a J-inch object glass, it is seen to be made up of rounded transparent bodies, each formed by an albuminous coat filled with gelatinous starch which is called amidin. Many of these granules possess a spot, or hiliwi^ round which are collected a number of parallel annular depressions known as rings. The base of all starch is amidin, but the starch of each plant possesses some special characteristic, either in size, shape, hilum, or rings, which enables us to identify it with tolerable certainty. When starch is moistened with cold water and a quantity of boiling water stirred in, the granules swell and burst, and a mucilaginous liquid is obtained, but no true solution takes place. This preparation is called mucilago aniyli in the B.P. A similar effect is produced by heated glycerin, the result being called glycerinum amyli (Syn. Flastna). By boiling with water and a few drops of a dilute acid, an alteration in the starch slowly takes place, and it is converted first into a mixture of dextrin and glucose : — 3CgH;^o05 + HgO = 2CgHj^Q05 + CgH^^Og. On prolonging the boiling, more water is taken up, and the whole is con- verted into glucose : — ^CgH^gOg 4- 2 H 2 O = 2CgH220g. By the action of nitric acid, starch is converted into oxalic acid. The best test for starch is to make a decoction of the article under exami- nation, and when cold add a drop of iodine solution, which will produce a 240 CARBO-HYDRA TES. fine blue colour, which is amidin iodide. Iodine.) Under the microscope the presence of starch granules is fully confirmed by adding a drop of tincture of iodine, which colours them deep purple. Amylum, B.P., is described as the starch procured from the seeds of common wheat, Triticum viilgare. It should be met with in white columnar masses. When rubbed in a Wedgwood mortar with a little cold distilled water, it is neither acid nor alkaline to test-paper, and the filtered liquid does not become blue on the addition of solution of iodine Mixed with boiling water and cooled, it gives a deep blue colour with iodine. INULIN. Formula, CgHioOg. Is an isomeric variety of starch met with in the root of Lmla Helenium and many other plants. It is, like starch, insoluble in cold water, but freely soluble in boiling water, from which it deposits on cooling. By boiling with a dilute acid it is entirely converted into levulose. It is insoluble in alcohol and is turned brown by iodine, but does not precipitate with plumbic acetate or infusion of galls. GLYCOGEN. Formula, CgHioOg. Is a white tasteless body resembling starch, found in the liver of animals, and especially a constituent of the tissues of the foetal embryo. It is soluble in water and insoluble in alcohol. DEXTRIN (Syn. British Gicni). Formula, CgHioOg. This substance may be produced by three methods. That most commonly adopted consists simply in “ baking ” starch at a temperature approaching 350° F. Thus procured it is a yellowish powder, which dissolves in cold water, forming a somewhat gum-like solution, and when mixed with various colours is employed in the arts for calico-printing and other similar purposes. Upon boiling starch with water and a few drops of sulphuric acid, the mixture becomes perfectly limpid after a few minutes, owing to the con- version of the starch into dextrin. If the sulphuric acid be neutralized by calcium carbonate and the precipitated calcium sulphate separated by filtra- tion, and the filtrate be evaporated to dryness by a heat of 212° F., a residue of dextrin mixed with some glucose remains. The glucose may be removed by digesting with dilute alcohol, in which dextrin is insoluble. Too long boiling with acid will entirely convert the starch into glucose ; but if conver- sion into dextrin be effected by malt or diastase, no amount of boiling will decompose the dextrin thus formed. When seeds undergo germination, a peculiar nitrogenous ferment becomes active. It is termed diastase, and appears to be vegetable albumen in a state of metamorphosis. When a little malt (in which a considerable amount of diastase exists) is mixed with more than a hundred times its weight of gelatinous starch, and heated to 160° F., in the course of ten minutes or less, the mixture will become as mobile as water. The fact of starch invariably forming glucose as well as dextrin when treated with acids (which are not themselves affected, acting only by introducing the elements of water into the molecules of the starch) has led to the deduction that the molecular formula of starch must be CigHgQOig, and the reaction when it is boiled with acid requires then to be represented as follows : — ^18^30^15 + ^2^ ~ ^6^12^6 True dextrin must be carefully distinguished in the mind from the ordinary gummy and mucilaginous matters of plants. The gums, properly so called. G UMS.—SA CCHA ROSES. 241 are exudations from various parts of plants, chiefly from the stems. The leaf buds of the poplar., however, yield gum, as also the roots of the Malvacece and Orchidacece. The mucilage of fruits does not contain gum, but pectin. {See Griucosides.) GUMS. Arahin, CaCi^HooOii^, is the soluble portion of acacm gum 77 ii., B.P., which exudes from the stems of one or more undetermined species of Acacia. It is found in commerce as spheroidal tears usually from half an inch to an inch in length, nearly colourless, and opaque from numerous minute cracks, or in fragments with shining surfaces ; brittle; bland and mucilaginous in taste; insoluble in alcohol, but soluble in water. The aqueous solution forms with subacetate of lead an opaque white jelly (plumbic gummate). If an aqueous solution of iodine be added to the powder, or to a solution formed with boiling water and cooled, there is no appearance of a violet or blue colour (absence of starch). When arabin is boiled with dilute acid it is converted into glucose, which might be expected, seeing that gummic acid, is really isomeric with cane sugar, C;,oH220i;^. By the action of strong nitric acid, arabin forms mucic acid, and may be further distinguished from dextrin by not being precipitated by cupric sulphate. Any solution suspected to contain arabin may be tested by adding a few drops of ferric sulphate solution, when, if gum be present, the whole will become a jelly. Cerasin and bassorin are two other forms of gum : the former is produced by cherry trees, and the latter constitutes the chief portion of t 7 'agaca 7 ttha, B.P., an exudation from the stem of Astragalus verus. It is insoluble in cold water, but readily absorbs that fluid, so that it swells into a jelly. Besides bassorin, tragacanth contains a little arabin, starch, and fibre, and corresponds to the following official description and tests. Characters . — White or yellowish, in broad shell-like slightly curved plates, tough and elastic, but rendered more pulverizable by, a heat of 120° F. ; very sparingly soluble in cold water ; but swelling into a gelatinous mass, which is tinged violet by tincture of iodine (presence of a trace of starch only). After maceration in cold water the fluid portion is not precipitated by the addition of rectified spirit (absence of adulteration by soluble gums). A formula of C12H20O10 has been assigned to bassorin, but it is only doubtful. II. SACCHARHOSES, OR Sugars of the General Formula, CigHggOn. The principal members of this family are : — Saccharose, or Sucrose. Which is by far the most important. Para-Saccharose. Produced by the spontaneous rearrangement of the molecules of saccharose under the influence of diammonium phosphate. Melitose. Contained in the Tasmanian manna, yielded by various species of Eucalyptus. Melezitose. Is yielded by the manna of a species of Larix (larch), grow- ing in Switzerland. Trehalose. “Trehala manna, the product of a tree of Asiatic growth, is the source of this substance. R 242 CA RBO-H YDRA TES, Mycose. Is proc^uced from ergota, B.P., by the treatment of a solution of ergot in water with plumbic acetate, the decomposition of the lead salt remaining in the clear liquid obtained by filtration, with hydrogen sulphide, and evaporation, after again filtering, to the crystallizing point. These two substances both contain two molecules of water of crystalliza- tion. Lactose. Contains a molecule of water of crystallization. It is next to sucrose in importance amongst the members of the class under consideration, and besides that body, is the only one worthy of detailed notice. Maltose. Is the sugar existing in malt, and is very similar to glucose, but more optically active, rotating a ray of polarized light three times as much to the right. It appears by the latest researches however to be an isomer of lactose, and is obtained when diastase acts on starch. SUCROSE. Cane Sugar (Syns. Saccharose. Beetroot Sugar. Saccharum Purificatum^ B.P.). Formula, Ci2H220i;^. Procured from the sugar-cane (Saccha^'um officinaruni) cultivated in both the Indies. It is also produced from the sugar maple {Acer saccharinuni) of North America ; in Germany, and specially in France, from the beetroot, in which it is contained to the extent of 8 per cent, or thereabouts. The edible nuts consumed in most parts of the world usually contain several per cent, of sucrose ; and it is an abundant constituent of the juice of most grasses, of the sap of large trees, of the ‘‘ nectar’' of the majority of cacti, and of carrots, parsnips, turnips, and most roots. The sugar-cane, in which no other sugar than sucrose exists, is the source from which the greater bulk of the sugar consumed in the world is obtained. It contains i8 to 20 per cent, of crystallizable sucrose, and the preparation is conducted as follows : — The canes are crushed between rollers, and the juice allowed to flow into a large cistern placed beneath. Thence it passes into large pans, in which it is heated approximately to 212° F., and theri a mixture of calcium hydrate and water is added, by which mechanical impurities, vegetable wax and albumen, and calcium phosphate, are thrown down, and the solution is neutralized to prevent its conversion (as much as possible) into inverted sugar. The clear liquid produced on subsidence is run off into another vessel, evaporated to the crystallizing point, and then stirred frequently, so as to produce the granular form of “ raw,” ‘‘ moist,” or muscovado ” sugar. Were it not stirred, a dark coloured variety of “ sugar-candy ” would result. In order to remove the mother liquor (called “ molasses ”) from the product, it is put into barrels, perforated at one end, and standing with that end downwards. At the present time it is customary to evaporate the juice in ‘‘ vacuum pans” (large closed vessels from which air pumps serve to remove the air, together with. the aqueous vapour evolved during the progress of the evapora- tion). When these are employed, the evaporation is much more rapid, and, as it takes place below 150° F. instead of above 230° F., much less waste is caused from the production of un crystallizable sugar. Recently, machinery has been introduced which will remove the juice much more completely than the rollers commonly employed. A solid piston moves horizontally in a cylinder which it fits closely. This cylinder is closed at one end, and the cane having been introduced by a somewhat similar contrivance to that used in a chaff-cutting machine, the piston, at each stroke, cuts a slice off the end of the cane> and crushes it against the portion of the cylinder towards which it is moving, provision for the exit of juice being made by suitable apertures. The sap is much more thoroughly extracted by this SUCROSE.— CANE SUGAR. 243 contrivance, by which the canes are com^Dressed transversely, than by the rollers, which crush them longitudinally. Beetroot and maple sugar, when “raw,’' possess a peculiar taste, which nothing but habit renders agreeable for daily use. The former, however, when refined, is very nearly undistinguishable from cane sugar. The refining of sugar is practised chiefly in this country. It consists in removing the mechanical matters from a solution of “ raw ” sugar by adding albumen, either in the form of white of egg or serum of blood. The liquid is then filtered, first through canvas, to remove the coagulum, and afterwards through animal charcoal to remove the colour ; it is next evaporated to the crystallizing point at 160° F. in vacuum pans, and poured into earthen moulds, where it solidifies into masses of minute crystals, as seen in ordinary “ loaf-sugar.” Lastly, a saturated solution of pure sugar is passed through, by which the last traces of colour are removed, and the “ loaf” is then dried in a stove. This is the official saccharum purificatum. If a saturated, or nearly saturated, solution of cane-sugar be slowly cooled, without agitation, “ sugar-candy ” is formed. If sugar be liquefied without water being present, it produces a slightly yellow, transparent, amorphous mass, being in fact the substance known as “ barley-sugar.” The crystals of “ sugar-candy ” are doubly oblique prisms. Sucrose dissolves in cold water to the extent of three parts in one ; in hot water it is soluble to the extent of five parts or even more in one part. Ether does not dissolve it at all, alcohol not to any notable extent, but in proof spirit it is soluble to some extent. When rubbed, or broken, in the dark, it emits a flash of violet light, exhibiting the phenomenon of “ phos- phorescence.” It melts at 360° F., becoming transformed into a mixture of levulosan and dextrose, = CgH-^oOg + CgH;^206. As the heat increases water is given off and the dextrose is converted into glucosan. At about 410° F. it gives off more water, forming the caramel^ or “burnt sugar,” at one time official under the name of saccharum ustum, but now only employed as a colouring agent in culinar}^ operations. Finally, it gives off inflammable gases, chiefly carbonous oxide and marsh gas, and becomes entirely decomposed. Argentic, mercuric, auric, and some other salts are decomposed when boiled with sucrose, the metals being precipitated. Yeast, in the presence of warmth and moisture, causes dextrose and levulose to be formed, which afterwards yield alcohol. Strong hydrochloric and dilute sulphuric acids transform sucrose into inverted sugar rapidly. Sucrose is readily oxidizable, exploding when mixed with potassium chlorate by percussion, and catching fire when sulphuric acid is added to the mixture. Rubbed in a mortar with plumbic dioxide it also undergoes inflammation. Treated with warm nitric acid it forms saccharic acid (CgH;^Q03) ; and on boiling that product is con- verted into oxalic acid (HgCgO^). Potassium and sodium sucrates are produced by mixing the respective hydrates (in solution) with syrup. The former has the constitution, C;i.2H2iKOi;i, the second has a similar composition. They are both gelatin- .ous and not very soluble in water. Sucrose is recognized by the following characteristic reactions : — 1. It gives no brown colour when warmed with dilute potassium hydrate. 2. The addition of sulphuric acid produces a black colour in a cold and dilute solution of sucrose. 3. It does not form a precipitate when boiled with “Fehling’s solution” (cupric tartrate dissolved in potassium hydrate). 4. A solution of sugar rotates a ray of polarized light 73° 8' to the right. If inverted by treatment with dilute acid, it gives no reaction with sulphuric 244 CARBO-HYDRA TES. acid, but produces a brown colour with potassium hydrate in excess, and a red precipitate of cuprous oxide with Fehling’s solution. The invei'ted sugar thus produced rotates the polarized ray to the left 50° at 5 7 '2° F.' Sucrose is estimated by dissolving a known weight (say 50 grains) in 10,000 grain measures of water, containing 20 drops of sulphuric acid. This liquid is boiled for six hours with addition of water to make up loss by evapo- ration. It is then exactly neutralized by sodium carbonate, and a known quantity (say looo grains = 5 grains sugar) is treated as directed under Dextrose. When flour is mixed with yeast, as in bread-making, many substances are produced, amongst which the principal are sucrose and dextrin, which after- wards yield alcohol, carbonic anhydride, and succinic acid. The process of rendering bread light depends upon the evolution of the carbonic anhydride, which, by insinuating itself within the mechanical interstices of the dough,' pushes the particles asunder. Thus, when the bread is introduced into the system, it presents a much larger surface to the action of the gastric juice than it would if it had not been raised. Ordinarily, therefore, digestibility is con- joined with lightness ; and this has led to the idea that the two are insepar- able in this article of diet. The so-called “aerated bread,” made by mixing flour with carbonic acid solution under pressure, in special machinery con- trived for the purpose, is the offspring of this fancy ; and there is not the slightest reason to doubt that it is a wholesome and nutritious substance. That it is capable and worthy, however, of ’altogether supplanting fermented bread we cannot allow. During the course of fermentation the many sub- stances formed render the mixture of such a complex nature that it is doubtful whether any artificial mixture could profitably be made to possess all its properties. Hence we are of opinion that neither aerated bread nor any substance made without fermentation will ever supplant fermented bread, which is at once the most wholesome, digestible, palatable, and nutritious of all edible compounds. LACTOSE (Syns. Milk Sugar. Lactin. Saccharum Lactis^ B.F.). Formula, C12H32O11.H2O. Is produced by evaporating milk to the crystallizing point, after the re- moval of the cream by standing, and the casein by coagulation. The product, which is not perfectly white, may be decolorized by animal charcoal, after it has been redissolved in pure water. The solution, on careful re-evapo- ration, yields a white solid, to which the B.P. assigns the following pro- perties : — Usually in cylindrical masses, two inches in diameter, with a cord or stick in the axis, or in fragments of cakes ; greyish-white, crystalline on the surface, and in its texture, translucent, hard, scentless, faintly sweet, gritty when chewed. It is very slightly soluble in alcohol, and is quite insoluble in ether. Medicinally it is perfectly inactive, hence largely used in Continental phar- macy as a means of exhibiting active remedies in the form of powder. With alkaline bodies it forms salts, which are very readily decomposable. It only dissolves in cold water to the extent of 17 to 20 per cent., but is taken up by boiling water to the amount of 35 per cent. It reduces cuprous oxide from “ Fehling’s solution.” Lactose was formerly classed as an unfermentable sugar. It has, however, been found that it will ferment after some weeks when left in contact with yeast and water at 80 to 90° F. If calcium carbonate and decaying cheese, or gluten, be mixed with warm water and lactose, cal- cium lactate and alcohol will be formed in the course of a few weeks, the DEXTROSE, VEL GLUCOSE.— GRAPE SUGAR. 245 amount of the latter increasing as the strength of the lactose solution decreases, and depending also on the amount of calcium carbonate present. Lactose, Avhen oxidized with nitric acid, yields a considerable amount of mucic acid (CgHioOg), whilst sugars generally give an isomer — saccharic acid. In consequence of this fact, and because gum yields mucic acid when similarly treated, it is believed that lactose forms a sort of connecting link between sugars and gums. When lactose is boiled with a dilute acid, it is converted into galactose, a sugar isomeric with glucose. Oxalic acid results from the sufficient oxidation by nitric acid of this as of all other sugars. Sulphuric acid and manganic dioxide produce, from lactose, abundance of formic acid. Lactose reduces silver from ammonio-argentic nitrate, in the presence of potassium hydrate, very readily. Sucrose takes a longer time and acts less perfectly. A mixture containing lactose is used for silvering specula for telescopes and other similar purposes. Lactose is estimated by precisely the same process as Dextrose iguJiich see). III. GLUCOSES, OR Sugars of the General Formula CgH^oOg. The number of these bodies at present known does not exceed ten. The principal are : — Dextrose. The most important sugar of this division. Levulose. The result of the action of acids on the starch called iiiidin. It is also formed, together with dextrose, when sucrose is inverted. Mannitose. Produced by the oxidation of manna. Galactose. Produced when dilute acids act on lactose. It yields much mucic acid by oxidation, the others giving saccharic acid. Sorbin. May be procured from mountain-ash berries, in which it exists together with malic acid. Eiicalyn. Which is the so-called ‘‘sugar” of Australian manna. This sugar (and also sorbin) is not readily fermentable. Inosite. Is a species of glucose existing in the heart and other portions of the internal animal organism. It does not ferment with yeast ; but when mixed with cheese or decaying flesh, it undergoes the lactic fermentation. Evaporated first with nitric acid, and afterwards with ammonium hydrate and calcium chloride, it develops a rose colour. None of the above are so definitely crystal lizable as sucrose. They also produce a dark-coloured solution when boiled, with dilute potassium hydrate ; give cuprous oxide, when treated with Fehling’s solution ; and, when in solu- tion in cold water, are not charred by sulphuric acid. DEXTROSE (Syns. Glucose. Dextro-glucose. Grape Sugar). Formula, CgHi20g.H.20. Is the principal form in which sugar exists in ripe fruits, and of it the cry- stalline grains found in dried fruits consist. It is contained abundantly in the urine of diabetic patients. If consolidated honey be washed with alcohol, the fluid portion, dissolving, leaves almost pure glucose in a granular condition. The ripe fruit of the “dog-rose” {Rosce canmce fructus, B.P.), contains dextrose and levulose, to the extent of 30 per cent, of its weight. Five principal methods of procuring it chemically are known ; — I. By acting upon starch with diastase (a peculiar ferment found in barley which has been allowed to germinate — in other words, in malt). Treated in this manner it becomes hydrated, thus : — sCgH.gOg + H.O CgHl20g-^ 2CgHlA. . 246 CARBO-HVDRA TES. 2. By treating starch with sulphuric acid. Mucilage of starch is made by pouring boiling water upon the powder, and this is boiled with about i per cent, of sulphuric acid for five or six hours, the water lost by evaporation being supplied, from time to time, from a vessel of boiling water kept in readiness, for that purpose. Afterwards calcium carbonate, in the form of chalk or whiting, is added to the liquid, until effervescence ceases. The solution is then filtered, and the filtrate, upon evaporation, leaves glucose ; .and if the syrupy mass be allowed to stand for three or four days, the amorphous ^glucose, at first separated, will be trans- formed into a mass of crystalline grains. 3. By making a mixture of pure dry cellulose (in such a form aS “ cotton- wool or linen rags) with twice its weight of strong sulphuric acid, digesting in the cold for five or six hours, then pouring into a considerable quantity of water, filtering, boiling for a few minutes, and treating the liquid, as in the last case, with calcium carbonate. By this means more than an equal weight of sugar may be obtained from linen. It has been proposed to treat saw.dust (which has been deprived of its resinous constituents) in a similar manner, but omitting to boil the filtered liquor before neutralization, in order to obtain a substance which, when mixed with a nitrogenous body, would be available as bread. 4. By boiling cane sugar with dilute acid. Thus, sucrose will yield dex- ‘ trose together with its isomer, levulose, in equal proportions, the mixture being known as inverted sugar : — C12H22O11 + H3O = 2CgH3^2^6‘ Yeast, the ferment of fruits (denominated pectase), and spontaneous decomposition, will also cause sucrose to undergo the same metamorphosis. AVhen the mixture of levulose and dextrose (called /‘inverted sugar ’’), ob- tained as detailed, is, mixed with ten times its weight of milk of lirne^ contain- ing 6 per cent, of calcium hydrate, the dextrose only remains in solution, and if the mass be pressed it is expelled. On removing the calcium from the solution, by means of carbonic anhydride, and evaporating the filtrate from the calcium carbonate thrown down, pure dextrose results. 5. Treating any natural glucoside with dilute acid causes the production of dextrose (and levulose). Dextrose (Glucose) exhibits the following characteristic tests : — 1. Its cold watery solution is not changed by strong sulphuric acid, which distinguishes it from sucrose. 2. Heated with liquor folassos, it blackens, while cane sugar does not change. 3. It precipitates cuprous oxide from Fehling’s solution in a few seconds, becoming oxidized in so doing. Sucrose does not, except after long boiling. A hundred parts require 140 of water for solution, the same quantity of sucrose requiring only 30. Glucose is also less sweet than the latter. The crystals are distinguished from those of cane sugar by being cubical in shape,, instead of prismatic, and by never presenting large plane surfaces (such as are seen in sugar-candy). .When free from moisture, it does not lose weight when heated to 266° F. ; at a temperature of 340° F., however, water is given off, and a compound called glucosan, having the same composition as dextrin, is produced ; lastly, heated more strongly, it becomes cara 7 nel^ and finally burns away. Dextrose rotates the polarized ray to the right 56°. When subjected to prolonged ebullition with dilute acids, it is transformed into idmin and some other similar bodies. Calcium, barium, and plumbic oxides are capable of union with dextrose. The two former compounds pro- DEXTROSE.— LE VULOSE. 247 duce a salt containing three molecules of the oxide to two of glucose and two of water, thus (Ca 0 ) 3 .(CgHi 20 g) 2 . 2 H 20 . A compound of dextrose and sodium chloride possesses the constitution, 2C6H12Og.NaCl.H2O. In consequence of sucrose having to be transformed into glucose, before the fermentative process can be set up, the latter ferments much more quickly. Heated with nitric acid, glucose forms first saccharic and afterwards oxalic acid. There are two, principal processes for the estimation of dextrose (glucose), the one gravimetric, the 'other vMumetric. Both of these depend upon the almost instantaneous reduction of cuprous oxide from cupric tartrate in the presence of an alkaline, hydrate. {For volumetric process, see Author's Analytical Chemistry, 159, 160.) The gravimetric estimation is performed by adding excess of Fehling’s solution to 5 grains of sugar dissolved in 1000 grains of water, and boiling. The mixture is then filtered, and the precipitate of cuprous oxide on the filter dried and ignited in a tared porcelain crucible. A few drop^ of nitric acid are added to the residue, the liquid is evaporated to dryness very carefully with a lid on the crucible ; lastly, the whole is heated to full redness for ten minutes, transferred to a desiccator, and weighed when cool. 2 20'5 parts of cupric oxide, the resulting product, correspond to 95 parts of cane sugar, or TOO parts of glucose. In applying this test to the estimation of lactose, it will ,be found that 14776 parts of cupric oxide correspond to 100 of milk sugar. Fehling's solution of cupric tartrate in potassium hydrate is made by dis- solving 350 grains of pure crystallized cupric sulphate, reduced to powder, and pressed between bibulous paper till absolutely free from extraneous moisture, in a little distilled water, and adding 1730 grains of sodium potas- sium tartrate (Rochelle salts), then introducing 600 grains of pure potassium hydrate, dissolved in the smallest possible quantity of water, until the deep blue precipitate of cupric tartrate is entirely dissolved, using more of a ten per cent, solution of potassium hydrate jf necessary. The liquid must then be made up to 10,000 grain-measures, and immediately introduced into a well- stoppered bottle, as the carbonic anhydride of the air causes rapid deteriora- tion. Previously to every determination in which this solution is employed, it is necessary to boil a few drops with a quantity of pure water, and if any red precipitate is formed, the solution must be rendered incapable of producing such (when boiled with pure water) by the addition of solid potassium hydrate free from carbonate. LEVULOSE (Syn. Levo-glucose). Formula, C6Hi20g. This substance is formed artificially by boiling inulin with dilute sulphuric acid, and also, together with dextrose, when cane sugar is boiled with the same acid, and naturally in many fruits by the action of an acid or a ferment contained in the juice.’ It may be separated from dextrose by taking ad- vantage of its property of forming a solid compound with milk of lime con- taining 6 per cent, of calcium hydrate, as mentioned under dextrose. The maple, rose, lime, and other trees, sometimes bear upon the leaves, and other parts, a thick excretion, which occasionally becomes sufficiently solid to lose its adhesiveness, and so falls to the ground. This saccharine substance con- sists of dextrose and sucrose as well as levulose, and is popularly denominated honey-dew. Treacle and molasses (the former resulting from the purification of moist sugar, the latter from the preparation of that moist sugar from the sugar-cane) contain a proportion of levulose, and also dextrose, sucrose, and colouring matter. Honey, another substance in which it exists, is sometimes 248 CARBO-HYDRA TES. used in making confections ; sucrose, however, being more frequently em- ployed. Levulose is met with in a colourless uncrystallizable syrup which rotates a polarized ray io6° to the left at 57 ’2° F. It is more soluble in alcohol than dextrose, and as sweet as sucrose. It is similar in chemical reactions to dextrose. FRUIT SUGAR (Syns. Inverted Sugar. H^ney Sugar). Formula, CgHi20g. Is the mixture of equal parts of dextrose and levulose found in honey and many fruits, and also formed when cane sugar is boiled with dilute sulphuric acid, or warmed with strong hydrochloric acid. Owing to the excess of the laevo-rotary power of levulose over the dextro-rotary power of dextrose, inverted sugar turns the polarized ray to the left 50° at 57*2° F. It is similar in reactions to glucose. CHAPTER XVI. ORGANIC ACIDS. An acid is the result of the oxidation of an alcohol. All normal alcohols are characterized by their susceptibility to oxidation, the result of which is the production of one or more substances possessing acid properties, and forming in their turn a complete and characteristic series of salts, in conse- quence of the displacement of a portion of their hydrogen by the various metals and basylous radicals. The oxidation of an alcohol takes place by two distinct steps, the first of which consists in the removal of two atoms of hydro- gen, and results in the formation of a body called an aldehyd ; while in the second step the aldehyd takes to itself an additional atom of oxygen, and forms the acid. By distilling ordinary alcohol with any oxidizing agent, such * as a mixture of manganic dioxide and sulphuric acid Oxygen), we obtain its aldehyd as the result of the following reaction ; — Alcohol.- Oxygen. Aldehyd. Water. 2C2H5HO -1- O3 = 2C2H4O + 2H2O. The aldehyd produced is extremely unstable ; and by simply exposing it to the air, oxygen is at once absorbed, and acetic acid is produced ; thus, — Aldehyd. Oxygen. Acetic Acid. 2C2H^0 +02= 2C2Hj^02- The aldehyd is usually named after the acid, and not the alcohol ; thus, the one above referred to would be called acetic aldehyd. Aldehyds may be reconverted into the corresponding alcohols by the action of alkaline hydrates, a salt of the corresponding acid being simultaneously produced. Thus, benzoic aldehyd (oil of bitter almonds) yields benzyl hydrate and potassium benzoate when treated with potassium hydrate : — aqHgO + KHO = C7H7HO + KC7H5O2. , Nascent hydrogen also reconverts aldehyds into alcohols ; example, — CoH^O + H2 = C2H5HO. Aldehyds are characterized by all forming insoluble compounds with potassium hydrogen-sulphite, and this principle is taken advantage of in separating and obtaining them in a pure state. Unfortunately the names of the acids produced by oxidation from alcohol are merely arbitrary; most of them having been discovered and named before the alcohol from which they are derived. This circumstance causes consider- able confusion in the mind of a young student, as he has to learn that common alcohol yields acetic acid, while amyl alcohol yields valerianic acid. In theory, the oxidation is supposed to take place by the substitution of O 250 ORGANIC ACIDS. for Hg in the basylous radical of the alcohol {vide page 210). The new radical formed is called the oxygenated or acid radical. Thus : — The basylous radical {ethyl), C2H5 corresponds to the oxygenated radical {acetyl), C2H3O. The hydride’ The hydrate The oxide The haloid ether> '{ethane), C2H5.H {alcohol), CAi-,.UO ^ {ether), {C^ll-ND {ethyl chloHde) C2H5.CI Ifl I / hydride Tj lactic acid can be isolated, as described under Argentic Lactate. FERROUS LACTATE (Syn. Proto- Lactate of Lron). Formula, Fe2C3H503. This salt, which results from the solution of metallic iron in dilute lactic acid, is sometimes employed in medicine, especially on the Continent. Its crystals are clear, with a faint green tint, and are not readily oxidizable, even when in solution. HYDROGEN OXALATE (Syn. Oxalic Acid). Formula, H2C20j^2H20. Molecular Weight, 126. Exists in nature as potassium quadroxalate, or salt of sot'rel, in rhubarb, Rumex Acetosa, and R. Acetosella, but is usually prepared by the oxidation of a carbohydrate, such as starch, sugar, or cellulose. 266 ORGANIC ACIDS. Oxalic acid was formerly made by the decomposition of sugar by nitric acid. I part of sugar is heated gradually with 7 parts of nitric acid, B.P., and I part of water, to 212° F. When the action has ceased, the solution is evaporated to the crystallizing point. As the crystals are liable to hold nitric acid in mechanical combination, it is advisable to expose them to dry air, upon which efflorescence occurs, and a slight degree of heat will drive off most of this impurity. The crystals must be redissolved, and still further purified by recrystallization. It is occasionally necessary to repeat this pro- cess several times, after each of which it is as well to test the freedom of the crystals from the acid in question. The sugar method is now seldom adopted, and the following process is the best practical one at present known : — i part of sawdust, starch, or almost any non-nitrogenous carbonaceous matter, is mixed with a solution, in the least possible quantity of water, of 2 parts of potassium hydrate and i part of sodium hydrate. A shallow iron dish is coated to a depth of some inches with the pasty mass, and then submitted to a heat between 240° and 500° F., being kept below the latter temperature for two or three hours. The heat is then lowered gradually, five or six hours elapsing before it comes down to 300° F. ; after which it may be removed from the source of heat, and when cold treated with a little water at the ordinary temperature. This dissolves the excess of hydrate, etc. ; but as the oxalate which is produced is not very soluble, it is not affected. The dry cake upon the dish may contain 30 per cent, of oxalic acid. The alkaline oxalate thus produced is boiled with calcium hydrate and water, calcium oxalate being precipitated. The calcium oxalate is washed, decomposed with sulphuric acid, and the clear solution, obtained by filtration, evaporated nearly to the crystallizing point, when, if any calcium sulphate separates, it must be filtered, and the evaporation con- tinued till crystals are obtained on cooling. Oxalic acid occurs in colourless crystals, greatly varying in size, and having the formula, H2C2O4.2H3O. It is a strong acid, very poisonous, and readily dissolving in water and alcohol; and entirely dissipated by a heat below 350°. {For analysis, see AtUhor's Analytical Chemistry, 108.) The pure acid does not stain ; but the samples occurring in commerce sometimes colour paper yellow, through containing nitric acid, which can be detected by making a strong solution and adding to it a crystal of ferrous sulphate, when a brown or purple coloration shows the presence of nitric acid. Boiling a few crystals with an extremely dilute solution of indigo sulphate will also serve as a test, nitric acid discharging the colour. Water, at the ordinary heat of 60° F., dissolves i2’5 per cent, of oxalic acid ; alcohol, under the same circumstances, takes up 25 per cent. ; and in boiling water it is soluble to the extent of 100 per cent. Contamination with nitric acid greatly increases the readiness and extent of its solubility. After its water of crystallization has been expelled at 212° F., oxalic acid can be sublimed at 320° F. in crystals which are anhydrous ; but more or less decomposition invariably takes place. It is not oxidized by strong nitric acid, except upon long boiling. A property of oxalic acid which is found valuable in analysis, is its rapid and perfect oxidation when treated with manganic dioxide or potassium per- manganate and sulphuric acid. It is also readily oxidized by chlorine when moist or in solution. It constitutes a test for gold, in consequence of its power of precipitating that metal from auric chloride. Oxalic acid decomposes chlorides like sulphuric acid ; and, when added to cupric sulphate in solution, displaces the sulphuric acid, which enters into solution, cupric oxalate being thrown down. OXALIC ACID.—OXALATES. 267 Oxalic acid behaves as a dyad, and forms neutral and acid salts, termed oxalates, having the following characteristics in common. 1. Those of the alkalies are soluble in water, the neutral salts, however, more readily than the acid salts. The others dissolve in dilute mineral acids, but not in acetic acid. 2. All oxalates yield carbonous oxide by heat. Those whose carbonates are easily decomposed by that force, leave oxides, and evolve carbonic anhydride as well as carbonous oxide ; whilst those whose carbonates are tolerably stable, such as potassium and sodium, and in some cases (when the heat is not above dull redness) calcium, barium, and strontium, leave the metal as carbonate. 3. Oxalates, in which the metal is one which is readily reduced, give off carbonic anhydride only, thus : — AggCgO^ = Ag 2 + 2CO2. The plumbic oxalate is peculiar, giving, when heated in a closed vessel, plumbous oxide (Pb20). 4. Heated with sulphuric acid, they give, without exception, carbonous oxide and carbonic anhydride, a sulphate remaining, and no blackening taking place. {For detection of Oxalic Acid and Oxalates, see Author’s Analytical Chemistry, page 76.) AMMONIUM OXALATE (Syns. Amtnonic Oxalate. Oxalate of Ammonia). Formula, (NH 4 ) 2 C 204 . 2 H 20 . Is produced by neutralizing oxalic acid with ammonium carbonate, the latter being added until the solution does not affect neutral litmus paper : — 2H2C2O4 + N^H^gCgOg = 2 (NH 4 ) 2 C 204 + 3CO2+ 2H2O. It crystallizes in long colourless rhombic prisms, soluble in cold water but much more soluble in boiling water. When dried at 212° F. and heated, it gives off water and yields a sublimate of oxamide. (See Amides.) {For analysis, see Author's Analytical Chemistry, 108.) This substance is of importance as a reagent in analysis, being employed for the detection of calcium. It is formed spontaneously in solutions of cyanogen, by the combination of that body with water, thus : — C2N2 + 4H2O = (NHJ2C2O4. When distilled with phosphoric anhydride, ammonium oxalate gives up 4H2O, and forms cyanogen among other products. AMMONIUM HYDROGEN OXALATE (Syn. Btnoxalate of Ammonia). Formula, NH4HC2O4.H2O. Is less soluble that the normal oxalate, and when heated to 450° F. gives up a molecule of water and yields oxamic acid. {See Amides.) SODIUM OXALATE (Syns. Oxalate of Soda. Sodic Oxalate). Formula, NagCgO^. Results from the crude ingredients used in the manufacture of the acid, and is not otherwise interesting. 268 ORGANIC ACIDS. POTASSIUM DIOXALATE (Syns. Binoxalate of Potash. Salt of Sorrel). Formula, KHC2O4.2H2O. Is obtained in Switzerland by treating the juice of the plants mentioned under oxalic acid, and also of some members of the species Oxalis, with albuminous matter, or clay, for the purpose of removing the colouring and similar matters, and then evaporating the clarified solution until the potassium dioxalate separates out on cooling. A mixture of this, or the following salt, with citric acid, is employed to remove ink-stains from linen, under the designation of salts of lemon. From the power it possesses of dissolving metallic oxides, it is commonly used to polish copper, brass, etc. POTASSIUM aUADR-OXALATE (Syns. Salt of Sorrel. Potassium Tetr- Oxalate). Formula, KHC2O4.H2C2O42H2O. Is sometimes met with under the title of “ salt of sorrel,” so that it is probable that some plants owe their acid taste to this salt as well as to that just described. It may be substituted for the dioxalate for all practical pur- poses. It is about twice as soluble in cold water as the preceding salt. CALCIUM OXALATE (Syns. Caleie Oxalate. Oxalate of Lime). Formula, CaC204. Is contained as raphides in rhubarb and other plants, and is extensively produced in lichens growing on various kinds of limestones. It is the form in which both oxalic acid and calcium are precipitated for estimation, and is frequently met with as an urinary deposit, constituting the so-called mulberry calculus. CERIUM OXALATE (Syns. Cerous Oxalate. Cerii Oxalas). Formula, CeC204.3H20. This salt results from the addition of ammonium oxalate to a soluble salt of cerium. The reaction is ; — CeCla + (NH4)2C204 = CeC204 + 2NH4CI. The B.P. describes it to be. a white granular powder, insoluble in water, decomposed at a dull red heat into reddish-brown ceric oxide, CegOa. The production of this salt is one of the leading tests for cerium. {See sepa 7 'ation of Cerium and Iron in Author’s Analytical Chemistry, page 38 ; for analysis and impurities of Cerium Oxalate^ see ibid., page 108.) PLUMBIC OXALATE (Syn. Oxalate of Lead). Formula, PhC204. Is produced on adding any soluble oxalate to plumbic acetate, the reaction being (if we take ammonium oxalate) : — (NH 4 ) 2 C 204 + Pb2C2H302 = PbC 204 + 2 (NH4)C2H302. The most curious property of plumbic oxalate, is that of its leaving plum- bous oxide when heated ; thus : — 2 PbC 204 - Pb 20 + 3CO2 + CO. Plumbic oxalate dissolves in boiling ammonium chloride, and in cold -nitric acid, though not in acetic acid. SUCCINIC ACID.— SUCCINATES. 269 HYDKOGEN SUCCINATE (Syns. Succinic Acid. Volatile Salt of Amber [obsolete]). Formula, H2C4H4O4. Exists in amber, in several kinds of turpentine, and a few plants official in the B.P. ; such as Artemisia Santonica, Arte??tisia Absinthium., Lactuca vNosa. Succinic acid is frequently prepared either from butyric acid by the oxidiz- ing action of nitric acid, or 'from malic or tartaric acids by the deoxidizing effect of hydriodic acid. With malic acid the reaction is : — H2C4H405-h2HI = H2C4H4O4 + I2 + H2O. (Malic Acid.) With tartaric acid, more hydriodic acid must be employed ; thus, — H 2 C 4 H 40 , + 4HI = H2C4H404-F2l2-t-2H20. (Tartaric Acid.) Both of these actions may be reversed by suitable means, succinic acid being thus made to produce malic and even tartaric acid. Succinic acid may be produced, in an impure state, from amber, by dry distillation, acetic acid also passing over simultaneously, and, during the whole of the distillation, volatile oil of amber. This oil is analogous to that obtained on applying a similar process to other resins. The presence of acetic acid is caused by decomposition. If the watery distillate of mixed acids, which is never free from oily matter, be heated to 212° F., and immediately filtered, impure succinic acid separates in crystals as the temperature becomes lower. A large amount of impure succinic acid likewise crystal] izes out on the neck of the retort whilst the dry distillation is in progress. By treating these crystals with nitric acid until they are free from odour, and recrystallizing, the pure acid is obtained. Succinic acid is a white crystalline solid, differing from lactic acid in being almost insoluble in ether, and only oxidized with difficulty. It is not charred by heating with strong sulphuric acid. It is a dyad acid, forming neutral and acid salts. Like neutral lactates, oxalates, and acetates, these can combine with a molecule of acid to form salts analogous to potassium quadr-oxalate. {For detection of Succinic Acid and Succinates, see Author’s Analytical Ckemistry, 76.) AMMONIUM SUCCINATE (Syn. Succmate of Amitionia). Formula, (NH4)2C4H404. Formed by saturating succinic acid with ammonium hydrate, and crystal- lizing. It is sometimes employed as a means of precipitating iron for esti- mation, ferric succinate being, unlike most ferric salts, granular, and therefore can be readily freed from foreign matters by washing. FERRIC SUCCINATE (Syn. Succinate of Iron). Formula, Fe23C4,H404. An insoluble chocolate-coloured salt, produced by the action of the last- named salt on ferric chloride. When digested with ammonium hydrate, ferric hydrate is obtained. The resulting solution of ammonium succinate, when heated and hydrochloric acid added in excess, does not yield crystals on cooling. This is a very useful distinction between ferric benzoate and succinate ; the former, when similarly treated, forms abundant crystals of the but slightly soluble benzoic acid. ORGANIC ACIDS. 270 IV. TRIATOMIC AND BIBASIC ACIDS. May be viewed as being formed from the Oxalic series by the substitution of HO for H. HYDROGEN MALATE (Syn. Malic Acid). Formula, HoC^H^O^. Is derived from an alcohol of very little importance, and is contained in most fruits employed for domestic purposes. Unripe apples, mountain ash berries, and rhubarb stalks, are the sources more frequently resorted to for its preparation. The juice of either of these, preferably the second, is expressed, heated to boiling, and calcium carbonate is added till effervescence ceases ; the liquid when cold is filtered ; plumbic nitrate being added, the liquid is allowed to stand until plumbic malate becomes crystalline. The crystals are dissolved after a few washings with cold water, and sulphuretted hydrogen passed until the liquid smells strongly. Warm gently, filter, boil the filtrate till free from unpleasant odour, and evaporate on a water bath. The syrupy product yields crystals by spontaneous evaporation at about 100° F. Malic acid is a colourless, inodorous, deliquescent, crystalline acid, very soluble in water and alcohol. Only two classes of 7 tialates can be formed, of which the neutral is least stable. Calciimi vsxdXdXQ is soluble in water, but not in alcohol, even if 'dilute. Long boiling causes its separation from a strong slightly acid solution. Strong sulphuric acid when heated with a pure malate causes charring very slowly, though it does so rapidly with tartaric acid. Plumbic malate under- goes slight solution in dilute acetic and nitric acids, being changed from the powder form in which it is first precipitated to small needle-like crystals. This fact shows that the crystals are not soluble in dilute acids though the amorphous form is. Plumbic malate in the amorphous variety fuses in boil- ing water. V. TRIATOMIC AND TRIBASIC ACIDS. ACONITIC ACID. Formula, H3C6H30g. This acid exists in Aconitum Napellus, and is also produced by heating citric acid till it fuses and commences to discolour, when it gives up water thus : — H3CeHA-Hp = H3QH30e. Aconitic acid is very soluble in water, alcohol, and ether. HYDROGEN MECONATE (Syn. Meconic Acid). Formula, H3C7HO7.' May be prepared from opium by neutralizing a strong solution (obtained by treatment with water at 100° F.) with calcium carbonate, and after reducing to a small bulk on a water bath, introducing a saturated solution of calcium chloride until no more precipitate is formed. The insoluble matter is calcium di- hydrogen meconate, and must be washed and pressed to free it from solid matters. The precipitate is then treated with a little hydrochloric acid and boiling water, when it dissolves, and deposits crystals on cooling. Then, if the crystals be redissolved in hot water, and excess of hydrochloric acid added, meconic acid falls as the liquid cools, being only slightly soluble in water MECONIC ACID.- TARTARIC ACID. 271 containing hydrochloric acid. The crystals, which are coloured brown, may be rendered colourless by heating with two parts of water, and adding am- monium hydrate, the temperature being raised until perfect solution ensues. On cooling, the liquid becomes a solid mass. The dark liquid must be entirely pressed out of the crystals, and then these are made to undergo several successive recrystallizations from a saturated solution in hot water. After- wards, on introducing an excess of hydrochloric acid into a hot solution, the meconic acid is obtained in colourless plates on cooling. The crystals contain 3 molecules of water of crystallization, which, when driven off by heating to 212° F., leave the acid as a white pulverulent mass, soluble, like the crystallized form, in >vater, alcohol, and ether, and having a decidedly acid reaction. It communicates a red coloration to a solution of ferric chloride on carefully neutralizing the mixed solutions. This colour is neither discharged by mercuric cliloride (distinction from thiocyanates) nor by very dilute hydro- chloric acid (distinction from acetates). Meconic acid forms three classes of meconates with monad metals, — tri-, di-, and mono- metallic. The latter exhibit an acid, the former exhibit a neutral, reaction with litmus. The hydrogen-meconates of these metals are but slightly soluble, and form very small crystals. They may be produced by the neutralization of the acid with a carbonate or hydrate. This is the mode of preparing the mono-hydro- gen salts. The di-hydrogen salts may be produced by adding a portion of acid, equal to the first used, to the mono-hydrogen meconates. Of ammonium, sodium, and potassium meconates, the first has not been prepared, the other two have. The second (sodium) is crystallizable, and the last uncrystallizable. VI. TETRATOMIC ACIDS. Are derived from tetratomic alcohols by the substitution of i, 2, 3, or 4 atoms of O for a corresponding number of 7 nolecides of H. HYDROGEN TARTRATE (Syns. Tartaric Acid. Acidum Tartaricum. Essential Oil of Tai'tar [obsolete]). Formula, HoC^H^Og. Molecular Weight, 150. Exists in many vegetable productions, but is usually procured from potas- sium hydrogen-tartrate which is deposited from grape-juice during fermenta- tion. It is found in the free state in tamarinds and very acid fruits ; it is even a constituent, though to an extremely small extent, of potatoes. The usual process for the formation of tartaric acid is by treating potassium hydrogen-tartrate (cream of tartar) with calcium carbonate (in the form of chalk or whiting) and boiling water ; adding the carbonate until effervescence ceases. The solution is then mixed with calcium chloride until no more pre- cipitate is formed ; and the whole having been allowed to settle, the precipi- tate is washed by decantation with cold water till the washings are tasteless. The precipitated calcium tartrate is then transferred to a basin and boiled with dilute sulphuric acid for half an hour, which forms free tartaric acid and calcium sulphate. The bulk of the latter body having been separated by filtration, the solution is evaporated to a density of i'2i, and cooled, when the remainder of the calcium sulphate separates out, and the clear liquid is then crystallized. The reactions are : — 1. 2KHC4H^Og -1- CaCOg - K2C4H4^0g -1- CaC4H^Og -f CO2 -f HgO. 2. K2C4H40g + CaClg = CaQH^Og -f 2KCI. 3. 2CaC4H^Og + 2H0SO4 = 2H2C^H^Og + 2CaS04. 272 ORGANIC ACIDS. Tartaric acid is met with in colourless crystals, the primary form of which is the oblique rhombic prism. It is freely soluble in water and in dilute spirit, insoluble in ether, but soluble in absolute alcohol. The crystals fuse at 340° F., forming /;zape 110.) CITRATES. 279 CALCIUM CITRATE (Syn. Citrate of Lwte). Formula, Ca 32 CgH 507 . Is precipitated on adding calcium chloride to a neutral citrate, agitating well, and boiling, thus : — 2K^C6H507 + sCaClg = Ca32C6H507 + 6KC1. It is soluble in ammonium chloride and cupric chloride; forming cupric citrate, which is soluble in water ; thus differing from cupric tartrate, which is insoluble. MAGNESIUM CITRATE (Syn. [True] Citrate of Magnesia). Formula, Mg 32 CgH 507 . May be formed by the action of heat on a mixture of magnesium oxide or carbonate and citric acid. It is not used in this country, and is too deli- quescent to be obtained in definite crystals from a solution; but may be precipitated (from an aqueous solution) as a white powder by means of alcohol, in which it is insoluble. It is a wonderfully tasteless and efficient purgative, and is used in France as the basis of a preparation called limonade purgative. It is best produced in solution when required by mixing magnesium carbonate with a little sugar, adding water, and stirring in a solution of an equivalent weight of citric acid. Messrs. Southall, of Birmingham, prepare powders for use on this principle ; and the author has received a beautiful sample of true granular effervescent citrate from Messrs. Howard, of Stratford. In the B.P. liquor magnesice citratis^ magnesium citrate is first prepared in the presence of a good excess of citric acid, and the latter is then utilized to produce carbonic anhydride with the potassium hydrogen-carbonate. If the whole be properly ar^i quickly corked, the pressure of the enclosed gas will be about li atmosphere, and it will consequently effervesce freely on opening the bottle. CUPRIC CITRATE (Syn. Citrate of Copper). Formula, Cu 32 CgH 507 . This salt, unlike cupric tartrate, is soluble in water. It is formed, together with calcium chloride, when calcium citrate is digested in pure neutral cupric chloride. {See Author's Analytical Chemistry, 78,) FERRIC CITRATE (Syns. Ferri Citras. Citrate of Peroxide of Iron). Formula, Fe 22 CgH 507 . Results from the solution of freshly precipitated ferric hydrate in a hot solution of citric acid : — FegfiHO + 2H3C6H5O7 = Fe22.C6H507 + 6H2O. It cannot be crystallized ; but by evaporating and pouring out the syrupy liquid formed, on glass plates, it may be procured in scales. It does not form any precipitate when treated with potassium ferrocyanide. The solution, however, acquires a blue colour, dischargeable by ammonium hydrate. It is contained in the following B.P. salts. Ferri et Ammonias Citras (Syn. Ferri Anitnonio Citras). Formula indefinite. In the B.P. process for making this scale preparation, ferric hydrate is first made from liquor ferri persulphatis by the action of ammonium hydrate. It should be noticed, that the ferric sulphate is directed to be added to the ammonium hydrate, so as to prevent the precipitate containing an oxy- sulphate, 28 o ORGANIC ACIDS. which would injuriously affect the appearance of the scale. The pure ferric hydrate thus made is dissolved in excess of citric acii solution by the aid of heat, and when cold the acidity is neutralized 'by* t2| addition of a slight ' excess of ammonium hydrate. The 'whole is then filtefed^evaporated, and scaled at a temperature not exceeding i6o° F. Thus made, ferri et ammonicB citras is in thin transparent scales of a deep- red colour, slightly sweetish and astringent in taste. It feebly reddens litmus paper, is soluble in water, but almost insoluble in rectified spirit. Heated with solution of potash, it evolves ammonia and deposits ferric hydrate. When incinerated with exposure to air, it leaves not less than 27 per cent, of ferric oxide, which is not alkaline in reaction, because this scale differs from ferrum tartaratum in containing no potassium. A solution of 160 grains in a pint of vinum aurantii forms vinu 7 u fe 7 ’ri citratis, B.P. {For analysis, see Author^ s Analytical Chemistry, page 1 1 1.) Ferri et Cluiniae Citras (Syn. Citrate of Iron and Quinme). Formula indefinite.' This valuable salt contains three citrates, viz. ; those of iron, quinine, and ammonium. The B.P. process is divided into five distinct stages : — 1. Precipitation of ferric hydrate from ferric sulphate by pouring it into ammonium hydrate. 2. Precipitation of pure qumia from qumice sulphas, previously dissolved in dilute sulphuric acid, by ammonium hydrate. 3. Solution (after washing) of both these precipitates in excess of citric acid solution. 4. The addition of ammonium hydrate, carefully avoiding excess, so as to leave the solution feebly acid. 5. Evaporating and scaling at 100° F. Characters a 7 id Tests. — Thin scales t)f a greenish golden-yellow colour, somewhat deliquescent, and entirely soluble in cold water. The solution is very slightly acid, and is precipitated by sodium hydrate, and by both ferro- and ferric cyanides. The addition of a little ammonium hydrate causes a precipitate of hydrated qumia, soluble in a free excess. {For analysis, see Aut/wr’s Analytical Chemistry, page 1 12 . ) The fact that the solution affects both potassium ferro- and ferri- cyanides, and the greenish colour of the scales, prove that the iron is partly reduced in this preparation to the ferrous state, w'hich is not the case in the other scale preparations already mentioned. This is owing to the fact that the amount of ammonium hydrate which is added is not sufficient to fully saturate the acid, otherwise quinia would be precipitated. The colour of the scales can be altered at will, according to the quantity of ammonium hydrate used. BISMUTHOUS CITRATE (Syn. Citrate of Bis 77 iuth). Formula, BiCgH^O^. Is the white precipitate formed on adding a neutral citrate to a solution of bismuthous nitrate (or chloride). It is soluble in ammonium salts, and a solution in ammonium citrate and nitrate constiiutes liquo 7 ‘ bis 77 iuthi et a 77 i 77 i 07 iice citratis, B.P., which is prepared by distinct steps as follows : — 1. Bismuthous nitrate is prepared by dissolving bismuth in nitric acid, and evaporating to expel any excess of nitric acid. 2. To this solution citric acid is added, and then ammonium hydrate carefully until the precipitate first formed is redissolved. BENZOIC ACID. 281 By this means a colourless neutral or only feebly alkaline solution is ob- tained, which will mix with any quantity of water without forming a precipitate. It has a specific gravity of i'i2 2, and contains an amount of bismuth representing 3 grains of BigOg per fluid drachm. {For analysis., see Author's Analytical Chemistry, iii.) VII. AROMATIC ACIDS. HYDROGEN BENZOATE (Syns. Benzoic Acid. Benzoyl Hydrate. Flowers of Benzoin). Formula, HC^H^Oo. This acid occurs in several official substances, viz., balsamum Peruvianum, balsamum tolutanum, styrax, and benzoinum. It is frequently prepared by heating the last-named body in an iron vessel, having inverted over it a conical cap of thick paper, and covering this by a filtering septum of strong unsized paper. The whole is then subjected to a gradually increasing heat for a time varying with the amount of gitoTesin used. A small quantity will cease to evolve the acid in an hour or less, whilst several pounds will take five hours or more. The covering of filter paper is requisite to absorb oily and other bye-products, and to render it impossible for the sublimate to fall back into the vessel containing the benzoin. By breaking the residual mass into small fragments and re-heating, the total amount may approximate to 12 or 13 per cent. The residue of the first operation can be more readily broken, and is less liable to be charred, if the powdered benzoin be mixed with fragments of pumice or 'sand. In the wet process, benzoic acid may be extracted by digesting 10 parts of benzoin with 6 parts of calcium hydrate and 100 parts of water for five or six hours ; boiling for half an hour, filtering, and well washing the residue. The solution is then evaporated to half the bulk, and rendered decidedly acid by hydrochloric acid, upon which the calcium benzoate contained in the solution is decomposed, and the benzoic acid is deposited in white crystalline scales on the solution becoming cold. The impurities still contained may be removed by subjecting it, after drying, to sublimation, or by solution in boiling water and recrystallization. The vanilla-like odour of pharmaceutical benzoic acid is owing to a trace of a volatile oil formed during sublimation, and possessing the medicinal properties for which the acid is valuable. Thus the product of the wet process requires to be sublimed before it acquires the whole of its Pharmacopoeia qualities. Benzoic Acid should be in light feathery crystalline plates and needles, which are flexible, nearly colourless, and have an agreeable aromatic odour, resembling that of benzoin. , It is sparingly soluble in water, but is readily dissolved in rectified spirit, soluble also in solutions of the caustic alkalies and of lime ; and it is precipitated from these on the addition of hydrochloric acid unless the solution be very dilute. It melts at 248°, and boils at 462° F. \\hen heated to the last-named temperature, it passes off in vapour, leaving only a slight residue. The reactions taking place in the wet preparations are : — , 1. 2HC7H5O2 -f CazHO = Ca2C7H502 -f 2H2O. 2. CaaC^H^Og -f 2HCI = 2HC7H5O2 -f CaClg. The oxidizing action of the air on benzoyl aldehyd also produces this acid by the simple addition of one atom of oxygen. A process of great practical interest and importance consists in the formation of naphthalic (also called phthalic) acid by oxidizing naphthalin with nitric acid, and the transformation of this by neutralization with calcium hydrate, and subsequent heating with 282 ORGANIC ACIDS. excess of the latter. The calcium phthalate must be obtained in a dry state, and then afterwards calcined with the hydrate at 630° to 660° F. for six or seven hours. On treating the cooled pro'duct with boiling water, filtering, and adding hydrochloric acid in excess, benzoic acid crystallizes out as the tem- perature becomes lower. The following represents the decompositions which are known to take place : — 1. CioHg + 6HNO3 = + H2C2O4 + 4NO + N2O3 + 3H2O. (Naphthalin.) (Phthalic Acid.) 2. HgCgH^O^ + Ca2HO = CaCgH^O^ + 2H2O. (Calcium Phthalate.) 3. 2CaCgH404 + Ca2HO = Ca2C7H502 + 2CaC03. , (Calcium Benzoate.) The reaction by which benzoic acid is derived from calcium benzoate has already been given. A characteristic quality of benzoic acid, distinguishing it from cinnamic acid, is its resistance to oxidation by dilute nitric and chromic acids, which yield with the latter benzoic aldehyd. Benzoates of the monad metals, when heated, yield benzoyl aldehyd ; if mixed with an alkaline formate alone, they leave a carbonate (except the ammonium and argentic salts) giving off benzene and other hydrocarbons. Heated in contact with the air, all benzoates produce the metal, its oxide, or its carbonate, evolving carbonic anhydride and water. {For detection of Benzoic Acid and Benzoates, see Author's Analytical Chemistry, page 79.) AMMONIUM BENZOATE (Syn. Ammonice Benzoas). Formula, NH4CyH502. Is the result of acting upon benzoic acid with ammonium hydrate : — NH4HO + HC7H5O2 = NH4C7H5O2 + H2O. During evaporation this salt decomposes, evolving ammonia gas; and leaving a compound in which the freed acid is united to the neutral compound under consideration. It is a deliquescent salt, in colourless laminar crystals, soluble in water and in alcohol. It is entirely volatile by heat, and a strong aqueous solution, when acidulated with a mineral acid, lets fall crystals of benzoic acid. POTASSIUM BENZOATE. Formula, KC7H5O2. is formed by acting on an aqueous solution of benzoic acid with potassium carbonate. If an alcoholic solution of benzoic acid be employed, no decom- position occurs ; on the contrary, a solution of potassium benzoate is decomposed by passing carbonic anhydride through it, benzoic acid remain- ing in solution. CALCIUM BENZOATE (Syns. Calcic Benzoate. Benzoate of Lwie'). Formula, Ca2C7H502. Is contained in the solution produced on boiling benzoin (gum resin) with calcium hydrate. It dissolves in water to the extent of about 3I per cent., if it be cold ; to a much greater amount, if warm. FERRIC BENZOATE Benzoate of fron. Benzoate of Peroxide of Iron). Formula, Fe26C7H502. Is soluble in water, and may be obtained in yellow crystals by dissolving ferric hydrate in a watery solution of benzoic acid, and evaporating. When redissolved it decomposes, depositing an oxy-salt or hydrate-salt. Alcohol causes the same alteration. Ferrous Benzoate is dissolved by water. CINNAMIC AND SALICYLIC ACIDS. 283 HYDKOGEN CINNAMATE (Syn. Cinnamic Acid). Formula, HCgH^Og. This acid may be obtained from cinnyl alcohol and cinnamyl hydride by oxidation. By acting on styracin (mentioned under Cinnyl Hydrate) with potassium hydrate in a strong boiling solution, cinnamic acid and the alcohol whence it is derived are simultaneously formed. The most economical processes are — I. To extract it from the crystalline matter found coating the interior of the leaden vessels in which oil of cinnamon is brought to this country. j . 2. To act on balsam of Peru with calcium hydrate made into a thick paste with water. I. This crystalline deposit is treated with boiling rectified spirit, and filtered ; the impure cinnamic acid, which separates on cooling, dissolved in sodium carbonate and pure water ; hydrochloric acid added, and the crystals, which fall on cooling, pressed and dried. The portion insoluble in hot spirit is plumbic cinnamate. If it be boiled with sodium carbonate, and filtered, the filtrate on acidulation deposits the acid. II. If the mixture above mentioned be boiled and filtered, the residue again boiled (several times) with water, and the united filtrates mixed, calcium cin- namate separates in a tolerably pure state as the temperature becomes low. By decomposing this with hydrochloric acid and hot water, crystals may be procured after some time. On subjecting these to solution in ammonium hydrate and reprecipitation, or to sublimation, the pure acid results. Cinnamic acid is only slightly soluble in water at 60° F., but freely in hot water. A valuable distinction from benzoic acid consists in the fact that by distillation with plumbic dioxide, benzoyl hydride (recognised by its odour) is evolved. The same reaction occurs with sulphuric acid and potassium dichromate. ' The precipitate, on introducing a neutral cinnamate into a ferric solution, is yellow. Benzoates produce a more or less red deposit. Manganous ben- zoate is soluble. Manganous cinnamate, after a little time, is yellow, crystal- line, and insoluble. The cinnamates are of too slight importance to be given in a work of this character. One only is an exception. CINNYL CINNAMATE. Formula, C9H9C9H7O0. It occurs in sty rax prcsparatus^ B.P., in the form of styracin, which is its usual name. It is an oily liquid obtained by expression from the impure substances used in making cinnyl hydrate ipide ante). By other methods of preparation it is procured in prismatic crystalline masses, easily dissolved by ether. HYDROGEN SALICYLATE (Syns. Salicylic- Acid. Oxybenzoic Acid). Formula, C^HgO^, or H2C7H4O3. Was originally produced by the oxidation of salicylic aldehyd (oil of meadow-sweet), but is now extensively prepared from sodium phenate, made by heating carbolic acid with potassium hydrate : — CgHsHO + NaHO = CgH^NaO + HgO. The salt thus formed is then heated gradually from 212° up to 500° inaretor through which a stream of carbonic anhydride is kept passing. During this process a little carbolic acid is re-formed, and distils over, while sodium salicylate remains in the retort ; — 2CgH5Na0 + C02 = Na 2 C 7 H ^03 + C6H5.H0. 284 ORGANIC ACIDS. The sodium salicylate is then dissolved in a small quantity of water, and de- composed by hydrochloric acid, which the salicylic acid precipitates in pris- matic crystals. It is freely soluble in alcohol, ether, and hot water, but only to the extent of one part in 1800 of cold water. Heated, it melts and decom- poses, giving off carbolic acid. It is a powerful antiseptic, being used exten- sively to preserve milk and beer ; and its sodium salt, which is very soluble in water, has a great reputation in the treatment of acute rheumatism. Its ferric salts are soluble in water, and have a beautiful violet colour. {For detection of Salicylic Acid, see Author's Analytical Chemistry, 80.) HYDROGEN GALLATE (Syn. Gallic Acid). Formula, H3C7H3O5. Is produced by the decomposition of tannin {acidum tannicum, B.P.) by boiling with dilute acids. The B.P. method is to expose powdered galls, moistened with water, to atmospheric action. The temperature must be 70° to 80° F., the moist state should be maintained for about six weeks. At the termination of that period the galls are boiled with three parts of water, filtered, and the acid which falls on cooling dried slightly by exposure to the air. The adherent water is removed by pressure between filtering paper, and the product, unless nearly white in colour, redissolved in hot water, decolorized by animal charcoal, and crystallized. Characters and Tests. — Crystallizes in acicular prisms or silky needles, some- times nearly white, but generally of a pale fawn colour. It requires about 100 parts of cold water for its solution, but dissolves in three parts of boiling water. Soluble also in rectified spirit. The crystalline acid, when dried at 212°, loses 9 '5 per cent, of its weight. It leaves no residue when burned with free access of air. ^ When , heated, it loses water, becoming converted into pyrogallic acid. A solution of gallic acid in glycerin, containing one part in six by weight of the acid, is termed in the . glyceritiiwi acidi gallici. A moderate degree of heat should be applied to effect perfect solution. It possesses a slightly acid astringent taste. Ethereal and alcoholic solutions also redden litmus paper. Gallic Acid differs from tatinic acid also by not reacting with albumen nor alkaloid salts. The acid salts of this acid are alone undecomposed by expo- sure to the air. Solid gallic acid forms a bright-red liquid' with potassium and ammo- nium hydrates. Strong sulphuric acid gives, when hot, a similar reaction ; but the solution thus formed lets fall a red precipitate on the addition of water. The weak solution of calcium hydrate known as lime water, when added to a little gallic acid solution, forms a white precipitate, changing through blue and violet to a purplish colour. Potassium permanganate may be employed to estimate this acid, by a solu- tion of known strength (say i-io equivalent in a litre, or 1*58 percent.) being run into a solution of a weighed quantity of the gallic acid to be estimated, until it acquires a faint pink tinge. When gallic acid is added to auric and argentic salts, the metal is liberated slowly at the ordinary temperature ; and this reduction affords valuable means of obtaining desirable results in photography. On submitting the mixture to heat, very rapid deposition of the metals occurs. Gallic acid has been discovered to be a tetrad within the last few years, a compound having the composition Ba2C7H205 having been made. The gallates may be of at least six classes 3 viz., mon-, di-, tri-, and tetra- metallic, acid, and basic salts. {For detection of Gallic Acid, see Author's Analytical Chemistry, page 81.) TANNIC ACID. 285 Ferric Gallate. — Indefinite in composition, and of a blue colour, producing a colourless ferrous salt on boiling, carbonic anhydride being evolved. Veratria Gallate. — Is the natural form in which veratria exists in the follow- ing official vegetable productions, — sabadilla^ veratri viridis radix^ colchtci cormus, and colchici seniina. In preparing veratria, precipitation by ammonium hydrate is adopted, in order to remove the gallic acid in combination with that alkaloid, the ammo- nium hydrate being converted into ammonium gallate. TANNIN (Syn. Tannic Acid). Formula, C07H22O17. Molecular Weight, 618 . Is usually considered to be a glucoside ; but as it has been stated to be really an anhydride of gallic acid, we will look at it in this aspect for the time being. Of tannins there are many varieties, differing from each other sometimes by chemical and at others by physical peculiarities. The principal classes chemically distinguished are those forming (like galls, or ordinary tannic acid) blackish or purplish-black precipitates with ferric salts, and those yielding a greenish-brown. The Pharmacopoeia tannic acid is re- cognised by producing a gelatinous precipitate with potassium antimonyl tartrate, and also (when in watery solutions) with sulphuric, hydrochloric, and nitric acids ; by giving a purplish-black upon adding a ferric solution ; by throwing down a greyish compound when a solution of gelatin is introduced into its aqueous solution ; and by rendering alkaloids insoluble in water, though soluble in acetic and stronger acids. To prepare tannic acid, expose powdered galls to a damp atmosphere for two or three days, and afterwards add sufficient ether to form a soft paste. Let this stand in a well-closed vessel for twenty-four hours ; then, having quickly enveloped it in a linen cloth, submit it to strong pressure in a suitable press, so as to separate the liquid portion. Reduce the pressed cake to pow- der, mix it with sufficient ether, to which one-sixteenth of its bulk of water has been added, to form again a soft paste, and press this as before. Mix the expressed liquids, and expose the mixture to spontaneous evaporation until, by the aid subsequently of a little heat, it has acquired the consistence of a soft extract ; then place it on earthen plates or dishes, and dry it in a hot-air chamber at a temperature not exceeding 212° F.’ Thus made, it is found in pale yellow vesicular masses, or thin glistening scales, with a strongly astringent taste and an acid reaction ; readily soluble in water and rectified spirit, very sparingly soluble in ether. It leaves no residue when burned with free access of air. The majority of the forms of tannic acid exhibit an acid reaction (never very decided) towards litmus paper, are astringent but not sharp in taste, and form with gelatin the insoluble compound known as artificial leather. Tliey also give the characteristic reactions with ferric salts already mentioned, and show a similar behaviour towards albumen as towards gelatin. Quino-tannic acid (contained in cinchona bark), and the tannin accompanying salicin in willows, as well as that found in catechu, rhatany root, and rhubarb, are of the variety which engenders an insoluble ferric salt of a green colour. The purplish- black ferric salt is produced by the reaction with querco-tannic acids (of the oak), the tannin of bearberry leaves, and that obtained from other sources. From aqueous solutions the official or gallo-tartnic acid is thrown down by sodium and ammonium chlorides, potassium sulphate and acetate, etc. ; also by hydrochloric and sulphuric acids. The phenomenon of the precipitation without alteration of a substance not very soluble in water by one much more so, is by no means uncommon, espe- cially with hydro-carbonaceous compounds. 286 ORGANIC ACIDS. Gallo-tannic acid is taken up with tolerable freedom by both expressed and essential oils. The member of the latter in which it is especially and pre- eminently soluble is oil of bitter almonds. It dissolves also in glyceryl hydrate to the extent of about 15 per cent. (For details of the preparation of the solution see Grlyceryl Hydrate.) Its solution in glyceryl is official under the name of glycerinum acidi ta 7 inici. The formation of cupric taiinate., — Cu3(C27H220i 7)2 (?), — when a solution of cupric acetate is added to a watery solution of tannic acid, may occasionally prove serviceable as a test. It is of a pinkish colour. {For detection of Tannic Acid, see Author's Analytical Chemistry, page%\.) HYDROGEN PYROGALLATE (Syns. Pyrogallic Acid. Dioxyphenic Acid). Formula, HgCgHgOg. When gallic acid, or a watery extract of galls, is heated in an iron vessel covered with a diaphragm of filter paper, and having a thick paper cap in- verted over it, this acid sublimes in almost white, very light crystalline flocks. The heat employed must last for nearly twelve hours, and not vary much below 356° or above 365° F. The most advantageous method is to sublime gallic acid mixed with fragments of pumice stone, in a vessel through which a stream of carbonic anhydride may be passed. The crystals, when accurately examined, are seen to be prismatic plates. At 60° F. pyrogallic acid dissolves in rather more than twice its weight of water, is more soluble in hot water, but less so in ether and alcohol. It is derived from gallic acid by the with- drawal of carbonic anhydride, thus : — H3C7H3O5 = H3QH3O3 + CO2. It is employed as a reducing agent by photographers, and is also in com- mercial demand for making hair dyes. When in solution it is decomposed by exposure to the air, becoming brown by oxidation. In consequence of very small quantities of nitrous acid turning it brown, a colourless, watery solution may be employed as a test for that body. It is a weak acid, not decomposing all carbonates. The most important of the pyrogallates will be found undermentioned. The only noticeable general reactions are their pro- pensity to become coloured by atmospheric action, and the reducing action they exert upon auric, platinic, argentic, and mercuric salts. {For detectio 7 i of Pyrogallic Acid, see Author's Analytical Chemistry, 81.) Ammonium Pyrogallate is formed when ammonium hydrate is added to the acid. It is employed as a test, becoming brown by the influence of the air. Potassium Pyrogallate is the salt, the formation of which determines the absorption of oxygen in gas analysis. \See Nitrogen.) ' It becomes first pur- plish, afterwards dark-brown or black, by combination with oxygen. Argentic Pyrgoallate does not exist ; pyrogallic acid causing the deposition of the metal from argentic salts. Calcium Pyrogallate forms the fine reddish solution, quickly becoming deep brown, resulting from the addition of calcium. Ferrous Pyrogallate is contained in the beautiful bhle solution produced by introducing a ferrous salt into aqueous pyrogallic acid. A slight contamina- tion with a ferric salt secures the formation of a green-coloured liquid. Ferric Pyrogallate is a constituent of the fine red solution, the formation of which occurs on introducing a dissolved ferric salt into pyrogallic acid solution. CHAPTER XVII. ETHERS. The salts formed by the unsaturated hydrocarbons acting as basylous radicals, are called ethers. They are of three classes, viz. : haloid, simple, and compound. I. HALOID ETHERS. . t Are the result of the displacement of one or more atoms of hydrogen from a saturated hydrocarbon, by Cl, Br, or I, and are therefore the chlorides, bromides, or iodides of the basylous radical corresponding. They may also be viewed as the result of the displacement of HO from an alcohol by Cl, Br, or I ; and, like the alcohols, they run in series, and are monatomic, diatomic, or triatomic. , {a) Monatomic Haloid Ethers of the Series C^HoniiX. These may be produced by the following general methods : — 1. By the direct action of chlorine or bromine upon the corresponding saturated hydrocarbon : — CgHg + CI2 - C2H5CI + HCl. 2. By passing dry hydrochloric acid gas into the alcohol and then distilling: — C2H5HO + HCl = C2H5CI + H2O. 3. By heating the alcohol with bromine and iodine and phosphorus, so forming phosphorous bromide or iodide, which then react, thus : — + = 3C2H5Br + H3PO3. 3C2H.HO + PI3 =3C2H.I + HsP03. The haloid ethers are especially useful in making other compounds, owing to the variety of decompositions they undergo, of which the following are worthy of special note : — 1. The haloid ether, treated with ‘potassium hydrate (jor better, with moist argentic oxide), forms the corresponding alcohol : — 2C2H5l + Ag 20 + H 20 = 2C2H5HO + 2AgI. 2. The haloid ether, acted on by a potassium or sodium alcoholate, yields the simple ether corresponding. Thus : — C2H5I + Na(C2H5)'0 = (C2H5)20 + Nal. 3. By double decomposition with the silver salt of the required acid, any compound ether may be obtained from the haloid ether. Thus — C2H5I + AgC 2 H 302 = C2H5.C2H3O2 + Agl. 288 ETHERS. 4. By acting on the haloid ether with nascent hydrogen, we can obtain the original paraffin : — C2H5I + H2 = QHg + HI. 5. By heating the haloid ether in a sealed tube with alcoholic ammonia, we obtain the bromide or iodide of the corresponding amine. {See Amines.) 6. Acted upon by potassium cyanide, haloid ethers yield the cyanide of their basylous radical ; thus, methyl iodide and potassium cyanide give methyl cyanide : — CH3I + KCN - CH3CN + KI. But, as already seen {page 177), the cyanides of monad organic radicals are also the nitrils of the triad basylous radicals immediately higher in carbon value; therefore the above reaction may be shown as forming ethenyl or aceto-nitril, thus : — CH3I + KCN = {C2H3)"'N"' + KI. It will be sufficient to glance at the haloid ethers of methyl, those of ethyl, propyl, butyl, and amyl being very similar, only having higher boiling points as the number of their carbon atoms increases. METHYL CHLORIDE (Syn. Chloromethane). Formula, CH3CI. ' May be prepared by distilling together sodium chloride, sulphuric acid, and wood spirit : — CH3HO + H2SO4 = CH3HSO4 + H2O. CHsHSO^ + NaCl = CH3CI + NaHSO^. It is a gas with a peculiarly sweetish odour and taste, and only slightly soluble in water. It is, like most ethereal chlorides, combustible, and burns with a greenish flame. It is now prepared on an industrial scale from ’the residues obtained in the manufacture of sugar from beetroot. Exposed to sunlight in contact with excess of chlorine, it first becomes methene chloride, then chloroform, and finally carbon tetrachloride. METHYL IODIDE (Svn. lodomethane). Formula, CH3I. Is prepared by the action of phosphorus and iodine upon methyl hydrate (wood spirit), phosphoric acid being at the same time formed : — P2 + 5I2+10CH3HO = 10CH3I + 2H3PO4+2H2O. It is a slightly combustible, colourless, volatile liquid, evolving violet vapours (iodine) when inflamed. It owes its interest to its employment in the preparation of the radical methyl in the free state, by heating in a sealed tube with zinc and water : — 2CH3I + Zn - Z11I2 + (0113)2. METHYL BROMIDE (Syn. Bro7nomethane). Formula, CH3Br. Prepared’ exactly like the iodide, but using bromine instead ot iodine. Resembles the iodide closely. ip) Diatomic Haloid Ethers, Series CnH2nX2. These bodies are formed : — 1. By the direct action of chlorine on the olefines. 2. By the action of phosphoric bromide or iodide upon the aldehyd AfETHENE, ETHENE CHLORIDES.— CHLOROFORM. 289 or ketone of the monad series corresponding in number of carbon atoms. Examples : — CgH^O + PCI5 = C2H4.CI3 + POCI3. (Aldehyd.) (Ethene chloride.) CgHgO + PCI5 - CgHg.Cla + POCI3. (Acetone.) (Propene chloride.) » METHENE CHLORIDE (Syns. Methylene Chloiide. Dichloromethane). Formula, CH2CI2. According to Perkin, this body is best obtained by agitating an alcoholic solution of chloroform with powdered metallic zinc and a small quantity of ammonium hydrate. The reaction is doubtless brought about by nascent hydrogen, and is accompanied by the formation of marsh-gas : — 2CHC13-I-4H2 = CH 2 CI 2 + CH 4 + 4 HCI. It is a colourless liquid, boiling at 106° F,, and not solidifying at 0° F. It has been used as an ansesthetic under the name of bichloride of methyleiie. ETHENE CHLORIDE (Syns. Ethylene Chloride. Dutch Liquid). Formula, C2H4.CI2. Is produced by causing olefiant gas and chlorine to mix together over water, when a yellowish oily liquid forms and sinks to the bottom in drops. It possesses a peculiarly fragrant odour, and burns with a greenish flame. It is interesting as being one of the early discoveries in this branch of chemistry, having been first produced by four Dutch chemists in 1795. if) Triatomic Haloid Ethers, Series CnH2n_iX3. ' METHENYL CHLORIDE (Syns. Chloroform. Formyl Chloride). Formula, CH^'-Clg'. Is prepared by distilling spirit of wine with chlorinated lime and slaked lime in the presence of a considerable quantity of water, when chloroform and calcium formate are produced. This may be represented in one equation as follows : — 4C2H5HO SCazClO - 2CHCl3-f3Ca2CH02 + 5CaCl2 + 8H20. The real reactions which occur are more probably as follows. Keeping in mind that “ chlorinated lime ” can exercise both an oxidizing and a chloridiz- ing influence, we may consider that by the former the alcohol is reduced to aldehyd, and that by the latter hydrogen is displaced, forming trichloraldehyd, or chloral : — ^ • . 2C2H5HO + 6CI3 + O2 = 2C2HCI3O + 6HC1 -i- 2H2O. Immediately on its formation, however, the chloral is attacked by the calcium hydrate, and decomposed to chloroform and calcium formate : — 2C2HCl30-fCa2H0 = 2CHCI3 -f Ca2CH02. In practice, the ingredients should be mixed and heated gradually, taking care to withdraw the heat the moment the distillation really commences. After the distillation, the crude product is first washed by shaking up with dis- tilled water, and afterwards purified by agitation with an equal bulk of strong sulphuric acid. Finally, the chloroform is separated by a pipette, and recti- fied over a mixture of calcium chloride and slaked lime. Thus prepared, it is a limpid colourless liquid, of an agreeable ethereal odour, and sweet taste. u 290 ETHERS. Chloroform dissolves in alcohol and ether in all proportions ; and slightly in water, communicating to it a sweetish taste. Burns, though not readily, with a green and smoky flame. Specific gravity, 1*49. It is not coloured by agitation with sulphuric acid ; leaves no residue and no unpleasant odour after evaporation. It is only very slightly soluble in water (i in 200). Besides the well-known anesthetic properties of its vapour, chloroform is very useful to the analyst as a solvent for alkaloids as well as for iodine, bromine, camphor, resinous bodies, and volatile oils. Its striking power of dissolving alkaloids is utilized in isolating them for toxicological investigations, and in the assay of barks ; while its ability to dissolve, and show a colour with minute traces of iodine and bromine is made use of in the detection of these elements. It can be brought into contact with acids and alkalies in watery solution without change, and it is miscible with both turpentine and carbon disulphide. The most common adulterants of chloroform are alcohol, wood-spirit, methylated chloroform, and traces of sulphuric acid. The best reagent for detecting alcohol is a salt obtained by acting on ferric chloride with a mixture of potassium nitrate and ammonium sulphide, and called ferrous di-nitro sulphide. If chloroform be shaken up with this substance, it acquires a green colour in presence of the impurities mentioned. A very simple way of detecting alcohol, and at the same time of roughly estimating its amount, is to fill a burette with chloroform up to 20 c.c., and then add water to 100 c.c., shaking violently. Pure chloroform will sink to the bottom in clear globules; but in the presence of alcohol, the liquid, and the surface of the drops, will become dim and opalescent. After the chloroform has settled, a diminution will be observed equal to the amount of alcohol which has been extracted by the water, always allowing for of a c.c., which would be the natural loss by solubility, even with a pure article. Chloroform will keep well in a dark place ; but when exposed to air and strong sunlight it will resolve itself into hydrochloric acid, chlorine, and other products, unless it be entirely free from nitryl compounds, in which case it is said not to be affected by light and air. The presence of an exceedingly small quantity of nitric acid in the sulphuric acid used in the purification of chloroform, is sufficient to give it this tendency to spontaneous decomposition. Methylated chloroform can be de- tected by the offensive smell which it leaves upon a cloth dipped in it, and allowed to dry spontaneously. This smell is owing to its containing about 6 per cent, of an empyreumatic oil, a constituent of which is chlorine, and which is blackened by sulphuric acid. Lately it has been stated that chloro- form can be made from methylated spirit so as to be quite undetectable. A good test for small quantities of chloroform is to heat with a little aniline and alcoholic sodium hydrate, when a violent action ensues, and the characteristic smell of an alcoholic cyanide (isonitril) is evolved. METHENYL BROMIDE (Syn. Bromoform). Formula, CHBrg. When potassium hydrate and bromine are caused to act upon alcohol or wood spirit, this substance is formed. It is a heavy liquid, having a specific gravity of 2*13, and is a result of the action of calcium hydrate on bromal, in the same manner that chloroform is a product of the treatment of chloral with that reagent. It imparts its taste, which is sweet, and its smell, which is agreeable, to water, in which, like chloroform, it is slightly soluble. It dissolves iodine to a large extent, phosphorus and sulphur less rapidly, while it is itself dissolved by the volatile oils, ether, and alcohol. It decomposes on being boiled with potassium hydrate, potassium bromide and bromate being formed. It is only slightly combustible. lODOFORM.—STMPLE ETHERS. 29 1 METHENYL IODIDE, (Syn. Iodoform). Formula, CHI3. This body may be prepared by mixing solution of potassium hydrate and of iodine in alcohol until a light yellow solution is formed. The excess of alcohol is removed from this by evaporation. Iodoform melts at 240° to 250° F., and on volatilizing is partially decom- posed. It forms greenish-yellow plates, possessing a saffron odour. When mixed with water, it distils without alteration. Acid water and alkaline hydrates do not dissolve it, although it is soluble in all oils, ether, and alcohol. By the action of bromine, bromoform is produced ; and by heating in a closed vessel to 300° F. methylene di-iodide results. By distillation with mercuric chloride it has been stated to yield chloroform.^ and with mercuric cyanide, iodocyanoform. A trace of alcohol in any liquid is said to be readily determined by a test depending on the formation of iodoform. If the suspected solution be warmed to 150° F., with a little iodine and sodium hydrate, the reaction of these upon the alcohol causes the deposit of a yellowish crystalline body of CHI3. Many gummy matters, sugars, and hydrates of hydrocarbons, form the same precipitate under similar circumstances; and the potassium iodide and formate simultaneously formed are dissolved out by water, in which the iodoform is insoluble. The simplest explanation of the reaction is : — C2H5HO + 6KHO + 4I2 = CHI3 4 - 5KI -f KCHO2 + 5H2O. It may also be produced by treating alcohol, mixed with twice its weight of crystallized sodium carbonate, dissolved in ten parts of water, with its own weight of iodine. The mixture having been heated to 140° or 180° F. the precipitated iodoform is separated by filtration. More alcohol and sodium carbonate being added, and chlorine passed through, the sodium iodide formed is decomposed by the chlorine, and iodine is set free. A great excess of iodine will altogether prevent the required result. II. SIMPLE ETHERS. Are the oxides of the unsaturated basylous hydrocarbon radicals. The only series which directly interests us is the fatty series, the simple ethers of which may be prepared,— 1. By heating sulphuric acid with a continually maintained excess of the alcohol. {See Ethyl Oxide.) 2. By heating a haloid ether with the potassium or sodium compound of the alcohol. Example : ordinary alcohol, treated with metallic sodium, forms sodium ethylate ; and that acted upon by ethyl iodide, yields ethyl oxide. Thus : — 2C2H5HO + Na2 = 2C2H5NaO + H2. C2H5NaO 4- C2H5I = (C2'H5)20 4- Nal. Besides the ordinary oxide, we can have ethers in which the oxygen is combined with one molecule each of two different radicals, instead of two molecules of the same radical, thus producing a compound intermediate in its boiling point and general properties. For instance, taking the lower end of the series, we find : — Methyl oxide . . (CH3)20 boiling at 5*8° F. Methyl ethyl oxide . CH3.C2H5.O ,, „ 52*0° Ethyl oxide. . . (C2H-)20 „ „ 96*0° 292 ETHERS. METHYL OXIDE (Syn. Methylic Ether'). Formula, (CH3)20. Is prepared by heating sulphuric or boracic acids with a continually main- tained excess of methyl alcohol. It is a colourless gas, of ethereal odour and burning with a pale blue flame. It is soluble in cold water, and condenses to a liquid at 5° F. It is by means of this compound that we are enabled to detect ethyl in methyl alcohol. Pure methyl hydrate thus etherified and the vapour passed through a receiver kept at32°F. by ice, should yield us no liquid ether; but if it contain ordinary alcohol, then ordinary ether will condense. ETHYL OXIDE (Syns. Ether. Ethyl Ethylate. Sulphuric Ether, ^ther Purus). Formula, (C2H5)20. Molecular Weight, 74. Specific Gravity, 72. Vapour Density, referred to Air, 2*586. Referred to Hydrogen, 37. Is prepared by heating a mixture of rectified spirit of wine and sulphuric acid to a temperature of 284° F., and causing a continuous stream of alcohol to flow into the retort. The reaction is produced in two steps : — 1. The alcohol and sulphuric acid form ethyl hydrogen-sulphate and water: C2H5HO + H2SO4 = C2H5HSO4 + H2O. 2. The ethyl hydrogen-sulphate, meeting with a fresh quantity of alcohol, forms ethyl oxide, and reproduces sulphuric acid, which can then etherify a fresh quantity of alcohol : — C2H3Hso, + C2H5Ho (c,u,),0 + n,S0,. Great care must be taken in regulating the temperature and keeping alcohol in excess, as, if these points be not attended to, the sulphuric acid will absorb the elements of water and produce ethylene (olefiant gas) : — C2H5HO + H2SO4 = H2SO4H2O + C2H4. The process is in theory continuous, but in practice is limited by the fact that after a time the sulphuric acid gets too weak to perform its work, owing to the water contained in the spirit used. The acid also slowly volatilizes, partly in the state of oil of wine. The actual process, as laid down by the B.P., is as follows : — Mix ten fluid ounces of sulphuric acid with twelve fluid ounces of rectified spirit in a glass matrass capable of containing at least two pints, and, not allow- ing the mixture to cool, connect the matrass by means of a bent glass tube with a Liebig’s condenser, and distil with a heat sufficient to maintain the liquid in brisk ebullition. As soon as the ethereal fluid begins to pass over, supply fresh spirit through a tube into the matrass in a continuous stream, and in such quantity as to equal the volume of the fluid which distils over. For this purpose use a tube furnished with a stopcock to regulate the supply, connect- ing one end of the tube with a vessel containing the spirit raised above the level of the matrass, and passing the other end through a cork fitted into the matrass. When thirty-eight fluid ounces of spirit have thus been added, and forty-two fluid ounces have distilled over, the process may be stopped. Dis- solve ten ounces of calcium chloride in thirteen ounces of water, add half an ounce of slaked lime, and agitate the mixture in a bottle with the impure ether. Leave the mixture at rest for ten minutes, pour off the light superna- tant fluid, and distil it with a gentle heat until a glass bead of specific gravtiy 0*735 placed in the receiver begins to float. The ether and spirit retained by the calcium chloride and by the residue of each rectification, may be recovered by distillation and used in a subsequent operation. Thus made, ether contains about 10 per cent, of alcohol, and is a colourless. ETHER.— COMPOUND ETHERS. 293 very volatile, and inflammable liquid, emitting a strong and characteristic odour, and boiling below 105° Specific gravity, 0735. It evaporates without residue. Crude ether is purified from alcohol and water by first shaking up with water, to dissolve out the alcohol, and then rectifying over a mixture of calcium chloride and freshly burned calcium oxide, to remove the water. It is then found to have a specific gravity of 720, and boils at 96° F. Ethyl oxide^burns with a white flame, yielding carbonic anhydride and water as the sole products of its combustion. When a drop touches the skin, it evaporates so rapidly as to produce a sensation of extreme cold. It is only slightly soluble in water (i ether in 10 of water), but is entirely miscible with alcohol. It is also an excellent solvent of oils and fats, as well as of phosphorus, scammony resin, quinine, mercuric and ferric chlorides, and many other bodies. The vapour of ether is highly inflammable, and, when mixed with air, powerfully explosive. (^2^5)2^ + 6O2 = 4CO2 + 5 ^ 2 ^* 2 vols. +12 vols. = 8 vols. When passed through a red-hot tube, it yields, among other products, ethene, methane, aldehyd, and acetylene. Ether kept in a badly stoppered vessel, rapidly becomes acid, owing to formation of acetic acid,* thus : — {C,¥L,),0 + 2 O, = 2C,¥L,0, + H^O. When ether is mixed with an equal volume of sulphuric acid, it produces sulphovinic acid : — + 2U,SO, 2C2H5.HS0, + H 30 . III. COMPOUND ETHERS. These include all salts other than haloids or oxides which an organic basylous radical -can form with an acid, and correspond to the ordinary oxy-salts of mineral chemistry. The acidulous radicals may be either organic or inorganic, but the basylous radicals must always be organic. Compound ethers, generally, may be prepared by one or other of the fol- lowing methods. 1. By the direct action of the acid upon the alcohol. Thus, oxalic acid heated with alcohol yields ethyl oxalate : — 2C2H5HO + H3C2O4 = (C2H5)2C20^ + 2H2O. This process answers well for non-volatile acids of all kinds. 2. By distilling the alcohol with sulphuric acid and a sodium or potassium salt of the required acid. Example, acetic ether, B.P. : — CgHsHO + HgSO^ + NaCsHgOg - CaHg.CaHgOg + NaHSO^ + HgO. This process is suitable for all volatile organic acids not decomposed by heating with HgSO^. 3. By double decomposition of the haloid ether of the required basylous radical with a silver salt of the required acidulous radical. Example, the formation of ethene diacetate : — CgH^.Brg + 2AgC2H302 = C2H^.2C2H302 + aAgBr. The compound ethers are chiefly used as flavourings ; and by various mix- tures of their alcoholic solutions, the well-known artificial essences of pears, 294 ETHERS. pineapples, etc., are produced. At the end of this work will be found a table, showing how these essences are manufactured. To go fully into the com- pound ethers would be beyond the scope of the present work, and we will therefore only consider *a few of the salts of the leading radicals, which may be taken as typical of all the others. Besides the neutral compound ethers we have acid compound ethers, such as ethyl hydrogen sulphate, which can themselves act as regular acids by exchanging their undisplaced hydrogen for metals or basylous radicals. Thus : — Ethyl hydrogen sulphate, C2H5.HSO4, or sulphovinic acid. Ethyl sodium sulphate, C2H5NaS04, ,, sodium sulphovinate. {a) Compound Ethers of the Fatty Series (C,,H2n+i)'E'. In considering these, we shall first take the official ones, and afterwards shortly glance at the remainder. ETHYL NITEITE (Syn. Nitrous Ether). Formula, C2H5.NO2. This substance is produced by heating one part of starch with ten parts of nitric acid and passing the nitrous acid vapours thereby evolved into dilute alcohol kept cool in a two-necked bottle and connected with a well-cooled receiver. It is a pale yellow liquid with an apple-like odour, having a specific gravity of '947 and boiling at 62° F. It is not used pure in Pharmacy, but is the chief ingredient in spiritus etheris nitrosi^ B.P., which is essentially an im- pure solution of ethyl nitrite in alcohol with traces of aldehyd. It is prepared by distilling together alcohol, sulphuric acid, nitric acid, and copper wire. The reaction which takes place is somewhat complicated, but may be represented in one equation, as follows : — C2H5HO + HNO3 + H2SO4+CU - C2H5N02-fCuS04-F2H20. The use of copper is, doubtless, to cause an immediate commencement of the reaction, by at once reducing the nitric acid ; but as the sulphuric acid is also present, it prevents the nitrate radical from combining with the copper, and sets it free to act upon the alcohol, the copper being found at the end ot the process in the state of sulphate. If copper were not used, the nitric acid would be reduced by the alcohol only, and then a large quantity of aldehyd would be formed, thus : — 2C2H5HO + HNO3 = C2H4O + C2H5NO2 + 2H2O. For aldehyd is always formed when an oxidizing agent is reduced by alcohol. It has been found impossible to entirely prevent the formation of aldehyd, but the use of copper reduces the amount formed to a minimum. In practice a pint of the spirit is mixed gradually with 2 ounces of sul- phuric acid and 2J ounces of nitric acid, and the whole is poured into a retort containing 2 ounces of fine copper wire and distilled at a temperature com- mencing at 170° F. but never exceeding 180° F., until 12 ounces have come over. Half an ounce more nitric acid is then added, and 3 ounces more distilled. The 15 ounces of strong solution of ethyl nitrite are then diluted for use by adding 2 pints of recti&d spirit. Spiritus (Etheris nitrosi thus made should be transparent and nearly colourless, with a very slight tinge of yellow ; mobile, inflammable, of a peculiar penetrating apple-like odour, and sweetish, cooling, sharp taste. Specific gravity, 0*845. effervesces feebly, or not at all, when shaken with a little sodium hydrogen-carbonate (presence in very small quantity, or entire absence of free nitrous and acetic acids). When agitated with a solu- tion of ferrous sulphate and a few drops of sulphuric acid, it becomes deep NITROUS ETHER.— ACETIC ETHER. 295 oiive-brown or black (presence of nitrite). If it be agitated with twice its volume of saturated solution of calcium chloride in a closed tube, two per cent, of its original volume will separate in the form of ethyl nitrite and rise to the surface of the mixture. Only ^ of the whole of the ethyl nitrite separates on the addition of calcium chloride, therefore the two per cent, mentioned in the B.P. really corresponds to the ten per cent, of pure ethyl nitrite in the spirit of nitrous ether. The ab- sence of free acid is shown by the non-effervescence with sodium hydrogen-car- bonate ; and this is a test to which very’few commercial specimens will answer. In practical dispensing, when specially prescribed with potassium iodide, it is most important to apply this test before using the spirit, as it would be likely to set free iodine (see Action of Nitrites upon Hydriodic Acid), and spoil the mixture. Spirit of ?iitrous ether., before being added to potassium iodide, should always be shaken up with a little potassium carbonate to prevent such accidents. ETHYL ACETATE (Syn. Acetic Ether). Formula, C2H5.C2H30^. Molecular Weight, 88. Produced by passing carbonic anhydride into an alcoholic solution of potassium acetate, the bye-product (potassium carbonate) being precipitated. The reaction is thus expressed : — 2KC0H3O2 + 2C0H5HO + CO2 = 2C2H5.C2H3O2 + K2CO3 + H3O. The process adopted in the B.P. is the distillation of sodium acetate with alcohol and sulphuric acid, sodium hydrogen-sulphate remaining, and ethyl acetate and water distilling over. C2H5HO + NaC2H302 + H2S0^ = C2H5.C5H3O2 + NaHSO^ -f H2O. To the distilled product half its weight of calcium chloride is added in a stoppered bottle ; and the whole having been allowed to remain together for twenty-four hours, the ethereal liquid is decanted and rectified. Characters a 7 id Tests . — A colourless liquid with art agreeable ethereal odour. Specific gravity, 0*910. Boiling point, 166° F. Soluble in all proportions in rectified spirit and in ether. One part dissolves in 1 1 or 12 parts of water at 60° F. According to Mr. Umney, the above statements are not correct, owing to the ether not being rectified over potassium carbonate, as should be done in order to remove acetic acid. He says ; — I had my suspicions that if I could find a specimen in pharmacy that would answer to the Pharmacopoeia tests, I should in all probability find free acetic acid as an impurity. I also thought that some specimens might be contaminated with ordinary sulphuric ether. Accordingly I examined three, with results as under : — Specific Gravity. Boiling Point. Free Acid. A. ‘890 160° F . . none. B. *889 . . 158° . • C. •915 • 164° (10 per cent, of mono- ( hydrated acetic acid. Acetic ether is a good solvent of cantharidine, and is also, when mixed with ordinary ether, well adapted for taking up' morphia in toxicological analyses. It is somewhat astonishing that the excellent process first mentioned has not been adopted officially. 296 ETHERS. ETHYL NITRATE {^y^. Nitric Ether). Formula, C2H5NO3. Is prepared by distilling alcohol with nitric acid in the presence of urea, to decompose any nitrous acid formed, and so prevent the formation of nitrite and aldehyd. It is insoluble in water, and has a specific gravity of I 'll 2, and boils at 186° F. ETHYL SULPHATE. Formula, (C2H5)2S04. Prepared by passing the vapour of sulphuric anhydride into absolutely anhydrous ether. It is a colourless liquid, at once decomposed by the action of water into sulphovinic acid. ETHYL HYDROGEN-SULPHATE (Syns. Ethyl-sulphuric Acid. Sulphovmic Acid). Formula, C0H5HSO4. Is prepared by heating a mixture of rectified spirit and sulphuric acid to 212° F. C2H5HO + H2SO4 = C2H5HSO4 + H2O. When the mixture has cooled, it is freed from excess of’ acid by digestion with barium carbonate, and filtering out the barium sulphate formed. Barium sulphovinate remains in solution, and it is then carefully treated with dilute sulphuric acid, which precipitates barium sulphate, leaving pure ethyl hydrogen- sulphate in solution. As thus formed, sulphovinic acid, as it is usually termed, is a colourless, oily liquid, with an acid reaction, and having a specific gravity of i’3i6. It decomposes slowly but spontaneously at ordinary temperatures, and when heated with alcohol to 250° F. it yields ether. By dissolving oxides or carbonates of any desired metals in ethyl hydrogen- sulphate, a class of salts called sulphovinates is produced. Sodium sulphovinate is prepared by decomposing barium sulphovinate with sodium carbonate. It is a white granular product, deliquescent, soluble in 07 parts of water at 60° F,, and also soluble in alcohol. BaCl2 in solution should throw down no precipitate. ' ETHYL SULPHITE. Formula, (C2H5)2S03. . Is a limpid liquid having a specific gravity of i'o85, forming alcohol and sulphurous acid when it comes in contact with water. It is formed by the action of .sulphur dichloride, S2CI2, or sulphur oxychloride, SOCI2, on absolute alcohol. ETHYL HYDROGEN-SULPHITE, or, more correctly, ETHYL SULPHONIC ACID. Formula, C2H5HSO3, or C0H..SO2.HO. Is formed by the action of sodium sulphite on ethyl iodide. It can form salts like sulphovinic acid. This is a specimen of a class of compounds of which an immense number have been discovered of late years. The sulphonic acids are viewed as derived from sulphurous acid by the displacement of an atom of hydrogen by a basylous radical, thus : — SOjvo, 216 pages ^ price ys. 6d., containing : — 1. The Processes Employed by Practical Chemists, their Manipulation and. Raisons d'^Ure. 2. The Analytical Reactions of Metals and Acidulous Radicals. 3. The Detection and Examination for Impurities of the Official Chemicals. 4. Full Tables for the Detection and Separation of Bases, Acids, Alkaloids, etc. 5. Toxicological Analysis. 6. Ultimate Organic Analysis. 7. Volumetric Analysis of Metals and Acids. 8. Gravimetric ditto ditto ditto. 9. Special Processes of Interest in Medicine and Pharmacy, including the full Analyses of Water, Barks, Opium, Spirits, Urine, Urinary Calculi, etc., etc. The whole collected in a handy size, so that it lies well open on a table for laboratory use. TEXT BOOKS, continued. t A KEY TO ORGANIC MATERIA MEDICA. Third edition, 600 pages, 8m Price 12s. 6 d. This book includes full but concise descriptions of the Sources, Characters, Qualities, Chemistry, Adulterations, Preparations, etc., of all the Official and a large number of Non-official Drugs. It also contains special analytical courses for the detection of Resinous Drugs, and a specially written and original classification and description of the chief Starches occurring in Food and Medicine, with a view to their ready detection in presence of each other. In an Appendix are copious tables for ready reference in the Museum, rendering the practical acquirement of Materia Medica much simpler than' heretofore. In P?'eparation. A GUIDE TO STRUCTURAL AND SYSTEMATIC BOTANY. A GUIDE TO THE CORRECT WRITING, READING, AND DISPENSING OF PRESCRIPTIONS. All published by W. Baxter, at the offices of the South London School of Pharmacy ; and sold by Messrs. Bailliere, Tindall & Cox, King William Street, Strand, W.C. ; and Messrs. Simpkin & Marshall, Stationers’ Hall Court, E.C. AN INTRODUCTION - TO PHARMACEUTICAL AND MEDICAL CH EM ISTRY. PART II. (^Practical anti ^Inalgtfcal). ARRANGED ON THE PRINCIPLE OF THE COURSE OF INSTRUCTION GIVEN IN THE LABORATORIES OF THE SOUTH LONDON SCHOOL OF PHARMACY. BY DR. JOHN MUTER, M.A., F.C.S., F.I.C, PRESIDENT OF THE SOCIETY OF PUBLIC ANALYSTS. . , PUBLIC ANALYST FOR LAMBETH, NEWINGTON, SOUTHWARK, BERMONDSEY, ROTHERHITHE. THE WANDSWORTH DISTRICTS, AND THE BOROUGH OF TENTERDEN. AUTHOR OF “A KEY TO ORGANIC MATERIA MEDICA,” ETC., ETC. (SECOND EDITION— RE-ARRANGED.) ILonlion : PUBLISHED BY W. BAXTER, SECRETARY, AT THE OFFICES OF THE SCHOOL, KENNINGTON CROSS, S.E. ; and PUBLISHFD BY P. BLAKISTON, SON & CO., 1012, WALNUT STRFFT. 1880. ERRATA. Page 17, line -i2,for 273X765 X265’4 _ 273 x 765 x 265-4 (273 X 140) X 700, (273 + 140) X 760 , 19, ,, 3, ,, affected by dialysis, read effected by dialysis. , 29, line 12, for soluble in excess, read insoluble in excess. , 44, ,, 9, ,, NH4C2O4, read (NH4)2Co04. j 47 > ^2, 5, H2C2H4O0, I'ead H2C4pl40g. , 63, section 36,y&r hallogens, read halogens. , 66, line \ 2 ,for HgCy, read HgCy2. , 68, 12 from bottom, y&r NH4M0O4, read (NH4)oMo04. , 70, line i3,/^7r NH4M0O4, read (NH4)2Mo04. , 71, „ 5, „ NHCl, NH4CI. , 77, 9 from bottom, Sr or K, read Sr or Ca. , 87, line I, Tarred, yellow. , 104, ,, 9, ,, hypophosphate, hypophosphite. , 1 1 8, 2nd column, 5 from bottom, white = Ph, read white = Pb. , 135, line i$,for alicylate, read Salicylate. , 155. n 20, „ -1855 1895. , 168, lines 15 and 23,7^^416 read 420. , ,, ,, 16 and 24,7^^464 and 512, read 468 and 516. N.B . — Students are advised to correct the above-mentioned typographical errors with pen and ink before commencing to read this book. TABLE OF CONTENTS, CHAPTER I. The Processes Employed by Practical Chemists. 1-25. I. Solution .... PAGE 12. Specific Gravity . . PAGE 9-13 2 . Lixiviation 2 13 - Measurement of Atmospheric 3 - Precipitation 2 Pressure and Density of Gases 4 - Decantation 2 and Vapours 13-17 5 - Filtration .... 3 14. Crystallization .... 17-19 6 . Measurement of Heat . • . 3-6 15 - Spectrum Analysis 19-21 7 - Distillation 6 16. Analysis by Circular Polarization. 8. Sublimation 6 The Saccharimeter 21, 22 9 - Fusion .... 6 17. Electrolysis . . . . 22, 23 10. Evaporation 7 18. Pyrology 23-25 11. Weighing and Measuring . . 7-9 CHAPTER II. Detection and Separation of the Metals. 26-48. Reagents . . 26 Group Reagents . 26, 27 Group I. . 27-29 I. Silver . 27 2. Mercurosum , 28 3. Lead . 28 Group II. . 29-36 Division A. • 29-33 I. Mercuricum . 30 2. Bismuth 30 3. Copper 31 4. Cadmium 32 Division B. • 33-36 I. Arsenic 33 2. Antimony 34 3. Tin 35 4. Gold 35 5. Platinum 36 Group III. . • 36-43 Division A. . 1. Iron 2. Cerium 3. Aluminium 4. Chromium Division B. 1. Manganese 2. Zinc 3. Nickel . 4. Cobalt . Group IV. 1. Barium 2. Strontium 3. Calcium Group V. 1. Magnesium 2. Lithium 3. Potassium 4. Sodium 5. Ammonium 36-40 37 38 39 39 40-43 40 41 42 43 43-45 43 44 45 45-48 45 46 47 47 48 CHAPTER III. Detection and Separation of Acidulous Radicals. 49-81. 1. Hydrofluoric Acid and Fluorides 49 2. Chlorine, Hydrochloric Acid, and Chlorides .... 49 3. Hypochlorous Acid and Hypo- chlorites .... 50 4. Chlorous Acid and Chlorites . 50 5. Chloric Acid and Chlorates . 50 $a. Separation of Chlorates and Chlorides .... 50 6. Perchlorates .... 50 7. Bromine, Hydrobromic Acid, and Bromides . . . . 51 8. Detection of Chlorides in the presence of Bromides . . 51 vni TABLE OF CONTENTS. 9. Hypobromous Add and Hypo- bromites ... 10. Bromic Acid and Bromates 11. Iodine, Hydriodic Acid, and Iodides 12. Detection of Bromides in the presence of Iodides 13. Detection of Chlorides in the presence of Iodides 14. Separation of an Iodide from a Bromide and Chloride 15. Iodic Acid and lodates i^a. Detection of an lodate in an Iodide .... 16. Periodic Acid and Periodates 17. Water and Hydrates . 18. Oxides 19. Sulphur, Hydrosulphuric Acid, and Sulphides 20. Detection of a soluble Sulphide in presence of a Sulphite and a Sulphate . . ^ . 21. Thiosulphuric Acid and Thiosul- phates (Hyposulphites) 22. Separation of Thiosulphates from Sulphides .... 23. Sulphurous Acid and Sulphites . 24. Sulphuric Acid and Sulphates 25. Separation of Sulphides, Sul- phites, and Sulphates . 26. Carbon, Carbonic Acid, and Car- bonates .... 27. Boric Acid and Borates 28. Silicic Acid and Silicates . 29. Separation of Silicic Anhydride (Silica) from all other Acids 30. Hydrofluosilicic Acid . 31. Nitrous Acid and Nitrites . 32. Detection of a Nitrite in the presence of a Nitrate . 33. Nitric Acid and Nitrates . 34. Detection of free Nitric Acid in the presence of a Nitrate 35. Detection of a Nitrate in the presence of an Iodide . 36. Separation of Chlorides, Iodides, and Bromides from Nitrates. 37. Cyanogen, Hydrocyanic Acid, and Cyanides 38. Separation of Cyanides from Chlorides .... 39. Cyanic Acid and Cyanates, Cyanuric Acid, and Fulminic Acid 40. Thiocyanic Acid and Thiocy- anates (Sulphocyanates) 41. Ferrocyanic Acid and Ferro- cyanides .... 42. Ferricyanic Acid and Ferri- cyanides .... 43. Separation of Ferro- from Ferri- cyanides .... 44. Detection of Cyanides in the presence of Ferro- and Ferri- cyanides .... PAGE 45. 51 46. 52 47. 52 48. •53 49. 53 50. 53 53 51- 54 54 54 52. 55 55 56 53. 57 54- 57 57 55. 58 56. 57. 59 58. 59 59. 59 60 60. 61. 61 61 62. 61 63- 64. 62 62 65. 63 66. 63 67. 68. 63 69. 70. <53 71- 72. 65 73. 74- 75- 65 76. 65 77. 78. 65! 79- 66 ^ 80. 81. 66 82. 83. 67 Phosphorus and Phosphides Hypophosphorous Acid and Hy- pophosphites Phosphorous Acid and Phosphites Meta- and Pyro-Phosphoric Acids and their Salts . Orthophosphoric Acid (B.P.) and Orthophosphates Detection of a Phosphate in the presence of Calcium, Barium, Strontium, Manganese, and Magnesium. Detection of a Phosphate in the presence of Iron, Chromium, and Aluminium . Detection of Fe, Ce, Cr, Al, Mn, Ca, Sr, Ba, and Mg in the presence of Phosphoric Acid (Separation of Metals of the 3rd and 4th Groups when precipitated as Phosphates) . Separation of Manganese and Magnesium Phosphates Detection of Chromium in the presence of Manganese after fusion ..... Arsenious Acid and Arsenites Arsenic Acid and Arseniates Separation of an Arseniate from a Phosphate Manganic Acid and Manganates . Permanganic Acid and Perman- ganates .... Chromic Acid and Chromates Stannic Acid and Stannates (Stannites ?) . . . Antimonic Acid . . . Formic Acid and Formates Detection of a Formate in pre- sence of Fixed Organic Acids which reduce Silver Salts . Acetic Acid and Acetates . Valerianic Acid and Valerian- ates ..... Sulphovinates (Ethylsulphates) . Stearic Acid and Stearates . Oleic Acid and Oleates Lactic Acid and Lactates . Oxalic Acid and Oxalates . Succinic Acid and Succinates Malic Acid and Malates Tartaric Acid and Tartrates Citric Acid and Citrates Separation of Oxalates, Tartrates, Citrates, and Malates . Meconic Acid and Meconates Carbolic Acid (or Phenic Acid) and Carbolates (Phenates) . Benzoic Acid and Benzoates Cinnamic Acid and Cinnamates . Salicylic Acid .... Detection of Carbolic Acid in presence of Salicylic Acid . Tannic, Gallic, and Pyrogallic Acid PAGE 67 67 68 68 68 69 69 70 71 71 71 71 72 72 72 73 73 73 74 74 74 75 75 75 75 76 76 76 77 77 7h 78 79 79 79 80 8c 80 81 TABLE OF CONTENTS. IX CHAPTER IV. 1. Chlorides .... 2. Hypochlorites . 3. Chlorates .... 4. Iodides .... 5. Bromides .... 6. 'Hydrates .... 7. Oxides .... 8. Carbonates 9. Sulphides .... 10. Sulphites and Hyposulphites 11. Sulphates .... 12. Nitrates . . . d to the Examination of Official Salts. 82 - 112 . PAGE PAGE 82 13. Cyanides .... 103 . 85 14. Ferrocyanides 103 . 85 15. Ferricyanides 103 86 16. Hypophosphites and Phosphates 103 87 17. Arsenites and Arseniates . io 5 88 18. Borates .... 106 90 19. Acetates .... 106 94 20. Valerianates io8 97 21. Oxalates .... 108 98 22. Tartrates .... 109 99 23. Citrates .... 1 10 lOI 24. Scale Preparations . III CHAPTER V. Claalitative Analysis, as applied to the Detection of Unknown Salts. 113 - 137 . I. General Prelimin.^ry Examina- in presence of Phosphoric tion ..... 113 Acid ..... ^25 Case I. The Substance given Table F. Separation of Metals. is a Fluid .... 113 Group III. Division {b) 126 Case 2. The Substance given Table G. Separation of Metals. is a Solid .... 115 Group IV 127 2. Preparation of the Solution for Table H, Separation of Metals. Analysis of Metals, if the Group V. . 128 Substance be not already 4. Preliminary Examination for dissolved .... 117 Acidulous Radicals 130 3- Detection of the Metal 117 5. Preparation of the Solution before Table for Detection of a Metal proceeding to the Analysis of in a Solution containing one Acidulous Radicals 132 Base only .... 118 Case I. The Substance soluble Table for Separation of Metals in W ater, or has been given into Groups 120 in Solution 132 Table A. Separation of Metals. Case 2. The Substance in- Group I. . . . . 121 soluble in Water, but soluble Table B. Separation of Metals. in Acids .... 132 Group II. Division {a) 122 Case 3. The Substance in- Table C. Separation of Metals. soluble in Water and all Group II. Division {b) 123 Acids ..... 132 Table D. Separation of Metals. 6. Course for Detection and Separa- Group HI. Division {a) 124 tion of Acidulous Radicals 132 Table E. Separation of Metals. Separations , . . 133- -135 Group III. Division {a), 7 . Solubility . . , , . 136 CHAPTER VI. Detection of Alkaloids. 138-143. I. Aniline 138 12. Papaverine .... 141 2. Conia 138 13. Strychnia ..... 141 3 - Nicotia ..... 138 14. Brucia ..... 141 4. Quinia ..... 138 15. Veratria 141 Cinchonine in Quinine 139 16. Atropia ..... 141 Adulteration of Quinine Salts . 139 17 . Beberia ..... 142 5- Cinchonia ..... 139 18. Aconitia 142 6 . Morphia ..... 139 19. Delphinia ..... 142 7 . Codeia ..... 140 20. Colchicina ..... 142 8. Narcotia . ... 140 Systematic Course for Detection of a 9. Narceia 140 single Official Alkaloid 142 10. Meconia 140 Course for Detection of a Mixed 11. Thebaia . , . , . 141 Sample of Alkaloids H3 X TABLE OF CONTENTS. CHAPTER VII. Toxicological Analysis. 144-149. PAGE 1. Poisonous Metallic Salts . . 144 2. Mineral Acids .... 144 3. Arsenic, Antimony, Mercury, Reinsch’s Test . . . 144 4. Arsenic, Antimony, Marsh’s Test - 144 5. Arsenic, Fleitmann’s Test . 145 6. Oxalic Acid . . . .145 7. Hydrocyanic Acid . . . 145 PAGE 8. Strychnia . , . , . 146 9. Opium 146 10. Poisonous Alkaloids generally . 147 Proc'^ss Stas .... 147 Brunner’s Alkaloid Separation Table. .... 148 Process Sonnenschein . . 149 CHAPTER VIII. Volumetric Cluantitative Analysis. 150-162. 1. General Principles 2. Apparatus ..... 3. Standard Solutions 4. Calculation of Results 5. Estimation of Alkaline Hydrates 6. Estimation of Alkaline Carbon- ates 7. Estimation of Organic Salts of Potassium and Sodium 8. Estimation of Salts ©f Lead . 9. Estimation of Free Acids 10. Estimation of Hydrocyanic Acid 150 150 i5» 152 153 154 154 155 155 156 11. Estimation of Chlorides, Bro- mides, and Iodides . . 156 12. Estimation of Commercial Ar- seniate of Soda . . .157 13. Estimation of Arsenious Acid . 157 14. Estimation of Sulphurous Acid . 157 15. Estimation of Available Chlorine 158 16. Estimation of Ferrous Salts . 158 1 7. Estimation of Glucose and Lactose 1 59 18. Estimation of Urea . . .160 19. Estimation of Phosphoric Acid . 161 20. Valuation of Manganese Peroxide 162 CHAPTER IX. Gravimetric Cluantitative Analysis. 163-180. I. Preliminary Remarks 1. Preparation of Filters 2. Washing Precipitates . 3. Drying Precipitates . 4. Igniting and Weighing Precipi- tates ..... II. Gravimetric Estimation of Metals .... Estimation of Silver . {a) As Argentic Chloride. \b) As Metal. Estimation of Lead . {a) As Plumbic Oxide. \b) As Plumbic Sulphate. Estimation of Mercury {a) As Mercurous Chloride. {b) As Mercuric Sulphide. Estimation of Cadmium {a) As Cadmium Oxide. (b) As Sulphide. Estimation of Copper {a) As Cupric Oxide. (b) As Metallic Copper. Estimation of Bismuth , . 168 {a) As Bismuth Oxide. {b) As Bismuth Sulphide. Estimation of Gold . . .168 (a) As Metallic Gold, by Pre- cipitation. (b) By Cupellation. Estimation of Platinum . . 168 As Metallic Platinum. Estimation of Tin . . . 169 (a) As Stannic Oxide. (b) As Metallic Tin. Estimation of Antimony .. . 169 {a) As Metallic Antimony. {b) As Antimonious Antimonic Oxide. Estimation of Arsenic . . 170 (a) As Arsenious Sulphide. (b) As Magnesium Ammonium Arseniate. Estimation of Cobalt . . .170 As Potassium Cobaltous Nitrite. Estimation of Nickel . . . 17 1 As Metal. Estimation of Manganese . . 171 As Manganoso - Manganesic Oxide. Estimation of Zinc . . . 171 As Zinc Oxide. Estimation of Iron . . 1 71-172 (a) As Ferric Oxide. (b) Indirect Estimation by means of Metallic Copper. Estimation of Aluminium . . 172 As Aluminic Oxide. . Estimation of Chromium . . 1 72 As Chromic Oxide. 163-165 163 163 164 164 165-176 . 165 165-166 166 167 167 TABLE OF CONTENTS. XI PAGE Estimation of Barium . . 173 As Barium Sulphate. Estimation of Calcium . . 173 As Calcium Carbonate or Cal- cium Oxide. Estimation of Strontium . . 174 As Strontium Carbonate. Estimation of Magnesium . . 174 As Magnesium Pyrophosphate. Estimation of Potassium . . 175 (a) As Potassium Platino- chloride. (^) As Sulphate. Estimation of Sodium . . 176 (a) As Sodium Chloride. ( 3 ) As Sodium Sulphate. Estimation of Ammonium . . 176 AsAmmoniumPlatino-chloride. III. Gravimetric Estimation of Acidulous Radicals 176-180 1. Hydrochloric Acid and Chlorides 176 2. Hydriodic Acid and Iodides . 176 3. Hydrobromic Acid and Bromides 176 4. Hydrocyanic Acid and Cyanides 176 5. Estimation of an Iodide in pre- sence of a Chloride and Bromide 177 PAGE 6. Mutual Estimation of Chlorine, Bromine, and Iodine . . I77 7. Sulphides i77 8. Sulphuric Acid and Sulphates . 178 As Barium Sulphate. 9. Nitric Acid . . . .178 (a) In Alkaline Nitrates. ( 3 ) By Conversion into Am- monia. 10. Phosphoric Acid & Phosphates 178,179 (a) Alkaline Phosphates. (b) Phosphoric Acid in pre- sence of Lime and Mag- nesia. (c) Phosphoric Acid in presence of Iron and Aluminium. ((/) Separation from all Metals. 11. Arsenic and Arseniates . . I79 12. Oxalic Acid . . . .180 (a) As Calcic Carbonate. ( 3 ) Indirect Process by means of Auric Chloride. 13. Tartaric Acid . . . .180 As Calcic Oxide. 14. Silicic Acid .... 180 (n:) In Soluble Silicates. ( 3 ) In Insoluble Silicates. CHAPTER X. Ultimate Organic Analysis. 181-185. 1. Estimation of Carbon and Hy- drogen .... i8i 2. Estimation of Nitrogen . . 183 (a) Method Varrentrapp and Will. { 3 ) Process Dumas. 3. Estimation of Chlorine . . 4. Estimation of Sulphur and Phos- phorus .... 184 185 CHAPTER XI. Special Processes in Analysis. 186-200. I. Potable Water 186- -190 I. Total Hardness . 187 2. Permanent Hardness . 188 3- Chlorine as Chlorides 188 4- Nitrogen as Nitrates and Nitrites 188 5- Free Ammonia . 189 6. Albuminoid Ammonia 189 7. Total Residue . 189 8. Nessler’s Solution 190 II. Analysis of Cinchona Barks 191 (a) Quinine only . 191 ( 3 ) Mixed Alkaloids 191 (c) Complete Analysis for Al- kaloids . . . 191, 192 HI. Valuation of Opium . . 192 IV. Estimation of Emetine in Ipecacuanha . . .193 V. Estimation of Elaterin in Elaterium . . . 193 VI. Estimation of Scammony Resin in Scammonium . 193 VII. Estimation of Alcoholic Strength of Spirits, Wines, and Tinctures . 194 Table of Percentage Weights, Fownes .... 195 VIII. Examination of a Tincture FOR Methylated Spirit . 195 IX. Estimation of Free Sul- phuric Acid in Vinegar . 196 X. Analysis of Urine . . 196-199 XL Analysis of Urinary Cal- culi .... 199, 200 -« CHAPTER I. . THE PROCESSES EMPLOYED BY PRACTICAL CHEMISTS. It is advisable that the student should understand the raiso 7 i TBre of the chief processes he will be called upon to employ, before commencing in detail the study of Analysis. I. SOLUTION. This process consists in stirring a solid body in contact with a fluid until it dissolves, heat being occasionally used. Bodies which refuse to dissolve in any particular fluid are said to be insoluble in it ; the liquid used is called the solvent, and sometimes the menstruum ; a liquid having taken up all the solid matter possible, is said to be saturated. A knowledge of the solu- bility of various substances in the chief menstrua, such as water, acids, alkalies, alcohol, ether, chloroform, and glycerin, is of the utmost importance both to the practical pharmacist and the chemist. By such knowledge we are enabled to separate one body from another ; and by attention to minute details it is even possible to divorce bodies which are soluble in the same menstruum, but in different degrees. As an example we shall suppose three substances, one readily soluble, one partially so, and one but slightly soluble, in ether. By a careful use of three separate quantities of the liquid at dif- ferent temperatures, we can obtain solutions of all three. This process is named fractional solution, and is so frequently employed in the manipulation of fatty substances, that the necessity of a thorough acquaintance with the rela- tive solubility of bodies cannot be too strongly urged. In order to ascertain if any substance be soluble in any particular liquid, it is simply requisite to stir it into the fluid, applying heat if necessary. A portion of the liquid is then poured off, and heated until it has passed away in vapour, when, if any of the solid was held in solution, it will remain as a visible residue. As a general rule, the higher the 'temperature to which a liquid is raised, the greater becomes its capacity for saturation. Thus, one part of common nitre will require for solution about four parts of cold water ; but the same weight of the solid will dissolve in less than half a part of boiling water. There are many exceptions to this rule, notably that of calcium oxide, which is less soluble in boiling water than in cold. If lime-water be saturated at 32° F., it will, on being raised to 2 1 2°, deposit about half its lime. It would appear, indeed, that all bodies have a particular temperature at which their solubility- in cer- tain fluids attains its inaximum, and that with most substances such maximum is over 212°. Sodium sulphate, however, attains its maximum solubility in water at 60° ; but as the temperature increases, its solubility decreases, so that at 212° and 32° it is almost equal. Many bodies, during solution, absorb so much heat that any substance placed in the liquid has its temperature re- markably reduced. Potassium nitrate and ammonium chloride, dissolved together in water, form in this manner a very efficient refrigerant when snow or ice are not attainable. VOL. II. B 2 CHEMICAL PROCESSES. II. LIXIVIATION Is the digestion of a mixture of solids in a fluid, so as to dissolve the soluble portion. Its accomplishment is very simple. The solids, in the form of powder, are introduced into a vessel, and the water or other liquid having been added, the whole is well stirred. Remaining at rest until all the insoluble matter has subsided, the clear fluid, charged with all that was soluble in the mixture, is decanted, or poured off. On the large scale, in chemical works, the clear liquor is usually drawn off by means of a siphon, which may be described as a bent tube having one limb longer than the other. It is filled with the liquid requiring removal, and the longer end having been closed by the finger or a tap arranged on purpose, the shorter limb is plunged nearly to the bottom of the clear fluid to be drawn off On the tap being opened or the finger removed, an immediate stream issues from the longer limb, and continues to flow until the liquid has either been drained to below the level of the shorter limb, or the fluid in the receptacle supplied by the longer limb has attained the same level as that in the vessel which is being emptied. Why this should occur may be explained as follows : — The instru- ment commences to act by virtue of the increased weight of fluid in the longer limb, and once the motion so begins, it is perpetuated by the force of cohesion acting between the particles of the liquid. This may be familiarly illustrated by supposing a great weight of chain on the deck of a vessel, and when one end is thrown out over a roller fixed in the bulwarks sufficiently far to start the motion, the chain continues to run out until the whole is removed from the deck, however heavy the mass may have been. III. PRECIPITATION Is the mixing of two substances in solution so as to form a third substance, which, being insoluble in the fluids employed, sinks to the bottom, and is called the precipitate. The clear liquid which remains after the precipitate has settled down, is called the supernatant liquid. When precipitates are totally insoluble in water, such as barium sulphate, or argentic chloride, the operation is best conducted at a boiling heat, as the high temperature causes the precipitate to aggregate and become more dense, so that it subsides rapidly, and is less liable to pass through the pores of a filter. Other precipitates, which do not form completely and instantaneously, and which are not absolutely insoluble in boiling water, are better treated by being allowed to digest for several hours at a gentle heat. Amongst these may be noted calcium oxalate. On the other hand, there are some precipi- tates which must never be heated, but be allowed to form slowly by standing in the cold for several hours. To this class belong ammonium- magnesium phosphate, and potassium acid tartrate. When it is desirable in qualitative analysis to cause such precipitates to form quickly, resort may be had to violent shaking, or stirring with a glass rod, so that it scrapes against the sides of the vessel. Precipitates are separated from the supernatant liquor by one of two methods. First : — IV. DECANTATION, Which consists in allowing the precipitate to settle to the bottom of the liquid ; pouring off the clear liquor, then pouring on distilled water, and repeating the process until the precipitate is thoroughly washed. Second : — FILTRATION— MEASUREMENT OF NEAT 3 V. FILTRATION, Which consists in transferring the whole to a piece of folded paper or cloth, so that the liquid passes through, while the precipitate remains. This may be washed by the addition of distilled water. The liquor which has thus passed through the filter is called the filtrate. The process of precipitation is pro- bably one of the most common with which the practical pharmacist meets in manufacturing the various chemicals in which he deals, or that he is called upon to analyze ; and a knowledge of the exact quantities of the substances necessary to produce a given weight of precipitate desired, or, conversely, the weight of precipitate which a given quantity of any two substances will pro- duce, is of the highest importance. Full instructions for such calculations are found in Chap. I., Part I. VI. THE MEASUREMENT OF HEAT. The ordinary thermometer for measuring heat is a graduated vacuous glass tube containing mercury. It is thus constructed : — A tube of glass about a foot long, having a small and uniform bore, is selected, and one end is, by the aid of the blowpipe, closed and expanded into a bulb. This is cautiously heated in order to drive out a portion of the air, when the open end of the tube is immediately dipped into a cup of mercury, some of which rises into the bulb as the latter cools. Once more applying heat, the mercury is made to boil, and the remaining air is replaced by mercurial vapour. Again the open end is plunged in the vessel of mercury, and on cooling more mercury is sucked up. This operation is repeated until a sufficient quantity of mercury has been got into the tube, so that it fills the bulb, and stands, when cold, a few inches up the tube. The working part of the instrument is now nearly complete, and it only requires hermetically sealing to be finished. To ac- complish this, the open end of the tube is carefully heated, and a part of it drawn out, so that its diameter is reduced to about one-tenth ; the bulb is then heated until the metallic column rises above this reduced bore, when the application of the blowpipe flame fuses and closes the tube, and the mercury on cooling sinks back to its original level, leaving a vacuum in the upper part of the tube. The instrument is now ready for graduation, which is done by first plunging the bulb into boiling water or exposing it to the steam arising therefrom, when the point reached by the mercury after repeated experiments is noted, and a scratch made with a diamond or file. The same operation is then pursued with melting ice, and the point at which the mer- cury ceases to sink is noted, and marked as before. Thus, two exact and un- doubted indications of heat extremes, namely, the freezing and boiling points of water, being secured and marked, the subdivision of the scale into degrees and fractions is easily managed. There are three systems on which this mayb’e carried out : — (i) Fahrenheit, by which the distance between the two fixed points is measured off and care- fully divided into 180 equal degrees. (2) Celsius, or centigrade, by which the same distance is divided into 100 degrees. And (3) Reaumur, by which the distance is divided into 80 degrees. It is important for the purposes of calculation to remember that the space occupied by 180 F. degrees is exactly the same as that covered by 100 C. and 80 R. respectively; or, taking the simplest arithmetical ratio, we have 9 degrees F. being exactly as long as 5 C. and 4 R. Having thus obtained the value of a degree, it is evident a scale may be made of any length ; but it is of course needless to go lower than the freezing, or higher than the boiling, point of mercury, as it is only between these two extremes that a mercurial thermometer would be of an}r 4 CHEMICAL PROCESSES. use. The following shows the extreme possible scale that can be put on such instruments by each system : — Fahrenheit. Celsius. Reaumur. Mercury boils 662 350 Wn^pr hnils ? 9 T 7 TOO Wntpr fi'ppzpc; 0 0 -177 ATprriivy frpozps -40 —AO o o o In attaching the scales, the F. one is placed with 32 opposite the water- freezing scratch, and then, if the scale be correctly made, 212° will coincide with the boiling scratch ; but in the cases of C. and R., the zeros are placed at the freezing point, and the boiling points then coincide with 100° C. and 80° R. respectively. It is to be deplored that the chemists of all countries have not decided on the universal employment of one style of graduation for thermometers, as such an agreement between them would tend to vastly simplify calculations, or at least to diminish their extent. Fortunately, however, the change from one scale to another is not very difficult ; and as it is of importance to be able to translate the indications of any thermometer into the scale of the one in use, the following directions are offered. 1. To convert degrees of Centigrade into degrees of Fahrenheit; multiply by 9, divide by 5, and add 32. 2. From Fahrenheit to Centigrade; deduct 32, multiply by 5, and divide by 9. _ 3. From Eeaviniur to Fahrenheit; multiply by 9, divide by 4, and add 32. 4. From Fahrenheit to Reaumur; deduct 32, multiply by 4, and divide, by 9. 5. From Centigrade into Reaumur; multiply by 4, and divide by 5. 6. From Reaumur to Centigrade ; multiply by 5, and divide by 4. 7. Degrees of frost Fahrenheit (between 32° and o) into Centigrade or Reaumur; deduct from 32, then multiply by 5 or 4 respectively, and divide by 9, and put a minus sign before the answer. 8. Degrees below zero Centigrade and Reaumur (but still above -177 and -i4’2 respectively) into degrees Fahrenheit; multiply by 9, and then divide by 5 or 4 respectively, and deduct the result from 32. 9. Degrees below o Fahrenheit into Centigrade or Reaumur; add 32, then multiply by 5 or 4 respectively, divide by 9, and put a minus sign before the answer. 10. Degrees Centigrade and Reaumur (below -177 and -14*2 respectively) into degrees Fahrenheit ; multiply by 9, and divide by 5 or 4, as the case may be, deduct 32 from the answer, and put a minus sign before the difference. Thermometers intended for extremely low temperatures are filled with coloured alcohol. They may be used for almost any attainable cold, but are not available above 173° Fah., at which point alcohol boils. For heats above the boiling point of mercury, an instrument called the pyrometer is employed. LATENT HEAT. 5 It is in its simplest form a bar of platinum, fixed at one end, and acting on an index at the other. When the bar is heated, it expands and pushes forward the loose end, which causes the index to moye. Another form is a bulb and tube of platinum, filled with air, placed in the furnace, and connected outside with a U tube containing mercury. The expansion of the air acting on the mercury drives it upwards, and indicates the temperature. Maximum and minimum thermometers are furnished with a small index inside the tube, so constructed that it remains at the highest or lowest point respectively touched by the fluid since the instruments were set However useful the thermometer may be for ordinary purposes, a state ot heat exists which is not appreciable by that instrument, and requires to be measured in a totally different way. For example ; — When once a liquid (say water) reaches the boiling point, its temperature remains stationary, pro- vided the operation be conducted in an open vessel. The furnace underneath may be urged by any and every means known to science, and an immense amount of heat may pass into the liquid, and yet this excess of caloric remains unregistered by the thermometer. The heat thus apparently lost is called latent heat, and is necessary for the retention of the fluid in a state of vapour. Thus we see that vapours are only the corresponding fluids plus latent heat. All fluids are also only the corresponding solids, plus an amount of latent heat; because we find that if we take a pound of water at 32° (0° C.) and a pound of water at 174° (79° C.), and mix them, we shall produce two pounds of water having a temperature of 103° (39*5° C.). But if we mix a pound of ice at 32° (0° C.), with one pound of water at 174° (79° C.), and examine the mixture at the moment that the melting of the ice is complete, we shall find that the temperature of the resulting two pounds of water will be 32° (0° C.) ; in other words, that the pound of water has lost 174" (79° C.) of heat in melting the pound of ice. The heat thus rendered inappreciable by the thermometer during the change from a solid to a liquid is called the latent heat of fusion. It is estimated by means of an instrument called the calorimeter (the description of which will be found in any book on physics), and is expressed in thermal units. A thermal unit is the amount of heat required to raise one gramme, one kilogramme, or one pound, of water from 0° C. to 1° C. Either of these units may be employed, but the most generally recognised is the gramme. In the above example, we found that a pound of ice in melting would cool a pound of water through 79° C. ; and we therefore say the latent heat of fusion of ice is 79 thermal units. The reason why water should be taken as a standard is found in this result, it being the highest of all bodies as regards latent heat. To give some idea of how bodies vary in this respect, it may be mentioned that the latent heat of fusion of silver is 21, of tin 14, and of lead 5*4 thermal units. The heat masked when a liquid changes into a gas is called the latent heat of vaporization. It is made manifest in the ordinary process of distillation, and so great is it in the case of steam, that one pound of water boiled and the steam therefrom passed through a worm surrounded by 5 ‘36 pounds of water at the freezing point, will actually bring the whole contents of the condenser to 100° C. at the moment when the whole has passed away. Going upon this experiment, we therefore consider the latent heat of steam to be 536 thermal units. Freezing mixtures depend for their action on latent heat. A mixture of ice and salt, for example, melts so rapidly, and consequently abstracts heat from the surrounding bodies so completely, as to produce a degree of cold considerably below the freezing point of water. Besides this simple mixture, we have ammonium chloride and ammonium nitrate, and, a more energetic 6 CHEMICAL PROCESSES. mixture of snow and crystallized calcium chloride, which is powerful enough to freeze mercury. The most powerful freezing mixture known, is that of carbon disulphide and liquid njtrous anhydride, which produces a cold of - 140° C. VII. DISTILLATION Is the changing of a fluid into vapour by the aid of heat, and passing the vapour into a cooling apparatus, called the condenser, where, its latent heat being abstracted, it is again deposited as a liquid. This process is em- ployed for the separation of volatile fluids from non-volatile substances. The fluid which passes over and is condensed in the receiver is called the distillate ; while the non-volatile matter which remains in the retort is called the residue. By careful attention to their boiling points, various volatile fluids may thus be separated from each other. Suppose, for ex- ample, that we have a mixture of three substances boiling respectively at 180°, 220°, and 240°, and their separation is desired, we should introduce the mixture into a retort fitted with a thermometer, the bulb of which was placed just above the level of the fluid. The whole being then attached to the condenser, the heat would be gradually raised until the thermometer marked a little over 180°, when that temperature would be steadily main- tained as long as anything continued to collect in the receiver. When the liquid ceased to accumulate, the receiver would be changed, and the tem- perature raised to a little over 220°, and the distillation continued until the second liquid had ceased to pass over. The receiver being once more changed, the heat would be again raised, and maintained until the last liquid had been obtained as a distillate. This process, which is exceedingly useful in practical Chemistry, is called fractional distillation. VIII. SUBLIMATION Is the changing of a solid into a vapour by heat, and recondensing the vapour into a solid form in a cooled vessel. It is employed for the separation of volatile from non-volatile solids, and is thus conducted : — The substance to be sublimed is thinly spread over the bottom of a shallow iron pan, and the vessel is covered with a sheet of bibulous paper perforated with numerous pin-holes or with a piece of muslin. By means of a sand bath, the heat is slowly raised to the desired degree, when the vapour passes through the strainer, and condenses in a cap of wood or porcelain, lined with stout cartridge paper, and placed over the heating-pan and kept cool. Fractional sublimation is often useful, and may be employed in a similar manner to fractional distillation. IX. FUSION Is the heating of a solid until it melts. It is usually carried out in a vessel called a ‘‘crucible,” made of fire-clay. On the small scale, or for the pur- poses of analysis, fusion is generally conducted in porcelain crucibles ; or, where the substances are such as would attack porcelain, in vessels ot platinum or silver. Alkalies should be fused only in crucibles made of the latter metal.- A peculiar kind of fusion, called cupellation, is resorted to in the assay of gold and precious metals. The impure gold is wrapped in a piece of lead foil, and the whole is then heated in a little cup made of bone earth called a cupel, when the lead and all impurities fuse and sink into the substance of the porous vessel, leaving the pure gold as a metallic button, which may then be weighed. WEIGHING AND MEASURING. 7 X. EVAPORATION Consists in heating a fluid until the whole, or as much of it as may be required, passes otf in vapour. A solution thus treated until it has wholly passed into vapour, is said to be evaporated to dryness, and the solid substance remaining is called the residue. Solutions whicli contain any organic or volatile matter ought always to be evaporated on a water bath ; that is, in a vessel exposed only to the heat of boiling water. With ordinary non-volatile or metallic sub- stances in solution this precaution is unnecessary, and of no practical advantage. Evaporation may be conducted slowly, without raising the fluid to its boiling point, when it is called simple vaporization ; but when sufficient heat is applied, the evaporation takes place rapidly, and is accom- panied by the disengagement of bubbles of vapour, and the fluid is then said to be in a state of ebullition. All liquids possess the continual desire, as it were, to pass into vapour ; and the amount of elastic force which the vapour thus given off exerts is called.' its tension. The more the liquid is heated, the greater becomes its tendency to vaporize, and consequently the more powerful is the tension of its vapour ; and when the latter is sufficiently marked to overcome the pressure exerted by the atmosphere and the co- hesion of the liquid itself, ebullition takes place. The boiling point of a fluid is therefore the temperatiu'c at which the tension of its vapour is eqiLal to that of the supermcunibent atmosphere. If the pressure of the atmosphere be increased artificially, the boiling point of the liquid will rise in proportion. For example : boiling water in an open vessel under ordinary circumstances will have a temperature of 212°; but water in a steam boiler, under a pres- sure of 60 lbs. per square inch, will be found to be heated nearly to 264°. As steam under pressure can thus be obtained at high temperatures, it is made use of for the rapid evaporation of liquids on a large scale, by causing it to pass into a jacket or through a coil of pipes surrounding the evaporating pan. The apparatus thus made use of is called a steam hath, the heat ot which, according to the B.P., should be about 230° Fahr. The boiling point of liquids is very variable, as will be seen from the following table : — Ether, pure ..... Fahrenheit. . . 95 ° Centigrade. 35 ° (B.P.) . 105 40*5 Chloroform ..... . 142 61 Alcohol, rectified spirit, 84 per cent. • 175 79'5 „ proof „ 49 . 178*5 8i*4 Water, harom. press, at 29*92 inches Strong Sulphuric Acid .... . 212 100 620 327 Mercury ...... . . 662 350 If water be boiled in a chemically clean glass vessel, and more particularly if a precipitate be suspended in the water, the boiling does not take place regularly, but the liquid becomes heated aboye its boiling point, and suddenly rushes into vapour in gusts. This is called by practical chemists “ bumping,’’ and may be prevented by putting in a few fragments of platinum foil, which act as nuclei, to aid in the regular disengagement of the vapour. XI. WEIGHING AND MEASURING. Weight is caused by the attraction all bodies have for each other, which is known as gravitation. This attraction is exercised in proportion to the mass of matter existing in the bodies, and in inverse proportion to the square of the distance between them. As the earth is the largest body within our at- mosphere, it follows that its attraction is always greater than that of any 8 CHEMICAL PROCESSES. surrounding matter ; and the exercise of this excess of gravitation to the earth’s surface is the cause of weight. Weighing is performed by means of the well- known appliance called the balance, aided by weights made either according to the English or the metrical system. In the English weights of precision, any amount above lo grains is usually represented by a series of small brass cylinders, from lo to looo grains \ then follow 6, 3, 3, 2 and i grains in platinum wire, and afterwards *6, *3, *3, '2 and *i of a grain in platinum, or, more frequently, in aluminium wire. Quantities of less than grain are weighed by a small rider of gold wire placed on the beam of the balance. The foundation of the English system is the inch, which is the 3V part (nearly) of the length of a pendulum vibrating seconds of mean time in a vacuum at the level of the sea, and in the latitude of London : (the actual length of the pendulum is 39*1393 inches). One cubic inch of distilled water, measured at 60° F. and 30 inches barometrical pressure, weighs 252 ’45 grains, or 25 2 J grains nearly. There are 437*5 grains in an ounce, and 16 ounces (or 7000 grains) in a pound. Measure of capacity is obtained by weighing out 10 lbs. of water at 60° Fahr. and 30 inches bar., when the whole measures one gallon. The gallon is in turn divided into 8 pints ( == 20 ounces, or 8750 grains of water, per pint) ; the pint into 20 fluid ounces ( = 437*5 grains of water per fluid ounce); the fluid ounce is divided into 8 fluid drachms ( = 54*68 grains of water per fluid drachm) ; and, lastly, the fluid drachm is divided into 60 minims (= *91 grain of water in each minim). In the metrical weights of precision those above one gramme are in brass ; and then we have *6, '3, ’3, *2, *1, and following them "o6, *03, ‘03, *02, *oi all in platinum wire or thin foil. The quantities below *or (one centi- gramme) are weighed by a rider on the beam. The combination of 6, 3, 3, 2 and I have been chosen because they have been found to give the greatest number of possible combinations with the fewest weights. The metrical system is founded upon the metre., which is theoretically equal in length to the ten-millionth part of a quarter of the meridian of the earth. The metre is multiplied and divided entirely by 10, thus ; — Kilo-metre ..... lOOO’ Hecto-metre 100’ Deca-metre . TO’ Metre 1- Deci-metre . ’I Centi-metre . •01 Mini- metre . ‘001 The metre taking the practical place of the English yard, the decimetre consequently takes the place of the foot, and the centimetre of the inch ; and just as weight is got in our system from the cubic inch, so it is got metri- cally from the cubic centimetre, only much more simply, because i cubic centimetre of distilled water ^ measured at 4°C. and 760 millimetres bar.., weighs one gramme. The gramme is multiplied and divided exactly as the metre ; and measure of capacity is got from the fact that i kilogramme (1000 grammes) of water measures i litre, which becomes in turn the unit of capacity thus : — WEIGHT. Kilo-gramme CAPACITY. Kilo-litre NO. OF UNITS. lOOO’ Hecto-gramme Hecto-litre TOO’ Deca-gramme Deca-litre TO’ Gramme Litre 1 - Deci-gramme Deci-litre *I Centi-gramme Centi-litre •01 Milli-sramme Milli-litre ’001 SPECIFIC GRAVITY. 9 So we see that using water at 4° C., a gramme by weight and a cubic centimetre or a millilitre by measure amount to the same thing ; as likewise do a kilo- gramme by weight and a cubic decimetre or a litre by measure. The relation between the two systems is easily calculated from the following standards : — METRICAL I Gramme I Kilogramme I Litre I Metre ENGLISH. - 15 ’432 grains = 2-205 lbs. (or 15432 grains). = 1-76 pints (or 35 fl. oz. 2 drachms & ii minims). = 39 '3 7 inches. So that I decimetre is, as nearly as possible, 4 inches ; and i decilitre, a trifle over 3^ fluid ounces. [For full tables of both systems, see the Appen- dix ; AND FOR FURTHER PRACTICAL INSTRUCTION IN WEIGHING AND MEASURING, SEE QUANTITATIVE ANALYSIS.] XII. SPECIFIC GEAVITY "May be generally explained to be the weight of anything as compared with that of an equal volume of distilled water at a. temperature of 60°. An acquaint- ance with the various cases which may occur in the taking of specific gravity is of great importance to the pharmacist, as it forms an exceedingly ready method of testing the purity and strength of many substances. A knowledge of the specific gravity of the various bodies in which he deals, also enables the pharmacist to tell at once what any given volume of a liquid ought to weigh, or conversely, what size of a vessel will be required to contain any given weight. The following are the chief varieties of cases which may occur in connection with practically testing the specific gravity of liquids and solids ; — Case i. To take the specific gravity of a fluid. — A small bottle of thin glass is procured, and carefully counterpoised upon a balance. It is then filled with pure distilled water at 60° F., and the weight of the water thus in- troduced accurately noted. The bottle, having been emptied and dried, is filled with the liquid to be tested, also at 60° F., and the whole is again weighed. By this means, having ascertained the weight of equal bulks of water and fluid, it only remains to divide the weight of the fluid by the weight of the water, and the product will be the specific gravity required. To make the calculation clear, observe the following examples : — A counterpoised bottle filled with distilled water weighs 1000 grains; the same bottle filled with sulphuric acid weighs 1843 grains, then : — 1843 - I -843, the specific gravity of the acid. Again, the same bottle, carefully washed, and filled with rectified spirit, weighs 838 grains, then 838 . . 1000 “ specific gravity of rectified spirit. In practice, bottles are sold with little perforated stoppers, which, when en- tirely filled with the liquid, and the stopper carefully dropped in, so that no bubbles of air are allowed to remain between the stopper and the liquid, exactly hold a given weight of water, usually 1000 grains. A counterpoising weight for the empty bottle is also provided ; so that there is nothing further to be done but simply to place the counterpoise in one scale and the bottle, filled with the liquid under examination, in the other ; and having ascertained the weight, to divide by the known weight of water for which the bottle was constructed. To take the specific gravity of a liquid by means of the hydrometer. — The hydrometer depends for its action on the theorem of Archimedes. If a solid lO CHEMICAL PROCESSES. body be immersed in a liquid specifically heavier than itself, it continues to sink until it has displaced a bulk of fluid equal to its own weight, and then it becomes stationary. Suppose an elongated body with a weight at its base to cause it to float upright, which has a specific weight exactly half that of water, be immersed in that fluid, it will sink to exactly half its length, because its whole weight is counterpoised by a bulk of fluid equal to half its size. Hydrometers are long narrow glass or metal tubes with a bulb near the, bottom filled with air, and another smaller bulb beneath containing a sufficient quantity of mer- cury to weight it and cause it to float upright. There are two kinds of hydro- meters : (i) for fluids heavier than water, and (2) for fluids lighter than water. The graduation of the former is performed by immersing the instrument in water and introducing such 'a quantity of mercury as will cause it to sink, so that only about one inch remains unsubmerged, and marking this point i. The instrument is then plunged successively into several liquids heavier than water, the specific gravities of which are known, and the points to which it rises are marked and numbered. By this means a scale can be made between those points, indicating any gravity from i upwards. For hydrometers lighter than water, the first sinking in that liquid is continued by weighting until only the upper bulb is immersed; and this point having been marked i, the instru- ment is placed successively in known fluids lighter than water, the points to which it sinks marked, and by this means a whole scale is obtained. The hydrometers sold for B.P. purposes are generally four in number, the first ranging from 70 to I'oo, the second from I'oo to 1*30, the third from 1-30 to i*6o, and the fourth from i*6o to 2’oo. Such a set will take the gravity of any B.P. liquid except the exceptionally heavy liquor hydrargyri nitratis acidus, which has a gravity of 2-246. The following is a table of the specific gravities of the chief B.P. liquids. Fluids lighter than Water. yEther purus . . '720 Spiritus chloroformi . -871 yEther .... . 735 Liquor ammonire fortior . -891 Spiritus cetheris •809 Spiritus tenuior -920 Alcohol amylicum . •818 Acidum sulphuricum aromat. . . -927 Spiritus rectificatus . . -838 ,, hyclrocyanicum dil. . -997 ,, setheris nitrosi •845 Tinctura ferri perchloridi . . -992 ,, ammoniac aromaticus . -870 Fluids heavier than Water. Acidum aceticum dil. I -oo6 Liquor hydrargyri nitratis acidus 2-246 „ ,, glaciale I -o66 ,, plumbi subacetatis I '260 ,, carbolicum . I -065 ,, potassas I -058 ,, hydrochloricum . I -i6o ,, sodas . 1-047 „ „ dil. . I -052 ,, ,, chloratas Syrupus simplex 1-103 ,, nitricum I -420 1-330 ,, dil. I -lOI ,, aurantii 1-330 ,, nitro-hydrochloricum dil. 1-075 ,, ferri iodidi. 1-385 ,, sulphuricum I '843 ,, hemidesmi. 1-335 » „ dil. . ,, sulphurosum Extractum cinchonas flavas liq. 1-094 ,, limonis 1-340 I -040 ,, mori . 1-330 I -100 ,, papaveris . 1-320 ,, sarzae liq. Liquor antimonii chloridi 1-130 ,, rhasados 1-330 1-470 ,, rhamni 1-320 ,, arsenical is . 1-009 ,, rosas Gallicae 1-335 ,, arsenici hydrochloricus . I -009 ,, sennce 1-310 ,, bismuthi et ammonias citratis I -122 ,, tolutanus . 1-330 ,, calcis chloratas 1-035 Bromine .... 2-966 ,, ,, saccharatus . I -052 Chloroform 1-490 ,, chlori .... 1-003 Creasote .... I -071 ,, ferri perchloridi I -338 Glycerin .... 1-250 ,, ,, pernitratis ,, ,, persulphatis . I -107 I -.141 Vinegar .... 0 p I -019 SPECIFIC GRAVITY. 1 1 By Act of Parliament Sykes’ hydrometer is used by the officers of excise to indicate the strength of spirituous liquors, and thus facilitate the collection of the revenue. It is a short brass instrument with the stem graduated from o to 3 0, and a series of nine weights to place beneath the bulb. By thus being able to change the weight, the length of the stem is only of that it would need to be with a permanent weight, and so the instrument will work in a propor- tionately smaller quantity of liquid. In using it, the thermometer must also be employed; and by observing (i) the temperature, (2) the weight put on, and (3) the point to which it sinks on the stem, and referring to a book of tables which is sold with the hydrometer, the strength of the spirit is ascer- tained. Another modification of the instrument is found in Twaddell’s hydrometer, which is used in this country for testing the density of liquids having a greater specific gravity than water. It is so graduated that the reading of any indi- cated degree, multiplied by 5 and added to 1000, gives the specific gravity as compared with water. Specific gravity beads form the only other variation of the hydrometric idea. These are small loaded bulbs of known specific gravi- ties, which are thrown into the liquid to be tested, when the number marked upon the bead which just floats underneath the surface and shows no ten- dency to sink or rise, gives the specific gravity required. Hydrometers in any form must in accuracy rank considerably beneath that of the specific gravity bottle; but in commercial operations, where an approxim’atiori only to correctness is required, this little instrument is invaluable. ' Case 2. To take the specific gravity of a solid body in mass which is insoluble in and heavier than water. — The method by which this process is conducted was suggested by a theorem attributed to Archimedes, which may be thus expressed : — A solid on being immersed in a liquid is buoyed up in proportion to the weight of the' fluid which it displaoes, and the weight it thus apparently loses is equal to that of its own bulk of the liquid. A piece of the solid substance to be tested is accurately weighed, and is suspended by means of a horsehair from one arm of a balance so that it dips under the surface of a vessel containing distilled Avater at 60° F., when its weight is again noted. Its weight in water is deducted from its weight in air, the weight in air being divided by the differ- ence so obtained. Exampi.e. ’ A piece of marble weighs . . . .300 grains. Immersed in distilled Avater. . . . i88'9 „ Difference in Aveight . . . . . iii’i „ By dividing 300 by iii'i Ave obtain the product 27, which is the specific gi'avity of the marble. Case 3. In order to arrive at the specific gravity of a powder which is insoluble in and heavier than v/ater. — Weigh a portion of the poAvder in air, then introduce it into a counterpoised specific gravity bottle constructed to hold a knoAvn Aveight of Avater. Let the bottle be carefully filled Avith dis- tilled Avater, gently agitating to ensure that no minute bubbles of air shall remain attached to the particles of poAvder; then Aveigh the Avhole. From the Aveight of the poAvder in air, plus the knoAvn Aveight of AA^ater Avhich the bottle should contain, deduct the Aveight obtained in the second operation, and divide the original Aveight of the poAvder by this difference. Example. — 20 grains of a poAvder are Aveighed out, and poured into a counterpoised specific gravity bottle, constructed to hold 1000 grains of Avater. The bottle thus charged is found to Aveigh 1012 grains ; then. CHEMICAL PROCESSES. 2 0 grains + looo grains . = , 1020 grains. Weight of the bottle when charged | with powder and water. . . j ” Difference ^ „ Therefore, 20 grains divided by 8 grains will give 2 ‘5 as the specific gravity of- the powder. Case 4. To take the specific gravity of a substance in mass, insoluble in but lighter than water. — The difficulty met with in this case consists in the impossibility of weighing such a substance alone in water, because it floats on the surface of that liquid. It therefore becomes necessary to attach a piece of lead or other solid sufficiently heavy to sink it, and thus a complication is introduced. The light substance is first weighed in air in the ordinary manner, and is then attached by a horsehair or silken thread to a sinker, and suspended from one arm of a balance under the surface of a basin of distilled water, when the combined weight of both is ascertained. The light body is now detached, and the weight of the heavy solid substance by itself noted. By these means we obtain the following data : — i. The weight of the light body in air. ii. The weight of the heavy body in water. iii. The weight conjointly of the light body and sinker in water. We then deduct the weight of both in water from the weight of the sinker in water ; add the weight of the light substance in air ; and divide the weight of the light body in air by the product so obtained. Example. A light substance weighs 120 grains in air; being attached to a piece of lead, and weighed in distilled water, the united weight amounts to 40 grains, while the weight of the lead alone in water shows 50 grains. Then : — Weight of lead in water 50 grains. Weight of both in water 40 „ Difference . TO „ Add weight of light body in air . 120 „ Product . . 130 „ Dividing 120, the weight in air, by 130 obtained as above, we arrive at the decimal fraction *923 as the specific gravity of the light substance tested. Case 5. To obtain the specific gravity of a substance soluble in water. — Proceed exactly in the same manner as in Cases 2 or 3, according as the body is in mass or in powder ; but instead of water, use oil of turpentine or some other liquid in which the solid is insoluble. Having obtained the specific gravity of the substance as if water had been used, multiply the result by the known specific gravity of the oil of turpentine or other fluid employed. Example. — A lump of sugar weighing 100 grains was found to weigh when immersed in oil of turpentine, 45*62 grains. Then : — The weight of the sugar in air was .... 100 grains. „ „ oil of turpentine . 45 ‘6 2 Difference 54*38 Dividing 100 grains by 54*38 grains yields 1*84 as the specific gravity as if water had been used ; and by multiplying this result by *87, the specific gra- vity of oil of turpentine, we obtain 1*6 as the actual specific gravity of the sample of sugar operated on. ATMOSPHERIC PRESSURE. 13 Having thus considered in detail the various complications which may arise in taking the specific gravity of liquids and solids, it only remains to point out how the foregoing may be rendered subservient to commercial purposes. Case i. The specific gravity of a body being known, it is desired to ascertain the weight of any given volume of the substance. In order to obtain an answer, it is simply necessary to discover what would be the weight of the given bulk considered as water, and to multiply this amount by the specific gravity. • Example i. — What would be the weight of a fluid ounce of oil of vitriol ? We know that a fluid ounce of distilled water weighs 43 7 '5 grains, and in the Pharmacopoeia the specific gravity of oil of vitriol is given as i *843 ; so, if we multiply the former figures by the latter, we obtain 806 '31 grains, which is the weight of a fluid ounce of this acid. Example ii. — How much should a gallon of extractuin cinchoncRjiava’ liquidiLin weigh ? The weight of a gallon of water is 10 lbs., by multiplying 10 by lu, the specific gravity of the extract, we obtain 1 1 lbs. as an answer to the question. Example iii. — How much should a fluid ounce of pure ether weigh? The specific gravity of this exceedingly volatile fluid is *72, and we have already seen that a fluid ounce of distilled water weighs 437*5 grains ; multiplying the one number by the other gives 315 grains, which corresponds to the weight of a fluid ounce of the first-mentioned liquid. Case 2. Given the weight of any known bulk of a liquid, to find its specific gravity. — Divide the weight by that of the given bulk considered as distilled water. Example. — A pint of spirit weighs 7332 grains; — is it rectified or proof spirit? By dividing this weight by 8750, the ascertained weight of a pint of distilled water, we obtain as an answer -838. We knoAy, therefore, that the spirit thus tested must have been rectified and not proof, as the specific gravity of the latter would have shown *92. XIII. MEASUREMENT OF ATMOSPHERIC PRESSURE AND DENSITY OF GASES AND VAPOURS. Taking the density of gases and vapours involves many more complicated considerations than are required in the methods applicable to the specific gravity of liquids and solids. The standard adopted for gases and vapours is hydrogen, measured at a temperature of 0° C., and a barometrical pressure of 760 millimetres. The observation of the temperature is accomplished by means of the thermometer already explained; whereas the pressure of the atmosphere is ascertained by the aid of an instrument named the barometer. A pupil of Galileo, named Torricelli, and others had previously remarked that water in an ordinary suction pump refused to follow the piston higher than about 33 feet. But whilst the savans of the period attributed this circum- stance to “ Nature’s abhorrence of a vacuum,” the eminent disciple of Galileo conceived that the effect was due to a limitation or counter-balancing of at- mospheric pressure. Having thus advanced a stage in his chain of reasoning he concluded that if he employed a heavier fluid than water it would not rise so high in the tube as that liquid, but that its height would be in proportion to its specific gravity. Another link in the chain was now added, and his theory became complete when he argued that any liquid must rise in a sealed tube exhausted of air (having its open mouth dipping into a reservoir of the u CHEMICAL PROCESSES.., same fluid) until its altitude corresponded with, and balanced the weight of the superincumbent atmosphere pressing on the surface of the liquid contained in the reservoir. The barometer is constructed as follows : — The thick glass tube is sealed at one end, and rendered chemically clean. The mercury to be employed is purified by agitation with dilute sulphuric or nitric acid; kept under the cleansing liquid for several days, then washed with fresh acid, and its lustra- tion completed with distilled water. The purified metal and tube being both perfectly dry, the former is poured into the latter to the height of about six inches and boiled for a few seconds. A further supply of separately heated mercury is added, and ebullition again induced as before. Alternately filling up gradually and boiling, the process advances, until the barometrical tube is full, and not a particle of air remains ; in order to prevent subsequent fracture, the tube must be carefully annealed, that is, permitted slowly to cool. It is then simply to be closed with the finger, and inverted in a small vessel of mercury, taking great care that no bubbles of air pass in during the inversion. When this is done, the mercury sinks down from the top and stands at a height which balances the atmospheric pressure of the day, leaving above it a space known as the Torricellian vacuum. The instrument is then graduated in inches or millimetres from die surface of the mercury in the cup upwards. In practice, the graduation commences at 26 inches above the mercury surface, and ends at 32 inches, as the barometer never varies more than that. In millimetres likewise the graduation commences at 700 and ends at 800, for the same reason. The barometer is said to be at standard pressure when the column of mercury is 29*9 inches, or 760 millimetres long. A modern adaptation of the law of atmospheric pressure to the purposes of science is found in the aneroid barometer. It consists of a vacuous circular metal box, with a fluted lid, which is more or less affected by atmospheric changes, that is to say, when the pressure increases the lid is crushed inwards, and springs out again by its own elasticity, when the ' pressure diminishes. The atmo- spheric fluctuations are exhibited on a dial by an indicator placed in con- nection with the metallic moving surfaces. The instrument is graduated by placing alongside it a true mercurial barometer, and observing how far the index passes for each real rise ‘or fall of the mercury. The .aneroid, therefore, is only a true barometer when graduated thus side by side with a mercurial column. The most convenient and widely recognised scales, both for the thermo- meter and barometer, are those employed on the Continent for .the measure- ment of gases. Among scientific persons, whenever any volume of gas is mentioned, it is understood to have been measured at a temperature of zero, as indicated by the Centigrade thermometer ; and under a ‘pi^essure equal to sustain a column of mercury 760 millimetres in height on the French barometer. In the case of liquids or solids, when taking their specific gravity, it is not only possible but easy to obtain the water or other fluid required at the exact temperature necessary, by the use of cooling or heating appliances. With gas we can exercise no such manipulation ; and although we might control the temperature, we are absolutely powerless to influence the pressure of the atmosphere at the period of measurement. The measurement of gases is therefore conducted without any attempt to modify these conditions ; but the indications of the thermometer and barometer being carefully noted at the time of the experiment, a simple series of calculations enables us to ascertain how much the volume of gas would have measured had the test been con- ducted at a standard of temperature and pressure. The following are speci- mens of such calculations : — DENSITY OF GASES AND VA POUTS. 15 I. Correction of the volume of gases for temperature. — This calcula- tion is based upon the discovery that gases expand or contract one two- hundred-and-seventy-third part of their volume for each degree of tem- perature, Centigrade, through which their heat has been respectively raised or lowered. This fact, therefore, enables us, by a simple rule-of-three sum, to obtain the following result : — As 273 plus the temperature at the time of measurement is to 273 plus the required temperature, so is the volume of the gas at the period of measurement to the required volume. For example : — the volume of a gas at 15° C. was 100 cubic centimetres, what would it be at the standard temperature at 0° C. ? Then, — As 273 273 15 o 288 : 273 : : 100 which gives, as an answer, 94*795 cubic centimetres, the volume of the gas at standard temperature. 2. Correction of the volume of gases for pressure. — This calculation is based upon the rule that gases expand or contract in volume in inverse pro- portion to the increase or diminution of the pressure : that is to say, the greater the pressure the less the volume of the gas, and the less the pressure the greater the volume of the gas. For example : — At the moment of measuring 100 cubic centimetres of a gas, the barometer stood at 752 millimetres ; .what would the volume of the gas be at the standard pressure of 760 millimetres? Applying the rule of inverse proportion, we have the following simple directions for stating the sum : — As the required pressure is to the observed pressure, so is the ob- served volume to the required volume ; then 760 : 752 : : 100 which gives, as an answer, 98*95, the volume of the gas at standard pressure. The manner in which the specific gravity of a permanent gas is obtained is as follows : — A sufficiently large globe of very thin glass is procured, fitted with a brass cap and a perfectly air-tight stopcock. Inside the globe, projecting from the cap, a small, delicate thermometer must be fixed for the registration of the temperature, and a barometer of known accuracy placed within sight of the manipulator, to indicate the atmospheric pressure. The gas to be tested must be generated at the time it is required, and passed without delay into the previously exhausted globe, through a considerable length of glass tube filled with some hygroscopic mixture, such as fragments of pumice stone moistened with sulphuric acid, so that during its passage it may be robbed of every trace of moisture. Some pressure being necessarily used in obtaining • the gas, its elasticity when in the globe will, to a trivial extent, surpass the atmospheric pressure ; but by opening the tap for an instant, an equilibrium is established, and the necessity for barometric correction sometimes avoided. The filled globe is now weighed, and its weight noted, together with the indi- cation of the temperature shown by the little thermometer inside, and that of the barometer. Placed on the air-pump, the sphere is then carefully ex- hausted, detached, and the weight recorded. Finally, it is filled with pure, dry air, and once more tested by the balance, when, if the temperature and barometric pressure happen to be alike during all three weighings, the specific gravity required will be known by dividing the weight of the gas by that of the air. i6 CHEMICAL PROCESSES. The specific gravity of vapour is more difficult of attainment, and the process, which necessitates the most delicate manipulation,, is as follows : A thin, clean, dry, glass globe, about three inches in diameter, is employed ; its neck is drawn out into a fine tube in the blow-pipe flame, and the vessel is accurately weighed, and the temperature and pressure at the moment accurately noted. By gently heating the bulb and dipping the attenuated opening into the volatile liquid whose vapour is to be weighed, a suitable quantity (say loo grains) is driven into the globe by the pressure of the air. Attaching a handle by means of wire, the sphere is plunged into an oil bath, furnished with a thermometer, and is then heated somewhat above its volatiliz- ing point. When all vapour has ceased to issue from the globe, the orifice is hermetically sealed, and the temperature and pressure again noted. The apparatus is allowed to cool, separated from the handle, cleansed, weighed, and the weight noted. The last step is to break off a fragment of the neck beneath the surface of a sufficiently large vessel of mercury, when, should the experiment have been carefully performed, the liquid enters the globe, completely filling it, and the capacity is ascertained by emptying its contents into a graduated glass measure. If any residual air remain in the globe, it must be also measured and subsequently allowed for, but, supposing the experiment to have been perfectly successful, we have the following five data : — 1. Weight of globe filled with air. 2. Temperature and pressure at the time of weighing. 3. Weight of globe, plus vapour. 4. Temperature and pressure at sealing. 5. Capacity of the globe. Proceeding from these data, the first point is to find the actual weight of the globe. This is done by calculating the capacity of the globe from the temperature and pressure at the time of weighing to 0° C. and 760 mm. bar. and then multiplying the true volume thus found by *001295, which is the weight of a cubic centimetre of air (i litre at 0° C. and 760 mm. bar. = 1*295 gramme). Having thus obtained the weight of the air, it is deducted from the weight of globe and air, and the difference gives the true weight of the globe ; and by deducting this latter from the weight of the globe plus vapour, we obtain the actual weight of the vapour. But as this weight is that of the volume of vapour at the temperature and pressure at the moment of sealing, it must be corrected to standard temperature and pressure, and the weight of an equal volume of hydrogen ascertained. To do this, the capacity of the globe is once more put- down and reduced from the temperature and pressure at sealing to 0° C. and 760 mm. bar., and the resulting volume is multiplied by *0000896 which is the weight of i cubic centimetre of hydrogen (i litre at 0° C. and 760 mm. bar. = *0896 gramme). The product, which gives the actual weight of an equivalent volume of hydrogen, is then taken and divided into the weight of the vapour already found, and the answer is the density. Taking for example an experiment on the vapour density of acetic acid, in which the data were : — 1. Weight of globe + air, 12*486 grammes. 2. Temp, and bar. at weighing, 15° C. and 765 mm. bar. 3. Temp, and bar. at sealing, 140° C. and 765 mm. bar. 4. AVeight of globe -f vapour, 12*632 grammes. 5. Capacity of globe, 265*4 cubic centimetres. I. AVhat would be the true volume at 0° C. and 760 mm. bar., of 265*4 cc., measured at i5°C. and 765 mm. bar? CR YSTALLIZA TION. 17 273X 765X 265'4 _ (273 + 15) X 760 2. What is the weight of 253*2 cc. of air, at 0° C. and 760 mm. bar. ? 253*2 X *001295 = *328 gramme. 3. Knowing now the actual weight of the air enclosed at the time of weighing was '328, what was the true weight of the globe ? 12*486 - *328 = 12*158. 4. Knowing thus the true weight of the glass, what weight of vapour was in it at the moment of sealing ? 12*632-12*158 = *474 weight of vapour. 5. At sealing we had 265*4 cc. of vapour at 140° C. and 765 mm. bar., how much would that be at 0° C. and 760 mm. bar. ? .73x765x^5-4 ^^ (273 X 140) X 760 ' 6. Knowing now the true amount of vapour in the globe, what would that volume weigh, if it had been hydrogen ? 176*6 X *0000896 = *0158 gramme. 7. But this volume of vapour really weighed *474 gramme, therefore : — *474 *0158 30 and the vapour density of acetic acid is therefore 30. XIV. CRYSTALLIZATION. Many substances when dissolved in a boiling liquid separate out in masses as soon as the fluid cools. Such masses have a well-defined and symmetrical shape, bounded by plain surfaces and regular angles. These bodies are named crystalline ; the deposited masses, crystals ; and the remaining solu- tion, the mother liquor. Substances which are not susceptible of crystalliza- tion are called amorphous (/.^., formless) bodies ; while solids, such as glue and gums, which are soluble in water and yet not crystallizable are named colloids. Crystallization may also occur during solidification after fusion, and by the spontaneous evaporation of liquids holding crystalline substances in solution. All crystalline bodies invariably assume the same form, and may thus be unmistakably recognised from each other. The process is also useful for purification, as at the moment of crystallization all impurities are rejected, and may be poured off with the mother liquor. Many circumstances affect the size of the crystals produced in any solution ; as a rule, the more rapidly crystallization takes place, the smaller are the crystals. An example of the extreme variation in the size of the crystals produced from the same solution may be seen in ferrous sulphate. When allowed to deposit slowly, we have the ordinary well-marked crystals of the ferri siclphas of the B.P. \ but the same salt dissolved in boiling water, and the solution suddenly poured, with constant stirring, into spirit, gives the B.P. ferri sulphas gra?mlata, whose crystals are so minute that a lens is required to distinguish them. For the formation of large and well-defined crystals perfect rest is required, and it is often desirable to introduce pieces of wood or string so as to form nuclei on which the crystals collect. Good examples are seen in commercial crystallized sugar-of-milk and sugar-candy. Some bodies are capable of crystallizing in two or more forms, and are called polymorphous. A very interesting and VOL. II. c i8 CHEMICAL PROCESSES. beautiful instance of this property may be seen in mercuric iodide, the /lydrargyri iodidum riihrum of the B.P. As commonly sold, this is a red powder, and perfectly amorphous. If a little of it be heated, it becomes yellow, and when examined by means of a lens is found to consist of minute rhombic plates. Let it now be touched with a cold knife and its red colour will return, but instead of being amorphous, as it was originally, it exhibits a mass of diamond-shaped grains, called octahedra. Many substances on crystallizing combine with a certain amount of water, which would indeed appear to be necessary to their existence in the crystalline state. The water thus appropriated is named water of crystallization ; it may be driven off by heat and the substance crumbles into amorphous powder. The colour or many crystalline bodies is also apparently dependent on the water of crystal- lization. Take a crystal of the well-known deep blue cupric sulphate, and heat it in a small porcelain crucible, when it will subside into a white powder entirely destitute of crystalline form. But on cooling, if a drop or tw-o ot water be added, the powder will immediately reassume its crystalline form^ and regain its original blue colour. Early in the present century a relation called isomorphism was discovered to exist between crystalline form and chemical composition. Certain substances exist which resemble each other both in the shape of their crystals and in their general chemical composition, differing perhaps only in one ingredient. Such bodies are said to be isomorphoiis with each other. This relation is exemplified in magnesium, zinc, and ferrous sulphates, which when crystallized are alike in form, in the amount of water of crystallization, and in their general chemical constitution : — Magnesium sulphate ..... MgS047H20. Zinc sulphate . . '. . . . Z11SO47H0O. Ferrous sulphate ..... FeS 047 HoO. All crystalline substances possess forms belonging to one of six chief systems. These systems are based upon the mutual relations of certain imaginary lines called axes., which are supposed to run through the body ol the crystal, intersecting each other at its centre. These six systems of crystal- lization may be briefly mentioned. 1. The regular, or ciihic system, in which the axes are all equal in length, and at right angles to each other. To this belong the cube (sodium chloride, potassium iodide, and potassium bromide) ; and the octo- hedron, including alum and the diamond. 2. The square prismatic system, in which the axes are also at right angles, but one is longer or shorter than the other two. Potassium ferro- cyanide is an example. 3. The hexagonal system, having four axes, three equal in length, and in the same plane ; and one unequal and at right angles to the other three. Examples : ice, sodium nitrate, and the mineral called quartz. 4. The rhombic system, in which there are three axes, all at right angles to each other, but all differing in length. Potassium nitrate is an example of this class. 5. The monoclinic system has three axes, all unequal, two being oblique while the third is at right angles to the plane of the other two. To this system belong sodium phosphate, sodium carbonate, cane-sugar, borax, and the isomorphoiis sulphates of zinc and magnesium as well as iron. 6. The triclinic system, in which the three axes are all different in length, and intersect each other obliquely. Cupric sulphate and potassium acid chromate are examples. SPECTRUM ANALYSIS. 19 AVhen small quantities of crystalline substances exist in a solution together with a large quantity of uncrystallizable colloid bodies, their mutual separation is affected by dialysis. This process consists in introducing the' mixture into a glass vessel having a bottom made of vegetable parchment. This, called the dialyzer, is floated in a large quantity of distilled water in a basin. At the expiration of several hours the whole of the. crystalline bodies will have passed through the parchment, and will have become dissolved in the water in the basin, while the colloids remain in the dialyzer. A very good way of practising this process is to dialyze a solution of glue in which a few grains of salt 'have been dissolved, when the salt will be found to have passed into the water in the basin, while all the glue will remain behind. This process is sometimes employed for the separation of crystalline poison, like strychnia, from the contents of a stomach. XV. SPECTRUM ANALYSIS. In describing this extremely delicate, and for many purposes exceedingly useful, method of analysis, it may be advantageous to give a few words of preliminary explanation. Light is, according to the modern theory, con- sidered to be a series of undulations passing through space with immense rapidity, and acting upon the retina of the eye, but not necessarily upon the thermometer. These undulations always pass in straight lines, which are popularly known as rays, and the velocity of their passage is so great that light has been calculated to travel at the rate 'of 200,000 miles a second. When a ray of light touches the boundary line between a rarer and a denser medium, such as the surface of a mirror, a part of it is thrown backwards at an angle equal to that at which it strikes the denser medium : this change in direction is called reflection, the law being stated as, that the angle of inci- dence is equal to the angle of reflection. Usually a portion of the ray is not reflected, but passes through the denser medium ; although under some special circumstances the whole is thrown back. Refraction is the change in direction which a ray of light undergoes on passing at an angle through a transparent medium denser than the air, the sides of which are parallel, such as a sheet of glass. When the ray falls upon the glass, it is bent from its course, and emerges from the other side of the glass in a line parallel to, but not continuous with, its original course. As a rule, the denser the medium the greater is the bending, or refraction, which the ray undergoes. A prism is a triangular piece of glass, or other suitable transparent medium, which from the fact of its sides not being parallel, possesses the power of completely altering the direction of a ray of light, as well as bending it from its course. When a ray of sunlight is allowed to pass through a prism, it is thus deflected and dispersed into a number of rays differing in their degree of refrangibility. When these rays, as they pass from the prism, are caused to fall upon a white surface, they are observed to have a marked difference in colour. The image so produced is called a spectrum ; and when sunlight is thus treated it is found to give a spectrum consisting of the following colours : viz., violet, indigo, blue, green, yellow, orange, and red, which may always be mechanically recollected by the word vibgyor. The violet end of the spectrum, owing to its greater refrangibility, is always the nearer to the base or broad end of the prism. By this means of separating the rays of light, we are able to ascertain the peculiar properties of each of the colours which go to compose it, and we find that die chemical activity of light resides chiefly in the most highly refrangible 2 CHEMICAL PROCESSES. rays just outside the violet end of the visible spectrum, which are called the actinic rays ; while on the other hand, the heat transmitted by the sun is most felt at the opposite or red end of the spectrum. The actinic or chemical rays are those to which we are mainly indebted for many actions of chemical interest, such as the effect of the sun in photography, the formation of green colouring matter in plants, and the explosion of chlorine and hydrogen by sun-light. These rays may be rendered visible by passing them through a solution of quinine in dilute sulphuric acid, which possesses the property of causing the phenomenon of fluorescence, t.e., the so lessening the refrangibility of the chemical rays as to render them visible as a pale blue sheen when the quinine solution is held up to the sunlight. The invisible rays beyond the red end are entirely heat-giving. They are called the Herschellian rays, and may be separated by passing light through a prism of rock salt coated with iodine, which quite cuts off light and allows heat to pass. On the other hand a solution of alum cuts off heat, and trans- mits light. When the heat rays are allowed to fall on a piece of blackened platinum or charcoal in vacuo these bodies become heated to whiteness, thus exhibiting what is called calorescence. Further research demonstrated, that if we substituted the light emitted from various bodies in a state of incandescence to the action of a prism, the image or spectrum produced varied in each case, and was, moreover, almost cha- racteristic of the particular bodies employed. This discovery led to the invention of the spectroscope, which, in its simplest form, consists of a metallic diaphragm with a narrow slit, through which a ray of light from the burning body is allowed to pass and is condensed by a lens upon a prism of glass or, better still, a triangular bottle of thin glass filled with disulphide of carbon. At the opposite side of the prism is a short telescope, so arranged that an observer, looking through it, sees the spectrum or image produced by the light after passing through the prism. When ordinary solar light is examined through the spectroscope, a number of dark lines are found crossing the image at certain fixed points. They are called “ Frauenhofer’s lines ” and their position is characteristic of sunlight. It has been proved that such lines are only formed when the source of light contains volatile substances, as we find that the light emitted by a non-volatile heated body gives a continuous image devoid of lines. If, for example, a platinum wire be heated to a high temperature in a Bunsen burner, and the light thus produced be examined, no lines will be visible ; but if the wire be now tipped with a fragment of sodium chloride, and once more ignited, a bright line will suddenly appear in the yellow of the spectrum, and in so dazzling a manner as to render the whole of the rest of the image almost invisible. In carrying out this system of analysis therefore, it is only necessary to procure a perfectly clean piece of platinum wire, with one end bent into the form of a loop, and place a Bunsen gas burner in such a position that the rays from anything heated in it will pass into the spectroscope. The wire is then to be moistened with a little hydrochloric acid, and having been dipped in the substance to be examined, is to be held in the hottest portion of the* Bunsen flame, and its spectrum simultaneously observed through the spectro- scope, noting carefully the colour, number, and position of the bright lines pro- duced. When thus examined, we find that potassium exhibits one bright line in the red, and one in the blue ; lithium, one bright line in the yellow, and one more brilliant in the red ; strontium, one blue, one orange, and six red lines ; barium, a number of lines chiefly green and yellow ; calcium, three distinct bright yellow lines, one within green, and some broad but indistinct ones in the orange and red ; and lastly, sodium, the single bright yellow line already mentioned. CIRCULAR POLARIZATION— THE SACCHARI METER, 21 It is impossible in our limited space to go more deeply into this subject, except to explain that in absorption spectra, which are produced by the passage of light through certain incandescent vapours and coloured liquids, the bright lines are not seen, but dark ones are formed instead. The dark lines of the solar spectrum are examples of such absorption bands, being doubtless caused by the passage of the light through the vapour surrounding the sun. By means of such absorption spectra the presence of the smallest quantities of bloodstains on clothes may be detected for medico-legal pur- poses and the genuine colouring matter of wines may be distinguished from pigments fraudulently introduced. Excellent special treatises have been written on this subject. XVI. ANALYSIS BY CIRCULAR POLARIZATION. THE SACCHARIMETER. Crystals which do not belong to the regular system (notably calx spar), possess the power of double refraction. That is to say, when a ray of light falls upon them, it is divided into two rays, one of which follows the ordinary rule of refraction, while the other takes a totally different course. When these two rays are examined, they are found to differ in their behaviour : the one being capable of reflection by any suitable medium, while the other, when presented to the same medium, refiises to be reflected, but is entirely trans- mitted. Light when thus modified is said to be polarized, and the two rays are called respectively the “ ordinary ” and the “ extraordinary ” ray. Light may be also polarized by reflection from a piece of glass held at an angle of 56° 45', and indeed everything which interferes with the unrestricted course of a beam of light polarizes, to a greater or less extent. The most convenient polarizing medium is what is called a “ Nicol’s prism.” It is composed of a crystal of calx spar cut into two portions in the direction of its axis, and the two parts thus obtained cemented together with Canada balsam. When a beam of light enters the prism, it is polarized by the first portion of the crystal, and the extraordinary ray only passes through the second portion to the eye of the observer ; while the ordinary ray is completely reflected away by the layer of Canada balsam, and so lost to view. If the extraordinary ray of polarized light thus obtained be examined by means of another NicoFs prism, it will be found that when the two prisms are placed with the principal sections parallel to each other, the ray will pass freely ; but if the second prism be then turned round so that its chief section is at right angles to that of the first, the polar- ized ray will in turn be entirely reflected from the layer of bal-sam, and no light will now reach the observer’s eye. This holds good, so long as nothing intervenes between the two prisms ; but it has been found that certain bodies, such as sugar or quartz, possess the power, when interposed between the crossed prisms, of once more rendering the ray visible, and the observer finds that he has to turn the second prism still farther round to again produce total darkness. Such substances are said to possess the power of circular polar- ization, either in a “ right-handed ” or “ left-handed ” direction, according as it is necessary to turn the prism either to the right or left from its proper position to once more produce complete reflection of the polarized ray. Circular or rotary polarization was first observed by Arago ; and the two remarkable phe- nomena by which it is characterized, are called dextro- and laevo- gyration; from whence are derived the adjectives dextrogyrite and Iscvogyrite. The direc- tion of the rotation is indicated by the use of arrows, thus : Cane-sugar, camphor, tartaric acid, cinchonine, castor oil, croton oil, and oil of lemons rotate the plane of the polarized ray to the right ; while grape-sugar, quinine, 22 CHEMICAL PROCESSES. morphine, and oils of turpentine and valerian, cause a left-handed rotation. The amount of this rotation is fixed for each body, and increases with the quantity of the substance present in a given volume of solution, and also with the colour of the light employed, being least with red and increasing in regular order with yellow, green, blue, and violet, with which latter it is most marked. The chief application of circular polarization is to the analysis of sugar solu- tions, and the process is performed by means of the saccharimeter. This instrument in its simplest form consists of two Nicol’s prisms; the one through which the light first passes being called the polarizer, and that to which the eye of the observer is applied being denominated the analyzer. The latter having been turned until darkness is obtained, the solution to be analysed is placed between them in a clear glass tube lo inches in length and the analyzer is once more turned until darkness is obtained. The angle through which the prism has been turned is then read off from an approximate index and scale attached, and the amount of sugar calculated. An improved apparatus, in- vented by M. Soleil, is at present used, in which, instead of working from light to darkness, the colours produced by a pair of plates of quartz are utilized, a description of which will be found in any good work on Physics. XVII. ELECTROLYSIS. Electricity is one of the most powerful analytic forces with which the chemist has to deal. Its nature is less understood than that of the kindred forces of light and heat ; but it is believed to be merely an aspect of the particles of matter towards one another, by virtue of which a dual force is made evident, manifesting itself in attractions and repulsions, and by producing chemical action accompanied frequently by effects of light and heat. It has two forms, the one termed statical, and characterized by great density or tension., so that it readily escapes by sparks ; the other dynamic, or current electricity, which has a low tension but which can readily be obtained in enormous quantities. The former is that produced upon amber, resin, glass, sulphur, etc., by friction with such bodies as silk and flannel ; and we have merely local sensations when it passes through the body. On the other hand a galvanic current direct from a battery passes through the body with such difficulty that we have no sensation. When a coil intervenes, we have the well-known ‘‘ electric shock ” since this augments the tension, or power of over- coming obstacles which resist its passage. A simple piece of electric appara- tus formerly employed to produce a spark for the purpose of exploding gases was the electrophorus, which however is now superseded by the joint use of the battery and induction coil. It consisted of a sheet of resin upon a metal plate, and a brass disc furnished with a knob and a glass handle. The resin was excited by rubbing with flannel or a catskin, the disc placed on it, and the knob, when touched, gave a spark to any body connected with the earth. Current electricity, of far greater importance, results from the action of chemical agents upon various metals, the apparatus in its simplest form being called a voltaic or galvanic cell or element, and a combination of several cells being termed a battery, A galvanic element has several forms ; that of Grove, which is very exten- sively used and of great power, consists of an outer cell or jar of glazed earthenware in which is placed a cylinder of zinc, an inner unglazed porous jar, and a sheet of platinum, both metals furnished* with binding-screws for attaching wires to them. T^ie acids used are dilute sulphuric around the zinc, and strong nitric in contact with the platinum in the inner cell. The zinc constitutes the positive (or most attacked), the platinum the ELECTRO L YSIS—P YROLOG Y. 23 negative (or least attacked) metal ; but when wires are attached to these and tipped with platinum, the end of the wire connected with the zinc is termed the negative electrode, whilst that in union with the platinum in the battery, is the positive electrode. To explain this apparent contradiction we must imagine that the current generated by the zinc passes through the fluid in the cell and then through the platinum, while at the same time an opposite current is generated from the platinum through the liquid to the zinc, and thus the elfect of each current is felt at the ends of the wires from the oppo- site plate. These platinum electrodes (sometimes called poles), when placed near one another in a compound liquid, occasion the phenomena of electro- lysis, which is simply the splitting up of conductors of electricity into their elements or into simpler forms. For instance, a solution of HCl gives off Cl at the positive electrode and the H at the negative, as a result of the axiom that unlike electricities attract and like repel one another. Cl itself being electro-negative and H electro-positive. Dealing with HgSO^ we get H2 at one electrode and SO^ at the other, the latter however at once splitting up into O (given off) and SO3, which re-forms with the water present. This action is taken advantage of in the voltameter, an instrument for measuring the strength of an electric current by the amount of mixed gases (H and O) it will liberate from water. The instrument is a wide glass tube graduated in inches and fractions. It is filled with acidulated water and inverted over the two electrodes, when the two gases form and gradually displace the water from the tube. Sometimes separate tubes are used, one over the negative electrode, to collect the hydrogen, and the other over the positive, to collect the oxygen. The strength of the current is proportional to the quantity of gases set f^ree within a given time. It is somewhat remarkable that all the bubbles of gas arise from the surfaces of the electrodes themselves and none from the intervening liquid. This is accounted for by supposing that when one of the gases, — say H, — is given off at one electrode, the O pre- viously united with it seizes the H of an adjoining molecule of HoO aiKi thus sets free O to combine with the next H, until the last O reaches the second electrode and escapes. When sparks and strong heating effects (such as in the electric lights which is produced when two electrodes of carbon are approached so as nearly to touch each other) are desired, a number of cells must be used \ but for the purpose of exploding gases the expense of these is saved by employing an induction coil. The principle of this instrument is, that when an interrupted current of low tension, — in fact a series of charges, — is made to pass into a coil of thick insulated copper wire, surrounded by a much longer coil of thin wire also carefully insulated, electricity of high tension, giving long and powerful sparks, is produced by induction. XVIII. PYEOLOaY. Under this name are included all processes of analysis depending for their action on the use of fire, or, in other words, what were formerly called “ re- actions in the dry wayl^ The chief instruments used are the blow-pipe and the Bunsen burner. The blowpipe is a tube with a narrow nozzle, by which a continuous current of air can be passed into an ordinary flame. The ordi- nary gas flame consists of three parts, (a) A non-luminous nucleus in the centre, {h) A luminous cone surrounding this nucleus ; and (c) An outer and only slightly luminous cone surrounding the whole flame. The centre portion (a) contains unaltered gas, which cannot burn for want of oxygen ; that necessary element being cut off by the outer zones. In the middle por- tion (h) the gas comes in contact with a certain amount of oxygen, but not 24 CHEMICAL PROCESSES. enough to produce complete combustion ; and therefore it is chiefly the hydrogen which burns here, the carbon separating and, by becoming intensely ignited, giving the light In the outer zone (c) full combustion takes place, and the extreme of heat is arrived at, because chemical action is most intense. The outer flame, therefore, acts readily on oxidizable bodies because of the high ternperature and the unlimited supply of air, while the luminous zone tends to take away oxygen by reason of the excess of unburned carbon or hydrocarbons therein existing. For these reasons the former is called the oxidizing flame, and the latter the reducing flame. The great analyst Fresenius thus describes the use of the blowpipe : — The effect of blowing a fine stream of air across a flame is, first, to alter the shape of the flame, as, from tending, upward, it is now driven sideways in the direction of the blast, being at the same time lengthened and narrowed ; and, in the second place, to extend the sphere of combustion from the outer to the inner part. As the latter circumstance causes an extraordinary increase of the heat of the flame, and the former a concentration of that heat within narrower limits, it is easy to understand the exceedingly energetic action of the blow- pipe flame. The way of holding the blowpipe and the nature of the blast will always depend upon the precise object in view, viz., whether the operator wants a reducing or an oxidizmg flame. The easiest way of producing most efficient flames of both kinds is by means of coal-gas delivered from a tube terminating in a flat top with a somewhat slanting slit inch long and yf o inch wide ; as with the use of gas the operator is enabled to control and regulate not only the blowpipe flame, but the gas stream also. The task of keeping the blowpipe steadily in the proper position may be greatly facilitated by firmly resting that instrument upon some movable support. The reducmg^dimQ is produced by keeping the jet of the blowpipe just on the border of a tolerably strong gas flame, and driving a moderate blast across it. The resulting mixture of the air with the gas is only imperfect, and there remains between the inner bluish part of the flame and the outer barely visible part a luminous and reducing zone, of which the hottest point lies somewhat beyond the apex of the inner cone. To produce the oxidizmg flame, the gas is lowered, the jet of the blowpipe pushed a little further into the flame, and the strength of the current somewhat increased. This serves to effect an inti- mate mixture of the air and gas, and an inner pointed, bluish cone, slightly luminous towards the apex is formed, and surrounded by a thin, pointed, light-bluish, barely visible mantle. The hottest part of the flame is at the apex of the inner cone. Difficultly fusible bodiea are exposed to this part to effect their fusion ; but bodies to be oxidized are held a little beyond the apex, that there may be no want of air for their combustion. The current is produced by the cheek muscles alone, and not with the lungs. The way of doing this may be easily acquired by practising for some time to breathe quietly with puffed-up cheeks and with the blowpipe between the lips ; with practice and patience the student will soon be able to produce an even and uninterrupted current. The supports on which substances are exposed to the blowpipe flame are generally either wood charcoal, or platinum wire or foil. Charcoal supports are used principally in the reduction of metallic oxides, etc., or in trying the fusibility of bodies. The substances to be operated upon are put into small conical cavities scooped out with a penknife or with a little tin tube. Metals that are volatile at the heat of the reducing flame evaporate wholly or in part upon the reduction of their oxides ; in passing through the outer flame the metallic fumes are re-oxidized, and the oxide formed is deposited around the portion of matter upon the support. Such deposits are called incrustations. Many of these exhibit characteristic colours PYROLOGY. leading to the detection of the metals. Thoroughly-burnt and smooth pieces of charcoal only should be selected for supports in blowpipe experiments, as imperfectly-burnt and knotty pieces are apt to spirt and throw off the matter placed on them. The great use of charcoal lies (i) in its low degree of conductivity; (2) its porosity, which causes it to absorb fusible bodies and leave infusible ones upon its surface ; and (3) its> power of aiding the effects of the reducing flame. Platinum wire and foil are used for supports in the oxidizing flame, and the former is specially employed for trying the action of fluxes and the colour communicable to the blowpipe or Bunsen flame. The platinum wire, when employed for making beads of borax or other fluxes, should be about 3 to 4 inches long with the end twisted into a small loop. The loop is then heated, and dipped while hot in the powdered borax, when it takes up a quantity which is then heated till it fuses to a clear bead formed within the loop.' When cold, this is moistened and dipped in the powder to be tested, and again exposed to the flame, and the effect noted. For trying the colour im- partable to the flame by certain metals, the wire is first cleaned by boiling in dilute nitric acid and then holding it in the flame until no colour is obtained. The loop is then dipped in the solution to be tested, and held near the flame till the adhering drop has evaporated to dryness, and then heated in the man- tle of the flame near the apex of the inner cone, and the effect observed. The Bunsen burner consists of a tube having at its base a series of holes to admit air, and also a small gas delivery tube. By means of this contrivance the gas is mixed with air before it burns, and more perfect oxidation, and consequently much greater heat, is secured. Looking attentively at the flame of a Bunsen burner, we distinguish in it an inner part and two mantles sur- rounding it. The inner part corresponds to the dark nucleus of the common ‘ gas flame, and contains the mixture of gas and air issuing from the, burner. The mantle immediately surrounding the inner part contains still some un- consumed carbide of hydrogen ; the outer mantle, which looks bluer and less luminous, consists of the last products of combustion. This hottest part, — lying in the mantles surrounding the inner part of the flame, in a zone extending a few hundredths of an inch upwards and downwards from the transverse section of the flame across the apex of the inner part, — has, according to Bunsen’s calculation, a temperature of 4172° F. This is termed the zo?ie of fusion. The outer margin of this zone of fusion acts as oxidizing flame., the inner part of it as reducing flajjie. The spot where the reducing action is the most powerful and energetic lies immediately above the apex of the inner part of the flame. The Bunsen flame brings out the coloration which many substances impart to flames, and by which the qualitative analyst can detect many bodies, even though present in such minute quantities that all other means of analysis except the spectroscope fail to discover them. The subject of the coloration of flames will be discussed fully under each metal. CHAPTER II. DETECTION AND SEPARATION OF THE METALS. For the purposes of qualitative analysis, we employ certain chemicals either in the solid or liquid state, which 'by producing given effects enable us to detect the existence of the substance searched for. These substances are always kept ready for use, and are called reagents. They are of three classes : I St. Group reagents, which, by yielding a precipitate under certain condi- tions, prove the substance to be a member of a certain group of bodies. 2nd. Separatory reagents, by means of which the substance under examination is distinguished from the other members of the group. 3rd. Confirmatory reagents, by which the indications previously obtained are confirmed and rendered certain. The Metals are divided into five groups, each of which has its group reagent, as follows : — Group i. Metals, the chlorides of which, being insoluble in water, are precipi- tated from their solution by the addition of hydrochloric acid. They, are silver, mercurous mercury, and lead (the latter in cold strong' solutions only). Group 2. Metals, the sulphides of which, being insoluble in dilute hydro- chloric acid, are precipitated from their solutions by the addition of sulphuretted hydrogen in the presence of hydrochloric acid. This group includes mercury, lead, bismuth, copper, cadmium, antimony, - ^ tin, gold, platinum, and the metalloid arsenic, and is divided into two sub-groups, as follows : — A. Metals, the sulphides of which are insoluble in both dilute hydrochloric acid and ammonium sulphide. The precipitated sul- phides separated by sulphuretted hydrogen, are therefore insoluble after washing in ammonium sulphide. They are mercury, lead, bismuth, copper, and cadmium. B. Metals, the sulphides of which, although insoluble in dilute acids, are dissolved by alkalies, and the precipitates from their solu- tions by sulphuretted hydrogen, therefore dissolve in ammonium sulphide. They are gold, platinum, tin, antimony, and arsenic. Group 3. Embraces those metals, the sulphides of which are soluble in dilute acids, but are insoluble in alkalies, and which consequently having escaped precipitation in Group 2, are now in turn precipitated by ammonium sulphide. They are iron, nickel, cobalt, manganese, and zinc. In this group are likewise included aluminium and chromium, -which are precipitated as hydrates by the alkalinity of the ammonium sulphide. Magnesium would also be precipitated as hydrate, but as that would be inconvenient at this stage, its precipitation is prevented by the addition of ammonium chloride, in which its hydrate is soluble. SILVER. 27 Group 4. Comprises metals, the chlorides and sulphides of which, being soluble, escape precipitation in the former groups, but the carbonates of which, being insoluble in water, are now precipitated by ammonium carbonate. They are barium, strontium, and calcium. Magnesium is not precipitated as carbonate owing to the presence of the ammonium chloride, already added with the sulphide in Group 3. Group 5. Includes metals, the chlorides, sulphides, and carbonates of which, being soluble in water or in ammonium chloride, are not precipitated by any of the reagents already mentioned. They consist of magne- sium, lithium, potassium, sodium, and ammonium. As the analytical grouping of the metals is undoubtedly one which is most important to the student for practical purposes, we shall adhere to this arrangement in giving the methods for the detection and analytical separation of the metals used in Pharmacy. GROUP I. IMetals precipitable as chlorides by the addition of hydrochloric acid to their solutions. I. SILVER (Ag). {a) WET EEACTIONS. (To be practised upon a solution of argentic nitrate — AgNOg.) 1. HCl (^isf group reagent) or any soluble chloride gives a curdy white pre- cipitate of argentic chloride — AgCl — insoluble in boiling nitric acid but instantly soluble in ammonium hydrate. It is also soluble in KCy, NaoSoOg, and in strong solutions of soluble chlorides. 2. KHO or NaHO both produce a brownish precipitate of argentic oxide, AggO, insoluble in excess. A similar effect is produced by the hydrates of barium, strontium, and calcium. 3. KoCrO^ gives a red precipitate of argentic chromate — AgoCrO^^ — soluble in large excess of both nitric acid and ammonium hydrate ; and there- fore the solution should always be as neutral as possible. 4. HoS and NH^HS, both produce black argentic sulphide — AgoS — insoluble in excess, but soluble in strong boiling nitric acid. 5. KI and KBr both produce curdy precipitates, the former yellow argentic iodide — Agl — insoluble in ammonium hydrate, and the latter argentic bromide — AgBr — dirty-white and slowly soluble in ammonium hydrate. 6 . KCy gives a curdy-white precipitate of argentic cyanide — AgCy — readily soluble in excess’ and also in boiling strong nitric acid. 7. Many organic salts, such as formates and tartrates, boiled with solutions of silver, precipitate the metal as a mirror on the tube. 8. Fragments of copper, zinc, iron, and tin introduced into a solution of silver, all precipitate the metal. (d) DRY REACTION. (To be practised on argentic oxide — AgoO.) Mixed with sodium carbonate and heated on charcoal before the blowpipe? a bead of silver is formed, hard, glistening, and soluble in nitric acid, yielding solution of argentic nitrate to which the wet tests may be applied. {c) SEPARATION On adding hydrochloric acid, silver is precipitated as chloride together with the chlorides of mercurous mercury and lead, all other metals remaining DETECTION AND SEPARATION OE THE METALS. in solution. By washing the precipitate with boiling water, the plumbic, chloride is dissolved out, and the residue is then treated with ammonium hydrate, which dissolves out the argentic chloride, and leaves mercurous oxide on the filter. The filtrate on dilution and acidulation with nitric acid, redeposits the argentic chloride in a pure condition. ’ II. MERCUEOSUM (Hgg)". (a) WET EE ACTIONS. (To be practised on a solution of mercurous nitrate — (Hg^YzNO .^ — prepared by acting upon a globule of mercury with cold and dilute nitric acid, so as not quite to entirely dissolve the metal.) 1. HCl (isf group reagent) gives a white precipitate of mercurous chloride,. — (Hg2)"'Clo' — turned to black mercuros-ammonium chloride — NH3(Hgoy'Cr — by ammonium hydrate. It is also insoluble in boiling water, but soluble in strong nitric acid, being converted into a mixture of mercuric chloride — HgCl2 — and mercuric nitrate — Hg2N03. 2. KHO and NaHO both give black precipitates of mercurous oxide — Hg20 — insoluble in excess. 3. NH4HO produces a black precipitate of dimercuros-ammonium nitrate — 2NH2(Hg2)"N03H20 — also insoluble in excess. 4. SnCb boiled with the solution causes a grey precipitate of finely divided mercury, which if allowed to settle and then boiled with hydrochloric acid and some more stannous chloride, aggregates into a globule. {b) DR Y REA CTION. (To be tried upon mercurous iodide, hydrargyri iodidum viride^ B.P.) Mercurous compounds heated, break up into the corresponding mercuric salt, which sublimes, and metallic mercury, which also sublimes at a higher temperature. {c) SETAE AT/ON The addition of hydrochloric acid separates mercurous mercury from all other metals except silver and lead. The precipitated chlorides, having been washed free from lead by boiling water, are treated with ammonium hydrate, which dissolves the argentic chloride and leaves the mercury on the filter as black mercuros-ammonium chloride. III. LEAD (Pb). (a) WET REACTIONS. (To be practised on a solution of plumbic acetate — Pb2C2H302.) 1. HCl {ist group reagent) forms in cold strong solutions a white precipitate of plumbic chloride — PbCL — soluble in boiling water. 2. H2S after acididatmi by HCl {2nd group reageiit) gives a black pre- cipitate of plumbic sulphide — PbS — insoluble in ammonium sulphide. By treatment with boiling strong nitric acid it is decomposed, partly into plumbic nitrate, but chiefly into insoluble plumbic sulphate. It is entirely dissolved by hot dilute nitric acid with separation of sulphur. 3. H2SO4 gives a white precipitate of plumbic sulphate — PbS04 — slightly soluble in water, but rendered entirely insoluble by the addition of a little alcohol. It is decomposed by boiling strong hydrochloric acid. MERCUROSUM—LEAD. 29 and is also freely soluble in solutions of ammonium acetate or tartrate, containing an excess of ammonium hydrate. 4. KoCr04 gives a yellow precipitate of plumbic chromate — PbCrO^ — in- soluble in acetic and very dilute nitric acids, but soluble in strong boiling nitric acid. 5. KI gives a yellow precipitate of plumbic iodide — Pblo — soluble in boiling water, and crystallizing out on cooling in golden scales. 6. KHO and NaHO both cause white precipitates of plumbic hydrate — Pb2HO — soluble in excess, forming potassium or sodium plumbates — KoPbOo and Na^PbOo. 7. NH4HO causes a white precipitate of a white basic nitrate — Pb(N03)H0 — soluble in excess. S. KCy produces a white precipitate of plumbic cyanide — PbCyg — insoluble in excess, but soluble in dilute nitric acid. 9. Alkaline Carbonates cause a precipitate of “ white lead ” — (PbCOg)2Pb2HO — insoluble in excess, and also in potassium cyanide. 20. Fragments of zinc or iron in the presence of a little acetic acid cause the separation of metallic lead in crystalline laminae. {b) DR Y REA CTION. (To be practised on red lead — Pbg04 — or litharge — PbO.) Heated on charcoal in the inner blow-pipe flame, a bead of metallic lead is formed, which is soft and malleable and soluble in dilute nitric acid. The solution thus obtained gives the wet tests for lead. {c) SEPARATION, On adding hydrochloric acid, a great part of the lead present will pre- cipitate out as chloride, and may be separated from silver and mercurosum by washing the precipitate with boiling water, and testing in the solution with potassium chromate. The solution filtered from the hydrochloric acid pre- cipitate is then treated with excess of sulphuretted hydrogen, which precipitates the remainder of the lead together with Hg, Bi, Cu, Cd, As, Sb, Sn, Au, and Pt. The precipitate is well washed free from chlorides, and is then digested in water containing ammonium sulphide, which dissolves everything except Hg, Pb, Bi, Cu, and Cd, left insoluble as sulphides. These mixed sulphides are then heated with strong nitric acid till red fumes cease, a few drops of sulphuric acid added, the whole washed in a test-tube with a little water, cooled, and mixed with an equal bulk of rectified spirit. Any pre- cipitate will now consist only of mercuric sulphide and plumbic sulphate, the Bi, Cu, and Cd passing into solution. The precipitate is filtered out and percolated with ammonium acetate containing excess of ammonium hydrate, when the plumbic sulphate dissolves and is tested for in the liquid which passes through by adding potassium chromate. GROUP II. Metals which are not affected by acidulation with hydrochloric acid, but are precipitated by passing sulphuretted hydrogen through the acidulated solution. Division A. Metals which when precipitated by sulphuretted hydrogen as above, yield sulphides insoluble in ammonium sulphide. DETECTION AND SEPARATION OF THE METALS. I. MERCUmCUM (Eg). (a) WET EE ACTIONS. (To be practised on a solution of mercuric chloride — HgCl2.) 1. HoS after acidiilation by HCl (2nd group reagent) gives a black pre- cipitate of mercuric sulphide — HgS — insoluble in ammonium sulphide and nitric acid, and only soluble in nitro-hydrochloric acid. Care must be taken that the sulphuretted hydrogen is passed really in excess, and that the whole is warmed gently, as unless this be done, the pre- cipitate is not the true sulphide, but a yellowish-brown dimercuric sulpho-dichloride — Hg3SCl2. Although insoluble in any single acid, mercuric sulphide may be caused to dissolve in hydrochloric acid by the addition of a crystal of potassium chlorate. 2. KHO or NaHO both give a yellow precipitate of mercuric oxide — HgO — insoluble in excess. 3. NH4HO produces a white precipitate of an insoluble mercur-ammonium chloride — (NH2Hg)Cl — also insoluble in excess. 4. KI yields a red precipitate of mercuric iodide, soluble in excess of both the precipitant and of the mercuric salt. 5. SnCL, boiled with a mercuric solution, first precipitates mercurous chloride, and then forms metallic mercury, as in the case of mercurosum com- pounds. 6. Alkaline Carbonates (except ammonium carbonate) produce an immediate reddish-brown precipitate of mercuric oxy-carbonate. 7. Fragments of Cu, Zn, or Fe precipitate metallic mercury in the presence of dilute hydrochloric acid. {h) DR Y REA CTION (To be tried on mercuric oxide — HgO — and on Ethiops mineral ” — HgS.) All compounds of mercury are volatile by heat. The oxide breaking up into oxygen and mercury, which sublimes, while the sulphide sublimes unaltered, unless previously mixed with sodium carbonate or some reducing agent. {c) SEPARATION By acidulating with hydrochloric acid, and passing sulphuretted hydrogen, then washmg the preeipitate earefully with boiling water till free from chlorides., and lastly digesting it in w^ater containing some ammonium sulphide, we obtain mercuric sulphide associated only with the sulphides of Pb, Bi, Cu, and Cd. The precipitate is then treated with a little strong nitric acid, which dissolves all except the HgS. By washing into a test-tube, adding a few drops of sulphuric acid, and then an equal volume of rectified spirit, the HgS is deposited, mixed possibly with PbSO^. If these be filtered out and per- colated with ammonium acetate containing excess of ammonium' hydrate, the PbS04 will be dissolved, and the HgS wall be left on the filter as a black residue ; which may then be dissolved in hydrochloric acid, by the aid of a crystal of potassium chlorate, and the mercury proved in the solution, by boiling with stannous chloride. II. BISMUTH (Bi). {a) WET REACTIONS. (To be practised upon bismuthi subnitras, B.P., dissolved in water by the aid of the smallest possible quantity of nitric acid, and any excess of the latter carefully boiled off.) MERCURICUM— BISMUTH— COPPER. 31 1. HoS after acidulation by HCl {2nd group reagent) gives a black precipitate of bismuth sulphide — BioS.^— insoluble in ammonium sulphide, but soluble in boiling nitric acid. 2. H3SO4 gives no precipitate (distinction from lead). 3. NH4HO, KHO, and NaHO all give precipitates of white bismuthous hydrate — Bi3HO — insoluble in excess and becoming converted into the yellow oxide — BioO-^— on boiling. 4. HoO in excess to a solution from which the free acid has been as much as possible driven off by boiling, gives a white precipitate of a basic salt of bismuth. This reaction is more delicate in the presence of hydro- chloric than of nitric acid ; and the precipitate, which is in this case bismuth oxy-chloride — BiOCl — is insoluble in tartaric acid (distinc- tion from antimonious oxy-chloride). 5. KoCr04 yields a yellow precipitate of bismuth oxy-chromate — Bi202Cr04 — soluble in dilute nitric acid, but not in potassium hydrate (distinction from plumbic chromate). 6. KI gives a brown bismuthous iodide, soluble in excess. 7. Alkaline Carbonates give white precipitates of bismuth oxy-carbonate, insoluble in excess. 8. Fragments of zinc added to a solution of bismuth cause a deposit of the metal as a dark grey powder. {h) DRY REACTION. (To be practised upon hisnmthi sub}iit?'as, B.P.) Mixed with sodium carbonate and heated on charcoal before the blowpipe, a hard bead of metallic bismuth is produced, and the surrounding charcoal is incrusted with a coating of oxide, deep orange-yellow while hot and becoming paler yellow on cooling. {c) SEFARATION As already stated, bismuth is precipitated as sulphide by the action of sulphuretted hydrogen in the presence of hydrochloric acid. The precipitate having been washed and digested with ammonium sulphide is then heated in a small basin with strong nitric acid, and the whole having been washed into a test-tube with a little water, a few drops of sulphuric acid are added, and lastly, after cooling, some rectified spirit. This^ as shown previously, separates the mercury and lead, leaving only Bi, Cu, and Cd in solution. The solution is then mixed with excess of ammonium hydrate, which precipitates the bismuth as white Bi3HO, and leaves the copper and cadmium in solution. By filtering out, dissolving in a little hydrochloric acid, and pouring into water, the production of a white precipitate entirely confirms the presence* of bismuth. III. COPPEE (Cu). {a) JVET REACTIONS. (To be practised with a solution of cupric sulphate — C11SO4.) T. H2S after acidulation with HCl {2nd group reagent) forms a precipitate of brownish-black cupric sulphide — CuS — which is nearly insoluble in ammonium sulphide but soluble in nitric acid. Its precipitation is prevented by the presence of potassium cyanide (distinction from cadmium). When long exposed to the air in a moist state, it oxidises to cupric sulphate and dissolves spontaneously. 2. HH4HO causes a pale blue precipitate instantly soluble in excess, forming a deep bluesolution of tetrammonio-cupric sulphate— (NH3)4CuS04HoO. 32 DETECTION AND SEPARATION OF THE METALS. 3. K^FeCy-g yields a chocolate-brown precipitate of cupric ferrocyanide — Cii2FeCyg. This test is very delicate and is not affected by the presence of a dilute acid, but does not take place in an alkaline liquid. 4. KHO or NaHO precipitate light-blue cupric hydrate — CU2HO — insoluble in excess, but turning to black cupric oxy-hydrate — (CuO)2Cu2HO — on boiling. 5. KNaCj^H^Og and NaHO added successively, the latter in excess, produce a deep-blue liquid (Fehling’s solution), which when boiled with a solution of glucose (grape sugar) deposits brick-red cuprous oxide — CU2 O. 6. The Alkaline Carbonates behave like their respective hydrates. 7. Fragments of zinc or iron precipitate metallic copper from solutions acidu- lated with HCl. (I?) DRY REACTIONS. (To be practised upon cupric oxide — CuO — 01 verdigris — CU2O2C2H3O2.) 1. Heated with Na2COg and KCy on charcoal, in the inner blowpipe flame, red scales of copper are formed. 2 Heated in the borax bead before the outer blowpipe flame, colours it green while hot, and blue on cooling. By carefully moistening the bead with SnCl2 and again heating, this time in the inner flame, a red colour is produced. {c) SEPARATION. The addition of sulphuretted hydrogen in the presence of hydrochloric acid determines the precipitation of copper, together with the other sulphides of the 2nd group. Successive treatment with ammonium sulphide, nitric acid, sulphuric acid, and rectified spirit, as already shown (see a 7 tie), eliminates all but Bi, Cu, and Cd. The addition of excess of ammonium hydrate then separates bismuth and produces a deep-blue solution if copper be present. IV. CADMIUM (Cd). (a) WET REACTIONS. (To be practised with a solution of cadmium iodide — Cdl2.) T. HoS after acidiilatmi with HCl {2nd grottp reagent) gives a yellow precipitate of cadmium sulphide — CdS — insoluble in ammonium sulphide, but soluble in boiling nitric acid. This precipitate does not form readily in presence of much acid ; but its production is not hindered by the addition of potassium cyanide (distinction from copper). 2. NH4HO produces a white precipitate of cadmium hydrate — Cd2HO — . soluble in excess. 3. KHO or NaHO both give precipitates of cadmium hydrate — Cd2HO — insoluble in excess (distinction from zinc). 4. Alkaline Carbonates precipitate cadmium carbonate — CdCOg — insoluble in pvppcc {h) DR Y REA CTION. (To be practised on cadmium carbonate — CdCOg.) Heated on charcoal before the blowpipe, a brownish incrustation of oxide is produced, owing to the reduction to the metal and its subsequent volatiliza- tion and oxidation by the outer flame. {c) SEPARATION. Cadmium is precipitated, along with the other sulphides of the 2nd group, by the action of sulphuretted hydrogen in the presence of a slight trace of CA DMIUM--A RSENIC. 33 hydrochloric acid. The precipitate having been subjected to the successive actions of ammonium sulphide, nitric acid, dilute sulphuric acid, and rectified spirit, and lastly of ammonium hydrate, all as already described (see ante), the resulting solution can only contain Cu and Cd. If the solution is colourless, no copper is present, and the addition of ammonium sulphide will produce the cadmium as a yellow sulphide ; but if the solution be blue (indicating copper), then potassium cyanide is to be added till the colour is discharged and sulphuretted hydrogen passed, which will then precipitate the yellow cadmium sulphide, leaving the copper in solution. GEOUP II. Division B. Metals which are precipitated by sulphuretted hydrogen in the presence of hydrochloric acid, but yield sulphides which are soluble in ammonium sulphide. I. ARSENIC (As). {a) WET REACTIONS. (To be practised with a solution of arsenious anhydride in boiling water slightly acidulated by hydrochloric acid.) 1. HoS, after addulation 7 uith HCl, causes a yellow precipitate of arsenious sulphide — AS0S3 — soluble in ammonium sulphide, forming ammonium sulpharsenite— (NH4)3 AsS 3 — but insoluble in strong boiling hydro- chloric acid (distinction from the sulphides of Sb and Sn). This pre- cipitate is also soluble in cold solution of official carbonate of ammonia (distinction from the sulphides of Sb, Sn, An, and Pt). Dried and heated in a small tube with a mixture of NaoC03 and KCy, it yields a mirror of arsenic. 2. Boiled with KHO and a fragment of Zinc, arseniuretted hydrogen — ASH3 — is evolved, which stains black a paper moistened with solution of argentic nitrate and held over the mouth of the tube during the ebulli- tion {FleitmanE s test). 3. Boiled with -f of its bulk of HCl and a slip of Copper, a grey coating is deposited on the copper of cupric arsenide. On drying the copper carefully, cutting it into fragments, and heating in a wide tube, a crys- talline sublimate of arsenious anhydride — AS0O3 — is obtained, which, when dissolved in water, gives a yellow precipitate of argentic arsenite . — Ag3As03 — with solution of ammonio-nitrate of silver {ReincEs test). 4. Placed in a gas bottle furnished with a jet, together with dilute sulphuric or hydrochloric acid and a few fragments of zinc, arseniuretted hydrogen — ASH3 — is evolved, which may be lighted at the jet and burns with a lambent flame, producing As^O^. If a piece of cold porcelain be held in the flame, dark spots of arsenic are obtained, readily volatile by heat and soluble in solution of chlorinated lim’e {Marsh's Test). Note. — For reactions of arsenites and arseniates, see Acidulous Radicals. (f) DRY REACTION. (To be practised on arsenious anhydride — As^Og.) Heated in a small tube with NaoC03 and KCy, a mirror of arsenic is pro- duced, accompanied by a garlic-like odour. The same effect may be produced with black flux. VOL. II. D 34 DETECTION AND SEPARATION OF THE METALS. (c) SEPARATION. By passing sulphuretted hydrogen in the presence of hydrochloric acid, arsenious sulphide is precipitated, together with the other sulphides of the second group. The precipitate is washed and digested with water containing ammonium sulphide, which dissolves the sulphides of As, Sb, Sn, Au, and Pt. The solution is filtered, and a slight excess of HCl having been added, these sulphides are reprecipitated. The precipitate is filtered out and shaken up with a cold solution of official carbonate of ammonia, which dissolves only the arsenious sulphide, leaving the sulphides of Sb, Sn, Au, and Pt insoluble. From this solution, after filtration, the arsenious sulphide may be reprecipitated by hydrochloric acid, dried, and confirmed by heating with Na2C03 and KCy, and getting a mirror of arsenic on the tube. II. ANTIMONY (Sb). {a) WET REACTIONS. (To be practised with a' solution of antimonium tartaratum, B.P.) 1. IL^S, after acidiRation l?y HCl CSMSQS an orange precipitate of antimonious sulphide — Sb2S3 — soluble in ammonium sulphide, forming ammonium sulphantimonite — (NH4)3SbS3 — also soluble in strong boiling hydro- chloric acid, forming antimonious chloride — SbCl3 — but insoluble in cold solution of official carbonate of ammonia. 2. KHO and NaHO produce precipitates of antimonious oxide readily soluble iu excess to form antimonites (K3Sb03 or Na3SbOg). 3. Acidulated with HCl and introduced into a platinum dish with a rod of zinc so held that it touches the platinum outside the liquid, a black stain of metallic antimony is produced closely adherent to the platinum. This stain is not dissolved by HCl (tin reduced in the same manner is granular and soluble in boiling FICl). 4. Reinch’s test (see arsenic) produces a black coating on the copper, which, when heated, forms an amorphous sublimate of SbgOs close to the copper^ and insoluble in water, but dissolved by a solution of cream of tartar in which HgS then produces the characteristic orange sulphide. 5. Marsh’s test (see arsenic) yields stains of antimony on the porcelain not nearly so readily volatile by heat as in the case of arsenic, and not dis- charged by solution of chlorinated lime. 6. Fleitmann’s test will not act with antimony at all (distinction from arsenic). ib) DRY REACTION. (To be practised on antimonious oxide — SbgOg). Heated on charcoal with NagCOg and KCy before the blowpipe, a bead of metallic antimony is formed and copious white fumes of the oxide are produced. (e) SEPARATION Antimony is obtained as sulphide, associated only with As, Sn, Au, and Pt, by precipitating with sulphuretted hydrogen in the presence of hydrochloric acid, and digesting the precipitate in water containing ammonium sulphide. The solution thus obtained yields the sulphides on acidulation with hydro- chloric acid, and by shaking them up with solution of official carbonate of ammonia, the arsenic is dissolved (see a 7 ite). The precipitate, which can only now contain the sulphides of Sb, Sn, Au, and Pt, is boiled with strong hydro- chloric acid, which dissolves the Sb and Sn and leaves the Au and Pt insolu- ble. The solution is then slightly diluted and introduced into a platinum ANTIMONY— TIN— GOLD. 35 dish, and a rod of zinc hdd in the fluid so that it touches the platinum out- side the liquid, when both the metals are deposited, — the Sb as a black stain closely adhering to the platinum, and the Sn in the form of granules. Boiling with strong hydrochloric acid will then dissolve the tin, and leave the antimony. III. TIN (Sn“ or Sn‘''). (a) WET REACTIONS.- (To be practised with a solution of stannous chloride — SnCla — and one of stannic chloride — SnCl4 — prepared by warming the stannous solution with a little nitric acid.) 1. HoS, after acidulation with HCl, produces a brown or yellow precipitate of SnS or SnS2 respectively, both soluble in ammonium sulphide and in boiling hydrochloric acid. 2. KHO or NaHO both produce white precipitates of S112HO or S114HO soluble in excess, the former to produce stannites and the latter staii- nates. The stannous solution is, however, reprecipitable on boiling, while the stannic is not. 3. NH4HO produces similar precipitates, very difflcultly soluble in excess. 4. Acidulated, by HCl, and introduced into a platinum dish with a rod of zinc so held in the fluid that it touches the platinum outside the liquid, granules of metallic tin are deposited, soluble in boiling HCl, to form stannous chloride. 5- HgCls boiled with stannous salts, deposits a grey precipitate of metallic mercury. {b) DR Y REA CTION (To be practised on putty powder — SnOo.) Heated on charcoal with NaoCOg before the blowpipe, a bead of metallic tin is produced, and a white incrustation of oxide is formed on the charcoal. {c) SEPARATION. The separation of tin has already been described in connection with that of antimony ; and it is only necessary, after dissolving the granules in strong hydrochloric acid, to prove the presence of Sn by boiling with mercuric chloride. IV. GOLD (An). {a) WET REACTIONS. (To be practised with a solution of auric chloride — AuClg.) 1. HoS {group reagent) in the presence of HCl gives black auric sulphide — A110S3. If the solution be hot, aurous sulphide — AuoS — falls. Both are only soluble in nitro-hydrochloric acid, but they are soluble in ammonium sulphide when it is yellow. 2. NH4HO precipitates reddish ammonium aurate, or fulminating gold — Au2(NHg)20o — but KHO gives no result. 3. HoCoO^ (or FeSO^) when boiled with an acid solution throws down Au. Reducing agents generally act thus. The liquid containing the metal may exhibit a blue, green, purple, or brown colour. 4. SnCl2 throws down a brownish or purplish precipitate, known as purple of Cassius,” consisting of the mixed oxides of gold and tin. 5. Zn, Cu, Fe, Pt, or almost any metal, give a precipitate of metallic Au in a finely divided state. 36 DETECTION AND SEPARATION OF THE METALS. {b) DEV REACTION. (To be practised on any gold salt.) Heated on charcoal with NaoCOo, the metal is produced. (c) SEFARATION Gold is separated from other metals with great readiness, by taking advan- tage of the instability of its salts. To an acid solution oxalic acid or ferrous sulphate is added in excess, the mixture warmed and allowed to stand twenty- four hours, when all the gold present is found in the metallic state and may be filtered out. V. PLATINUM (Pt). {a) WET REACTIONS. (To be tested with a solution of platinic chloride — PtCl4.) 1. HoS {2nd group reagent) in presence of HCl, gives a hroivn precipitate of platinic sulphide — PtSo. This precipitate forms slowly, and is readily dissolved by yellow ammonium sulphide. 2. KCl in presenee of HCl, especially after addition of alcohol, produces a yellow crystalline precipitate of potassium platinic chloride — PtK3Clg — soluble to a moderate extent in water, but not in alcohol. Decomposition takes place when this is strongly heated, metallic Pt and KCl remaining. 3. NH^Cl gives a precipitate of ammonium platinic chloride — Pt(NH4)oCIg which is almost identical in properties, but is more readily decom- posed by heat, pure platinum remaining. 4. Zn, Fe, and several other metals decompose platinic salts with the pro- duction of the metal. {h) DRV REACTION (To be practised upon potassium platinic chloride — PtKoClg.) Heat on charcoal, with or without Na3C03, before the blow-pipe. The metal is produced by reduction. (e) SEFARATION Platinum is readily separated by taking, advantage of the fact that its compounds with potassium or ammonium and chlorine are insoluble in alco- hol. To a clear solution containing the Pt as chloride, add NH^Cl, evapo- rate over a water bath till the mixture be dry, add a little water and evaporate again, then pour over some methylated spirit and a drop or two of HCl. On filtering, all other metals are dissolved out as chlorides, leaving the Pt salt alone on the filter. GROUP III. Metals which escape precipitation by sulphuretted hydrogen in presence of hydrochloric acid, but which are precipitated by ammonium sulphide in the presence of ammonium hydrate, ammonium chloride having been previously added to prevent the precipitation of magnesium. Division A. hletals which, in the ensured absence of organic matter., are precipitated as hydrates by the addition of the ammonium chloride and ammonium hydrate only. FLA TINUM—IRON. 37 I. IRON {Ferrous, Fe ; and ferric, Fe2). {a) WET REACTIONS. (To be practised successively on solutions of ferrous sulphate — FeSO^ — and ferric chloride — FeoClg.) 1. NH^HO in the presence of NH^Cl {group reagent) yields either a dirty- green precipitate of ferrous hydrate — Fe2HO — or a reddish-brown precipitate of ferric hydrate — Feo6HO. The former is slightly soluble in excess, but the latter is insoluble, and it is therefore preferable always to warm the solution with a little nitric acid, to ensure the raising of the iron to the ferric state, before adding the ammonium hydrate. The presence of organic acids, such as tartaric or citric, prevents the occurrence of this reaction ; and therefore, if any such ' admixture be suspected, the solution should first be evaporated to dry- ness, the residue heated to redness, and then dissolved in a little hydrochloric acid, heated with a drop or two of nitric acid, diluted, and lastly, the NH^Cl and NH^HO added and boiled. 2. NH^HS, added to a neutral 'or alkaline solution, produces a precipitate of ferrous sulphide — FeS — which is black (distinction from Al, Ce, Cr, Mn, and Zn), and readily soluble in cold diluted hydrochloric acid (distinction from the black sulphides of Ni and Co). This re- action takes place even in the presence of organic matter, and the precipitated sulphide, if exposed to the air, gradually oxidizes to ferrous sulphate — FeSO^ — and disappears. It is insoluble in acetic acid (dis- tinction from MnS). 3. Kj^FeCyg, in a neutral or slightly acid solution, gives, with ferrous salts, a white precipitate (rapidly changing to pale blue) of Everett’s salt — potassium ferrous ferrocyanide — KoFeFeCy^ — and with ferric salts, a dark blue precipitate of Prussian blue — ferric ferrocyanide (Feo)o3FeCyg. These precipitates are decomposed by alkalies, producing the hydrates of iron, and forming a ferrocyanide of the alkali in solution ; but the addition of hydrochloric acid causes the re-formation of the original precipitate. 4. KgFe2Cyi2 gives, with ferrous salts, in neutral or slightly acid solutions, a dark blue precipitate of Turnbull’s blue — ferrous ferricyanide, Fe3Fe2Cyi3 — but with ferric salts it gives no precipitate, simply producing a brownish liquid. With alkalies, Turnbull’s blue is decomposed, yield- ing black ferroso-ferric hydrate, and a ferricyanide of the alkali ; but the addition of hydrochloric acid reproduces the original blue. 5. KCyS gives no precipitate with ferrous salts, but with ferric compounds it yields a deep blood-red solution. This colour is not discharged by dilute hydrochloric acid (distinction from ferric acetate), but imme- diately bleached by solution of mercuric chloride (distinction from ferric meconate). 6. KHO, or NaHO, produces effects similar to those of ammonium hydrate. 7. Na2HP04 in the presence of NaCoH302 or NHj^C2H302 gives a whitish gelatinous precipitate of ferrous or ferric phosphates — Fe32PO^ or Fe22PO^ — insoluble in acetic acid, but soluble in hydrochloric acid. The previous addition of dtric or tartaric acids prevents this reaction. 8. NaC2H302, added in excess to ferric salts, produces a deep red solution of ferric acetate — Fe26C2H302 — which on boiling deposits- as’ a reddish brown ferric oxyacetate — Fe204C2H302. This precipitate dissolves slightly on cooling ; but iron can be entirely precipitated in this form if the solution be instantly filtered while hot. 38 DETECTION AND SEPARATION OF THE METALS. 9. Alkaline Carbonates, added to a ferrous salt, precipitate white ferrous carbonate — FeCOg — but with ferric salts throw down the reddish-brown ferric hydrate already described. ip) DRV REACTIONS. (To be practised on ferri peroxidim hydratum, B.R) 1. Heated on charcoal before the inner blowpipe flame, a black magnetic pow- der is obtained, which is not the metal, but is ferroso-ferric oxide — FegOj. 2. Heated in the borax bead in the inner blowpipe flame, a bottle-green colour is produced ; but in the outer flame the bead is deep red while hot, and very pale yellow when cold. (0 SEPARATION The solution, after treatment with sulphuretted hydrogen, in the presence of hydrochloric acid, so as to cause the .entire separation of the metals of the first and second groups, is evaporated to dryness, and heated to ensure the de- composition of any organic matter. The residue is drenched with strong hydro- chloric acid, and then water added, and the whole boiled, adding a few drops of HNOg to raise all the iron to the ferric state. On adding NH^Cl to this solution, and then NH4HO in slight but distinct excess, boiling and filtering rapidly, the iron is precipitated as ferric hydrate, and with it may also be found the hydrates of Ce, Cr, and Al. The precipitate is fused with excess of KNaCOg and KNOg, and the residue boiled with water, when everything dissolves but Fe and Ce, which remain as red oxides. This residue may then be dissolved in HCl, and the iron tested for by K^FeCy^ in a portion of the solution. [For separation of iron in the presence of phosphoric acid, see Separation of Phosphates, Chap. III.] II. CEEIUM (Ce). {a) WET REACTIONS. (To be practised on Cerous Chloride — CeCl2 — prepared by boiling eerii oxalas, B.P., with sodium hydrate, washing the insoluble cerous hydrate with boiling water, and dissolving it in the least possible excess of hydro- chloric acid.) 1. in the presence of NH^Cl [group reagent) gives a white precipitate of cerous hydrate — Ce2HO — insoluble in excess. 2. KHO and NaHO give a similar precipitate, turning to yellow ceroso-ceric oxide — CegO^ — on the addition of chlorine water. 3. (NHJoCoO^ gives a white precipitate of cerous oxalate — CeCo04 — in- solubledn excess, and not readily dissolved even by hydrochloric acid. The presence of citric or tartaric acid does not interfere with this reaction. 4. K0SO4 in a saturated solution causes the formation of white crystalline potassium cerium sulphate — K3Ce (804)3 — soluble in hot water. [h) DRY REACTIONS. (To be practised on ceiii oxalas, B.P.) 1. Heated to redness in contact with the air, a deep red residue of ceric oxide — Ce^O ^ — is obtained, difficultly soluble even in strong hydro- chloric acid. 2. Heated in the borax bead, cerium behaves like iron in the outer flame, but the inner flame yields a colourless or opaque yellow bead. CERIUM— ALUMINIUM— CHROMIUM. 39 ic) SEPARATION. Proceed exactly as for iron, and to the remainder of the solution, after testing the portion for that metal, add citric acid, and then excess of ammo- nium hydrate. The presence of the organic acid prevents the precipitation of the iron by the ammonium hydrate, and then the addition of ammonium oxalate proves the cerium. This separation is equally good in the presence of phosphoric acid. III. ALUMINIUM (Al). ia) WET REACTIONS. (To be practised on a solution of aliiin^ B.P. — NH^Al (S04)oi2H20.) T. NH^HO in presence of NH^Cl [group reagent) gives a gelatinous white pre- cipitate of aluminic hydrate — AI36HO. This precipitate is slightly soluble in a large excess of the precipitant, but separates completely on boiling. 2. KHO and NaHO both give a similar precipitate, soluble in excess, but reprecipitated by boiling with an excess of ammonium chloride, or by neutralizing with hydrochloric acid, and boiling with a slight excess of ammonium hydrate. 3. NaoHPO^ in the presence of NaC2H303 or NH4C2H3O2 gives a white precipitate of aluminic phosphate — AIPO3 — insoluble in hot acetic .acid, but soluble in hydrochloric acid. The presence of citric or tar- taric acids prevents the occurrence of this reaction. if) DR Y REA CTION. (To be practised on dried alum^ B.P.) Heat strongly on charcoal before the blowpipe, when a strong incan- descence is observed, and a white residue is left. Moisten this residue with a drop of solution of cobaltous nitrate — C02NO3 — and again heat strongly, when a blue mass is left. This test is not decisively characteristic, as other substances, such as zinc and earthy phosphates, show somewhat similar, colours. [c) SEPARATION. Aluminium is precipitated by ammonium hydrate in the presence of am- monium chloride, together with Fe, Ce, and Cr, as already described in the separation of iron. The precipitate is fused with KNaC03 KNO3, and the residue digested with water and filtered. This yields a solution containing the aluminium hydrate dissolved in excess of the alkali, and the chromium as a soluble chromate. By acidulating with acetic acid, and adding disodium hydrogen phosphate and boiling, the Al is precipitated as phosphate, and the chromate is not affected. IV. CHROMIUM (Cr). [a) WET REACTIONS. (To be practised on a solution of potassium chromic chloride prepared by dissolving potassium dichromate — ICCrgO^ — in water, acidulating with hydrochloric acid, heating and dropping in rectified spirit till the solution turns green.) I. NH4HO in the presence of NH4CI {group reagent) precipitates green chromic hydrate — CrgfiHO — slightly soluble in excess, but entirely reprecipi- 40 DETECTION AND SEPARATION OF THE METALS. tated on boiling. The presence of citric or tartaric acid interferes with the completeness of this reaction. 2. KHO, or NaHO, gives similar precipitates ; freely soluble in excess when cold, but entirely reprecipitable by continued boiling. 3. NaOCl, or PbOo, boiled with an alkaline solution of a chromium salt, pro- duces a yellow solution of sodium chromate — Na2Cr04. 4. NaoHPO^, in the presence of NaCoH302 or NH4C2H3O2 throws down pale green chromic phosphate — CrPO^ — soluble when freshly precipitated in excess of hot acetic acid, and freely soluble in hydrochloric acid. The presence oforganic acids prevents this reaction. f)) DRV REACTIONS. 1 . Heated in the borax bead in the inner blowpipe flame, a fine green colour is obtained. 2. Fused on platinum foil, with a mixture of KNaCOg and KNO3, a yellow residue is obtained, consisting of chromates of the alkaliesused. This mass is soluble in water, yielding a yellow solution turned deeper in colour by the addition of hydrochloric acid, owing to the formation of dichromates, and becoming green on warming and dropping in rec- tified spirit. (c) SEPARATION. Chromium is precipitated as hydrate by NH^Cl and NH4HO, after sepa- rating the metals of the first two groups. [See Separation of Fe.] The precipitate is fused with KNaC03 KiN03, which forms potassium chromate, known by the bright yellow colour of the residue. On boiling with water, acidulating with acetic acid, and adding disodium hydrogen phosphate, and again boiling, any aluminium is precipitated as phosphate, and the chromate remains as a yellow solution turned green by boiling with HCl and rectified spirit. This course is only good in the ensured absence of phosphoric acid (for details in presence of which see Sepai'ation of Phosphates, Chap. III.). GROUP III. Division B. Metals the hydrates of which, being soluble in excess of ammonium hydrate in the presence of ammonium chloride, escape precipitation by that reagent, but are separated as insoluble sulphides by the addition of ammonium sulphide to the same liquid. I. MANGANESE (Mn). {a) WET REACTIONS. (To be practised on a solution of potassium manganous chloride, prepared by heating a solution of potassium permanganate with hydrochloric acid, and dropping in rectified spirit until a colourless solution is obtained.) I. NH4HS in the presence of NH4CI NH^HO {group reagent) precipitates a flesh-coloured manganous sulphide — MnS — soluble in dilute and cold hydrochloric acid (distinction from the sulphides of Ni and Co). It is also soluble in acetic acid (distinction from zinc sulphide). This precipitate forms sometimes very slowly and only after gently warming. If a good excess of NH4CI has not been added, or if, after adding the excess of ammonium hydrate, the solution be exposed to the air, a portion of the manganese will sometimes precipitate sponta- MANGANESE— ZINC. 41 neously, as manganic dioxyhydrate — MnoOo2HO — and be found with the iron, etc., in the first division of the third group. In this case its presence will be easily made manifest during the fusion for chromium by the residue being green. It is therefore evident that small quan- tities of manganese cannot be perfectly separated from large quantities of iron by NH^Cl and NH^HO only. 2. KHO and NaHO both yield precipitates of manganous hydrate insoluble in excess, and converted by boiling into dark brown manganic dioxy- hydrate — Mn2022H0. 3. NH^HO gives a similar precipitate, soluble in excess of ammonium chloride, but gradually depositing as Mn2022 H0 by exposure to the air. For this reason, if the presence of manganese be suspected, the addition of NH^Cl and NH^HO must be followed by instant filtration, and any cloudiness coming in the filtrate must be simply taken as indicating manganese, and disregarded. 4. K,FeCy« gives a precipitate of manganous ferrocyanide — MiioFeCyg — very liable to be mistaken for the corresponding zinc compound. (/;) DR Y REA CTIONS. (To be practised on manganese peroxide — Mn O2.) 1. Fused on platinum foil with KNaCOg and KNO3, a green mass of manganates of the alkalies is formed. This residue is soluble in water, yielding a green solution, turning purple on boiling, owing to the for- mation of permanganates. The solution is rendered colourless by heating with hydrochloric acid and dropping in rectified spirit, the operation being accompanied by the odour of aldehyd. 2. Heated in the borax bead in the outer blowpipe flame, a colour is pro- duced which is violet-red while hot, and amethyst on cooling. The bead is rendered colourless by the reducing flame. {c) SEPARATION. Manganese, when precipitated as sulphide by ammonium sulphide in the presence of ammonium hydrate, is easily separated by dissolving in dilute hydrochloric acid, which does not affect ‘the sulphides of Ni and Co. The solution is then boiled with excess of sodium hydrate, which precipitates the manganese and leaves the zinc. The precipitate is then confirmed by fusion with KNaCOs KNO3, when it gives the characteristic green mass. Another way is to add to the hydrochloric acid solution an excess of sodium acetate^ and then pass sulphuretted hydrogen, which will precipitate the other metals, leaving the manganese in solution because its sulphide alone of all the group is soluble in acetic acid. II. ZINC (Zn). {a) WET REACTIONS. (To be practised on solution of zinc sulphate — ZnSO^.) 1. NH^HS m the pi^esence of NH^Cl and NH^HO {group reagent) gives a white precipitate of zinc sulphide — ZnS — insoluble in acetic acid, but readily soluble in dilute hydrochloric acid. 2. KHO, NaHO, and NH^HO all give precipitates of gelatinous white zinc hydrate, soluble in excess to form zincates. The addition of sulphu- retted hydrogen or ammonium sulphide reprecipitates the zinc as zinc sulphide — ZnS. 42 DETECTION AND SEPARATION OF THE METALS. 3. K^FeCyp, gives a gelatinous white precipitate of zinc ferrocyanide — ZnoFeCy^j — insoluble in dilute acids. 4. Alkaline Carbonates precipitate official zinci carbo 7 ias — zinc hydrato-carbon- . ate — ZnC03(Zn2HO)2HoO — insoluble in excess of the carbonates of potassium and sodium, but soluble in that of ammonium. The latter solution, diluted and boiled, deposits the oxide. {b) DR Y REA CTIONS. (To be practised on zinci carbonas, B.P.) 1. Salts of zinc heated leave the oxide, yellow while hot, and white on cooling. 2. Heated on charcoal before the blowpipe an incrustation forms, yellow while hot, and white on cooling. Moisten with a drop of cobaltous nitrate — C02NO3 — and again heat in the outer flame, when a fine green colour is produced. {c) SEPARATION. The addition of ammonium sulphide in the presence of ammonium chloride and ammonium hydrate precipitates zinc sulphide together with the other metals of the group. This precipitate is treated with cold dilute hydrochloric acid, which dissolves the Zn and Mn, and leaves Ni and Co insoluble. The solution boiled with excess of sodium hydrate deposits the Mn ; and the filtrate treated with excess of acetic acid and sulphuretted hydrogen deposits the Zn as sulphide. III. NICKEL (Ni). {a) TVER REACTIONS. (To be practised on a solution of nickelous sulphate — Ni SO4.) T. NH4HS i 7 i the presence of NH^Cl and NH.^HO {group reageiit) gives a black precipitate of nickelous sulphide — NiS — slightly soluble in excess but entirely precipitated on boiling. It is not soluble in cold dilute hydro- chloric or in acetic acid, but requires boiling with strong hydrochloric acid and sometimes even the addition of a drop or two of nitric acid. 2. KHO or NaHO both give a green precipitate of nickelous hydrate — NizHO — unaltered by boiling (distinction from cobalt). 3. KNO3 added to a neutral solution, followed by an excess of acetic acid, gives no precipitate (after standing some hours) on the addition of potassium acetate and rectified spirit (very useful separation from cobalt). 4. KCy in excess produces a greenish-yellow precipitate of nickelous cyanide — NiCyg — which quickly redissolves. On adding a drop of hydro- chloric acid and boiling in a fume chamber, and repeating this till no more fumes of hydrocyanic acid come off, and then adding sodium hydrate, a precipitate of nickel hydrate is produced. It is better, although less convenient, to use a strong solution of chlorinated soda . — NaClNaClO — in the last stage, when nickelic hydrate — Ni6HO — is slowly precipitated (distinction from Co, which gives no precipitate). 5. Alkaline Carbonates behave, so far as colour and solubility in excess is concerned, like their respective hydrates. {b) DRY REACTIONS. 1. Heated on charcoal with NaoC03 in the inner blowpipe flame, a grey metallic and magnetic powder is produced. 2. Heated in the borax bead in the outer blowpipe flame, red to violet brown NICKEL— COBALT— BARIUM. 43 is produced while hot, and a yellowish to sherry red when cold. These colours might be mistaken for those of iron ; but on fusing a small fragment of potassium nitrate with the bead, its colour at once changes to blue or dark purple (distinction from Fe). IV. COBALT (Co). • (a) WET REACTIONS. (To be practised on a solution of cobaltous nitrate — C02NO3.) 1. NH^HS m the presence of NH^Cl and {groiip reagent) gives a black precipitate of cobaltous sulphide — CoS — insoluble in acetic and cold dilute hydrochloric acid, and requiring to be boiled with the strongest HCl, often with the addition of a drop or two of nitric acid before solution is effected. 2. KHO, or NaHO, gives a blue precipitate of cobaltous hydrate — Co 2 HO — rapidly changing to pink on boiling (distinction from nickel). 3. KCy gives a light brown precipitate of cobaltous cyanide, rapidly soluble • in excess but reprecipitated by excess of dilute hydrochloric acid. If, however, the HCl be added drop by drop just so long as it causes the evolution of hydrocyanic acid fumes on boiling,* soluble potassium cobalticyanide — Kfi^^sCyis — results, which is not decomposed by hydrochloric acid ; nor is any precipitate produced on adding excess of sodium hydrate or chlorinated soda (distinction from nickel). 4. Alkaline Carbonates throw down basic carbonates, behaving like the respective hydrates. {L) DR Y REA CTIONS. 1. Heated on charcoal with Na2C03 in the inner blowpipe flame, the cobalt separates as a grey magnetic powder. 2. Heated in the borax bead, first in the outer and then in the inner flame, a fine blue colour is produced. It is an important distinction of cobalt from copper, manganese, etc., that prolonged heating in the inner dame does not affect this blue. if) SEPARATION. The sulphides of nickel and cobalt are easily separated from all the other of this group by their insolubility in cold dilute hydrochloric acid. They may then be dissolved in strong acid, the solution diluted a little and nearly neu- tralized by KHO, and then the cyanide separation above described applied. It is to be noted however, that no truly satisfactory separation of Ni from Co exists. GROUP IV, Metals, the hydrates and sulphides of which, being soluble, are not precipi- tated by the addition of NH^HO and NH^HS in the presence of NH^Cl, but separate as insoluble carbonates on the addition of ammonium carbonate to the same solution. I. BARIUM (Ba). {a) WET REACTIONS. (To be practised on a solution of barium chloride — BaCb.) I. (NH 4 )oC 03 in the presence of NH^Cl and NH^^HO {^group reagenf) pro- * This must be done in a fume chamber, as it is a highly poisonous operation if the fumes should happen to escape into the room. 44 DETECTION AND SEPARATION OF THE METALS. duces a white precipitate of barium carbonate, BaCOg, soluble with effervescence in dilute acetic acid. 2. H0SO4 and all soluble Sulphates give a white precipitate of barium sul- "phate — BaSO^ — insoluble in ammonium acetate or tartrate (distinction from PbS04) and also in boiling nitric acid. 3. KoCrO^ gives a yellow precipitate of barium chromate — BaCrO^ — in- soluble in water and in dilute acetic acid, but soluble in hydrochloric acid (distinction from Sr and Ca). 4. NH4C2O4 gives a white precipitate of barium oxalate — BaC204 — not readily formed in the presence of much acetic acid. 5. Na2HP04 gives a white precipitate of barium hydrogen phosphate — BaHP04 — soluble in acetic acid, and to some extent in ammonium chloride. (^) DRV REACTION-. (To be also practised on barium chloride.) A platinum wire dipped first in hydrochloric acid and then in the salt, and held in the inner blowpipe or Bunsen flame, the outer flame is coloured yellowish-green. {c) SEPARATION. After removal of the metals of Groups i, 2, and 3, the addition of ammo- nium carbonate determines the precipitation of Ba, Sr, and Ca as carbonates. This precipitate is dissolved in acetic acid, and on the addition of potassium chromate the barium precipitates, leaving the other two metals in solution. II. STRONTIUM (Sr). . {a) WET REACTIONS. (To be practised on strontium nitrate — Sr2N03.) 1. (NH4)2C03 {group reagent) in the presence of NH4CI and NH4HO gives a white precipitate of strontium carbonate — SrCOg — soluble in dilute acetic acid. 2. H2SO4, or a soluble sulphate (preferably calcium sulphate), yields a white precipitate of strontium sulphate — SrS04 — which only separates com- pletely from dilute solutions on allowing them to stand in a warm place for some hours. It is insoluble in a boiling strong solution of ammonium sulphate rendered alkaline by ammonium hydrate (distinc- tion from calcium sulphate). 3 . The other reactions are similar to those of calcium. {b) DRV REACTION. (To be also practised on Si*2N03.) A platinum wire moistened with hydrochloric acid, dipped in the substance and introduced into the inner blowpipe or Bunsen flame, colours the outer flame crimson. {c) SEPARATION. Strontium is precipitated in the 4th Group by ammonium carbonate, along with Ba and Ca, as already described. The precipitate having been dissolved in acetic acid, and the barium separated by potassium chromate, a small portion of the solution is tested by saturated solution of calcium sulphate : — if a precipitate be produced, the presence of strontium is evident. In this case some very dilute sulphuric acid is added, and the whole set aside in a warm place for some hours, when strontium sulphate separates. If the sulphuric STRONTIUM— CALCIUM— M A GNESIUM. 45 acid be added too strong, some CaS04 may also separate, and the precipitate should be digested for some time at a gentle heat, with a strong solution of ammonium sulphate containing a little ammonium hydrate, which dissolves CaSO^ but leaves SrSO,^ insoluble. III. CALCIUM (Ca). {a) WET REACTIONS. (To be practised on a solution of calcium chloride — CaClo.) 1. (NHJ2CO3 in presence of NH^Cl aiid NH^HO {group reagenf) pro- duces a white precipitate of calcium carbonate — CaCOg — soluble in acetic acid and settling best on warming. 2. (NHJgCoO^ precipitates white calcium oxalate — CaCoO^ — insoluble in acetic or oxalic acids, but soluble in hydrochloric acid. 3. H0SO4 in strong solutions produces a precipitate of calcium sulphate, CaSOj^. Being slightly soluble in water, it does not form in dilute solutions, nor is it precipitated by a saturated solution of calcium sulphate (distinction from Ba and Sr). It is soluble in a boiling saturated solution of ammonium sulphate containing excess of ammo- nium hydrate, but quite insoluble in a mixture of two parts alcohol and one part water. 4. Na^HPO^ produces a white precipitate of calcium phosphate soluble in acetic acid. {b) TRY REACTION. (To be practised on calcium carbonate — CaCOg.) A platinum wire moistened with hydrochloric acid, dipped in the substance and held in the inner blowpipe or Bunsen flame, colours the outer flame yellowish-red. This reaction is masked by the presence of Barium or Stron- tium. {c) SEPARATION Calcium is precipitated in the 4th Group by ammonium carbonate (after removal of the metals of the ist, 2nd, and 3rd groups) together with Ba and Sr. The precipitate is dissolved in acetic acid and the barium precipitated by potassium chromate. A portion of the solution is tested for strontium with CaS04, and if found absent, calcium is at once proved by adding ammonium oxalate to the remainder. If strontium be present, it is separated as already described by adding very dilute sulphuric acid, and the calcium is tested for in the filtrate by ammonium oxalate. GROUP V. Metals not precipitable either as sulphide, hydrate, or carbonate, including magnesium, the precipitation of which as hydrate or carbonate has been pre- vented by the presence of ammonium chloride. I. MAGNESIUM (Mg). {a) WET REACTIONS. (To be practised on a solution of magnesium sulphate — MgS04.) 1. Na2HP04 in the presence of NH4CI and NH4HO, produces a white crystalline precipitate of ammonium magnesium phosphate — MgNH4P04. It is slightly soluble in water, and scarcely at all in water containing ammonium hydrate, but is however entirely soluble 46 DETECTION AND SEPARATION OF THE METALS. in all acids. In very dilute solutions it forms only on cooling and shaking violently, or rubbing the inside of the tube with a glass rod. 2. (NH4)oHAsO^ produces a similar precipitate of MgNH^AsO^ possessing like features. 3. KHO, NaHO, and NH^HO give precipitates of magnesium hydrate — Mg2HO — insoluble in excess, but soluble in the presence of ammonium salts. The alkaline carbonates (except ammonium carbonate) pre- cipitate magnesium carbonate, also soluble in ammonium salts. 4. Ca2H0 and Ba2H0 produce a similar effect. Either of these reagents is useful for the separation of magnesium from all the alkalies except ammonium. The solution, which must contain no ammonium salts, is treated with excess of either lime or baryta water. The precipitated magnesium hydrate is then filtered out and excess of ammonium car- bonate added, which precipitates in turn the excess of Ca or Ba employed and leaves K, Na, or Li in solution. (P) DEV EE ACTION. (To be practised on magnesia^ B.P. — MgO.) Heated on charcoal before the blowpipe, it becomes strongly incandescent, and leaves a white residue, which when moistened with a drop of solution of cobaltous nitrate — C02NO3 — and again heated, becomes rose-coloured. This test is not however infallible. (^) SEPAEATION. After separating the metals of the preceding groups by H^S, NH^Cl, and NH^HO, NH4HS and (NHJgCOg, all as already directed, the solution should be concentrated to about half its volume by evaporation and divided into a large and a small portion. The larger part is saved for the detection 'of the alkalies, and the smaller is made perfectly cold and treated with ammonium hydrate in excess, and then with disodium hydrogen phosphate, well shaken and set aside for some time, when the magnesium will separate as MgNH,P 04 II. LITHIUM (Li). {a) WET EE ACTIONS. (To be practised on a solution of lithium chloride, prepared by dissolving lithium carbonate in dilute hydrochloric acid.) 1. NaoHPO^ in strong solutions produces a white precipitate of lithium phos- "phate — Li3P04 — on boiling only (distinction from Mg). It is soluble in hydrochloric acid, and reprecipitated by boiling with ammonium hydrate. 2. NaoCOg, and even NaHO, in very strong solutions yield the carbonate and hydrate respectively. 3. PtCli gives no precipitate (distinction from potassium). (d) DE Y EE A CTION. (To be practised with lithium carbonate.) A platinum wire, moistened with hydrochloric acid, dipped in the substance and held in the inne 7 ' blowpipe or Bimsen flame, colours the outer flame carmine red. The presence of sodium disguises this reaction. {c) SEPAEATION Lithium is detected in the solution which is left after the precipitation of magnesium by disodium hydrogen phosphate.' After filtering out the mag- LITHIUM-^PO TASSIUM—SODIUM. 47 nesium precipitate a little more phosphate is added, and the whole evaporated to dryness. The residue is treated with a little boiling water, and any white insoluble matter may be taken as lithium phosphate, provided it gives the characteristic carmine flame test above described. III. POTASSIUM (K). WET REA CTIONS. (To be practised on solution of potassium carbonate treated with dilute HCl till effervescence ceases, forming potassium chloride — KCl.) 1. PtCl^, in strong solutions, gives a yellow crystalline precipitate of potas- sium platino-chloride — K^PtClg — soluble on great dilution, especially on warming, but insoluble in acids, alcohol, and ether. 2. HoCgH^Og throws down, from strong solutions only, a white crystalline pre- cipitate of potassium hydrogen tartrate — KHC^H^Og — soluble in much cold water, rather freely in hot water, readily in acids and in KHO or NaHO, and not formed unless the original solution be nearly neutral. Its separation is facilitated by stirring and shaking violently, in which case it settles quickly. 3. HoSiFg (hydrofluosilicic acid) yields white gelatinous potassium fluosilicate — K2SiFg — sparingly soluble in water. TRY REACTION-. (To be practised on potassium carbonate — K0CO3.) Dip a platinum wire, moistened with HCl, in the salt. Held in a Bunsen flame a violet colour is imparted. The masking effect of Na {yelloia) is obviated by viewing the flame through indigo glass. IV. SODIUM (Na). WET REACTIONS. (To be tested with solution of sodium chloride — NaCl.) 1. KSh’Og {potassium metantimoniate) gives a white granular precipitate of sodium metantimoniate — NaSbOo — from strong solutions only, which must be neutral or alkaline. This precipitate is insoluble in alcohol. 2. H2SiFg gives a similar precipitate to that obtained with K salts in concen- trated solutions only. Sodium salts are, practically, all soluble in water, and there is no thoroughly trustworthy wet reaction which can be applied to detect small quantities. If we have a solution which gives no precipitate with any of the group reagents, but leaves, on evaporating, a fixed residue capable of imparting a strong yellow colour to the Bunsen flame (dry reaction), we may infer with certainty the presence of sodium. . SEPARATION When the filtrate from the precipitation of K by PtCl^ is treated with H2S, to separate the excess of Pt completely, filtered, and evaporated to dryness^ a pure sodium salt is left. SEPARATION OF POTASSIUM ANE SODIUM FROM AIL OTHER METALS. The portion saved for K and Na after separation of all other metals (see separa- tion of Mg) is evaporated to dryness and heated till ammonium fumes cease 48 DETECTION AND SEPARATION OF THE METALS. to be evolved, the residue is taken up with the smallest possible quantity ot water and any insoluble matter filtered out. The flame test is applied to the solution ; and if yellow, Na is present. The test is then repeated, using a piece of indigo blue glass to cut off the yellow, and any violet indicates which is proved by adding platinic chloride and alcohol, and getting the yellow potassium platino-chloride. V. AMMONIUM (NHJ. WET REACTIONS. (To be tested with solution of ammonium chloride — NH^Cl.) 1. PtCl| produces a heavy yellow precipitate of ammonium platino-chloride — (NH4,)2PtClg — which, being rather soluble in water, is not formed in dilute solutions, unless alcohol, in which it is insoluble, be added in considerable quantity. When ignited, pure spongy platinum is left. This precipitate may be distinguished from that with K salts by add- ing, after ignition, a little water and AgNOg, when no white precipitate of AgCl is formed (the K salt leaves KCl on being strongly heated). 2. HoC^H^Og yields ammonium hydrogen tartrate — (NH.4)HC4H40g — almost identical with KHC^H^Og in its properties. On ignition, however, the latter gives a black residue, which turns moistened red litmus paper (KoCOg and C), the former leaving pure C without reaction. 3. NaHO, or Ca2H0, boiled with the solution causes the evolution of ammonia gas — NHg. A glass rod dipped in HCl or HC3Hg02 produces, when held over a mixture evolving NHg, white clouds (solid NH^ salts), and moist red litnuis paper is turned blue. 4. Nessler’s Solution (Hgl2 dissolved in KI and KHO added) gives a yellow or brown colour or a b}vwn precipitate of N(Hg2)'T with all NH^ salts. This reaction is extremely delicate, and the estimation of NH^ in water is founded upon it. TRY REACTIONS. Ammonium salts volatilize (i) with decomposition, leaving a fixed acid {e.o., phosphate); (2) with decomposition, leaving no residue whatever (^r.^., sulphate, nitrate); (3) without decomposition, when they are said to siMime {e.g., chloride, bromide, etc.). SEPARATION OF AMMONIUM FROM ALL OTHER METALS. Ammonium is at once separated from any mixture by boiling with potassium hydrate in excess, when it is given off in the form of ammonia gas — NHg. CHAPTER III. DETECTION AND SEPARATION OF ACIDULOUS RADICALS. 1. HYDROFLUORIC ACID and FLUORIDES. (The test for fluorides undernoted may be practised on fluor spar — Ca Fo.) Hydrofluoric Acid, or Fluoric Acid, is known, — 1. By its strongly acid reaction and corrosive power. 2. By the action upon glass from which it dissolves out silicic acid — Si O2 — thus roughening the surface and rendering it semi- opaque, or translucent, and white : a colourless gas, silicic fluor- ide— Sip4 — passing off. Fluorides are detected as follows : — The mineral or salt is finely powdered, and introduced into a leaden dish with a little sulphuric acid. A piece of glass, previously prepared by coating its surface with wax, and etching a few letters on the waxed side with the point of a pin, is placed over the dish, waxed side down. A gentle heat is then applied, but not sufficient to melt the wax, and the operation continued for some time. The glass is then taken off, and the wax removed from it ; when, if fluorine was present, the letters \vritten on the waxed surface will be found engraved upon it by the action of the hydrofluoric acid. 2. CHLORINE, HYDROCHLORIC ACID, and CHLORIDES. Free Chlorine — Clg — may be detected, — 1. By its odour. 2. By turning paper dipped in solution of potassium iodide brown. 3. By bleaching a solution of indigo or litmus. Hydrochloric Acid — HCl — may be recognised, — 1. By its acidity and odour of its fumes. 2. By producing dense white fumes when a rod dipped in ammonium hydrate is held over the mouth of the bottle. 3. By giving a curdy white precipitate of argentic chloride with argen- tic nitrate, instantly soluble in ammonium hydrate. Chlorides give the following reactions (to be practised with any soluble chloride, say NaCl) : — 1. Heated with sulphuric acid, they evolve white fumes of HCl. 2. Heated with H2SO4 and Mn02 they evolve chlorine. 3. AgNO;^ in the presence ^T/'HNOg gives a white precipitate of argentic chloride — AgCl — insoluble in boiling nitric acid but instantly soluble in ammonium hydrate. 4. The solid substance mixed with K2Cr207 and distilled with H2SO4 yields chloro-chromic acid — CrCl202 — in red fumes which, when passed into dilute ammonium hydrate, colour it yellow, owing to the formation of ammonium chromate — (NH4)2Cr04. E VOL. II. DETECTION OF ACIDULOUS RADICALS. 50 The yellow should change readily to green on the addition of a few drops of sulphurous acid. Insoluble Chlorides should be first boiled with strong sodium hydrate and the whole diluted and filtered. The chloride is then transferred to the sodium and is to be searched*for in the filtrate by acidulating with nitric acid and adding argentic nitrate, as above described. 3 . HYPOCHLOROUS ACID and HYPOCHLORITES. Hypochlorous Acid is rarely met with, and it is hardly necessary to mention its reaction. However, the chlorine-like smell, the disengagement of chlorine when HCl is added, and the action of blue litmus, first reddening and almost instantly bleaching, are sufficiently distinctive. The odour, bleaching power, and action of HCl are properties possessed by hypochlorites in common with the acid itself. They are also indicated by their ready solubility in water. 4 . CHLOROUS ACID and CHLORITES. Chlorous Acid is a link between hypochlorous and chloric, and as such is worthy of a passing notice. It is energetic in entering into combination with hydrates, but does not act upon carbonates. Its solution has the properties of chlorine, but in an intensified degree, and is quickly decomposed by heat. Chlorites are usually soluble in water, and only the silver and lead salts are of slight solubility. The former is not decomposed by boiling, and may thus be distinguished from the hypochlorite. Care must be taken that the heat does not reach 105° C., as the argentic chlorite then explodes. 5 . CHLORIC ACID and CHLORATES. Chloric Acid is a syrupy liquid readily decomposed by heat or reducing- agents, often with explosive violence. It is colourless, strongly acid, and has no bleaching properties. Chlorates (to be practised on potassium chlorate — KCIO3). 1. Heated on charcoal, they deflagrate. 2. Heated with strong sulphuric acid, they evolve chlorine peroxide — CloOj. — which is yellow and explosive. 3. Their solutions yield no precipitate with argentic nitrate; but if a little of the solid be heated to redness, and the residue dissolved in water, a precipitate of argentic chloride is obtained. The same reduction from chlorate to chloride may also be effected by adding zinc and dilute sulphuric acid to the solution. 5 a. SEPARATION OF CHLORATES AND CHLORIDES. Add excess of argentic nitrate, filter out the argentic chloride formed, and then acidulate with sulphuric acid, and drop in a fragment of zinc, when, if a chlorate be present, a second precipitate of argentic chloride will form. 6. PERCHLORATES. Are distinguished from chlorates — 1. By giving off perchloric acid, when heated with sulphuric acid, with- out explosion or evolution of chlorine peroxide. 2. Like chlorates, they require reduction to chlorides before giving a precipitate with argentic nitrate. BROMINE COMPOUNDS. 51 7 . BROMINE, HYDROBROMIC ACID, and BROMIDES. Bromine is distinguished, — 1. By its appearance — heavy, reddish-brown liquid, giving off reddish fumes of a very penetrating, unpleasant odour. 2. By turning starch paste yellow or pink. 3. When present in small quantity in solution, on adding a few drops of chloroform and shaking, asi orange colour is imparted to that liquid, which sinks to the bottom of the aqueous solution. 4. By the bleaching power of its solution. Hydrohromic Acid is known, — By its acid reaction and the production of fumes of bromine with nitrous acid. Bromides are all soluble in water, except the silver, mercurous, and lead salts ; they are detected by the following characters (to be practised on potassium bromide — KBr) : — 1. Heated with strong sulphuric acid, they evolve red vapours of bromine. 2. A similar effect is produced by sulphuric acid and metallic dioxides, such as PbOg, Mn02. 3. Mixed with starch paste, and a few drops of chlorine water care- fully added, they give an orange colour (starch bromide). 4. Mixed in a long tube with ether, chloroform, or carbon disulphide, and a few drops of chlorine water added, the whole, when shaken well together, leaves a characteristic reddish-coloured stratum of free bromine, dissolved in the menstruum used In the case of ether, the stratum is visible on the top, while with the other two it is noticed at the bottom of the liquid in the tube. 5. With argentic nitrate they give a dirty-white precipitate of argentic bromide, insoluble in nitric acid, slowly soluble in am- monium hydrate. 6. Distilled with potassium dichromate and sulphuric acid, red fumes are evolved, which give no colour when passed into ammonium hydrate. Insoluble Bromides should be first boiled with NaHO as described under insoluble chlorides. 8. DETECTION OF CHLORIDES IN THE PRESENCE OF BROMIDES. (To be practised on a mixture of KCl and KBr.) The solution is divided into two parts, in one of which the bromide is proved by the addition of chlorine water, and shaking up with chloroform. The second portion is evaporated to dryness, and the residue placed in a tube re- tort with a little potassium dichromate and sulphuric acid. Into the receiver is placed a little dilute ammonium hydrate, and distillation is proceeded Avith, when, if a chloride be present, the liquid in the receiver will be coloured yellow. 9 . HYPOBROMOUS ACID and HYPOBROMITES. These are very similar to hypochlorites, and react as follows : — 1. They decompose by heat, leaving a bromide ; 2. On boiling with an alkali, a mixture of bromide and bromate results ; 3. The acid kself is straw-yellow in colour, and bleaches powerfully. 52 DETECTION OF ACIDULOUS RADICALS. 10. BROMIC ACID and BROMATES. These are recognised — 1. By deflagrating on charcoal, leaving the corresponding bromide. 2. By liberating bromine on the addition of dilute sulphurous acid. 11. IODINE, HYDRIODIC ACID, and IODIDES. Iodine is readily known by its glistening black scales, its odour, the violet vapour on heating, and the production of blue iodide of starch on adding a solution to starch paste. Hydriodic Acid, in the gaseous state, is known by the formation of a brown colour on holding paper moistened with chlorine water (blue if also dipped in starch paste) over a tube in which it is being evolved. The solution decom- poses on exposure to the air, becoming yellow or brown on account of the separation of iodine. Thus, if the solution be colourless at first, acid in re- action, and giving no effect with starch paste, but producing a blue on exposure to the air, or more rapidly on adding HNOg or Cl water, HI may be inferred with certainty. Iodides are readily known by the following reactions (which may be prac- tised on solution of potassium iodide, KI) : — 1. The light yellow precipitate of argentic iodide — Agl — formed when a solution (containing alkaline metals only) is added to argentic nitrate dissolved in water. The precipitate, when freed from the supernatant liquid, does not dissolve in hot HNO3 and is practically insoluble in ammonium hydrate, being thus distinguished from a chloride. 2. A neutral solution (produced, if alkaline in the first place, by the cautious addition of dilute HNO3; W dropping in KHO solution until test-paper is unaffected) gives with one part of cupric sulphate — CuSO^ — and three parts, or rather less, of ferrous sulphate — FeS04 — dissolved in a little water, a greyish precipitate of cuprous iodide — (Cu2)'T'2. The same precipitate is produced if sulphurous acid — HgSOg — be used with the cupric sulphate instead of ferrous sulphate. 3. Palladious Chloride — PdClg — or palladious nitrate — Pd2(N03) — gives a black precipitate of palladious iodide — Pdig — decom- posed somewhat below the tetnperature of boiling mercury, iodine being evolved, and the metal left. This is a very ex- pensive but efficient separation. 4. Mucilage of Starch and nitrous acid or chlorine water (if not added too plentifully), produces blue iodide of starch, decomposed by heat but re-formed on cooling ; also destroyed by excess of Cl (iodine tri-chloride — ICI3 — being produced). The nitrous acid may be replaced by potassium nitrite — KNO2 — and dilute H2SO4, the HNO2 then being set free in the solution. An iodide treated with strong H2SO4 yields HI at first \ but this acting on the excess of acid, is transformed into free I, the H2SO4 at the same time being reduced by the hydrogen to sulphurous acid — H0SO3 — or even to sulphuretted hydrogen — HoS. 5. When mercuric chloride — HgClg — in aqueous solution, is cautiously dropped into a liquid containing an iodide, a stage is reached at which a permanent precipitate of red mercuric iodide — Hglo — is produced. The reaction is not reliable unless great BROMIDES— IODIDES— CHLORIDES. 53 care be taken, as too rapid or insufficient addition of the HgClo may either dissolve the precipitate or fail to form it. If ac- tually produced, however, its colour and insolubility indicate iodine with certainty, since Cl, Br, and Cy are colourless and soluble when combined with mercury (ic). 6. Plumbic Nitrate or Acetate — Pb2(N03) — or Pb (0211303)2, throw down yellow Pbl2 from cold solutions. This precipitate is soluble in hot water, and dissolves slightly even at ordinary temperatures ; consequently the test cannot be relied on to give any effect in weak solutions. 12 . DETECTION OF BROMIDES IN THE PRESENCE OF IODIDES. (Practise on a mixture of KBr and KI.) Add to the solution a very small quantity of starch paste and then a drop or two of chlorine water, when a blue colour will be produced proving the iodide. Continue to add more chlorine water until this blue is entirely dis- charged and then shake up with chloroform, when, if a bromide be present, the characteristic golden colour will be communicated to the chloroform. 13 . DETECTION OF CHLORIDES IN THE PRESENCE OF IODIDES. (Practise on a mixture of KCl, KBr, and KI.) Add excess of argentic nitrate, warm, pour off the supernatant liquid, wash with warm water, and shake up the precipitate in dilute solution of ammonium hydrate (i in 3). The argentic* iodide will remain insoluble, while the chloride will dissolve and may be detected in the solution after filtration by reprecipita- tion with excess of nitric acid. As argentic iodide is not absolutely insoluble in ammonium hydrate, a mere cloud on adding the nitric acid is to be disre- garded. This test is only accurate in the ensured absence of a bromide, proved as above directed (see 12). If a bromide is present, the chloride can only be proved by the distillation with potassium dichromate and sulphuric acid (see 8). 14 . SEPARATION OF AN IODIDE FROM A BROMIDE AND CHLORIDE. (Practise on a mixture of KCl, KBr, and KI.) T. Add to the solution a mixture of one part cupric sulphate and three parts ferrous sulphate, or mix the solution with excess of cupric sulphate and drop in sulphurous acid till precipitation ceases. The iodide will separate as cuprous iodide — CU2I2 — leaving the bromide and chloride in solution. Unless care- fully done, this separation is not absolutely accurate. 2. Add to the solution palladious nitrate until precipitation ceases. Filter out the palladious iodide which separates and pass sul- phuretted hydrogen through the liquid to remove excess of palladium and again filter. Boil to expel the excess of HgS, and the bromide and chloride remain in solution. 15 . IODIC ACID and lODATES. The acid is a crystalline solid, breaking up by heat into oxygen and violet vapours of iodine. lodates are known, — I. By giving a blue with starch paste on the addition of sulphurous acid. 54 DETECTION OF ACIDULOUS RADICALS, 2. By yielding a precipitate of ferric oxy-iodate on adding ferric chloride. 15 a. DETECTION OF AN lODATE IN AN IODIDE. (Practise on a solution of iodine in heated potassium hydrate — KI+KIO3.) When excess of tartaric acid is added to potassium iodate, iodic acid is set free ; and when the same acid is added to potassium iodide, hydriodic acid is set free, and potassium hydro-tartrate formed. Thus : 5KI + KIO3 + - 5HI -t- HIO3 -1- dKHQH^g. If these acids be thus liberated together, they immediately decompose, forming water and free iodine : 5HI-f HIO3-3I2 + 3H3O. If therefore starch paste and tartaric acid be added to pure potassium iodide no coloration takes place, because only hydriodic acid is liberated ; but if the sample contains potassium iodate, an immediate production of free iodine ensues, which turns the starch blue. 16 . PERIODIC ACID and PERIODATES. Periodic Acid is known, — 1. By its strongly acid deliquescent crystals, decomposed by heat into iodic anhydride — I2O3 — and ultimately into I and O. 2. By the production of I, by the action of organic and other reducing agents. . Periodates are distinguished, — I. By precipitating with barium chloride — BaCl2 — in a neutral solution and digesting in ammonium carbonate to which some NH^HO has been added. The periodate is not decomposed. . lodates leave barium carbonate, which when washed dissolves in acid with effervescence. 2: By adding Hg2N03 and treating the yellowish precipitate with SnCl2. It turns green, Hg2l2 being produced. 17 . WATER and HYDRATES. Water is recognised, — 1. By its absolute neutrality to test-paper. 2. By its evaporating without residue, fumes, or odour of any kind. 3. By its turning white anhydrous cupric sulphate blue. 4. By its yielding pure hydrogen when boiled and the steam passed slowly over ferrum redactim,, B.P., heated to bright redness in an iron tube. 5. By its undergoing electrolysis, and yielding hydrogen at the negative and oxygen at the positive electrode. . The soluble Hydrates, viz., KHO, NaHO, LiHO, Ba2HO, Sr2HO, and Ca2HO are known, — 1. By being more or less soluble in cold water, yielding solutions which are strongly alkaline to test-paper. 2. By dissolving in hydrochloric acid without effervescence and with- out smell. 3. By giving a brownish-black precipitate of argentic oxide — Ag20 — with argentic nitrate. • OXIDES— SULPHUR COMPOUNDS. 55 The insoluble Hydrates are recognised, — By giving off steam when heated in a dry test-tube and leaving a residue which behaves like the corresponding oxide. 18. OXIDES. All oxides are insoluble in water. Those of K, Na, Li, Ba, Sr, and Ca, when placed in contact with that liquid, unite with it to form hydrates, which dissolve with a greater or less degree of readiness and give the characters of the soluble hydrates already mentioned. Xormal Oxides can only be recognised by negative results, such as : — 1. Heated alone, they are not changed; except argentic oxide, which leaves the metal, and mercuric oxide, which volatilizes and breaks up into the metal and oxygen. 2. They are insoluble in water (exceptions K, Na, Li, Ca, Ba, and Sr, converted into soluble hydrates) but soluble in hydrochloric or nitric acid without effervescence and without smell. 3. After dissolving and removing the metal by H3S or Na^COg as most convenient, no acidulous radical other than that of the acid used to dissolve is found. 4. Boiled with strong NaHO and filtered, or fused with KNaCOg and digested with water, the solution gives no reaction for any acid radical except the soluble hydrate or carbonate employed. Peroxides, on account of their containing an excess of oxygen, differ from normal oxides, — 1. By giving off oxygen when strongly heated. 2. By evolving chlorine when heated with hydrochloric acid. 19. SULPHUR, HYDROSULPHURIC ACID, and SULPHIDES. Ordinary Sulphur is recognised, — 1. By its burning entirely away with a pale blue flame, and evolving sulphurous anhydride. 2. By its insolubility in all ordinary menstrua, such as water, alcohol, and ether, but dissolving readily in carbon disulphide. 3. When slowly heated in a tube, it first melts, then thickens, then melts again, and finally boils, the vapour taking fire and forming sulphurous anhydride. Precipitated Sulphur possesses the above characters and is specially distin- guished from ordinary sulphur by being quite amorphous under . the niicroscope, while the latter is crystalline. Hydrosulphuric Acid (sulphuretted hydrogen) is known, — 1. By being a colourless gas with a disgusting odour of rotten eggs and inflammable, burning in the air to produce sulphurous acid. 2. By turning a piece of paper black, which has been moistened with solution of plumbic acetate and held over the mouth of the tube or jet from which it issues. Normal Sulphides are divisible into five classes : — I. Soluble i’-* iaciuaing the sulphides of K, Na, NH^, Ca, Sr, Ba, and Mg. 56 DETECTION OF ACIDULOUS RADICALS. 2. Insoluble in water, but readily soluble in dilute hydrochloric acid, including those of Fe, Mn, Zn. 3. Insoluble in dilute, but soluble in strong boiling hydrochloric acid, including the sulphides of Ni, Co, Sb, and Sn (PbS is also slightly affected, but separates on cooling, as chloride). 4. Insoluble in hydrochloric acid, but attacked by strong heated nitric acid, being converted wholly or partially into sulphates. These include the sulphides of Pb, Ag, Bi, Cu (arsenious sulphide is slowly affected). 5. Not dissolved by any single acid, but converted into a soluble sulphate by the action of nitro-hydrochloric acid, or hydro- chloric acid and potassium chlorate ; including those of Hg, As, All, and Pt. Sulphides soluble in water or in hydrochloric acid are recognised, — 1. By giving off sulphuretted hydrogen when heated with that acid, which gives the smell and reactions already noted. 2. Soluble sulphides precipitate solutions of lead and cadmium, black and yellow respectively. 3. Soluble sulphides give a purple colour with sodium nitroprusside only after the addition of a soluble hydrate. Sulphides insoluble in hydrochloric acid are best detected, — 1. By heating with strong nitric or nitro-hydrochloric acid, diluting the solution, and testing for a siilphaie with barium chloride (see 24). 2. By fusion with KNaCOg and KNO3, digesting the residue in water, filtering and testing the solution for a sulphate formed by the oxidizing action of the potassium nitrate. 3. Mix a little with sodium carbonate and borax, and heat on charcoal before the blowpipe. Remove the mass thus obtained, place it on a clean silver coin, and moisten with a drop of distilled water ; when, owing to the formation during ignition of sodium sulphide — NaoS — a black stain of argentic sulphide — AgoS — will be pro- duced. Polysulphides as commonly met with are those of the alkalies, and are soluble in water. They are known, — 1. By the deep yellow or orange colour of their solutions. 2. By evolving sulphuretted hydrogen accompanied by a deposit of sulphur when treated with hydrochloric or dilute sulphuric acids. The polysulphides which are insoluble in hydrochloric acid, such as iron pyrites — FeSo — copper pyrites — FeoCiuS^ — etc., are best proved by fusion and conversion into sulphate. They may, however, be recognised by heating with hydrochloric acid and zinc, when the excess of sulphur will pass off as HoS, leaving the norm.al sulphide. 20. DETECTION OF A SOLUBLE SULPHIDE IN PRESENCE OF A SULPHITE AND A SULPHATE. Pour the solution on a little cadmium carbonate — CdCOg — filter, and treat the insoluble matter with acetic acid to remove any unacted-upon cadmium carbonate. If a sulphide have been present, a yellow residue of cadmium sulphide will remain insoluble in the acetic acid, while cadmium sulphite and sulphate will be found in the first filtrate, if Uicst rciHicals were present (see separation of sulphites and sulphates). HYPOSULPHITES—SULPHUROUS ACID. 57 21. THIOSULPHUmC ACID and THIOSULPHATES (Hjrposulphites). The acid is not known in the free state ; but its salts, commonly known as hyposulphites, are usually soluble in water, and exhibit the following charac- ters ; — 1. With either dilute or strong HCl and H0SO4, they yield SOo gas and a yello7v deposit of S {distinction from sulphides^ poly- sulphides., and sulphites). 2. AgNO;^ gives no precipitate at first, owing to excess of a hypo- sulphite dissolving argentic hyposulphite — AgoS303 — but on continuing the addition, this Ag2S203 is precipitated of a white colour. The salt splits up spontaneously, becoming yellow, brown, and lastly black, and being changed completely into argentic sulphide — Ag2S. The same decomposition of the precipitate occurs on substituting HgNOg or Pb2NOg for AgN O3 ; and in all three cases heat accelerates the action, and H2SO4 is the by-product. 3. Fe2Clg, Na20Cl2, and Cl water convert hyposulphites into sulphates, even without applying heat. Na2S203 H2O + 4Na20Cl2 - 2NaHS04 + SNaCl. ' The first produces a reddish-violet colour, and this gradually disappears as FeCb is formed. {This colour is not produced by sulphites.) 4. HCl and dilute H2SO4 evolve H2S tvhen zinc is dropped in. The reaction is, — 4 Zn -f loHCl + Na2S203 = 4ZnClo + 2NaCl + 3H2O + 2KS. 22. SEPAEATION OF THIOSULPHATES FROM SULPHIDES. Having obtained a good preliminary idea by heating with H2 SO4, add to a portion of the original solution — ZnSO^ — in excess, and filter. {a) Precipitate white, and soluble in HCl, with smell of H2S = Sulphides. (/ 3 ) A portion of filtrate heated with H2SO4 deposits S and smells of SO2 ; and another portion added to a drop or two of ammonio- cupric sulphate instantly causes decolorization = Hyposulphites. 23. SULPHUROUS ACID and SULPHITES. Sulphurous acid in solution is recognised, — 1 . By its pungent odour of burning sulphur. 2. By adding barium chloride in excess, filtering out any precipitate of barium sulphate which may form (owing to the fact that all samples of the ordinary acid contain sulphuric acid), and then adding chlorine water and getting another copious white pre- cipitate of barium sulphate owing to the conversion of the sulphurous into sulphuric acid by the oxidizing action of the chlorine water, thus : — H2SO3 -f- BaClg -f- CI2 + H2O = BaSO^ -f 4HCI. 3. Treated with zinc and hydrochloric acid, it evolves sulphuretted hydrogen, thus : — 3Zn + 6 HC 1 H2SO3 = 3ZnCl2 + H2S -}- 3H2O. DETECTION OF ACIDULOUS RADICALS. 58 4. When a solution of iodine is dropped into the liquid, its colour is discharged, owing to its conversion into hydriodic acid by the hydrogen of the water, the oxygen of which passes at the same time to the sulphurous acid, forming sulphuric acid. H2SO3 + I2 + H2O = H2S0^ + 2 HI. Sulphites are known by the following characteristics : — 1. All except the alkaline sulphites are sparingly soluble in water. 2. When heated with sulphuric acid they evolve sulphurous anhydride, without deposit of sulphiu'. . 3. Acted on with zinc and hydrochloric acid, they evolve sulphuretted hydrogen, which blackens a piece of paper moistened with plumbic acetate and held over the mouth of the test-tube. 4. A salt of silver, mercury, or lead, produces a precipitate, which on heating turns dark, owing to the formation of a sulphide and free sulphuric acid. 5. By boiling with barium chloride and chlorine water or nitric acid, barium sulphate is produced, and precipitates. 6. The acid gas — SO2 — combines directly with peroxides to form sulphates. For instance : — Pb02 + S02-PbS0^. This reaction is utilized in gas analysis, to separate SO2 from a gaseous mixture. 7. K3Cr207 and HCl give a beautiful green coloration of chromic stdphate or chloride. This test is very delicate, but by itself is not conclusive. 24 SULPHURIC ACID and SULPHATES. The acid is detected as subjoined : — 1. By its appearance. A heavy, oily, odourless, and nearly colourless liquid, powerfully acid and corrosive. 2. By its charring effect. This is made evident when the strong acid is dropped upon white paper, wood, etc., or when the dilute acid is evaporated in a basin containing a little white sugar. The carbonization is due to the power the acid has of abstract- ing the elements of water from organic bodies. 3. By liberating an explosive gas from KCIO3 when heated with it. The test is not available with dilute acid. Sulphates are soluble in water, with the exception of basic sulphates (soluble in acids) and BaS04, SrS04, CaS04, and PbS04. (Ag2S04 is only slightly soluble.) When those insoluble in dilute acids are required to be analysed, they are decomposed either by boiling with potassium or sodium hydrates or by ignition with KNaC03, the latter being preferable. The sulphate radical, being brought into combination with K or Na to form a soluble sulphate, is to be tested for in the filtrate after boiling with water. Sulphates are recog- nised by the following characters : — I. BaCla or Ba2N03 produces a white precipitate of barium sulphate — Ba SO4 — insoluble in boiling water and also (after washing to remove excess of BaCb) in boiling nitric acid. This wash- ing is necessary, as the addition of a strong acid to a solution of barium chloride often causes the reagent to crystallize out, and this is then mistaken by the student for a true precipitate of sulphate. CARBON— CARBONIC ACID— CARBONA TBS. 59 2. The addition of a soluble salt of lead or strontium also causes the formation of insoluble sulphates ; but these reactions are never in practice used, the barium chloride being at once the most delicate and serviceable reagent. 3. Heated with a little NaoCOg on charcoal in the inner blowpipe flame, sulphates are reduced to sulphides, and the residue placed on a clean silver coin and moistened with water, leaves a black stain. 25. SEPARATION of SULPHIDES, SULPHITES, and SULPHATES. Pour the solution on an excess of cadmium carbonate, digest at a gentle heat, filter, and examine the precipitate for a sulphide as already directed (19). The filtrate, which may contain the sulphite and sulphate, is precipitated by barium chloride, the insoluble pi^cipitate filtered out and boiled with a little hydrochloric acid, which will dissolve the barium sulphite with evolution of sulphurous anhydride — SO3 — and leave the barium sulphate insoluble. 26. CARBON, CARBONIC ACID, and CARBONATES. Carbon is known ; — ■ • I. By its black colour and the production of a gas when burnt, which is odourless, so heavy that it can be poured from one vessel to another, and causes a white precipitate when passed into solu- tion of calcium hydrate. 2. By its capability of removing many vegetable colouring matters from their solutions. Carbonic Acid is not known in the free* state, splitting up into carbonic anhydride — CO2 — and water. CO2 is recognised, — 1. By being odourless and giving white insoluble CaCOg (or BaCOg) when passed into a solution of Ca2HO (or Ba2HO). 2. By turning blue litmus purple or wine-red, the original tint being restored by heat, the COo escaping. Carbonates are mostly insoluble in water, the alkaline carbonates alone dissolving. CaCOg, SrCOg, BaCOg and MgCOg (also MnCOg and FeC(?g) dissolve in water containing CO2 (especially under pressure) forming bicar- bonates or hydrogen carbonates, from which CO3 passes off on boiling. All carbonates give off CO2 on ignition, except Iv2COg and NagCOg. A white heat is needed to decompose BaCOg and SrCOg. A few carbonates yield the metal on heating, but the majority leave the oxide. Their recognition depends upon, — 1. Effervescing with a solution of almost any acid (HgS and HCy excepted), organic or inorganic, and giving off an odourless gas — CO 2- 2. When the gas given off is poured or passed into a solution of calcium hydrate, a white precipitate of CaCOg falls, which dis- solves on continuing to add CO2. When the gas given off has the odour of H2S or SOo, either of these may be removed by passing through K2CrOj^ and HCl, which is rendered green, and the unacted-upon CO2 is allowed to pass into calcium hydrate solution as before. 27. BORIC ACID and BORATES. Boric (or Boracic) Acid — HgBOg — is a common substance, distinguished as under : — 6o DETECTION OF ACIDULOUS RADICALS. 1. It is a white crystalline solid, giving off water on being heated and leaving the a?ihydride — B2O3. 2. When warmed with alcohol, a greeft flame is produced on applying a light to the latter. 3. When dissolved in hot water and a piece of turmeric paper dipped in the solution, the yellow colour is unaffected ; but upon drying the paper it becomes brownish-red. All borates dissolve in dilute acids, but few in water, and when de- composed by hot acids, let fall crystalline boric acid on cool- ing, which answers to the above characters. The presence of soluble borates is detected by the following tests : — 1. They give, on heating with calcium chloride, rendered slightly alka- line with ammonium hydrate, a white precipitate of calcium borate, soluble in acetic acid,^and so distinguished from oxalate. 2. On rendering the solution just acid with hydrochloric acid, and then dipping in a piece of turmeric paper, and drying the same after immersion at a gentle heat it will be turned red. 3. Besides these two tests, which are in themselves, taken together, quite conclusive, borates give a precipitate with argentic nitrate soluble in nitric acid. 4. When a little of the solid borate is moistened, first with a drop of sulphuric acid and then with about a drachm of spirit of wine, the alcoholic solution of boric acid so obtained burns with a bright green flame. 5. When KHSO4 (potassium hydrogen sulphate) is heated with a borate in the blowpipe flame on platinum wire, the flame is tinged green. 28 . SILICIC ACID and SILICATES. The acid H^Si04 is scarcely ever met with, and we have practically to deal with the anhydride — Si02 — which is totally insoluble in water and dilute acids, the acid dissolving slightly in both. Si02 is characterized, — • I. By its infusibility when heated. 2. By its insolubility in water and all acids except HF. 3. By forming, when heated with H2SO4 and CaF2 in a leaden vessel, gaseous silicic fluoride — SiF^ — which deposits the acid — H^SiO^ — and forms hydi'ofluosilicic acid — H2SiFg — and HF, in contact with moisture. Silicates are not as a rule soluble in water, K4Si04 and Na4Si04 being the only ones thus affected, especially when much KHO or NaHO is present. Many of them do not dissolve in strong acids (a few are decom- posed by hot H2SO4, but by no other acid), but all are split up by the action of gaseous hydrofluoric acid or a mixture of CaFg and H2SO4. 1. On adding HCl to a soluble silicate H4Si04 falls as a gelatinous, — scarcely visible, — precipitate, slightly soluble in water. On evaporating to dryness and heating to 280° or 300° F., the addition of a little HCl and water always fail to affect the Si02 which is left as a white gritty residue. 2. NH4CI precipitates H4Si04 from a soluble silicate. 3. Silicic anhydride is separated from all acidulous and basylous radicals by fusing the finely powdered insoluble silicate with Na2C03 (or fusion mixture)^ in a platinum crucible; boiling with water, filtering, evaporating nearly to dryness, adding dilute HCl until the whole is acid, re-evaporating, moistening with HYDROFLUOSILICIC ACID— NITROUS ACID. 6i water, and when dry heating to 280° or 300° F. On adding a little HCl, SiOo alone remains insoluble. 29. SEPARATION OF SILICIC ANHYDRIDE (SILICA) FROM ALL OTHER ACIDS. Fuse the substance with a large excess of KNaCOg in a. platinum crucible, and when all action has ceased, cool, and boil the residue with water. The silica passes into solution with the other acid radicals, and the metals are left as oxides. Acidulate the solution with hydrochloric acid, evaporate to dry- ness, and heat the residue to 280° Fah., and maintain the heat for some time. Drench the residue with strong hydrochloric acid, then add water, and boil, when the silica will alone remain insoluble. 30. HYDROFLUOSILICIC ACID (H2SiF6). This acid is only known in solution. 1. It is very acid, and dissolves metals with the evolution of hydrogen, forming silico-fluorides which decompose by heat, leaving fluorides, and giving off silicon fluoride — SiF4. 2. It gives off hydrofluoric acid when evaporated, and should not, therefore, be heated in glass vessels, as they would be etched. 3. The majority of silico-fluorides are soluble, the exceptions being KgSiFg, BaSiFg, and Na2SiFg, which are insoluble, especially in presence of a little alcohol. 4. It does not precipitate strontium salts, even from strong solutions, but throws down BaSiFg on adding BaCl3 and alcohol, as a white translucent crystalline precipitate. 5. Potassium salts throw down gelatinous KoSiFg. 31. NITROUS ACID and NITRITES. Nitrous Acid (so called commercially) is nitric acid containing nitrous anhydride. It is yellowish in colour, and evolves reddish fumes. • Nitrites are all soluble in water, the least so being argentic nitrite. They are known as follows : — 1 . They give red fumes when treated with strong sulphuric acid, be- cause the nitrous acid is thereby decomposed into nitric acid, and nitric oxide which then fumes in contact with the air. 2. They give an instantaneous blue colour with potassium iodide and starch paste on the addition of a few drops of dilute sulphuric acid. The sulphuric acid liberates hydriodic acid from the iodide, and nitrous acid from the nitrite ; the hydriodic acid is decomposed by the nitrous acid into iodine, water, and nitric oxide : — 2HNO2 + 2HI = I2 2H2O -f 2NO. \Nitrates^ it must be. remembered, would give frequently a similar re- reaction after standing, through the possible reduction of some portion of their nitric acid to nitrous acid ; so that unless the reaction appears instantly, and is confirmed by others, it is not safe to rely upon it as a test.] 3. They give a dark brown colour with ferrous sulphate without the previous addition of sulphuric acid^ as 7 'equired by nitrates. 4. Potassium dichromate in solution is converted into a green liquid by the addition of a nitrite and an acid. These two latter sub- 62 DETECTION OF ACIDULOUS RADICALS. stances also reduce an auric solution, forming a precipitate of the metal, possessing a dark colour. 32. DETECTION OF A NITRITE IN THE PRESENCE OF A NITRATE. Add a little potassium iodide and starch paste, then introduce a small pinch of powdered metallic zinc, and lastly acidulate with acetic acid, when, if a nitrite be present, a blue colour will be produced, due to the liberation of iodine. This test *is often a very necessary one when dealing with drinking water, the presence in which of nitrites, derived from the oxidation of com- paratively recent organic contamination, is a dangerous indication. 33. NITRIC ACID and NITRATES. Nitric Acid is strongly acid and corrosive, fumes in the air, and readily dis- solves most metals. It may be at once recognised by the following charac- ters : — 1. When poured on a piece ot copper foil, and a piece of white paper held behind the test-tube, it is observed to be filled with orange-red fumes of nitric peroxide — N3O4. 2. AVhen dropped on a piece of quill in a basin, or if the solution be weak when evaporated in contact with the quill, the latter is stained yellow. This stain is intensified to orange on adding an alkali, and is not discharged by warming, both of which decolorize the corresponding stains produced by iodine and bromine. 3. Dropped on a few crystals of brucine, a deep red colour is produced. Nitrates are characterized by the following properties : — 1. All nitrates are soluble in water, especially when slightly acidulated with nitric acid. The nitrates of the alkalies are only decom- posed by a very high temperature, but most of the nitrates of the heavy metals, such as copper, mercury, and lead, when heated are readily decomposed, leaving a residue of oxide. Argentic nitrate, however, when heated leaves metallic silver. 2. When heated with sulphuric acid they evolve pungent fumes ot nitric acid. 3. When heated with sulphuric acid and a piece of copper wire, they produce red fumes of nitric peroxide (caused by the union of the nitric oxide evolved with the oxygen of the air). 4. When mixed with a solution of ferrous sulphate in the presence of sulphuric acid, a black coloration is produced, which is due to the production of nitric oxide, and its absorption by the ferrous salt. On heating, the colour disappears, and the ferrous is changed to the fa' 7 'ic sulphate. There are two ways of apply- ing this test. {a) Place a drop or two of the suspected solution on a white porce- lain slab or crucible lid, and having added a drop of strong sulphuric acid, put a small and clean crystal of the ferrous sul- phate in the liquid, when a black ring will gradually form round the crystal. if) Place the suspected solution in a tube, and having added some strong solution of ferrous sulphate, cautiously pour some strong sulphuric acid down the side of the tube, so that it sinks to the bottom by reason of its great gravity without mixing with the fluid. If nitric acid be present, a dark line will be formed at the junction of the two liquids. CYANOGEN— HYDROCYANIC A CID— CYANIDES. 63 5. Treated with sulphuric acid, and a few drops of indigo sulphate added, the blue colour of the latter is destroyed, being tchanged to yellow (not characteristic). 6. The most delicate test for nitrates is, however, phenyl-sulphuric acid. This reagent is prepared by dissolving one part of carbolic acid in four parts of strong sulphuric acid, and then diluting with two parts of water. A few drops of the solution to be tested are evaporated to dryness on a porcelain crucible lid over the water bath, and while still over the bath a drop of the reagent is added, when a reddish colour is immediately produced, owing to the formation of nitro-phenol. 34. DETECTION OF FREE NITRIC ACID IN THE PRESENCE OF A NITRATE. Digest with excess of barium carbonate ; filter, and add to the filtrate some dilute sulphuric acid, when, if the free acid were present, a precipitate of barium sulphate will be produced. This test is only good in the ensured ab- sence of sulphates and of any other acid capable of dissolving barium carbo- nate. It will also serve for detecting free hydrochloric and acetic acids in presence of their salts. 35. DETECTION OF A NITRATE IN THE PRESENCE OF AN IODIDE. The fact that the addition of strong sulphuric acid liberates iodine, renders the proof of a nitrate by the ordinary iron process doubtful in the presence of iodides and bromides. In this case warm with a little zinc amalgam and add a little acetic acid and starch paste, when the nitrate, being reduced to nitrite, will cause the liberation of iodine, and colour the starch paste blue. Another process is, to evaporate to dryness with excess of potassium hydrate and a little sugar, and then fuse the residue, when, if a nitrate be present, ammonia gas — NHg — will be given off ; and will turn moistened fed litmus paper blue. The first process is as a rule the better of the two, and zinc amalgam is easily made with a drop of mercury and a fragment of granulated zinc. A third process is, to boil with stannous chloride and a large excess of hydrochloric acid, which will produce ammonium chloride from a nitrate ; and by boiling, the liquid with excess of potassium hydrate, the ammonia gas may be evolved. 36. SEPARATION OF CHLORIDES, IODIDES, AND BROMIDES FROM NITRATES. Digest with argentic sulphate, which will precipitate the hallogens as silver salts, and leave the nitrate in solution. 37. CYANOGEN,* HYDROCYANIC ACID, and CYANIDES. Cyanogen is a colourless gas, which is recognised, — ■ 1. By its odour of bitter almonds. 2. By its burning in the air with a peach-blossom coloured flame, pro- ducing carbonic anhydride and nitrogen. Hydrocyanic Acid is volatile, soluble in water, and possesses a characteristic faint sickly odour. Its reddening action on litmus paper is very transient. Its tests are four in number, as follows : — I. The Silver Test . — Argentic nitrate added to a solution of prussic 64 DETECTION OF ACIDULOUS RADICALS. acid, gives a curdy white precipitate of argentic cyanide. The . precipitate is soluble in ammonium hydrate and in strong boil- ing nitric acid, but not in dilute nitric acid ; nor does it blacken on exposure to the light. Dried and heated it darkens, evolving half its cyanogen, leaving a mixture of silver and argentic para- cyanide. During the action effervescence is observed, and a bright glow seems suddenly to pass through the mass. 2. Scheele's Iron Test. — An excess of solution of potassium hydrate is mixed with the solution. To this a mixture of a ferrous and a ferric salt is added, and the whole acidulated with hydrochloric acid. If hydrocyanic acid be present, Prussian blue will be formed. The explanation of the test is as follows (according to Gerhardt’s view). (1) The hydrocyanic acid and the potassium hydrate form potassium cyanide. (2) The addition of the ferrous salt produces ferrous cyanide. (3) This reacting with the excess of alkali forms potassium ferrocyanide. (4) On the addition of the ferric salt, it is at first precipitated by the excess of alkali, as ferric hydrate, which on acidulation dissolves to ferric chloride, forming ferric ferrocyanide (Prussian blue). (1) 6HCy-!-6KK0 = 6KCy + 6H20. (2) 6KCy + 3FeClo-3FeCyo + 6KCl. (3) 3FeCy2 + 4KHO = K4FeCy6 + 2Fe2HO. (4) 3K4FeCyg + 2Fe2Clg = (Fe2)23FeCyg + 12KCI. Or the whole may be shown in one equation, thus, which is quite suffi- cient : — i8KCy + 3FeCl2 + 2Fe2Clg = (Fe2)o3FeCyg + 18KCI. 3. The Sulphur Test. — A few drops oi yellow ammonium sulphydrate is added to a solution of hydrocyanic acid, and the whole evapo- rated to dryness at a very gentle heat, with the addition of a drop of ammonium hydrate. A residue is thus obtained which strikes a blood-red colour with ferric chloride, not dischargeable by hydrochloric acid, but at once bleached by solution of mercuric chloride. This colour is due to the formation of ammonium sulphocyanide (which takes place when an alkaline sulphide, containing excess of sulphur, is brought into contact with cyanogen) — 2HCy + (NHJ2S + 82= 2NH^CyS + H2S. and subsequent production of red ferric sulphocyanide. 4. SchbnheiEs Test. — It has been stated that a Very delicate means of detecting HCy is based upon its action on filtering paper, soaked, first, in a three-per-cent, alcoholic solution of guaiacum resin, and then in a two-per-cent, solution of cupric sulphate, and exposed to the air. The presence of HCy causes the pro- duction of a blue colour. The paper may be either moistened with the suspected solution or exposed to its vapour. Cyanides are known, — 1. By giving off the odour of hydrocyanic acid when heated with sul- phuric acid. 2. By answering to all the tests for hydrocyanic acid above mentioned. 3. In using the silver test to a soluble cyanide, the reagent must be added in excess, as argentic cyanide is soluble in alkaline cyanides to form double cyanides of silver and the alkali used. CYANOGEN COMPOUNDS, 65 Excess of argentic nitrate, however, decomposes these com- pounds, and forms insoluble argentic cyanide. The previous addition of a slight excess of dilute nitric acid ensures the imme- diate separation of the argentic cyanide, by preventing the re- action just referred to. 4. Insoluble, cyanides yield cyanogen when heated per se in a small dry test-tube, the open end of which has been drawn out into a jet after the introduction of the cyanide. The application of a light to the jet causes the characteristic flame of cyanogen. 38. SEPARATION OF CYANIDES FROM CHLORIDES. Acidulate slightly with nitric acid, add excess of argentic nitrate, wash the precipitate thoroughly with boiling water by decantation, allow it to settle completely, pour off all the water, and boil with strong nitric acid, when the argentic cyanide dissolves, leaving the chloride insoluble. The solution in nitric acid is diluted and hydrochloric acid added, when any dissolved silver is detected by precipitation, as chloride. 39. CYANIC ACID and CYANATES, CYANURIC ACID, and FULMINIC ACID. Cyanic acid is characterized, — 1. By being a colourless liquid, having a strong pungent odour, greatly resembling acetic acid, or sulphurous acid when in small quantity, and forming ammonium bicarbonate on adding water. 2. By changing into a white solid isomer oxi keeping, heat being evolved, but no decomposition occurring. Cyanates are known, — 1. By giving, when moistened, a bicarbonate. (The potassium salt — KCyO — for instance, forms potassium bicarbonate — KHCO3.) 2. By producing urea when evaporated with an ammonium salt. Cyanuric acid is a polymeric modification of cyanic acid, which is recognised, — 1. By being a crystalline solid, yielding cyanic acid on applying heat. 2. By not being decomposed by strong hot HNO3 or H2SO4. Fulminic acid (intermediate between the two above acids) differs from both By the fearful explosibility of its salts. 40. THIOCYANIC ACID and THIOCYANATES (Snlphocyanates). Sulphocyanic acid is known. By being a colourless very acid liquid, which is not poisonous. Snlphocyanates are recognised, — 1. By being usually colourless and soluble, and evolving hydrocyanic acid and depositing sulphur on heating with sulphuric acid. 2. By producing with a ferric salt, a blood-red solution of ferric siilphocyanate — Fe26CyS — the colour of which is not destroyed by HCl, but disappears on adding mercuric chloride — HgClg. 41. FERROCYANIC ACID and FERROCYANIDES. Ferrocyanic acid (or hydroferrocyanic acid) is recognised, — By being colourless at first, but rapidly decomposing and depositing Prussian blue. VOL. II. F 66 DETECTION OF ACIDULOUS RADICALS. Ferrocyanides are mostly insoluble in water, except those of the metals of the first and second groups. They are characterized, — 1. By giving off hydrocyanic acid and forming a deposit on heating with sulphuric acid. 2. By giving with a ferrous salt a white precipitate of ferrous potassium ferrocyanide — K2Fe(FeCyg) — changing quickly to blue. 3. By yielding with a ferric salt a dark blue precipitate of /erne ferrocyanide — (Feo)23(FeCyg). This precipitate and (i) are both insoluble in HCl, but KHO decomposes them, producing potassium ferrocyanide. When it is boiled with HgO and water, mercuric cyanide — HgCy — and FegOg remain. 4. Cupric salts produce a reddish-brown precipitate of cupric ferro- cyanide — CugFeCyg — insoluble in acids, dissolved by NH^HO, but left unaltered on evaporating off the ammonia. 5. By precipitating a white ferrocyanide from a solution of a lead salt. 6. By yielding a white mercuric ferrocyanide in a mercuric solution. 7. By giving no effect with magnesium salts but a white gelatinous precipitate, soluble in NH4,H0 on the addition of a solution containing a zinc salt. 8. By producing with argentic nitrate — AgN O3 — white gelatinous silver ferrocyanide, dissolved by NH^FtO. None of these precipitates can be produced in alkaline solutions; and they form best in neutral., or slightly acid, solutions. 42. FERRICYANIC ACID and FERRIC YANIDES. Ferricyanides are based upon hydroferricyanic acid (or ferricyanic acid) — HgFe2Cy|2 — which is characterized, — By being a reddish-brown liquid decomposed by boiling, with evolu- tion of HCy. Most ferricyanides are insoluble, those of the alkalies and of the barium group being exceptions. They are recognised, — 1. By yielding an odour of hydrocyanic acid, and a deposit on heating with sulphuric acid. 2. By producing with a ferrous salt dark-tinted TurnbulPs blue — Fe3Fe2Cy;^2 — insoluble in acids, but forming KgFe2Cyi2 when boiled with KHO. 3. By producing a brownish coloration when added to a ferric salt in solution, from which H2SO3, Stannous Chloride— SnCl2 — and other reducing agents throw down TurnbiUIs blue or Prussian bhte {distmctmi between HgFe2Cyi2 cind H^^FeCyg). 4. By giving no precipitate in a lead solution {another distinction of a ferricyanide from a ferrocyanide). 5. By throwing down mercurous ferricyanide of a brownish-red colour from a mercurous solution. 6. By yielding with argentic nitrate solution an orange precipitate of argentic ferricyanide. 7. Mercuric salts, giving no precipitate. 8. Stannous salts, a white precipitate, soluble in HCl. 9. Stannic salts, no visible alteration. 43. SEPARATION OF FERRO- FROM FERRI- CYANIDES. Acidulate with hydrochloric acid, add excess of ferric chloride, warm gently \ the ferro-cyanide will be precipitated. Pour off some of the brownish PHOSPHORUS COMPOUNDS. 67 liquid and heat with a little zinc amalgam, when a blue precipitate will form, owing to the reduction of the ferri- to ferro- cyanide. 44. DETECTION OF CYANIDES IN THE PRESENCE OF FERRO- AND FERRI- CYANIDES. Acidulate slightly with nitric acid and add an excess of a mixture of ferrous and ferric sulphates, warm gently, and allow the precipitate to subside. Pour off a little of the supernatant liquid, add to it excess of potassium hydrate and then acidulate with hydrochloric acid, when the production of another blue precipitate will prove the cyanide. 45. PHOSPHORUS and PHOSPHIDES. The non-metal phosphorus has two varieties, characterized and distinguished as follows : — A. Ordmary phosphorus. This is a yellowish wax-like solid, inflammable in a warm room, when exposed to the air in a dry state. Solu- ble in ether. B. Red, or amorphous phosphorus. This is a dark reddish-brown solid, not readily inflammable. Not giving off vapours when exposed to the air, nor soluble in ether and CSg. Phosphides are of little importance. They have usually the odour of phos- phorus, and give off spontaneously inflammable phosphuretted hydrogen with water or dilute acid. 46. HYPOPHOSPHOROUS ACID and HYPOPHOSPHITES. Hypophosphites are based upon the hydrogen salt, which is a colourless liquid, oxidized in the air. The silver salt alone is insoluble in water, and few are insoluble in alcohol. The following reactions serve for their detection : — 1. When heated in a solid state, they take fire, evolving phosphuretted hydrogen, and leaving a residue of pyrophosphate. 2. With argentic nitrate they give a white precipitate, which turns brown owing to its reduction to metallic silver. 3. With mercuric chloride they yield, when slightly acidulated with HCl, a precipitate of calomel, which, on heating, turns dark, owing to a reduction to the metallic state. 4. Treated wdth zinc and sulphuric acid (nascent hydrogen) they yield phosphuretted hydrogen. 5. After removal of the base, the free hypophosphorous acid, when boiled with solution of cupric sulphate, will give a deposit of metallic copper. 6. Treated with ammonium molybdate they give a fine blue precipitate. As afterwards mentioned, phosphates give a yellow, and conse- quently when the solution contains both classes of salts the precipitate is green. This forms an excellent and rapid me .hod of checking any commercial sample of hypophosphites. They are distinguished from phosphites by not giving precipitates with neutral barium, or calcium, chloride, or with plumbic acetate. The 4th reaction above given is equally applicable to phosphites. In performing the 5th reaction, the base, if calcium, is removed by oxalic acid, if barium, by sulphuric acid, and if a heavy metal, by sulphuretted hydrogen. 68 DETECTION OF ACIDULOUS RADICALS. 47. PHOSPHOROUS ACID and PHOSPHITES. Phosphites are formed from phosphorous acid, which is the only comparatively stable liquid possessing the power of evolving hydrogen phosphide — PHg — on being heated. The salts are distinguished as follows 1. Heated on platinum foil, they burn. They are powerful reducing agents. 2. The only phosphites soluble in water are those of K, Na, and NH^, but acetic acid dissolves all, except plumbic phosphite. 3. With zinc and sulphuric acid , (nascent hydrogen) they yield phos- phuretted hydrogen, burning with an emerald-green colour, and throwing down AggP, as well as Ag from AgNOg in solution. 4. They give precipitates with neutral barium, and calcium, chlorides, and also with plumbic acetate, which hypophosphites do not. 5. Heated with mercuric chloride or argentic nitrate, they yield a precipitate of metallic mercury or silver. 2 HgCla 4 - aHgPPg 4- zH^O = zHgPO^ 4- Hgg 4- 4HCI. 48. META- AND PYRO- PHOSPHORIC ACIDS AND THEIR SALTS. As already stated in Part I., phosphoric anhydride can combine with water in three proportions, forming either meta-, pyro-, or ortho- phosphoric acids, each of which can form salts. Metaphosphoric Acid is a glassy solid, not volatile by heat. It is freely soluble in cold water, and is converted by boiling into orthophosphoric acid. It is known by giving a white precipitate with argent-ammonium nitrate, and by its power of coagulating albumen. Metaphosphates are known by, — 1. Giving no precipitate with ammonium chloride, ammonium hydrate, and magnesium sulphate, added successively. 2. By giving a white precipitate of argentic metaphosphate — AgPOg — with argentic nitrate only in neutral solutions, and soluble both in nitric acid and ammonium hydrate. Pyrophosphoric Acid is also soluble in water and convertible by boiling into orthophosphoric acid. It gives a white precipitate with argent-ammonium nitrate, but does not coagulate albumen. Pyrophosphates are insoluble in water, except those of the alkalies. Their tests are not very well defined, but they give, — 1. A white precipitate of argentic pyrophosphate — Ag4.P207 — with argentic nitrate in a neutral solution only and soluble both in nitric acid and ammonium hydrate. 2. NH4M0O4 does not produce an immediate precipitate. 49. ORTHOPHOSPHORIC ACID (B.P.) and ORTHOPHOSPHATES. B.P. Phosphoric acid is a liquid with a strongly acid reaction, which is con- verted by heat first into pyro- and finally into meta- phosphoric acid, which remains as a glassy residue. It is, — 1. Not volatile by a red heat. 2. It gives a yellow precipitate of argentic phosphate — Ag3P04 — when treated with argent-ammonium nitrate, soluble both in nitric acid and ammonium hydrate. Phosphates are as a rule insoluble in water, except the alkaline ones. They are readily soluble in dilute acids and entirely re-precipitated on neutral- izing by an alkali or alkaline carbonate. Calcium, strontium, and barium PHOSPHATES. 69 phosphates are only partly soluble in dilute sulphuric acid, being converted into a soluble phosphate and an insoluble sulphate of the metal. If the insoluble sulphate be filtered out, the addition of an alkali causes only a slight precipitate of a dimetallic phosphate, and a phosphate of the alkali used is left in solution; but it is only after the use of sulphuric acid that any phosphate thus remains dissolved. The presence of Phosphates is detected as follows : — I. With barium or calcium chloride white precipitates are produced, soluble in acetic acid (distinction from oxalates) and all stronger acids. 1. With argentic nitrate a lemon yellow precipitate of argentic phosphate forms, soluble both in nitric acid and ammonium hydrate. 3. With ferric chloride in the presence of ammonium acetate a white precipitate of ferric phosphate appears, insoluble in acetic acid. 4. With magnesia mixture phosphates yield a white crystalline pre- cipitate, forming slowly in dilute solutions, consisting of ammo- nium-magnesium phosphate — Mg(NH^)P04 + bHgO — soluble in acetic and all acids. 5. With solution of ammonium molybdate in nitric acid a yellow precipitate is produced, insoluble in nitric acid, but soluble in ammonium hydrate. 6. With uranic nitrate phosphates yield a yellow precipitate of uranic phosphate, also insoluble in acetic acid. 7. With mercurous and bismuthous nitrates white precipitates are formed, the former soluble and the latter insoluble in nitric acid. 8. With any soluble salt of lead a white precipitate of plumbic phosphate is produced, soluble in nitric acid, but insoluble in acetic acid or ammonium hydrate. It is important to note that all these reactions may be caused by arsenic acid, except that with argentic nitrate, argentic arseniate differing from argentic phosphate in being brick-red instead of yellow. 50. DETECTION OF A PHOSPHATE IN THE PRESENCE OF CALCIUM, BARIUM, STRONTIUM, MANGANESE, AND MAGNESIUM. Dissolve in water by the aid of the smallest quantity of nitric acid, then add excess of ammonium acetate, which will remove the excess of nitric acid with- out rendering the solution alkaline. In this solution the phosphate may be proved by adding a drop or two of ferric chloride and warming, when a white precipitate of ferric phosphate — Fe22P04 — will form, insoluble in the acetic acid liberated. 51. DETECTION OF A PHOSPHATE IN THE PRESENCE OF IRON, CHROMIUM, AND ALUMINIUM. Dissolve in the smallest possible quantity of hydrochloric acid, add some citric acid, and then excess of ammonium hydrate. By this means an alkaline liquid is obtained, owing to the power of the organic acid to prevent the pre- cipitation of the metal by the ammonium hydrate ; and in this liquid, when cold, mag 7 iesia mixture (ammonio sulphate of magnesia) causes the precipitation of white crystalline magnesium-ammonium phosphate. 70 DETECTION OF ACIDULOUS RADICALS. 52. DETECTION OF Fe, Ce, Cr, Al, Mn,Ca, Sr,Ba, and Mg IN THE PRESENCE OF PHOSPHORIC ACID (SEPARATION OF METALS OF THE 3rd AND 4th GROUPS WHEN PRECIPITATED AS PHOSPHATES). The separation of the insoluble phosphates of the metals of the 3rd and 4th groups is a very important point, as, in the case of the presence of phosphoric acid, the entire inodiis operandi already given under the separations of the metals, is useless. To determine the presence or absence of this complication, the solution, after removal of the metals of the ist and 2nd groups by HCl and HgS, is evaporated to dryness and the residue heated to destroy oxalates and other organic matters. The residue is then dissolved in hydrochloric acid, diluted, and boiled with a few drops of nitric acid to raise any iron to the ferric state. A small portion of this prepared solution is then mixed with excess of nitric acid and ammonium molybdate — NH4M0O4, — and warmed for some time, when the production of a yellow precipitate of ammonium phospho-molybdate proves the presence of phosphates. When this has been discovered, the remainder of the solution is treated with ammonium chloride and ammonium hydrate, as already explained under the metals, the group precipitate is filtered out and dissolved in the smallest possible quantity of hydrochloric acid. To this solution is added first a quantity of disodium hydrogen phosphate, and then an excess of ammonium acetate containing some free acetic acid, and the whole is boiled and filtered. By this means the phosphates are divided into two groups as follows : — A. Insoluble in acetic acid, and consequently on the filter— Fe, Ce, Al, and a little Cr. B. Soluble in acetic acid, and consequently remaining in the filtrate, — . Ba, Sr, Ca, Mn, Mg, and the bulk of the Cr. These groups are then to be treated as follows ; — A. Percolate the precipitate with a little boiling dilute solution of potassium hydrate ; when any aluminium phosphate will dissolve, and be found in the filtrate by boiling with a slight excess of acetic acid. The insoluble matter on the filter is dissolved in dilute hydrochloric acid, and a portion of the solu- tion tested for iron by potassium ferrocyanide. To the remainder of the solution add some citric acid, then excess of ammonium hydrate, and finally ammonium oxalate, when the production of a white precipitate of cerous oxalate proves cerium. B. The solution, if green, contains chromium, and a little of it evaporated to dryness with excess of potassium hydrate and a crystal of potassium chlorate, and the residue heated to redness, becomes green, if manganese be present. (See 53.) Add to the remainder of the solution potassium chromate in slight excess, and warm, when any barium separates as barium chromate. Filter, if necessary, and add a few drops of very dilute sulphuric acid ; warm, and let it stand for some time, when strontium will precipitate as strontium sulphate, insoluble on filtering out and boiling with strong solution of ammonium sulphate containing a slight excess of ammonium hydrate. Add to the filtrate some more ammonium acetate, and then excess of ammonium oxalate, and warm, when calcium will separate as calcium oxalate. Filter, if necessary, cool thoroughly, and add some citric acid and excess of ammonium hydrate, when any manganous or magnesium phosphate will be re-precipitated. If no manganese was previously found by the fusion, then this is all mag- nesium; but if manganese be present, the following separation must be applied to the precipitate after filtering. The addition of citric acid is un- necessary if no chromium be present. ARSENIOUS ACID AND ARSENIDES. 71 53. SEPAEATION OF MANGANESE AND MAGNESIUM PHOSPHATES. Dissolve in HCl, add excess of ammonium acetate, boil, and drop in ferric chloride until the precipitate turns red, then filter. This removes the phos- phoric acid, and leaves the Mn and Mg in solution as chlorides. To this solution add NHCl, NH^HO, and NH^HS, and warm, when the manganese •will precipitate. Filter, cool the filtrate thoroughly, and add some more am- monium hydrate and some disodium hydrogen phosphate, when the magne- sium will separate as a white precipitate of magnesium ammonium phosphate. 54. DETECTION OF CHROMIUM IN THE PRESENCE OF MANGANESE AFTER FUSION. The deep green of the potassium manganate produced by the fusion, entirely masks any yellow potassium chromate which may be formed at the same time. On treating the manganese residue with water, it gives a gj'een solutio?i., which is eiitU'dy decolorized by boiling with hydrochloric acid and dropping in recti- fied spirit. On the other hand a chromium residue gives a yellow solution^ turned green by a similar treatment. If, therefore, on thus boiling with acid and spirit, any green colour remains undischarged, then chromium was present as well as manganese. 55. ARSENIOUS ACID and ARSENITES. Arsenious Acid — HgAsOg — is not known in the free state \ but its anhydride — AS2O3 — is common. The latter has the following qualities : — 1. Dropped upon red-hot charcoal or coal, or heated in a dry tube with black flux, or a mixture of dry sodium carbonate and potassium cyanide, the metalloid As is set free, and volatilizes with a garlic odour, producing a steel-grey mirror on the sides of the tube. 2. Dissolved in water only, and argent-ammonium nitrate added, a canary-yellow precipitate of argentic arsenite — AggAsOg — is produced, soluble in excess of either NH4HO or HNO3. 3. A pure aqueous solution, mixed with cupr-ammonium sulphate, gives a bright-green cupric arsenite — Scheele's green— also soluble in NH4HO or in HNO3. 4 . Any solution yields all the tests for arsenic (see page 33 ). Arsenites behave peculiarly in many respects. Ammonium arsenite leaves arsenious acid on evaporating a solution, while potassium and sodium arsenites possess a degree of alkalinity which no excess of arsenious acid will disturb. Ba, Sr, and Ca form soluble hydrogen salts. All other arsenites are insoluble. Neutral solutions of arsenites are possessed of the undermentioned distinctive peculiarities : — 1. CUSO4 throws down greenish cupric arsenite. 2. AgN03 is transformed into yellow insoluble argentic arsenite. 3. H2S does not form a precipitate, except in the presence of hydro- chloric acid, when yellow arsenious sulphide falls. 4 . The solution gives the usual tests for arsenic (see page 33 ). 56. ARSENIC ACID and ARSENIATES. Arsenic Acid — H3ASO4 — is known definitely, but its anhydride — AsgOg — is also of some importance, and should be first considered. It is recognised, — ■ 72 DETECTION OF ACIDULOUS RADICALS. By being a white crystalline solid, totally volatilized at a very bright red heat, owing to splitting up into AsgOg and oxygen. The acid is known by the following characters : — 1. The crystals are deliquescent, white, and strongly acid. Before being dried at 212° F., they contain water of crystallization. 2. If heated to 300° F., they, produce pyro-arsenic acid — H4AS2O7 — which develops heat on being dissolved in water. More Strongly heated (403° F.) metarsenic acid — HAsO^ — results, and finally AsgOs- 3. It is strongly corrosive, and blisters the skin. It gives hrick-red Ag3As04 on adding argent aiiimonium nitrate. Arseniates are characterized by behaving in every respect exactly like phos- phates, except that they give a brick-red precipitate with argentic nitrate, instead of a yellow. Insoluble arseniates are best treated by boiling with NaHO, filtering, exactly neutralizing the filtrate with dilute HNO3, and then getting the brick-red precipitate with AgN03. 57. SEPARATION OF AN ARSENIATE FROM A PHOSPHATE. This can only be done by acidulating with hydrochloric acid, and diligently passing a slow stream of sulphuretted hydrogen through the solution, kept warm until the whole of the arsenic is removed. 58. MANGANIC ACID and MANGANATES. Manganic Acid — H2M11O4 — is not known in the free state, neither is its Anhydride — Mn03— but the salts are well known. Manganates are unstable compounds, and only the alkaline salts dissolve in water, forming green solutions. 1. Soluble manganates decompose spontaneously, depositing MnOg (or MnOzHO), the green colour changing to purple or reddish violet, owing to the formation of a permanganate. 3K2Mn04 + 3H2O = KgMngOs + 4KHO -f MnOzHO. 2. Dilute acids effect this change more rapidly, and the reaction is very delicate. The free hydrate is then replaced by a chloride, nitrate, or sulphate. 3. Strong, heated H2SO4 acts as represented in this equation : — K2Mn04 -f 2H2SO4 = K2SO4 -f MnS04 + -F Og. 4. Strong HCl causes the evolution of Cl The other actions are similar to those of permanganates, but less energetic. 59. PERMANGANIC ACID and PERMANGANATES. Permanganic Acid appears to be a violet liquid, volatilized in fumes of the same colour by heat, and condensing to a dark-brown sublimate. It de- composes below 100° F., evolving oxygen, and is stated to be a power- ful bleaching agent. It attracts moisture strongly, and detonates when quickly heated, ddie salts (permangantes) behave as follows : — Permanganates are known, — 1. By the magnificent violet colour of their solutions, which is entirely bleached by oxalic acid or by heating with hydrochloric acid and dropping in rectified spirit. 2. By giving off oxygen on heating and leaving a green residue. CHROMIC, STANNIC, ANTIMONIC ACID. 73 3. By giving off oxygen when heated with sulphuric acid, often with explosive violence. 4. By evolving chlorine when simply mixed with hydrochloric acid. 60. CHROMIC ACID and CHROMATES. Chromic Acid — H2Cr04 — not being definitely proved to exist, is represented by its anhydride — CrOg. This is a dark-red crystalline solid, and when mixed with an aqueous solution of hydrogeii peroxide — H2O2 — a deep blue liquid results, which is believed to contain perchromic acid — HCr04 or H2Cr20g. The liquid decomposes rapidly, unless ether be added, which lengthens its existence. This test, for either CrOg or H2O2 is exceedingly delicate, the ethereal solution of perchromic acid separating from the water and thus concentrating the colour into a small bulk of ether. Chromates of the alkalies are soluble, while those of the other metals are chiefly insoluble, but have very brilliant colours. They are very poison- ous, and are detected as follows : — 1. Soluble chromates give a yellow precipitate with plumbic acetate or barium chloride, soluble in nitric acid, insoluble in acetic acid. The lead salt is darkened in colour by alkalies, and dissolves by free excess of hot KHO. 2. With argentic nitrate a dark-red precipitate, also soluble in nitric acid, and in NH4HO, but not in acetic acid — HC2Hg02. 3. Boiled with hydrochloric acid, and alcohol, or any reducing agent, (for instance, sulphurous acid — HgSOg) they turn green, owing to the production of chromic chloride (or sulphate). 4. Treated with sulphuretted hydrogen, in the presence of hydrochloric acid, they turn green, and a deposit of sulphur takes place : — 2K2Cr20y + 16HCI + 6H2S = 2Cr2Clg + 4KCI -f- 3S0 + 14H2O. 5. Chromates, when treated with an acid, turn orange; and dichro- mates, when treated with potassium hydrate or any alkali, turn yellow. In this way they are mutually distinguished. 6. Heated with strong H2SO4 they give off oxygen. 7. Treated with an excess of sulphuric acid, and shaken up with ozonized ether (solution of hydric peroxide in ether), they give a gorgeous blue with the most minute traces. 61. STANNIC ACID and STANNATES (Stannites ?). This is an unimportant compound, and is thrown down by an alkaline hydrate from a stannic salt. It is sometimes stated to be endowed with the com- position Sn4HO, and at others, Sn02HO(HoSnOg). Stannates are formed by the solution of the acid in an alkaline hydrate, and are detected in the examination for metals. Stannites are said to be formed by the solution of stannous hydrates in an alkaline hydrate. They decompose on boiling with KHO, forming stannates and throwing down metallic tin. 2Sn2HO + 2KHO = KgSnOg + Sn -f- 3H2O. 62. ANTIMONIC ACID. This is the white precipitate having the composition HSbOg formed on adding strong HCl to potassium antimoniate ; and it is detected in the examination for metals. 74 DETECTION OF ACIDULOUS RADICALS. 63. FORMIC ACID and FORMATES. Formic acid — HCHOg — is the organic ” acid which contains the highest percentage of oxygen and approaches most nearly in composition to the supposititious carbonfc acid — HgCOg. It is a tolerably stable liquid, boiling at the same temperature as water. Formates are all soluble in water; under the influence of heat and reagents formic acid behaves as follows : — 1. Distils without blackening or decomposition, the vapour being very acid. 2. Heated with H2SO4 it evolves CO, which, being free from COo, gives no effect when passed through lime-water, but burns with the usual pale blue flame. 3. It is distinguished from other acids derived from carbon (except carbonic and oxalic), by not undergoing charring, when mixed with sulphuric acid and heated. The reaction is : — H2SO4 + HCHO2 = H2SO4 + CO + HgO. 4. It readily reduces argentic nitrate, when mixed with a little solution of sodium hydrate, and heat applied, metallic silver separating. It does not reduce platinic and auric chlorides when boiled with them, unless sodium or potassium hydi'ate he added. This is owing to the volatility of the acid. 64. DETECTION OF A FORMATE IN THE PRESENCE OF FIXED ORGANIC ACIDS WHICH REDUCE SILVER SALTS. Distil with dilute sulphuric acid at the heat of a water bath, neutralize the distillate with sodium carbonate, add a slight excess of acetic acid, and boil with argentic nitrate, when a dark deposit of metallic silver will form. 65. ACETIC ACID and ACETATES. This acid is characterized by its boiling point, its odour of vinegar, and the difficulty with which it is oxidized. The strong acid chars when heated with strong H2SO4. Acetates are without exception soluble in water (AgC2H302 and HgC2Hg02 are sparingly dissolved). They are decomposed by a red heat, yielding acetone if the heat rise gently and the mass be not alkaline, and leaving a carbonate, oxide, or metal, according to the nature of the basylous radical. When heated with alkalies 7 ?iarsh-gas — CH4 — is evolved. The reaction is of this type : — NaC2H302 + NaHO = Na2C03 + CH4. In the case of no hydrate or carbonate being present, the following is an example of the effect of heat on acetates : — Ba2(C2H302) = BaC03 + (Acetone). Acetates of easily reducible metals, such as copper, yield, when heated, a distillate of acetic acid, leaving a residue of the metal, or, in some cases, of oxide. The presence of acetates is analytically determined as follows : — 1. By evolving an odour of acetic acid when heated with sulphuric acid. 2. By a characteristic apple-like odour of “ acetic ether,” — C2H5(C2H302) — which they evolve when heated with sul- phuric acid and rectified spirit. 3. By the deep red colour which they produce with neutral ferric VALERIANIC, OLEIC ACID. 75 chloride, — ferric acetate Fe2(C2Hg02)6 — dischargeable by both hydrochloric acid and mercuric chloride. 4. Mercurous nitrate, when added to ^n acetate in strong solution, yields a crystalline white precipitate, which, on heating, leaves a residue of metallic mercury. This reaction is not, however, characteristic. 66. VALERIANIC ACID and VALERIANATES. Valerianic acid is a liquid, which is : — Volatile, malodorous, colourless, and oily. It reddens test-paper, and dissolves in most menstrua. The general characters of Valerianates are : — 1. A more or less strong odour of valerian root when warmed or moistened. 2. They give, when heated with sulphuric acid, a distillate, which, on the addition of solution of cupric acetate, forms, after the lapse of some time, an oily precipitate ; gradually solidifying, by the absorption of water, into a greenish-blue crystalline solid. 67. SULPHOVINATES (Ethylsnlphates). These salts, derived from ethyl hydrogen sulphate, behave as follows : — 1. Heated with strong sulphuric acid, they evolve a faint ethereal odour. 2. They give no precipitate in the cold with barium chloride ; but on boiling, a white precipitate of barium sulphate falls, and a smell of alcohol is perceived. The addition of a little solution of barium hydrate after the chloride and before boiling facilitates the reaction ; but in this case all metals precipitable by a fixed alkali must first, of course, be removed. 3. Heated to redness, they leave a sulphate of the metal. 4. Heated with sulphuric acid and an acetate, or with strong acetic acid, they evolve acetic ether with its characteristic apple odour. 68. STEARIC ACID and STEARATES. This acid is usually so distinguished by its appearance and behaviour on being heated, that further tests are useless. The characters are : — 1. A white, odourless, fatty solid, melting by heat, and then exhibiting an acid reaction. 2. Giving, when dissolved in KHO and the solution as nearly neutral- ized as possible, a white insoluble precipitate of plumbic stearate — Pb2(Ci8H3502)— on the addition of plumbic acetate, which is insoluble in ether (distinction from plumbic oleate). Stearates of the alkalies are alone soluble in water. Any stearate heated with dilute HCl gives the free acid, which floats as an oily liquid, solidifying on cooling to a white mass. This test is applicable to the analysis of soap {hard, containing Na, or soft, in which K is present). 69. OLEIC ACID and OLEATES. Oleic Acid is usually an oily liquid, but remains solid below 59° F. when crystallized from alcohol. It has no reaction, taste, nor odour, does not dissolve in water, but is taken up by cold H2SO4 (with decomposition) and by ether. 76 DETECTION OF ACIDULOUS RADICALS. Oleates of K and Na alone dissolve in water. Acid oleates are all liquid and soluble in cold absolute alcohol and ether. 1. They do not separate out from either of these solvents when a hot solution is cooled {distinction from stearates a 7 id palmitates\ 2. Plu 7 nhic oleate is precipitable like plumbic stearate, but is separated and distinguished from it by dissolving in ether. 70. LACTIC ACID and LACTATES. Tlie pure strong acid resembles glyce 7 'in in appearance, liberates hydrogen on adding zinc, and distils with partial decomposition. It dissolves in ether. It gives pure CO when heated with sulphuric acid. Lactates are not very soluble in water. They, — 1. Are insoluble in ether. 2. Arge 7 itic Lactate — AgCgHgOs — when boiled gives a dark precipitate, which on subsidence leaves a blue liquid. 3. Strong solution of an alkaline lactate when boiled with HgNOg, de- posits C 7 'i 77 is 07 i or pi 7 ik mercurous lactate — HgC3H503. 71. OXALIC ACID and OXALATES. The acid is very common, and is recognised, — 1. By its colourless prismatic crystals, which are strongly acid, effloresce when exposed to dry air, and volatilize on heating with partial decomposition. 2. By the complete discharge it effects of the colour of a solution of potassium permanganate — KoMn^Og — acidulated with dilute H2SO4. 3. By reducing AUCI3 with the precipitation of the metal. 4. By producing free H2SO4 when added to solution of CUSO4. (This is one of the very rare instances in which SO4 is replaced by another acid radical and H2SO4 liberated.) 5. By giving the reactions of an oxalate. Oxalates of the alkalies are soluble, the others insoluble, in water. Insoluble oxalates dissolve in hydrochloric but not in acetic acid. They are known by — 1. Not charring when heated, but only turning faintly grey; followed by a sudden glow of incandescence, which runs through the mass. 2. Not charring when heated with sulphuric acid, but yielding CO and CO2 with effervescence. 3. Not effervescing with cold dilute sulphuric acid; but at once liber- ating CO2 with effervescence on the addition of a pinch of manganese peroxide. 4. With calcium chloride or barium chloride in a neutral or alkaline solution, they give a white precipitate of calcium or barium oxalate, msoluhle m acetic acid, but soluble m hyd 7 'ocliloric acid. (For separation of oxalates from tartrates, etc., see No. 76.) 72. SUCCINIC ACID and SUCCINATES. This acid is a white crystalline solid. It is known, — 1. By not charring with strong hot sulphuric acid. 2. By subliming in a tube open at both ends, in silky needles, without givmg off an h'ritatmg vapour (distinction from benzoic acid). MALIC, TARTARIC ACID. 77 3. By burning, when heated on platinum, with a blue smokeless flame. Succinates are recognised as follows : — 1. With ferric chloride, a brownish-red precipitate of ferric succmate — formed. 2. With hydrochloric, and sulphuric, acids, no precipitate is produced {distmction fro?n benzoates). With phwibic acetate, a white pre- cipitate of plumbic succinate, soluble in succinic acid, succinates, and plumbic acetate. 3. Barium succinate is soluble in hydrochloric acid, hence no effect results from the addition of succinic acid to barium chloride ; but alcohol and ammonium hydrate give rise to a white pre- cipitate {another pomt of distinction fro 7 ti benzoates). 73. MALIC ACID and MALATES. Malic Acid — H2C4H4O5— is a colourless, crystalline, very deliquescent acid, freely soluble in water and alcohol. Acid malates are most stable. The characters are : — 1 . Calcium chloride, added to a neutral solution of a malate, gives no precipitate. Alcohol, however, even if added in small quantity, throws down a white precipitate \ and boiling aids the effect. 2. Strong H0SO4 gives no charring for some time {a tartrate is carbon- ized in a few minutes). 3. Amorphous plumbic ?nalate fuses below 100° C. in water, but not in an air-bath. 74. TARTARIC ACID and TARTRATES. Tartaric Acid — HgC^H^Og — is a strong acid, soluble in water and spirit. 1. It forms usually oblique rhombic prismatic crystals, of an acid taste. 2. It is decomposed by heat, giving off the odour of bur?it sugar, and leaving carbon. A similar effect is produced by boiling with strong H2SO4, which blackens and carbonizes it in a few minutes. 3. With potassium acetate — KC2H3O2— it produces a white crystalline precipitate of potassium hydrogen tartrate — KHC^H^Og — in either an aqueous or an alcoholic solution, soluble in much water, but not in spirit. Stirring or violent shaking promotes the formation of the salt. The same compound is produced on adding any potassium salt, provided the liquid contain free excess of tartaric acid only. Tartrates of the alkalies are mostly soluble ; but the others are insoluble. The hydrogen tartrates of K and (NH^) are nearly insoluble. Tartrates are recognised by the following characters ; — 1. Heated to dull redness they char rapidly and give off a smell of burnt sugar. The black residue contains the metal as car- bonate if it be K, Na, Li, Ba, Sr, or K ; but the tartrates of other metals usually leave the oxides, or more rarely (as in the case of Ag2C4H^Og) the metal. 2. Heated with strong sulphuric acid, they blacken rapidly, and give first a smell of burnt sugar, and afterwards evolve SOg. 3. Neutral solutions (free from more than a trace of ammonium salts) give, on adding calcium chloride, a white precipitate of calcmm tartrate, which, when freed from other salts by washing, dissolves readily in cold solution of potassium hydrate, but is again pre- DETECTION OF ACIDULOUS RADICALS. to cipitated on boiling. The precipitate is soluble in NH^Cl, but not in NH^HO. 4. Mix a tartrate with sodium carbonate, and filter the slightly alkaline solution, so that the only metal present shall be sodium. If this clear solution, after slight acidification with acetic acid, be mixed with argentic nitrate, the whole, on heating nearly to boiling in a clean tube, deposits a beautiful mirror of metallic silver upon the test-tube employed. 5. A tartrate prevents the precipitation (more or less perfectly) of the salts of Pb, Bi, Cd, Cu, Pt, Peg, Mn, Ni, Co, Cr, and Zn, by an alkaline hydrate in excess, or a phosphate. 75. CITRIC ACID and CITRATES. Citric Acid — HgCgHgO^ — is soluble in water and alcohol, but insoluble in pure ether. It entirely burns away when heated to redness in the air ; blackens slowly when heated with strong sulphuric acid ; and when neutral- ized by ammonium hydrate, and the solution cooled, the solution gives no precipitate with calcium chloride until it has been boiled. Added to ferric, chromic, or aluminic salts in solution, it prevents their precipitation by ammonium hydrate. Citrates exhibit the following characters : — 1. Heated alone, they char slowly, and evolve an odour of burnt sugar, but not so intense as that of a tartrate. At a dull red heat, the citrates of K, Na, Li, Ba, Sr, and Ca leave their carbonates; but those of most other metals leave the oxides. Argentic citrate leaves the metal. 2. Heated with strong sulphuric acid, they slowly blacken, and evolve a slight odour of burnt sugar. 3. Mixed in the cold with calcium chloride, in the presence of a slight excess of ammonium hydrate, they give no precipitate ; but on boiling, calcium citrate — Ca32CgH507 — separates as a white • precipitate. If this precipitate be filtered hot, and washed with a little boiling water, it is found to be quite insoluble in cold solution of potassium hydrate, but readily soluble in neutral solution of cupric chloride. 4. Mixed with argentic nitrate and boiled, no mirror of metallic silver is produced. 76. SEPARATION OF OXALATES, TARTRATES, CITRATES, and MALATES. If the solution be acid, neutralize it with sodium hydrate ; but if neutral or alkaline, it is ready for use, and is treated as follows : — A. Acidulate slightly but distinctly with acetic acid, bring the whole to the boil, and add a drop or two of calcium chloride ; and if it produce a precipitate, add it till precipitation ceases. Keep the whole nearly boiling for a time, till the precipitate aggregates, and filter. The precipitate, after washing, should be quite in- soluble in cold solution of potassium hydrate. B. To the filtrate from {A) mixed with some more calcium chloride, ammonium hydrate is added in slight but distinct excess, and the whole thoroughly cooled. Calcium tartrate precipi- tates, and when it has settled clear, the liquid is poured off and preserved for (C). This precipitate, after washing, should MECdNIC, CARBOLIC, BENZOIC ACID. 79 be entirely soluble in cold solution of potassium hydrate, and reprecipitable by boiling. C. The liquid is slowly boiled for some time ; and if a precipitate does not form readily, a little more CaClg and NH^HO added, and the boiling resumed. The precipitate, when it begins to sub- side well, is filtered out while still hot. It should be (after washing) quite insoluble in cold solution of potassium hydrate ; but soluble in perfectly neutral solution of cupric chloride. D. To the filtrate add alcohol, when calcium malate will separate ; but this portion of the separation is not infallible, and the pre- cipitate must be carefully examined to see that it really is malate. 77. MECONIC ACID and MECONATES. Meconic Acid is a white powder, with a strongly acid reaction, soluble in water, alcohol, and ether. Meconates communicate a red colour to ferric chloride solution. This colour is not discharged by HgCl^ 7ior by dilute HCl. By this means it is distin- guished from a sulphocyanate and an acetate. 78. CARBOLIC ACID (or Phonic Acid) and CARBOLATES (Phenates). The qualities of this acid are very distinctive. 1. It is a colourless, crystalline solid, melting at 94” F., and not vola- tile at 212°, having the odour and taste of creasote, being very poisonous, and not reddening test-paper. 2. The crystals deliquesce readily, forming a liquid which does not mix freely with water, but incorporates readily with alcohol, ether, and glycerin. 3. Mixed with HCl and exposed to the air on a strip of deal, it be- comes greenish blue. 4. It coagulates albumen. It does not rotate polarized light. 5. Saturated with ammonia gas — NHg — and heated in a closed tube, anilme is formed. CgHjHO + NH3 - C6H5H2N + H2O 6. It resembles HCy in not decomposing carbonates. 7. NH4HO and CaOClg produce a blue liquid. 8. It unites directly with strong H2SO4 to form sulpho-phenic (or sulpho-carbolic) acid — CgH5HS04. Carholates give the following reactions : — 1. When heated alone, they evolve the odour of carbolic acid and de- compose. 2. Heated with strong sulphuric acid, they also smell of carbolic acid. 3. Ferric chloride causes a reddish-violet colour. Sulpho-Carholates behave similarly, but also give the reactions of a sulphate with barium chloride. 79. BENZOIC ACID and BENZOATES. Benzoic Acid is of characteristic appearance, being usually seen in light feathery, flexible, nearly colourless crystalline plates or needles, and contain- ing a trace of an agreeable volatile oil. 8o DETECTION OF ACIDULOUS RADICALS. 1. It is only slightly soluble in water, but dissolves freely in S. V. R., and in solutions of soluble hydrates. 2. Heated in the air, it burns with a luminous smoky flame ; and when made hot in a tube open at both ends, sublimes in needles giving off an irritating vapour. Benzoates possess the following general qualities : — 1. Heated with sulphuric acid they evolve the odour of benzoic acid, and darken. 2. Ferric chloride, in a solution made slightly alkaline by ammonium hydrate, gives a reddish-white precipitate — ferric benzoate — Fe26(C7H502) — soluble in acids {benzoic included). If this precipitate be now filtered out and digested in ammonium hydrate, it is decomposed into a precipitate of ferric hydrate, and a solution of ammonium benzoate, which is separated by filtration and treated as in 3. 3. Strong hot solutions of benzoates yield crystals of benzoic acid when hydrochloric acid is added, and the solution allowed to cool. 4. When distilled with potassium dichromate and sulphuric acid, they do not yield a distillate smelling of oil of bitter almonds (absence of cinnamic acid^ which would form benzoic aldehyd when treated thus). 80. CINNAMIC ACID and CINNAMATES. This may be recognised by reaction 4 {above) and also, — By giving the product of benzoic aldehyd — C^HgO — when heated with Pb02. Cinnamates yield a precipitate of, — Yellow ferric ciimamate — Fe26(CgHy02) — with ferric chloride (benzoates give a reddish precipitate). 81. SALICYLIC ACID (H2C7H^03). This acid occurs in large prisms, when crystallized from a solution in alcohol in which it is readily soluble. It is freely dissolved by hot water, but not readily by cold, requiring 1,800 parts of the latter to completely dissolve it. 1. Its aqueous solution gives with Fe2Clg a deep violet coloration. The compounds with methyl, ethyl, etc., give this reaction, as well as the ordinary salts. 2. Its methyl salt, formed by warming a salicylate with sulphuric acid and wood spirit, has a very fragrant odour. From most other solid bodies it may be separated by taking advantage of its exceptionally great solubility in ether. In the event of its presence in an organic liquid (such as milk) it or its salts may be procured in a pure condition by dialysis. The liquid is placed in a dialyser, and this floated on pure water. The salicylic acid or salicylate is found after some time to have entirely passed through the septum, and may be obtained by evaporating the aqueous solution and, when reduced in bulk, shaking with ether. 82. DETECTION OF CARBOLIC ACID IN THE PRESENCE OF SALICYLIC ACID. Boil 10 grains in half an ounce of water, cool, decant the solution and add to it I minim of a saturated solution of KHCO3, ^ niinim of aniline, and 5 drops of solution of chlormated Iwie^ when, if carbolic acid be present, a deep blue is produced. TANNIC, GALLIC, PYROGALLIC ACID. 8r 83. TANNIC, GALLIC, and PYROGALLIC ACID. Tannic Acid is soluble in water and alcohol, and very soluble in glycerin. It is insoluble in pure dry ether, but dissolves readily in ether containing a little water. Gallic Acid is slightly soluble in cold water, but readily in boiling, it is also freely soluble in glycerin, and slightly in alcohol and ether. Pyrogallic Acid is very soluble in water, the solution rapidly absorbing oxygen from the air and becoming brown. - It also dissolves in alcohol and ether. DISTINCTION BETWEEN GALLIC, TANNIC, AND PYROGALLIC ACIDS. Behaviour of the Acid with Gallic. Tannic. Pyrogallic. Ferrous Salts . . A dark solution is formed, gradually de- positing a precipitate. The same effect as Gallic. A blue solution. 1 Ferric Salts . . Purplish pre- cipitate im- mediately formed. Same as pre- ceding. A red solution. Calcium Hydrate in the fotm of Milk of Lime. A brownish pre- cipitate, be- coming deep brown in a few seconds. A white preci- pitate slowly changing. Instantaneous production of a purple so- lution becom- ing brown by oxidation. Gelatin .... No precipitate (except in the presence of gum). Immediate brownish ' precipitate. No precipitate. VOL. II. G QUALITATIVE ANALYSIS, AS APPLIED TO THE EXAMINATION OF OFFICIAL SALTS. I 82 QUALITATIVE ANALYSIS. ^ ‘d 5-1 o i-rt ^ -r! ,dl U ^ £ -| S ° S °| o g ^ 5h TH 5-( Oj "r; > ■s§.Hir|^ 8 ': ^ dJ ’X 3 ' ■ S|-g O O tiO, CU c c/3 ., oS 1 nj cA) g ^ ^ 0 ) ^ S 8 S 3 ^ g-O-S § B,“-S S o - ' g -"O S F c - 7:3 •| (U ct5 o 'F 03 (-1 'C § IF (S d c S ‘n OJ a; ^ (U O o (U FI a U1 cu ^ 1 j o '^■' (u d (u ^ fe: T3 ^ r o - ^ - -3 t3 5 -h q. F -■ F o ^ ^8 Qh.S ga a; g rF ^ S 2 ^ 2 s ''d "g S (U c ^ F bO^ -Td O ^ B B 5x X3 7 :^ rF ^ c/3 - 13 go 3 u .0 g « § 3 o o. 3 “04 rF O r^*' F ' .2 p c/3 F o ,. . 2 F 2 -73 ^ F 8 F 4-> F tf •d 2 '8 2 '1^ X! S ^ .-^ 2 73 73 ^_a o -d FU in 3 o C« cu cn f33 ^ F M-l O ^ F O ^ (U CJ .2 F X d 73 Ph d F c/3 c/3 F d O > o| §•0 c/3 F F d rv-F rrt FF F ,F .if 73 d rd ^ F ^ F 73 ^2 ^ FBi-2 F -5 8 cf rF Iz; , (u -i ^ ^ (^ >%'X2 ^ G C o ^ o cr* c G , 0 ) ^ rt r-. . O - 8^*0 > G .t:J H s 0.2 ••' .2 _ _ _ cd >H rj c^ c^ W'O 8 o te ^ }-( td^ 3 , ’o G X 'X> m 3 gj Ml U ^ iS cd I 2 o ^ G Bh3 ^ (D ” 2 Tj 0^3 2 3 G ;h d G o 2 -:? 3 § G r-! ,0 CL) OJ o cd G fe 3 • ^ G^ L. 0.3 2 c/. o "5 O 73 c 3 W S -'2 G (U G ^ tj >-. ^ o 2 rG B s:s 1 §■ OT £ ■ r.T3 T3 (U >*1 G ^ O ga o ".a.'s “■g rt (U .G G G 2 o G ^ oi o « - H O! O (U ■4-> .(-> C r^ r.^ ^ o .!-> _cd ‘Gh.; Gh. . g a y 0 ^ iP S.3 G3 >,3 . T3 G O 5-1 >-i 43 _ - G .G "G .2^3 ..H G G rG <3 .G (3 (3 G G ..Ji .G ^ -G rG G ^ 05 3 3 C« 3 U <3 o " G G ^ bJD.i rGi O !t G G Tj .2 ^ rrt 'g "g ^ G 'G Tj -5^ cd O . "g ^2 rG 2 § ^ ^ *G .3. CO H g G G S (3 (3 g3 'On'tj 'o G yg G. 8 ■| " ^ G G o5 £ .£ ‘c o 1° ^ G ^ cn 71 G 2 yj £ ^ N Ch o ^ >.S3 o 3 r^ ^ cd CO 3 G ^ 3 G P o = G to cr rG (3 l.b g ■G G (U £ G^'d G G- G 3 : }-H G 3 O G O Tj p ^Ij ^3 "B G'5b8 G 'd G .tj O (3 Cl. t/3 ^ C3 G ^ 2 "oT T3 B G *G T3 T3 'u G (3 G ^ £ G Gt3 2 >■ P rG £ C G 0 G 1 N <3 < 30 ^ CD '43 ^ 'G G d5 rG G b ^ b/j B G r^ X5 o5 G C r£ G ^ 3^2 £ tS.3 O h-i <3 ■ 0 G G 02 I G ^ 33 ' .tt fO ,tj G § ^ S g.d 1 ^ 2 ^ pp G T3 O <3 £ 3 G •£ £ 3 to Td to M-, G O o O G ^.2 d rG td .2 ■l II _H ,G o M-i yg 3 O ^ yj •*-* cd P ^ aj o j= i: JiE a=^ s ? g ^ H ^ O t;S 'G G .Tj £ 2 3 ^t° rG T2 0) (3 (J tu — td c/3 G ^ 3 !3 8 ^ G - . .3 O G 5h Tj Oj .i G G ^ .tj CL, G -G <3 ^3'gf .3 <3 2 o o 3 '="1^3 •b G £ £ G .Ct.G G g C^ U rG O 2 ^.2 G ^ G G d3 G ^ ..PPG 3 .3 ^ X ^ (3 ^ Cd ^ G £ G y^ .2 £ <3 > ■p Lr" 0 G 0 5--^ fC G G T5 3 3 tn 4-> cj (3 G £ rG G Cd yi G M-I 0 c/5 (U rili cr G .G , yi '$ 3 .3 0 <3 3 0 u <3 in G T3 ^. O G 2-^1 8 g a G's g 2^ O G O ^ to _b G 3 _G T3 § G T3 <3 5-1 U CL • ^ G G r§ G.3 ^ Ut 3^.2 :|PD a (3 .3 0 ^ ii ^ ^ t^ . L^rt- G (3 £o^ o t3 o PP ^ 'o 84 Q UA LIT A TIVE ANAL YSIS. (U o _, S ^ §h4 a S 'Jj c/3 ^ O 8'^ 2 -S :5 ex' S d ^ .13 o O ^ ecs^-v-^pq •73 ^ (U ‘o (1) CO >-i qj 43 (U ^ ^ ^ 4h P, 0> ci^ ^ H ■° S""£-s « B.-SS § g^'S'S-S > 1 C s-( H 13 .31 Pi 5-1 ^3 o ^ •S S l-J S ■^1 a^s < O in M3 X 04 2 O 5i (D ^ s .■3 cj bJD .3 ^ Oh c 3 73 'u O qj qj ‘43 3 gS &. 5-1 o Gj a, g 'o 33 OJ gS .a cT 14 38 =! O P in c/: 53 q4 T3 5h w >^ :3 ^ o O 3 ir o ^ 73 • p 7^ 'a 3 H ^ O 3^ a cn c/3 .3 .3 c/3 bX) OJ O qj ^ O 4-) qj qj ^ g g5 •43 3. 04 r2 § > O qj in rQ gJ ^3 'T3 04 o t: 33 o c/3 i— I *3 04 t:? C4 •3 ^ ■S o a 04 04 °'S^- ^ S.s . 3 O 3 T3 3 -2 I qj 3 O 04 3 14 6 O 3 O ^ 5- 5-1 ’3 •r' 3 3 '14 .. U 3 g3 O 3 a in -m O <14 . 3 : a o ■S ° fi .2 a o qj c/i "2 bJD •-3 d ^ O Bra £P g :3 2 .■§ ^ ’vS"? -2 3 'a 14 X c^ a o 3 gS 04 04 04 a Bra , 'Z 3 Q-5 «V L_I a? Sii o 0^3 2 3 u 04 „ a ^ 3 .o'5 04 cS K I ^ ._ 04 T3 3 > '^-> CoS o 2 2« S I 2 I " o __ ._ a rp ^ F*C ’id o a O U— < fH o 04 'rJ ^.'§'^38 00 ^ra'B'ri S g >3 t>3 ^ ^1 O M 14 ra !>^ ^ 3 O gS U 00 3 3 'C X • o o 04 3 u ■3 gS bO 3 g5 ^.2 r2 3 3:! S 3 ,"2 5-1 bo 5-1 O >1 04 O S 3 2 3 ^ d o .033'^ •C > cn 3 3 il> - 04 gS 14 O •>.a'3H s "3 3 ^ i^ § ^ Ph3 if O 3 g Sf ’3 ^ ^ ’o 04 3.1 04 3 04 04 ra bo'o, ^ % 3'bi)_3 77 3 ' pl, -!-> ^ o ho . 30 I -iS 04 04 3 o ^ PQ -Tl! 3 gS 3 3 r3 }_, 5_ ^ 3 .13 3 3 3^ ^1 II O 14 a s gs 3 U 2 3 04 a ’3 111 0 04 • 3.2 • !-• • ^ 04 0.2 G S-i 5'S fl i 3 0 ^ 6 32 3 p: ^ CJ 04 P3 EXAMINATION OF OFFICIAL SALTS. 85 ^ 2 ^ oV ^ 2 o'B'^ *S '> (U o 73 £ ij III a 0,0 *0 a -M 0H.(U 2 ^ T3 T3 'H £‘2 (U 4J C/3 3i "2 ^ 'S 'o rt O ^ Qh 2 ^ cS'^ Ui VC cu 'O ^ O S (U HS . 2 -^ 0 c/3 fcJD W I « g • C ^ (-1 c/3 -c-; s-( •S V/5 .ti .-. c3 > V'’ ^ O o S rt ‘Fj ^ •1 a a a 2 ^ o c/3 . c . O (U U 2 a; > bJO u.^ C (-H 13 c/3 o ^ c ccS .2 13 s 'o > a S-^- .2 2 2 bX) c .2 'm o u 13 g o .£ . 8 n ’}Z; rC r2 W .si-.-S -^-' O Q. c .2" 13 D O bJD CJ 5 -h ^ >-• c § c. O ^ ^ <3 P-G P ^ ^ 03 ^ 's^ c3 § ^ Vi > 1 §£■§ »— 1 C3 CJ ° a e S S.3 2 2 'a a ^ 0 ^ 1 0 2‘-^ 33 ^ .G 0 ;G .2^’'p 2 0 G 2 2':'8 ^0 2 » -3 g 2 ^ 0-2 ^ rt ’bb _ > 2 S '^'2 .2 8 ■a 2 £ . I 8-5 2^ ■5.-^0 Oh ^ C 03 •- .2 ^ 2^’o O g _o .c 2 ^;l- o i5 ^ 2 i3 3 a o ^2 o 03 11111 3 ‘rC d( S 03 rXC 3 O ^ 3 : c 3 c/3 3 -i-> c/3 ' o 73 ■v: C O 3 03 U o 03 ^ 2 ■? &■ - 6 03 O 03 tr> ^.,_^ >§ iSa 03 ^ 0-. P O . O o -p .2^T3 13 bO 03 > 4-> 13 3 0.73 13 .. c/3 13 03 a a 13 ^ 2 ^2 S C 3 3 13 .2 ^ G O o 33 33 03 O 3 .3 ^ *■£ ^ 2 o. o 'C 13 ^ C cn 3 03 ^ > 3 ^ .2 > Jh 03 o 0.1 0 c/} P O 13 U ^ o ^ J3 "8 8 .03 2 'o 2 U--I • ^ O o p 3 a^ ' — 13 13 2 ‘o ’P 03 2 S ‘rC 3 3 v« g. 3 ^ G 2 .2-55.2 .-GOO 13 ^ 3 ^ O 3 13 13 3 G 03 13 S - 13 rti ^ 2 03 ■G >-i G O. 13 03 c/3 1X c/3 Gj O G PH'3 >^rG 03 'B o3 .2 g:^ o.c; o 03 73 3 3 C/3 , O G c: i^l3 .-G 1:3 03 ^ 8 03 o 7:3 o 13 P >^ O" g o c /3 G2 2 > C/5 o 2 > ^ 03 ^ rr-l Vfl 13 3 ' 03 13 3 03 13 rt 3 ■G SO, B-1 u o-^.S O •— v.-, 03 ^ 0> 2 P ^-G O o o G Oh >-H blD' c/i 3-3 55 w >% c/3 t. .-H O 13 }-i ■ o, i-i a^.a O ^ G ' ^ 03 4-5 s-i bO o^G .2 ,-£ 0 13 o !2 03 ‘G G 13 .2 P CJ2 > 3 13 Oh >3 G 55 o O 13 i| cCJ ■< ^■g 'g ^ --0 ;|V3 3 13 O C/3 ^ 03 ^■§ cS^ c J 2 ’55 P c/3 G 3 O I - §phO o F 86 QUALITATIVE ANALYSIS. T3 o C3 <3J a Sc S) r5 -S C t/5 j_, Ph ^ 2 c. P TO ^ ^ t>0 TO ^.S O ij bJDX5 .S s > Vh - O s QJ TO O! O OJ ft >> c« I— ( Cfi I I >-< (U 1-1 _ o 5 TO ^ .2-S.y o ^ ."p ftlw trt P -TO TO TO .TO -P O P (U r2 'PS ^ O P5 o o3 (U o ft TO bjD-P TO ^ TO 2 .2 p OJ > be , (U P3 TO 5 TO sft/" X O ft 2 to^ O i^'TO.2 •ft2f •ft TO ^ (U P S TO g ft TO5 'P p O TO W) ^ P ^^TO P 'P .5 “ I §:s (D .TO o TO > ^ CD TO ' to TO ft" g ‘be TO ^ TO o ^ P TO P 'n B ft pH.ft o .5 Sc^.e-ft TO 2 o P ^ P o ft p S p 2 CD ^ O TO pH TO CD P-.TO P TO P P fl, CD w O H_> CJ ^ CD fti TO xi •-; TO O .ft P ft o ift^ .2^ ^ p ii3 OJ rTO 2 ^ P O 5-( H-J 77 ft TO O. .rH CD 73 TO r-f.ral- o ft "ft H c ^ p ^ ^ -ft 2ft ^ (U ft TO H-> TO .TO TO TO ft 2 CD (]J .2 TO 73 P Ch— I be o .2 •8 P P TO P > _.S "ft 0 0) *2 p TO ft p III I > CD CD TO ’'"*0 o i Ch-( ' O P CD . .ft ^ 2 .TO 'ft O ^ gj be fH ft TOft Pft ft a; ^^ft ^ ^ TO"ft bJO ft «H-i TO TO TO TO O -TO TO ft .t:! TO 2 S TOh (U ft 5-1 .ft p o .S ft P" Ill“-|i ^ 1Z3 _, 73 ft P 0) P ft .X ft TO ^ 2 CD CD g-s «.S" CD O CJ > CJ .TO o be TO CJ CJ TO r2 P TO P ft TO ll^l "lllil P TO TO P ft ft TO 2 ft .TO ^ .ft .TO > SC"' ft o >-i . ft TO P c/j TO TO ij TO^S^ p., P P C ft ft-P ft TO O O P CJ o ft .2 TO N .2" g P o 2 2 TO ft Ph TO TO -2 2 p S TO TO TO P P ^ ftft P ft ^ X "43 -i3 ^ ^ ^ P TO ft « = c 3 --a P CJ ft > JO P P a; OJ bxj ft ft TO TO os 2 3 3 2 TO CD TO O ^ ft TO Ph,2 CD beft ’2 CD TO s c i § - 2 -s -S ' 5 b'i .TO ^ 'S '-S O ^ CD _ c7 Ph •ft CJ ffi CD p P C! ft TO ft ft § O P ft !ft "TO h 2 TOh Ph TO ^ o"ft 3 o H TO CD CD CD ft s CJ o TO ft CD be ft .S "2 "o P ^ ft .2 P o ft 2 " CJ P 4-> cd ^ ■^3 TO CJ r§ TO 2.S O 3 TO gi.^ ft o CJ i: — ' CJ p 2 J-H ^ O be TO 2 p CJ o 2 !to .2 o ft p. ^ 2 CJ o TO 'P TO oj C+-I 73 O .2.S TO TO ^ “I I" be3 p P c„ p ft ^ ^ ft -TO TO TO TO O CJ ^ft 'O 73'' P ft P ft O g CJ ^ ft 1 ^ • ^.2 p 1 ^ • ^ c P gyri Viride. ►•2 CD ft ^ CD .Q 2 "ft ;».> TO ft . ft ft ^*>S4 ^ zs ^ a TO . o CJ TO 3 C ft O EXAMINATION OF OFFICIAL SALTS. 87 ^ ^•1 (U s5 a CO 'T3 ^2 2 w ^3 o .ti o Qh -l N (U (L) 3b 2 'o 3 p ^'b 0 .p 0 p: , •X3 .-b b ^ >>.2 ^ ^ p b 2 0 On'^b > b p .2 Scii 4-> p .2 33 2 •p 2 CO b p 0) wb > t ^ oi^ P .33 IgS HJ i2 cj b J.2 u ,T3 . o § J-l 'r^ *~i ' O I 0 0^2 CO (U C3 cj gq vT' ^ Z3 JD O si d oj bn ^ ‘o o K*" CO 1 - 7-5 CL) Cj Lli •2-^» o 'Tj •ri CO .i=J •5 '> bO 'll} ‘S •-' £H 'S §2 2 -■■3 H cS O -*-» .fH p3 t3 P A .t:i (L) O r2 (L) 1 ^ O <-t-i 'd 'O .ti . P P 0..2 o3 <^-H CO O u >% P P d Ch-I 0 ) o C3 2 s 5 ^ . 22 ^- ^ 2 I •'S .> c:5 t>o-2 0^0 o b bXD c^- g P _ s a;-5 s 0.2 2 T3 2 CO CO H -O v2: 2 ^ 2 . oj CO HH b *2 p 3 o5 W CLT!^ r7^ ^ .0 ^ ^ S 2 i3 O b3 b -b b. Oh 33 O 6 3 “ S3 g-g O V, 0-- - g 3 S "c 73 j_t3 ,S(D'^^Sbbb ^-2 O o CO 2 o5 >^■K .2-| a ^ ^ 0) 33 T3 C/2 r0 o o5 cS rrH , ^ 2 ^ cij b 0) OJ !> >1 CJ tH 5^0 C3 X Cb (U -l ^ p |S p l-'S ^ KH CO 5? P ^ b3 sg O N p ^ b ^Ph **v» ^ ^ <: •c g O U ^ .t:! _ P ^ C 3 Q Qj :> o ^ cn ^’1 "3 < 1 ^ 4 _> p ^ S-, ^3 rP E O I S cr' cu oj ."P rp •" g -"S 13 (/} O ^'3 ^.rP'^PP O O O ^ O S P .P P ^<1 ^-c c « S ^ O o S C O rP .O P .S . H-> p T 1 _P P ^ <-1 2 p o p P.|p Q O CJ H ^ s a p p g 3 O 03 i=c - _ OJ O o „ ^ p O P oj 03 03 O O ^ Cj ti P P .jO C P ^ X Oj 03 I? p O on P. P o p a ^ >-^ p P n ^ 03 ^ ai P P p . o 03 cj SP^^OP03g p 2 rP O S S.S 00303'tjPP'P'^ " •£ g •■§ -air ^ c g ^.e -3 ° s Sj ^ . O cn 03 P o p: 03 o a o O P 'P ^ 2 Ph ^ 03 So ^ >-. f 1 O '-o p p ^ p Ph O T 3 P _ , 03 P c/5 "hIj r1 "p _ _ ■^^a^g^Po3^ 3'S S.SP^ 2 pp ^ p .o 'S ‘p p a C« P 4-> P }-, Gj y ,03 O Oh c« 03 _T ^ p s o o c 2 > p o ^ O S i^OnP POO Ph ^ S c/5 c/5 Ph 03 O ^ ^ P P P ^ 03 ^ P p a p o OP 3 _ pL, c/5 03 P s ^ 1 ^ p o p -a •I'? M ?j e-B a p p p p w OOP 42 03 03 p P 3 As 7 ? 03 P 03 03 2 P p P T2 P P -5 I 03 P P a p P cj ^ (35 03 P P > • P o ^sS !p P P 4 -> !>^ O CQ fH g 2 | w ® Kk CD J 2 i Oh -:S °-s 'o nd B E ^ p bo.p . p p o tJ s 02 ^ o in ^ ^ P P B^ . 2 ffi p O rP in t? Ph O cn O 03 P > 03 O ^ cP P ^ O 03 Ph o p p I s o S p" *03 ,B in ^ > O O O tp O p o o PU P !>> P 03 in P3 > P ^ i s . p p ■p •'p B S 2 Sm B .3 P 3 O Sh i"^ SW -S' -S-s ^ St 3 - 3 « §. ^ EXAMINATION OF OFFICIAL SALTS. 89 o I o o w ^ ri a ^^.2 S U 2 ai ^ ^ ^ 5h O O C P PI OS T3 _ ^ T3 .ti T3 a nd SH (U (U (U X J;h ^ pin O cS a a o U CJ 20 'Td W ' 5 ^ ■S ^ ^ g-s g, o ^ o 2 o ^ PI T-t -H oj ^ ■g sI'S.^ g § "S '5 -2 c, •n >-l .tp *— ' (U ^ y TO Ol 2 fl ^ .2 S p> ■g 2 ^ 2 T3 Jli >. rP| W5 P ^ (U 2 (U t3 -2 d) C3 ^.2 iS o 2 pp ccJ ^ O) dj 2 p p . a 2 o <-! ^ 2 § U-5--C a 2 2 o o p rt oS > }-i ^ T3 ■E.T3 S' S^^~ I 1^ 'S^‘0 ’!2 ’ T3 O O c/3 ID ■55 o y S-S'o|a. SJ S g.2.^ 5 = ° ^ ■ CCj O rP| CO D >-1 ^ 'TP P 1=5 o S s p 2 D 3 tJD 13 >-. P ^ .P o3 D 2 S > pH o bJO ^ T3 ^ 0^20 D D ^O p §W - u'55 ^ 2 rH O ^ P—H O . CO .-P DO ^ "o 2 g CU I =1 I pp D iP ^ 4-J 'P n Ph o ^ p ^ p ^ o 2s Py P3 rP "S .2 ’2 rt si ll ri *“« ^ rH s in 8< P3 k- P' § D 2 ^ D P -P D U) 2.S .B ^ o p '■ 2 S 3 D s’|s ■||^ C/^ 4 P X a rF' a cj " o 2 2 p Ph D 2 O D :z: ^ i) o CO > o. ^ P-i oj ^ > D S 03 D o bO < ■pH 4 ^ *0 P D P >1 Ph CO D dJ O .-p "O ^ r-; ^ oT P ”*'5 Tflr2 O 3 2 }-H D VI -p D ’bJDrP p .P D o g D O G p W p D -H ^ -P D ■P i-> > Ph D CJ ^ 'C ■2 i u ^jp .y bO 2 ^ D o p pH P o XJ ^ P3 B ’2 D P'5 >^■ o -ii aj P ^ ;a s -c S 0 'S ll.s J ^f2 Ph 'S ^ <5^ .Q 2 D JP So CO 03 •J3 D P3 CO *p 2 Pi .2 > bX) u S o ^ c-3 CO «S 'S •g' ? p Co O D 01^ ^ .Co O §H ^ s C 'w/ 5 :: ^ gw ^ 55 D Ferri Peroxidwn _ It dissolves completely, though slowly, without the None of importance. Hydratum. aid of heat in hydrochloric acid diluted with half its Ferric volume of water (Feo 03 would require heat) ; and Oxy-hydrate. solution gives a precipitate with potassium fer- rocyanide, but none with potassium ferricyanide Name, Proof of Presence of the Proper Constituents. Proof of Freedom from Impurities. 90 QUALITATIVE ANALYSIS. c o ^ a o ^ Si OJ >73 '3 o ^ o JL s “I p. c S ^.2 ^ p Pi o O tp rr-( O zs ^ rP C u br) .d o K> CAl o ^ O JH a d 07 : 13 '^ -55 ^ ^ O crt aS d 8 S ^ ; a § g OJ Tg o .d ^ T 3 p „'^ Ti Jd r-1 O ,d ci d o> o §•2 q 00 - d O O 'd >^ .^>^ 2 ,0 ' gd ^ u - Soi ^'^ ^"d^d'd-ri :>^a O Ph (U 2 fl _ g .:: ” -»-' d p fj c 3 h|I^ - d 2'^^^ g' 0'0 A O cj c3 ^ -d ';^ cs >^ d 2 . d ^ g O g.l (U di di d Cl _ di oj oj O ^ d ° U-i .2 0 o o 2 ^ ffi Pi ^ .0 d^ tAi P ■>^ a o o ^ ^-^.2 ^ O bJO !-h v^. -d *-' d ^ in Q o .V 2 H (U d (d ^ d rrt t+H ^ di § 0) 2 ^ - in p (1) d ^ in d d ^ - d d Pd d ±7 o bo in G in oj O c di pi in d 2 -p "o za w .^o ^ .2 'o g t! ^ -d o d ^ 'd ^ 2 ^ ^ a; G d ^ t-H }li .d o d ^ in rri ^ .2 ^rP (U d rri O vSS ^ ^ d 'g E a ^.2 |8 >^1 ^ XI ^ d G di ^ >o..2 a 5d ^3 o -g tT ! 2 O .2 P‘^.2 ■ ' ' d boi— I „ -M O •'-' > Odd o .2 -5 o d O boHj ■sS ■° 2 > d -di d o > 2 d p g g^’g-2 d d ti p o ^ a cu d o ^ ^ d p i ^ a'^ g 3 I a j "o 3 ‘2 in'c c/3 c/3 o d p O a .2 r - i -> 2 o •:= I— I P ^ o -T d c d O d c/ g . ?s o d 00 ■•§ s -d ^•d ^ cn. a> d 'x 4° ^ 2 C d I 2 U •S 5 . |'|.'2 1^0 EXAMINATION OF OFFICIAL SALTS. 91 S 6 .2 ^ ’S o C (U >^.2 6 ^ c ^ 4-) rK UJ o ^ ^ S o ^ S § i; 0^-1 C W2 ^ §1 « ^ O (U 52 in <+H C\5 °o _ gcc g 2 bX) C O Crt ..-H ^ n T3 Gj 'Cl ^ -( o o OJ H dJ H3^ 'o^ c o i!^.2 o Pnt ^ O ^ •— oS d • O cj bO O 5_ a fer O i/> •5b;§ 3 '^ S 3 O rC -C c« r-i •c 3 a =3 "2 § o Sc= , "t§ £ -c a >^ ^ qj rO }-l T3 d . ^ i^3.3'^ U O O T-J Ph O u 52 .2 oj ^ p 'C 0 P .i (U a rt, o3 tfi .2 ^ >H ^ o < 1 ^ 3. '' u ci ^3 a 5 3^0 2 ^•n3 0 c/: in p: o 3 ic 3 in in in __Q P. ■C > 3 .P >. in bj3 V O rp ^ P Pd P r-. • a p a 3 .2 a di 3 3 "p p p3 ^ 3 3-3 cn p ."P cn ^ bX)S 3 P P P P r— J ^-H O o g W - 3 3 3 3 t3 S Ic.:& g.- g .3 ° o, ' P -- ^3' « P 5-1 C biDp:; bX) P £l £ ^ TO tn p ^^-> P P C > ^_ S’S'Eio P rH '+1 3 P O O dJ o *c 2 ^ p Ph ^^33^ y prj in « 33 oU d ^ cn 4-> 3 pd p 3 P 3 0 3 p dj bxipd _ p .td Pd 2 >3 u > o n-j ^ p Td •pd o 2 'O dj Td 'C 'o d> p O *t3 ’5h ^ rB ^ 1 1 V.I .p o ^ Ph 'C ..B bX) P 3, a 3 ^ w bP y rH P X J_ 73 ’(U O P I ^ ? J.H ..3 ‘P ’bb3 ^ o in cn in (V ^ o Pd X *P (U ^ >» y H bX) a y o 2 *- P !h = 1 y a 5-1 P y a p p .p. 03 p 3 ^ o y a o si a 3 y ' y Td _ y Pd PnPi 6 •: a iT 3 2 p B.t p-p 3 bX 3 a 3 O y .2 yd ^ 33 § 3 ' ”p o p « o.td yd dj a •3' 3 3^2^ 8 p ^ }-i ^2 yd ^ ^d ^ o p p yd cd .spy y (u P P O o yd ’x S 3 o p y- O P3 3 bc3 3 p c y TT yd P 3 !d y c 2 .2 dT ^p.3 in y ^ ^ ^ g.S fH, g^rg rO rp S o ^ '^ ' ' d ^ >^ tJO o "g ^ xt o O o CU d ^ • •71) G T3 G^ G bx) in O >-i c ) G K> aj U £ cy o 'O l-^’^s s §l§ r-5 . h ^ ^ "5 o 1 > O ^ o (U _0 u g:: G -O ^ H o ^ t; G G3 i-rt *G H-H (U .9 ^ c/5 o cL» o .. .9 G .G -o ^ ^ _^.52 S .05 o T-s in ■d ^ ^ & 2 G3 ^ S -E - 41 : G3 tS 2 c/5 G 2 ^ W O G G- a p •'^ G 'H-, is in ^ CU > dH o c« ij ^>-4-1 C/J bO G d g g-*. B ° rt ° 2 g g S S (U ,0 ^ .2 So ^ ^ "5 X5 CO 2 ^ ^ . C/5 ^ CU ^ >n -, 2 ■-G ^ .2 -G d'T rB .ti 0 ^ 2 "Oh o O > 2 C« rQ G C/5 rb> . . G .. rrt § rO CU tS ^ fg " o H u o c/5 g (U H REsi-l o; OJ G 'o I 2 §.2 P o G» .Vi ,‘L) „ Cj »7-i 5 1^1 cj Ci . .G OJ O Si !-i CL ^ ^ Td g 3 G Cj c /3 c /3 c g g ^ CO • j -4 W2 Ph^ !-| O oi,G o.tjO W rG .g .-G ,0 .S2 i| CL^ ^ ’g i2 G G ^ 6 P S .'2 3j=S^ U .s'S bt)' “ ri g § 'I ■- C S a •d •■' 1 -S d £ « S 3-S si '-G ^ ^ c /3 - . Zj > XJ -(-> OD G G G p O rG •G bCrG G •'^ G ^ Gh c /5 O O yj > Gh O OJ d) (L) GCI ^> rG G 5i) •'g ^ .G c/5 O OJ 2 8 2 'o G S O o’t3 2 >-( r 2 G^:: S o .y o *xi rG G O ^ ^ G "O •'' ^ C /3 , — I ^ -S Ph ^ • (U r] ■'^ rO G t3 O G 5 c/5 io G c/5 d> ,0 ^ G G ^ S "' S G ^ P 7 ^ -K (U G d) o d) 3 ’p' .s ^ GrS^G a 2 cl O O O G -G G rP G G ► O ^ d) O G d) 5 S r. O CLi Kn'4-H ^ c /5 ^ g) o d) ^ c/5 .SH.-g >8 rG X rG-G CL ^ ^ o . ^ ' -V *13 a G^o 'G ^ ^ d) ^ hO C ^ 5 O s ^ d) T3 O ^ ;3 G P ^ 13 g 4 -. -G O 'T 3 • G -G ■G O G d) G G Is-S g’S “ ■G 3 D rr-( 30 C« rS rP ^ H ^ d) U r^ rj-t c*) ■ d) p G G-i ^ ?G o c/5 G cO p G c/5 3 ;-, 3D O G3 c« fH o d) .rH ^ 3 D .11 4-) d) G rG Gh C/5 G ‘g 'tD • G d> G g 3 G G .r, 3 D rG ^ o o - G *4 G .i 2 rP d/ G C4-I - G'O d> ^ g a d> ^ G rg G ^ 30 .G ^ c ■§■.; 'o 15 O .G rH G rG •> o ^ S 3 D 3 D d) G P cu rG W .SP 3 D rG P c /7 S| .2 t' 1 ^ Crt ^ Cj_, G O ■*^ d» ^ g'' a 2 .a G o a >• a d) •; G C/J ^ •g: >^ |i .§ s 4-> C/7 G d) P G '' u G P P G p rr-; G d5 a ^ r 3 F 3 D ^ g rJ 3D t/5 G P.2 rB H4* .2 ^ a r4 a G a 0 > rG >-' fq i«-S 0 G < S d) rB.'S O O g I g C5 W 94 QUALITATIVE ANALYSIS. ^ h a O *bJ0'-M ^ O T3 (u (U fe 4 -> 'c .-!=; -b a oT si i “•'H-s g.a S.O o S 2 Sig-g 4 ->O^Or 2 C:=!^ o O^ ^.^.2'J- - cj (U o "3 ^ x: Ph S 'B 3 !-r£.y P -4^ P o (1) 2 ^ Ph P .ti rH ^ OJ p “•&=« 8^ o P2 c^ -b .■p ^ t> +J S P 3 ^ • p tJ p CTj 'P .Pnp^ ’Sh 3 8 w 'ji; Ch P ^ oj *-i w ^ S ^ ‘p 'E p - p ^ • p ■ 0*^3 V ^ D. P -P .12 P^ ^ OOPO^g.g^ P Ph ^ -b . P ^ }-H rP 3 P < 1 ^ p 'p or (D 3 r- -' p p 3 ^ p o O P o lO O ^p ^ P4 „ ^'0 >b cj o ^.3S fc! P "d ^ 3 p (U P P3 . . o p S 3 p P p p o O PI ^ o 3 “■2 '4 *b 3 o o CQ M H o s <1 o cx5 o5 >-i O P Ph.^O 2 's^ > o tu rP .■p 'P 'I Pn.ti P, O Ph . O <3 "'72 p 0" S 'd *5 ^ • d « s s 3 p O t+_| c/. ^ 5 P O T3 -i <+-. d5 ® p (U }-l p o .2 ^ P4 i-> , 4, p ^ - - r 7 -( 3 • dJ 3 a -p ^ *P ^ p P -.Li ■P ^ ^ rr-< > > o H-> P P I— I ^ 2 d3 3.> >. dJ tJOrP 2 - .2 I in b in O o3 b oS ’w •^3 ^ ^ u S § p ^ P -H I I'S 1"^ o g ^ S rO EXAMINATION OF OFFICIAL SALTS. 95 c5 ^ c- rS 2 .'T' O O O b o cn c g ’55 g np ^ ^ ^ 2 O PI 3 o 3 S -b P o .b b: .2 T3 ^ •- P3 "> >^o O p CD C 3 ^ O . CAl CCj P.'^ ^ P 0-1 CCj o ^ (U P O o s'i o Ig-S ° § s 8 -3 ■b m p > 'Bb o o ■p -P ’ — ' _Q ^ o P g (D O o 'p CA! O rb cS " Op p S ^ P cd P pH cj o P o > o .-p i .b 2 ^ S « cd hP B ‘ ^ O O S ^ s' a s Ph cd O cd O S o o 2 o p b oj.s.s-e-o “* O bn b cd w2 o PI s_ O O S O ^ b ^ .b O -P cd P* t 3 ^ o .^ • g’ij .3 '8 o 8 o " •2".S ^ ^ b ^ Ph ■s ^ ^’o ■ o b ,P P c/3 .-H o o rb 'o CA! O C« .P P P P P ’o ^ ^ ^ ^ O b b rP (-5 }-i O -(_> c/3 -O’ i-rt r-i ^ • hh 2 ^ S Ss ^ S c 0-3 ^ " O .2 'o o o b b P 'b p ^ b. B’^ S p b O -a NS ^b 1:3 Tp — ' 73 P 7^ ^ ^ cu c/3 -P o 'T; ^ . ^ CTJ O "S i; -J ^ =.2 § g. T' C 1^3 ^ O »— H 73 O ^ tP 7 o'g .2 I ^2 'P bi P b P ’2 Cd S b 4-J •p O ^ P a| O Id P Cd O o b b cd c/3 b CD O C/5 ^ hS ^ o (U in td ■ O 4-) 2 o-b 7 hP ^ P ^ o c/3*' >H, o p b Q. c/3 . — I •'-< •:-' b (U CD .b .b b b S ^ *b o 9 oj b o 73 .2 £? . p in P 73 O b o b 'C IJ c^ P •2 b rt > So (D O b pO" o 0_ c/3 C O rb b ^ . >. ^ O 73 -p l-s-S i b b o > 2 b . P^b 73 W 3 1^ O p b P C/J p J-H b s 2 b p rq o b S-i P o b 2 p .2 'b b Phtp b P b in ^ P^ B ^ W :8 b >^'o b 4-> P P o HH b ,2-Jd o Vh 73 P P P O O p -x3 O 73 o c/3 b b 8 t3 bOH o 7s Oh (U '7! c/3 o <7b p ^ u b £ I'c 'S 'c 3 B' b bJ0“^ P O ^b in P pH (U o > o g c/3 CSh O (U ^ O > ''7^0 b b fH O S c/3 P W p b P O O b b 73 'Sb b 77 7 S 'o P b -j;5 b c/3 b cd c« b b .b & o B HH b p b .2 biD p b cAi cd bX) b 7 ^ b P ' b '^ P O P b 'o b 73 III' 93 b ^ b ^ b O c/i t; 'w/ P Ph ^ b 2^ Oh b O O 7 ^ S -5 si's ^ U_, (V rT^o o §•! s 3l ■=" ? b b 73 b to o ^ in ^ pq b in *0 52 p P o p -P § o S3 IPHU ^ i |l p S .3 g c/3 O M b i5 o fg .2 pq 96 QUALITATIVE ANALYSIS. O .Jl- G Quo ^ O ^ Ph (U Pi ^ O § P- CL, « ^ ^ ^ d) uu CC rP ^ O !-i oi hD,P3 ^ ^ P iC oj Lm ‘ > s ^ ^ s p p 'JO ■■" .2 ^ 2 ^^-:p w 53 (u -T3 P o g Tp 'P 2 "2. 'IJ r-i < 23^0 _ *0 T3 ;P G G ^ G ci W3 o -P *r^ c/5 .P OpHoj^^ O^ ~ G ^ § Q S c/5 -p p -- ^ .p^ p „ ^ ^ ^ g 2:5-P ^ . r-^ P O G .2 ^ 4-. 2 ^ P G 'P 2 S p ^SS'5"rt p ^ :2 ^ G G G P P •5 p,<«:h g3 o P O o ^ e 2 ‘i=^ 'p ^ s o-a ^ ^ 'O no G IIj o , G g: ^ a; g:: Cl, ^ 2^"g 'Sh S 'S 2 00 ‘ p -p ^ G P P P -G 00 ^ ^ a 'p ^ d) ^ p d) ,- g <2 B'^ _ c/5 .2 P o 2 § 1=1 |.S ■3 s 3 3 G ^ G O P P O JO G3 O P -p cAi H 2 -2 2 'P s I s § Lh G P O P P > 'bb ^ :2 c/5 L-I ?, P3 , >^ G3 c/5 CO '' P G "p P > o 2.2'bb-p 2 G O •g:: -p P P 'JO O O, ^ ^ P G p JO 0 a 2 bx) L-, Ph S.2 c G G G P 't .a p S ^ S 1.1^' 0.'&l2 1 B- G c/5 'JO JO >s tH G^ s e G CO *< P § I U3 O O 'TO 2 P 2^2 p G 2 :>< ^ ^ a a. a .a JB 'g g O P G O o G ■'-H P ^ P O CO _co S .'p 2 •■ 2 2 P d TO CTi P I p ^ ^ P 05 P O coi 2 Ci ^ P oi P > p Gi P p 2--'^ ^ 'B ^ 'B ^ . p C+H CO O P o . > Lh •G? P- O g CO GC P Ph § a P, G O .G P Ip O .Pi G ^ "P TO'O^ o3 P p ’SL 2 jO G2 CO G 'TO P ‘p 'B G ^ 'TO JO G T 3 p . Gj 4-1 -i-> g !h G ^ a p ^ a -2 FC O CO .2 >-. Ph p -tC GC G P • JS. Q G I p - 5 3 c^ G sG O >1 S.U^ 'TO G o g; 3 6-3 .9 i P d b£).0 P P P 'P P CO G c P O G ^ ^ 2 p p -sl CO 4-« P G > 05 'bb G O P 2 'p p Lh Ph p '2 G P G G O ^ G 4-> G >^ P JO d) P G .GJ p rp ^ 'TO o p CO G CO .G, P Cl, O -G* X 2 d) P P p .-P _G 'B ’n ^ o • G O O 'p p G -c5 CO P >• C 4 _, Lh '2 p G p . p CO CO O - S 2| G ^ G CO .a G P -2 o ^ p 4-j G G O O *iC G3 G P G -p a H.a CO CO . G 3 I, '^'B 2 3 2 6 .2 G 'S L-, d Gb P p -P > nG (j • ^ .G 2 bi3 G 5-1 d 'TO O >^ *H ^P P Q .-^ 4-> P .a 'o CO P P p p p: d) 4-4 p CO nG P G t G (U p p G JO G .P P rP ^ >-H G CO P P , ■3° t/^ Ch-i S E! 2 o 2 ^ G ° I |l P rB G .p S; $ .2 -I G § P . 1^2 't'P § ^ _C5 § ■S I S ... is b a e; EXAMINATION OF OFFICIAL SALTS. 97 t/3 yj W O (L) fH CJ ^ .2 ^ ^ ^ oj I °"s ^ o3 P-, O Dh'+-i 'G o 2 c3 & o 4-> O ^ ^ O^ ^ rs ^ _ bi (U ^ o 2 •'^ s be ^ u S T3 .a % .'d 5-( ^ -Q "0^0 ^S U m! cj _ rQ CO ^.2’^ 2 ^ OJ "' a S a iii o T3 o o o c .d 0) 'T^ CLi •73 ^ 'o 2 T-! i2 ^ CO (U i±il rrl 2 S-P ^ ^ .d ^05 Ph ^ O p c/2 0) 0 >.3 ^ ^ .'a Ti ^ '2 in P p 4-. g -p .-p pq .2 2 P )-H nd '1^ P .n 2 .2 ^ 'd P > p p ^ I'o ^ riJ CO r0 2 CO 'w g 6'^ o ^n ^ ^ cj (U Si c (U ■£ 1 1 2 2c„^ .^5 0 o 2 ^ 2 j 0 o (u -*d o - g ’g G -5 jh x3 '^-> g s= §-2 rt p (U (U rP ^ ^ P T3 G tU d> P3 g p CO .2 p p U o in d? 'P '+-' s 2^^ '-2 2 o a g 0) P % p p • ■^ o ■s g iig s 'rP U 0 O 2 5-1 > P.2 o 'd 2 -p a ,g CO p 8 p^g p p H o cd G ^ tu QJ ^ ,a p a -p § 2 - > dJ OJ ^ 0/ pcj > o 4-> Clj i-l C-: "P d ^ It! p ll.oi ^cs-is p p VOL. ^ o ?v id ^ rd a ►ib dd fd h P P 5 e-e - 4 .“ s S: II 1^.^ cot ^ ?S ^ .-S IJ. Potassa It forms a yellow solution with water, which has the About three-fourths of its weight are dissolved by Sulphurata. odour of sulphuretted hydrogen, and evolves it freely rectified spirit (proof of proper percentage of sulphide). Potassium on dropping into it excess of hydrochloric acid, sul- Polysulphide, phur being at the same time deposited (proof of poly- 98 QUALITATIVE ANALYSIS. g I— < oj 1 TO (L) in 55 b b cy .2^ b •+13 .-b b C/5 ^ bX) -S TO O > g ■b (U ^ ^ > rb TO 01 -(-> bT* ^ rQ ij tyo 'b --, S ^ ^ ,b ^ rb o > rO bJO ’b o "05 Oh ’d ^ cb >^<42 rO O 3 II o b ^ b TO ^ ^ 2 ^ ili H o b 'b "aT§ "b ’Oh b b 2 3 o rb TO b 3 c/3 o o ^ > b •rS b C/5^ 2 b _ b N 3 •''•2 ■b ^ b ^ S 2 2 o 2 b o > §3 a ^'"to ^ 2 Td 2 c/3 §■§11 b b b b O qj ;h •s'as S-§'3 TO !-i TO CA! OnrO b ^ OJ Ib 'd g ° § ■5^ 3 3 _ ’o TO t3 ^ TO CD b Oh St3 O bO b b hO o b o (V > o ■S . 0) o 6 g OX Oh CT! 1—] b hH ^ TO r .-H b bU 55 b Oh 2 ^ TO b bH3 ■ o 03 > o •TS 3 o b TO b 03 0^.2 ^ 5-1 c/3 Tj .'S.'S 'O o .3 b rrt '3 cq b .3 TOJ qj I— I t/j Q 3 3 2 b TO b . ^ b 2 b TO b ^ 3 ^3 c/3 b O Cfi c /3 C /3 • fh O) • F, b £ So 3 "O 2 b' CO W H »— ( w PM w o Pm W nd § CO W H M w PM CQ (3.2 o ^ P 03 • Ub P OFb 2 2 0) 3 o b b o ^ g ^ ■X3 d b _o ‘in TO 03 TOD *3 >-> c /3 3-h HJ 0-1 03 U— I b 03 O b b o O) ^2 Fb •-> 4-> o &3 o 03 03 'V C« Fb o 2^cg *5x) S ^ rr^ ^ f2 ^ o 03 *b 2 • rr< "55 b •TO 2 d Oh 03 o o) > S'b-b u O b O 3 c« TOO TO b TO t 3 "d TO .9" o O rO T 3 b ^ o> 2 b TO3 O "d b b o o c/3 2 3 03 03 TO .2 (FH (1 ^ bD 2 +-. O! )-H ‘d 3 "j-i J-i d <1 O Odd p's b b b p 2^3 •b b"-b .2 3 f3" ’to ^ 3 3 2 d § 2 P 3 03 O ."d bt/2 > O.b b O 5-i --p p O 3 b ^ Oh 2 b- Op X b 3 ^ c/} 5-h C/3 ^ ^ 2 s-i O) W 3 Fb ^ b --p b Oh Ph O • d 03 . — I o ^ Fb X o k: b p, 03 c /0 ^.b ^ ?3 b 03* 03 v:, d 73 fd •.. 4 .§:s « ^C0 O ft -> 'Tj ^ C .'i=! d .B" o ^ ’S U 0) D-i ^ 5-1 r-i '*-' (D ^ !> O S ft CA! XJ ■ft rd o 'd. ft rft* 2 ft d ^ ft .d d 2 2 S ^ d ft a a -§^1 I cd g 5^ g-5 O d .-. *00 ^ ^ .d d 2 -s ^ ft d ^ d2 a ^ ft ft ^ a ^ft (U u ft ^ d ■ d (u (U ft ft cd d ’g. -ft (U •s|g . 2 g ft2^ o o ^ o +-. a > '^.3 go B ^ 2 g 9 S to in > 5ba sft- s -si d -*-> d ^ q"2 o ,ft ft cd in . o '■^ ft in 5-1 O O 5-, CJ (U O d to d (U ^ ft ft ft *S U-« ^4-> to ^ o .2 c CO > d c-i (u .2 M ’-' O ’ft ft CIh °-a 8 o •Sft r-< Ph"^ (u a S3 d ii ft d (U X .3 'a o ^ p p d .*tH ’Xj •3fe p p ft d ^ d a 2 3 d ^ ft p d iT ^ d 3 ft. in d d ft. o 0^X0 ■g-o^a “ o I a S 2'S s > ft o 3, d c/3 ift d 3 h be .3 a ft ^ d p .a ^ d ft a o o d ft cfi 'si; 3 d o d ft c/3 d ft S 'p IS ^ p ^ -a d CO p Co d ^ ft ft ■3^3 ,S2 CO ^ a ^•1 c^ o ■' CO ■f d ^ "in . P C-i «4-> § d ft ^ft c^ CO ^2 . 5^ ^ p a N Zinc Sulphate. drate soluble in excess ; and the subsequent addition of galls (absence of iron) ; and when acidulated' with of ammonium sulphide gives a white precipitate (proof sulphuric or hydrochloric acid gives no precipitate with lOO QUALITATIVE ANALYSIS. CJ , i; }-< 'o ^ -• OJ <*S pH 0 ) (U o TO ^ :==; 2 o P P, P •- P OJ «r ^.5 P O p-§ S’^ O D 5 il-S c 3 5 -g p.s a 8 ^ ^p p ^ 2 s ^ be 1) O ■ Is. ° C^ I ^ ^ ^ M O op O 'P > p CJ c3 ^ P Sh O S g p p P •-H ;-! fH Ph p h CJ 3 CJ c be Crt P P CJ OS o P CJ c /2 be o p p --r ^ a ■*^ p oj ’> a >^CJ;^ ^ Gj P P oS 'o P P — Gj a -cu P.'S g oj 1 S' O S 3 ° CJ c^ ]P CJ P g Gi ■§-“ S 2 O p a c« P 2 O cr> •p g 5 g O P O ^g Ch_ O ^ o p "o p P cfi o O CA! 'P CJ g 5 CO p CJ be o Vi P 3 P tj o 1 _> CJ v-> p p p. CJ p * P CJ p ^ *CJ 8 2 Vh P p p o O O P C-I CO O CJ o ,t o -I p p. ^ CJ 1 -J gJ p p cj in CJ ^ > P ’ 5 b^ C-i o o Si o o a As o O T 3 a •n o p o o (i-S (t> S-H •-! ’O ^ ^ p‘o u P'S^ a p •c 2 ^ p O O u in (U P ^ CJ a I p g-i C a. ^ p p 2 „ s S' 2 O *P P >-i g pP^.CJ cr oj Gi ;-H t— < 2 CJ a p p d P CJ .PT O O P_, ^ 2 ^ a p'^ “a ^ SB > u-» 8 > .2 2 ,CJ CJ § go g 'S g I g 2 ^ sj gli ■S^-S an’^ p o CJ o^ — p 'B CJ p p ^ H CJ 4 -> a p •g a CO p Tl P P Gi 1 -^ rrt •ti ^ d . CJ CJ - 4 -» § J kS* P C^ c /3 .2 ^ C^* .2 CJ ^4 s g V ^ P p ^ CJ -p ih^ S §■§ J ^ s 6 ^ ^ 'g P >^"P S C /3 ^ CO . p ?< »-i 'OU 1 § EXAMINATION OF OFFICIAL SALTS. a oj =3 cr* O) s '> o (U bJD < 1 > ci O 2 g § « s h C -a O ^ o ^ ^ ^ o ^ o t/i (u ^ xo 03 ;z; a ^3 x3 OJ ^U3 T3 C cj ^ c/3 C/3 OJ 03 ^ Cl o ^ VO '-^ Cfi cj ^ 03 ^ c3 d & .ti c/3 ;h 2 § o ^ d 03 03 d > a d ."d 03 Cl •52 4-. o d d 03 c/3 O d Oh V4_, O i3 c3 ■^ >-. 03 >H d O d <13 d ^ ^ _r d d d d O - T3 d d‘G.2 o cfl 03 •r; o d p> 03 03 03 03 d : .. d i s i i « 0.0 c/3 'Oi O O 03 ;_ .0 ^ C« C/3 . d d W . bX 3 b£)^ ^ J_> .S d d ^ I Q, S ^ d ^ ^ O 4 -. , C3 Ph O c/3 O d d § I d. ^ ‘d d cAi d 03 ^ ^ > - I d o d ’d O) 03 d *-• 'd -2 ■2 'g ‘Sh d 03 P-id g'o 3 g d S ■ ^ c/3 <13 r,-l <13 03 di CQ H v Ph d 03 »■ 03 03 p d d 03 d H-> _ rH d > .. 03 r3 d 2 «-Ss c/3 d d 03 ><| , , ^ o d -. *-< o d & 2 I s 5 ^ “c “ > 'd ^ id 03 d b ^ -d ^ CL) 2 Ph 13 -d o 2 d ^ 12 2 d O cn 'B 2 'S 2 c/3 d Sr, C/3 t>X3 d C/3 crt |:H P O O O O T3 O 03 d bl o d c/3 g ^ o Mg d C/! 03 hi 03 -d & d Ph o O 2 2 -d 2 ^ ■d d d ><1 d o A c/3 Jj O 03 d III -II? d 2 ^ p 03 d a d d o c/3 03 03 ^ d ■ft ■p 'B 03 d 2 d Pi ^ rrt d ’o S P .2 2 "Bbd d ^'a ^ !-h a .a ° a ^ p o d o 03 „ « a,3'’S''§ I o 2 §'^ i g-s --^2 P d ^ 03 d X P ^ r9 a ’p d'T: “' S 3 S 3 o iT 2 ^ a H-> o d rd , — I _2 03 d d d ^ ^ H P ^ t d '^'u P ^ d ^ 2 o 03 . d 03 03 ,, 4-1 03 2 (,j 03 c^ }-i d Sh^^ O Xh d O 'o d ^ p o _P d d ™ rd d d P CA! > >-. d o _ i> (-! d ft 2 d d ^ d o .: d d P P d c/i 03 a d c/3 d ^ d a p d 2 03 o o a d 03 >v d d d c/3 ^ p 03 P 'm rrH P d 23 *2 d 03 u *d r2 '' d O rQ o ^ 2 23 P ^d d 'S .2 o d P ^ a p 2 2 p d P o d d P d d 2 -2:^ o d 2 P d .a 1 -" 03 s d a d bX3 O ^ c/3 vS d '5b 03 p id) ft''^ d P d 03 d >-H .^3 ^ ^3 ., O; ^ ^ £-a o a ^ a g -.3 p p d V -^d d

^ . ^ o3 4-> -i-> > §.BC o S Q g-^ ■5 ? O o .a a o >^ a c d a a" .a ’ jIh CJ S '> oS ;-H o OJ rB '> O ^ U1 d -d .tij ^ .a^ >H ^ O OJ .a tx) oj d CJ d 'P "3 - t 3 o ."G "o oj G .a .a .a'p G rG G G 3 d rG G w G .a 0 c3 0 (4 .S G c3 CO ra pH 'S CO G G G w G G G d G G G G >.0 wT.! o o3 &P cge bJO to !g 5-1 > 'G (U ^ 'q. c3 ^ TU o o rQ *£ tx:^ G •G Oj > ^ O ^ .G ^ G G ‘o ^’^-!a a W I G G X! O .- S-Ss? 3 -IS ^ S^.a^’G G O ^ G ^ ^ G § a 1 W3 JGG G t. >^o S rG h a ° G - - cu G ^ G G trt , G G G o G ^ ^ 2 dB 6 -o •S g “* - i-N G C ^ I b G rQ , G bX) . ■ ■ CO’-' • G si G a G Sh g (U '•-' 1^1 S.I O G G O _ G G B > G "o O c /2 G r^ CJ VU Oh CO .G "g .a G G O to CO d b G a ^ oj o o G ^ g S ,, d ^ d G P. G rG g 1-5 S -G rG G G > O 'd d^:>> d G G ^ O CO CO ri L> G ^ G ^ G G G 3 a G a- iG G G G 2 O 03 . -;5 I 5 •&c^ s 1 '^ G G .O ‘,a G ■5 o3 r-* Si ^ •'t 2 '-' a ^ ^ ^ a ’s "S -5 m Plumbi Nil EXAMINATION OF OFFICIAL SALTS. 103 SH rH ^ O 3 oT 5 rs o ‘S c/3 d ^ o a> o ^ c /3 3 . oi '' ' .-g X5 .S"'o (J d cu Si; o ^■5 iTS . T3 /3 ,co O ^ o 9 ^ o Pi- 03 Ci^ .tP C^ s .'S ^ o o u o p ^ d ^ C! r— ( U O ^ p § •'S nils 03 ‘cO >.^3 CO -2 (U • p> o ^ ^ ^ .> PI.3 -5 g ri.ti ^ p .2 ^'S *r2 V (13 P'2 CO ,3 c -S p =: pp 2 -c. O 03 PlH^ H > 03 P r- P 2 yp .2 rr-l CO Tj CO P P c3 Pi- _ C/3 ^ C/3 CO 2 s o ^ Ph 3 4 J 03 'o.'H CO 03 I *-^ i^ C /3 O O 3 'P T 3 ^ aS Pi 03 ■ P- ^ ■ '* t; 4P o 3 ^ <1 ^ _ ^1 S 03 ^ p (ii -P ^ p 2 o . 2 il o ^ ^ ^ ^ ' 2 ' 2 ' 2*2 OJ T 3 p Tp 2 03 ,tp 03 -P o d ifi !-i P P P- p ffi > nd p s 4 -> TO ;p- ^ o o 03 *-• Phc3 P •*' o C 2 CO P ' P ^ 03 P 03 ’-^ 3-g.a ■S g.S 03 OOP o h 9 >-i >1 V- ,03 '"O c2 2 .2 'rp ^ P-S.3 3 p o p.3-^ 05 W P )-♦ § P=< c /3 ,2 03 ^ P 03 cr' d 03 03 _i p; no n ci5 ccS P -P P -P « 3 o 3 P o c/3 > OMO'P O 2 9 p p 3 S-a^ .5 'DO, bC ci 03 p .2 2 o j- 3 p p- H tn Pk m 0 W Ph np § 05 W H i-i w Ph 01 o W p^ o Ph 3 0 rip P CO w CO ^3 CO P -P -P p CO 0 rH H--g ;-! P !> <— 1 3.2^ 3^^ O 2 S P o 2 P^' 03 p ' — '■ p oj cS P P 3- 1 n P m ' P rS 2 2 ^ § ^ p 3 ^ CO O P- CO bJO P ll'bb •- 2.0 i ^ .p o 3 a o ‘I O 'o 3c >> hri •S 03 a r 2 CO p 2 p o -k « fiL i TO O a nj .a 'p o s .a o P- Ic"" P. 104 QUALITATIVE ANALYSIS. bJD Oh O 'O OJ "O ^ > (U ^ 'rt CJ c« S O O -i-> -* 'O o S'§ o ^2 O rC> O a V, B ^ ^ B'B s-i vil .ti c!j ^ c/3 Vh C c/3 • r2 ■T3 .t^ ^ cc3 dT O O Cfl c ■g s s ^ o-S &i:4i Ch^ 2 Oh l-g-il I ^ ^ 2 Oh W O 'O c« OniH ^ O § ^ 0 ^ 03 1 "' oS 2 03 > o 2 -M u t: > o 2 ^ O 03 03 O o 03 i/3 CTj .0 O cj'nd 03 03 O O OS ^2 o'^ § 7"2 § s's ^ " c| s'S aj O ."tJ .nVoc *5 S o: cii •r Oh O !> 03 c/3 cr T3 2 ^ o CD >-i Xj o s T3 O 03 > o‘1 03 c/3 O -rO, 03 O Oh 03 03 rO ^ VO t;; ^ O «H-I B a 03 £ « M s ^ 2 o2j 03 ^2 t/3 03 03 (J 03 03 13 2 c/3 .32 i-i O 03 ^ .ti -^2 2 2 -03 03 O 'T3 ^2 0 - 03 fO C -j 03 .2 .'O c« '■ 03 B'B rC’^ bc.ti 03 o 1 .0 :o ^ ° S S.S'o 03 03 3-T 03 ^ O) ccj 03 2 2 S ^ o So o o c/3 ^ rH-'S C O ^-’ rn-H .2 03 2 > too bx) 2 2 o c ccj P JH . 0 03 i-2 0 2 o bJD i3 03 03 03 ^ O 2 o2 -2 *c/3 -l 4-> Oh O 2 03 ^ '5 o S.2 "S bJDii i/i 2 crt , 03 *-i o O ^ 2 03 C^ C3 2 .-H ^ O) Cij =* 7h 5^ O 0-1 o o o ^ 2^ 2 03 ^ Ph c« 2 O .2 03 ^ g. 03 0^ 2 Pi 0-1 O ^ 03 bC g c/3 03 03 '•-> b! a Oh :l^ ■ O *03 ' cfi ccJ CJ .2 ‘-S a.2 . 'O! s § i ^ O X3 13 "■' O su c5 cj Oh ^ 2 ^ g W '73 03^ 2 cn . 03 2 .2 2 o W3 g ^ •t^2 Oh'^ O ^33 2 o 9 2 2 'O O O 03 o -S 03 "S . u n 'S.2 §3 ^ - 03 t3 03 •!= 4-> C/3 Cj O » 5: *si ,'si ."2 *03 .<1 o 03 0^ C/3 ^ g 2 >-| jo rij ^'2 'o^ ^.2 S cS 03 be'*-' w o P ^ c^ o o ■5X32 d 03 . ^ o o 03 ^ Oh 03 s O r- in cj o o o H-> _. 2.^ cn .0 O 03 coo Pi 2 4-> Cfi b£) 0.2 i5' ^ .2 'S'^ o ^ ^ o W 03 C3 tn 2 Pi b£)^ ^ .2 S S 5^ s'? 2 S §' s _, a^s 0 Pi bO 3 2s 3 > O Pi. 5 bb g ^ 03 O *5 Oh o ^ q=l O 'd t" 03 O H-> oj 2 .t3 o ” Oh O ^ O o o 03 Pi ^ o Pi Pi 03 °1 --o ^:a-5-S 03 O) c^ .2 jB o 03 Pi O Oh*o: 22 o Oh ^ 2 13 *03 ’2 >->c?i! 03 o Co 4 h ■S.K-S. Oi C« ^11 ^ o C3 .2 ^ cog M, EXAMINATION OF OFFICIAL SALTS, lo; S O y, d O 2 ^ c:a .'S a 8 § o ^ t>X)rd X3 ^ c rt >^ .J2 ’ft •B g J= O -s ■2 § - O-ii-S ^ , H . CT? P-i-H * . o .a — — — bO 'P w . 5 ^ a y, 'g ^ ^ c^ 7 ^ O Qh X 2 C I— I (U CQ .5 cj 'T^ 73 (U C!-^ o; o O! I •« .’2 13 S i.S S^-ooi Cl. U g^ S .^2 0 .-B ° 'o 3 > g ^'S ■p I'-B oj oj ^ !=! ^ c3 O § & .2 -H-» rG g bx):^ CO .ti C3 o ^ O ’C3 dj . CTi d) -M N CO C-) *-S (j O >-H 2 ^ ^ ^ u W 00 CO r5^-55 o ^ ^ It! CO g H_) t._ ’C 3 o o O o ro E g i? o 3 9 E E a E O =! ag £ s J-H ^ Ph. ^3 fi .TP ci a 73 P ^P P r-| 3 • .-1 CO P P P P ;-i P __P E p P CO 3 rO d) >-i a 3 "i s c_ O O^y P h .2 Ei .ti ^ O 73 c^ O ^ fl O (L) 13 CT' E -(-» ccS E c ° o 2.2 o 3 §’^E ^ c ^ ^73 ■ fl cj d) C^-S S « .. •S ^ ^ o ^ « (U o C 3 01 01 tj ^ C3 dl ^ 5 -< Ph Ph O 2 ‘_§cS ^ o g '£ a 3 g a 01 J=l H a 23 cj d) 3 ’3 ' CD .^^Ch-. d) ^ ^ . rP a .2 3 ’E,’ O •iP' CO CJ 2 O PhPh ^d-i d) o o .. jc g E oi^-E.P 73 ^ ^ ^ >H ■ • ■ O oj 1 +-. d) 0 ^P 01 *7 CO E b o P CO cj p ^ •- .2 ^ o 3 .2^ p P E 'E P E rE P P rP 01 k^ 73 fcJ0+-> o 2 .2 P p c /2 p g-E CCS CEE'S 3 -^3 CO . cj E'.p'Eh P S o 2 P rP ^ a^ a 3 s p ^ g ’^2 ’-' E .p Ph '•-> cO CO be 73 73 I— ' ^ c> 01 P ■ ’ ' ' P '-' 7 Ji5 . .2 P3 O p p a p ^.2 EE - g ° cj >. P P^ . ^ P VP 73 P 5 P cj s 3 o^ p E p E p E: - g^g- 'p> 2 I S 3 o y’S'g ° 2 g §3 P 01 E p 2 S ,. O’l 'E P' ^ p 01 p 4-> O Cj CO ^ 73 .-P §6 P .2 01 p S g 3 .S_- > p >^.2 ^ ^ p ^ rp ^ O ^ rH P b .2 p p a pi p •-' a P cj p .P O p p Ph 2 p p .p rH E yo P -p OP rr 03 E 2 e a^:'^ p g p be .2 '5 p p p X p p x: o p o p 7- = ° ii- P >-i _Q ]> E ^ be-r; 13 3 .OP'" 2 p Ej ^ •E P y P 3 a'p E p’g p| •- P 'O f G .2 ° ”1= *E p oT P P 73 .P o 'm 'n a o > P E ^ O ■p CO .— , oj S P p >3 “-a °;&c '£-’2 J 3 u ”'s « 3 O' a" "-H 3 P .2 p ."iP c/2 E ^ ’ Sh ^ > P -7 £3 d O .t:! O M fl o d ^ 5 > 2 o ^ rr-( O “ M • ^ 2 "2 TO NJ C/2 •ti 2 r^-2 C2j ' c f: ^3 ^ ^ ^ oS ;:2 (U ^ S --d CC3 . r-l 4J o ‘r^ d 2 o d d d X d O o 2 0-1 ^ § s| il"' o o -2 H . "-" tj OJ X5 OJ 'dS ^ c3 f ) d ‘Sh ‘G 2 dJ (U 1 g .2 o o P 3 U <+H 21 -d! rP o ^ .2-^S d.^ rp g "3 .3 I O g 8 8‘-g o ±! P O - 'dJ (U o « rP ^ ,(U 'p! > o d ^ P 'd 2 c+H Ph o .-d .Jd ^ +_. (XJ 2 'G ^ *Td .2 ^ 2 S 'S ^ d§ ^ 3 pop; d I — I m c^ .'d d 2 3 c/3 W2 C3 ]-< P. W 3 3 "df o d g p . p 3 o 2 ^ 2 p rH 8 < 3 .2 d .3 o 3 d ^ > 4-> ^‘d P ^ P d5 ^ 3 3 d! 3 p p ^ p 2 d d p o 0.2-2 p, p .8 2 d o P PhP o u'3.2^ (U O P O p p >-l o S 2 i-r3 _0 i ^ d -r d c/2 p .1^ c /2 c/2 X rP rp _ Oj O bX) P ?o d d c /2 P o d p p dJ p . . p • p 8 *2 !-i ^ p oj p 3 o. ^ 8'3 p ^28 'g ‘5 xd P d 3 S-l .P d rP bJD dJ -i-j oj cj p 2 g 8 p ,p dj p d P '2 d ct'mp Gi dj p P P OX) p ^ P p d d •-g o •? H g .., 2 C/2 P So £ '^•32 ^ . dJ X Ph p d 3 p GO p o ^ -P Ph ^ Ph O 3^ p d 3 p Pa ^5 t: dj d .2 P !-h — p p 3 p d rri P' pHd^d 3 p ^ p p M hX)' •nH c/2 -d P JH 3 bx).^' p p §1^- H3 i3 -o g •' P c /2 . CO CO P $-( 0£ P Phx! JJ CO w H < H W o ^'2 2 ■ ■ .p g-2 p dj > d d . p '' o /— •p d 2 d !> dJ d O ‘o 3 2 H-, P o p .p d ^ ^ P '— ' P H-. _ dJ O P c ":s S e 2 g d Cl P Gj Oli O •d Od d Od >> d P o p P CO O W ■p s i'5 .a .8^ ^1-3 < EXAMINATION OF OFFICIAL SALTS. . 107 (U ^ o rs P c3 p I > sm-M (U 0) rO (U ^ > ■ — ' — '+H nj ^ ^ ■TP (U •3 S^G.S CP O 'u P *rG U cd p C/} % > m-h cd cd P G rG '-I P^ c/5 O in ^ TP G P.3 -2 S^o3 A ^ ^ P-- i2 3 -2j . 3 S 3 3 .G "2 ^ 05 cAi TP 3 a p p 3 P Gi p P Gd -G "o coh cu 05 o Cd 3 G cd pp 3 05 G P .^.G P TP ^ +-> G -53 o O P. a Pi -G G nd G • G G P • P ^ 3 >^T3 ^ 3 ---3 td 2 ^ G 3 • T tP crt P G c/5 .3 G 3 ■e 3 _ p G e G G p G G G P G 3 3 S l8 p 3 p p.^ P P 05 TP ^ fe G ^ P >H •-GP P p3 G P B Z^S G rP' G 3 S p o3 -p 3 3^ <^ G cd G P P c/5 3 P P ^ 3 .3 .3 .a G 3 3 3 G g: ^ 3 p o PUP bX)GP G G P a P 2 .G rG .i3 G .3 '-U-. P fe P a p GPP p 3 p *3 c/5 3 p 3 ."G c/5 G 3 a Td P 3 3 bJ3 P 3 G • G P P G cd 3 3 ’im P a __G 3 > a - .2 T3 'P 7d X gj Ss? ii'S . p o CJ "p p 23 p. ^ W O) P.3 i| I-S 3 3 3 a >^3 G P in 3 3 ' p +-> G ■~' P • G 3 ^ 'So ;_ §1 •p o G P 1”? P ^ G G H T3 § p "P V o P -G cG G Us s ii « 3 "p "o a c/3 C3 ^ C/5* O P T3 O P ‘G O in ■K -p 3 3 a CG f~i i-G o I 3)3' ^ ■pG G c+H in in O G- 'P G ^ 3 'p 2 p s,“ 3 3 s U .a o ^ ^ in 3 SC S "o. 3 o cA) Tb .'G ,cA! G 3 G P .px G G 3 P G .G W5 t3 O Ills G P G •4-> *_G P P 2 ^ P Ph ^ G P P P Gi 5c “1 i 8 o in >. P P C P G T3 3 G P 3 G .-G too ^ ^ 2n3 «'§ c ^222 G S ^ 2 p;r 33 p p t3 ■p P G pG G "G p P-i GP G, SI T3 P in P Oh a - ^ P Tl3 P P 3 P G P . in 05 G *3 p 2 _ r"j Oj TI3 c/i 3 p M G o G ^ a P G 2 ‘G -G G P P ^ G ^ Gi c/5 G <1^ <1^ T:? .ti > P 3 -G c« 'G g .. 5 : W."2 " P G G Ph S3 g3 . ^G P G ^ .3 ’5o c/5 3 G ^ p - ^ O ^ ^pG G •p 3 rn M-H P P G G G 3 >. a .3'^ - aoj.a g3 •p .G ^ G P pG ^ ^-i G ^ ^ .3 ° p bp pp.4 2 G' pG ^ cd G +-> 3 3 p3 G ^•3 0-2 ^ g's;g3 1 .> 3? g a t^n G G ^ c/5 e 2 T3 .2 G Q, P G .2 T3 3 3 ^ G a 3 P 3 .2 3 p| a .a 3 Si T3 G 3 G o 0-.9 (U ^ 3 ^ a 3 g ^ .a Co 'G O an c-J •S G ^ a p 3 §1 a 2< PlH ^ P S=! N ’^1 O io8 QUALITATIVE ANALYSIS. E aj H > h 'P to o > aj blD S O > s U ^ e- • S'Sol ° ^ c3 P 'id ^ ^1^0 §3'^ = ^ ^ u o .2 '"'5:-x:! ^4-. X o5 ^ *o O (u .X ^ o 2 3 O C c.^ O O y Q c X O .X ;-H X a X , o ii o^ a !=! (U X O ^ a1^ .a >> a X X a i3 X 2 o ^ X o gJ ~r*^ g " " ^1 X X OS ^ rT' M TO 2 ^ in d ^ S <; ij bJO cu ' G ^ OJ Crt o . rH a G X c/3 ^ 2x X o G ^ .3 o ^ Gj X X G . G 73 ^''’2 P3 G.a X b ^ X 3^ X (u a G .a X ^ SH 03 I? G ^ . ;xsra S X 03 *1^ ^ 3 ^ x X c/3 G ^ G Cvj G G (L) > X G > 3 X G 3 . ^ G ^a ? so’i ^■3 5 I rX ^ O G ■ 2 c^ 5 ax G b^lb:; >-. G .a 'o) X 03 G .G 3 x5 3 ^ ^3 X 03 !_ X G G G •“I c /3 > 3 ^ a? 2 ^.2^ o „ ^ ^'' 2 t.x3 ^ X o 3 G 3 X 02 3 |x3 w '^1 ^x H X o G 03 C G „ 1-^ G G *G 3 < 2 G 3 ^ 3 X G X 3 G >.^.2 . 2^X 03 ^ X 'I X (D S r^ 2 O a c/3 .G G . 'U ^ X X G }-i X G O 03 a o G G a ^x- o 3 G I ^ C/3 X 03 O 3-g >^ ^2 G ^ X G G X 3 H ^ 3 °-f 3 ^ 1'^ G 3^2 2^ W 2 03 4-> G &x ^ O x'^ c ^ ^ ^ 3 .2 0 CG 4-» 2 ^ G X -M c/3 3 G 03 3 o x3 2 X X X 2 a X G G p C^j O G G 3*3 03 O G 03 ^ ^22 X ^ b X S 3 S-, a X ^ 2 3 ^x X X >> 03 X 2 ^ G G 03 c /3 C /3 X 03 b 2 3 to in G O X ^ bO G X . a X _ X ^ X O c/3 03 X ^ 3 r" XX .a a 03 0X0 O 03 G 03 73 03 Q g 2 O 03 X > 03 a G C O cT X 03 .a ^ g g a ^ ^ X s ■3 ^ ^ X 'i .bj ^ 2 > ^ 2 G G .G 1:2 nS G X > • 3 5i § 'o ^ X o v2 ?S X 'cr ^ G G . 2 3 ‘g g ao . 03 3 G ^ a oo X .Oi i.^ O 03 U EXAMINATION OF OFFICIAL SALTS. 109 a to < 1 ; «*-. > O J-i iS 8 § ^ a ^ ^ O cS _ ID O ^ f 'S.s ii to •ti ID X! o .^Jnd D ■'5 8 •£.S« O „ •- B o'B ^ a ’o D o ( 3 j ‘bi: S a. “ * O t3 S ’S i-o|| l1 §sl z_j • rt ^ cii b ^ ^ G ^ 5.E5 ^ o CO «Gi ^ O O ^ '.B ^ CO CO ~, cj G ^ I ° S c p S g 5 o G '-’ .p ,1 |.f ^ ^ ^ ■ ^ aj D ^ bJD O ^ ,N G -l31o 73 ^ 3 - 4:3 oj .. D 2-0 ccJ C 9" • 'S'? &.2 G '^'S. s § G ^.2 Li^ '4-> o ^ ^ s ^ G o D > ^ o p D O ^ P D i-( ^ ■ - p/r^S < 1 ^ a > D rP O >- b>..P X > G-:d 5bs!i D ^ G !- +e rP .2 ^ P 4J CO cj G P Pf T 3 ^ S £ o D O p O ■p 5-1 o 5-1 Bi p p^ 93 l> P3 O CO CO U ,P ■P3 D > CO ‘co >> P 13 H p G .2 (U u p'^ D ^ CO £-5 D o iT-2-^ ft 2 ^ O -G *rP T3 G ft^ ^ P G G ^ P .2 G K* 5-1 P s_ *co >73 o.*G ^2 .ft w G ^ 00 .. p 2 ftrP P ^ rP ^ip.2 p . O D B ft o P CO o G D ft 'O 'Ph'5 8 'g O -'Sft rH D ft -c^ 0 •32 5-( o; fe W • -H fi| 5-( > ^ D CO .w •^ D 33 G ^ c/T.£ ft .2 ft 2 ft _ bX3 o .2 p ^ *=^'^£.'2 2 P (j o P oT 'ft 5-1 "jd +j ^ ft ft CJ ft Oft >-. o .2" CO ^ ft G O ^■‘ 5-1 ^ D •^.ft ^ S " S 5h O ^ -'-’ I ■ •- p 8 ft^ G G ^ ^ ft 'g O'B P G P G^ P ^ rft S)Ji-^ D G T> P ? 93 S-^ ^ fts .2 a 1j .2 ^ft G P tuO D G ft P ft CO 13 D o £ G ft P . G ft CO ^ 2 > -73 'o £ > G D ..s'B .ft 5 h c/3 -73 ft G '--d G ft ft D G ^'P .ft ^£0 ft ft P _ TO D ^ 3 P G CO ft G 4-» o 8 ^ 3 o bc^ ft o D ^ ft o ft p ■?:: D o P ft ft o ■II CO D G rj^ w P P G 5h .M _ rri o ^ •p >N p 3 -p P O G bJD W3 ^ ^ CO b/D ft CO G P ft O CJ P 5h •— ; CO P G 2 ft G ' — ' ^ CO P ^ G O P •r-( cJ P G ft O ft § 5« H 2 ° ’ 5-1 "p }-l p ^ p ft ft o t§8 D ^ D . o.S bC D 2 'S p G ft O D > ft <1^ G V ,3.y 111 'P ft D G ft CG CO <1 2 g p CJ ft CO ft 1 l S I P ^ CO ft ^ ft 8 a bo • ft - ^'o ^ §.2 '<> -ci id ^ feS ^ p H :§ <-5 ^ ^ 'o .2 ft C/5 CS in 4-> P A S ft CO J3 CO b p o 93 'I ffi ‘S.s _ p -s I D P S ft a G 8H P G o g I Proof of Presence of the Proper Constituents. Proof of Freedom from Impurities. I lO QUALITATIVE ANALYSIS. C! b£) O !-( aj Gj O ^ 'o 'Td <0 ’d !=1 cj s ^ bJD S CA) 73 'g -3 d o3 P o3 ^ 'V (u .P 3^ 11 ° :ii ■ ' P o ai W H <1 d a H 0) be d 03 o 73 o o3 Cl O c ^ ^ ^ u oj (U P-i't 3 o3 c cu P P ‘o o > P ■ S'sbs Is1 siS O (J ^ 3 3 S p 3 p S 3 rO S 8c3 c3 5- O q=! 73 *C C >-.'C ^ C • 1 ^ 1 ^ 1 'Sli (U N CA! ‘C 73 O O 73 P ^ S3 •'P ^ o o o <3 73 P ^ P 3 3-^2 CO CO c .-i <1 ) M p .C O 3 ^ cihc^ o3 P CO o 3 -73 2 ^ a CO iP CO "p • j 3 S P'> . 5-( > 1 > ‘Jh c2 ^ P .13 C X ^ ^ *C CO 3 co'' ^ p P P - c3 C be G § O (U .P d ^3 3 (L) ^ .tij p 3 ^ 43 C OJ 'd .3 P C' CJ .13 S s ^ .a.d C -'''d ’d ■C P CU ^ JJ !-( CvS p 3 O Q Cj_, JO CO Q p CO (U CO .3; H (U ^ ^ 0/ P CO p d „ 'P O cj cj 7 K ^< VO 73 •■fe 3 3 lu 8 § .T3 GO I ’^3 I • ^ c ii ^ d G EXAMINATION OF OFFICIAL SALTS. Ill a c3 C! 3 CT* s *> o u -l .t^ O _ 0 'O ‘S OJ c:l CJ O c/3 '-M (U O X ■ a o 53 o p. oS . Ou-£ c« cu -4-» T3 o £ rt ^ O .p "d P ri, OJ •-' a ^ ’o •d y rP ^ ^ o.a O cn -g O 2 o 'rS I •' . 2 ^ 2 As'o rH P OJ O ^ ^ bJD gS p: c/3 C/3 O o£ > £ “ S .d c/3 4-> ->Td p ,0 (U PH 4-1 J-> od P -d .y o Eh ^ i-t CO . ^ T3 crt (t) 4_> <*? (D cj Ph rt o y:; •£ o Oh 'o ^ Jd Td O gS -id 3 3^ 2 o ..■5 t? =" ^ o; C (U <0 gS c/2 C o • a| >-H .;rl ,0 tn 'h-h t/? dJ c^ (U g3 O ■id Ph Ph K. '+H ^ o 3 .P cr > ^ 3 ^ TH gS o; rP 3 ^ 0^0 Ui !/3 -Td ‘o ^ p fl (U (U ^ O P. o ^ ^ #s 2 '^ PP3 0 / o ■g-^ 2 5. c 3 'S o 3 P P £ 2 3 OH -d c! -id 3 . --aH g a c 3 Q PH Ph g 3 Gj o'2‘S s dd ^ ^ P '3 P ’-! ' P y Oh .y 3 2 ^ Crt r-d 3 c/3 la ^ 3H 9^ O „ •-H Gj oS — I (1) ^ 4-. P rrt 3 ^ P P' >>2 “ cn p fT^ y in I-HH E-i r£ 3 -p o ' t: b/D^D P 3 P o d ^ al P biD £ P p5 P 2 £ o.SPav- S c a °.a (U cn >-^ >-i ^ P i 8 Sio.a O S o o^ "d -4 Sd .^-2 - P 3 S -P ‘rd 9^ ^ ^ £ dj p £ p p y p o !> o . P 'o3 P G3 -y xJ ; bc rH P 'PH £ 5 > PH •go d 8 ^ p HP P P p 7d P Ph 9 a 3 £ p Pd Gd P cn p - P £ P ! 3 D .2 £ p (-H 3 -d — 3 53 p P .: OJ Ph f^-P 2 p o -d P c/3 2 cn c y .-P O .3 c/3 "xH .N Ph2 2 73 p o y d 3 y p ^ CH a 3 £2 £ d! 2 ^ .y .2 biD o p O O Oh 3 S ^ P fcJD ■^G > 'o s« .y O P y S 3 2 9 o y p ^ o o -3 73 3,3 !-h cAi o y Oh ^ c/3 p « ^£ -y p § a as a bO c/3 O P 2 > c ■ 3 3.2 02 y.p ^ a "d 8 h o p a p ^ p X p p p p p go 2 2 92 o p Oh (iJ' o 9 dO d: o o 2^3 P o o d P3 p o3 N I S I i G .'bn id 2 'S ^ p . 5i HH pLl P ^ 3 P 3 ^ k! O >H ^ bi 3 ^ 5 y •■ts O o O 3 P a 2 < 2 py 1 12 QUALIIATIVE ANALYSIS. 0) d x) 'tn o s d j-> u > ;s o2 bb ^ o o w C a; - . ' 7 , "S ^ o ^ > rP H < «< P P c/2 d O O ^ H P s ^ o;^ 4 -> cj <2 .-i 3 a o -g 43*' O 43 o 55.^ o 0 ^-[2 O i~* o. § f ^ ^ '1 2 ^ g,'2 ^ I i.s s- 3 U^| s ^ iu ^ 'p 2 _ (U CJ C "5 (U ^ ;-H u nz! C5 p, O P T 3 p >-. P. OJ (U L> S?."^ o g 2 .-,-2 &>s a a S-'. o c: I'S 2 3 ,, P ^ P nzJ S ^ T3 P S P p. O P ■' oi P .P <1^ — ri 3 rP c/2 'P cn I ^ P p O O cn O fc-“ g.'« vU n ^ p ,s 02 +-> P b cn P ^ P a '■^ p p p ro ^ 'g 4 ^ O C-t-l 'P •-“ §M .P'P ^ S ’’O *l-> 043 cAit /3 0 -5 6 ^ ^ p'' '> ^ B .2 B p >< ‘g p '5 .•p 33 ^ 2 .&§S^S p - p bX) p 2 P S .&’p p ^.-P a; 'B 2 t>X)-P ^ ^ pH P a ^ g p ^ .P P c _ s 3 O 'g P 3 ^ 2 P p 4 , > '33 cn ^ 2 B: '- B o ^ sn C T-* rn “g'S S'? c S °'-5 u 0 ^ r^ •p P- 2 B P P ^ rH B 'o P c3 B3 P W2 "2 • p > >.'s S'! "■ Sl|- 1 a " “ i2 3 c'“ ► 3 -g 33 43 X) B ^ t/2 aj P cn P o C3 P P rp 'P' p (U --H P B p^B ^ o l| p P t 3 P P »N rv P •P P Pn-TZi >-. >H rP X 5 g P u Oj ^ p a s-l C« H-» ,. P ^ ?s > 1 »H 4 > ^ I nb o P ‘tl c “ ■S S i.ssB P S O .33 S'l • p ^.S <^4: I CHAPTER V. QUALITATIVE ANALYSIS, AS APPLIED TO THE DETECTION OF UNKNOWN SALTS. I. GENERAL PRELIMINARY EXAMINATION. Under this head are included, — 1. The observation of the physical properties of the substance sub- mitted for analysis. 2. Its behaviour when heated, either alone or in the presence of reducing agents or fluxes. 3. Its reaction with test papers j the colour it communicates to flame, etc. So particular and minute may this examination be, that in the larger works on chemical analysis many pages will be found devoted to it ; but for the pur- poses of the analysis likely to come before the ordinary chemical student, it is sufficient to only carry it the length of a few readily obtainable and unmis- takable inferences. In discussing the appearances to be obtained and the in- ferences to be drawn, we will take two distinct cases ; — First, the best method of procedure in event of the substance being a fluid; and, — Second, in the event of its being a solid. Case I. THE SUBSTANCE GIVEN IS A FLUID. Step 1. Carefully mark its reaction with blue and red litmus paper. Evapo- rate a little to dryness at a gentle heat on a clean porcelain crucible lid, observing the nature of the residue left, if any ; and finally raise this residue to a red heat, carefully noting whether it is volatilized, blackened, or altered in colour any way. From a careful study of these points, the following simple inferences may safely be drawn ; any appearance not referred to being neglected as not afford- ing a really distinctive indication. A. Neutral, no odour, and leaving no residue whatever. Probably water, B. Strongly acid, leaving no residue. Probably an ordinary volatile acid, such HCl, HNO3, HCgHgOg, etc. C. Strongly acid, leaving a residue, fusible by heat and also strongly acid. Probably a non-volatile mineral acid, such as H3PO4. D. Strongly acid, leaving a residue, which on heating chars, and en- tirely burns away. Probably free organic acid, such as H3C6H5O7, HC7H5O2, etc. E. Neutral or slightly acid, leaving a residue, which volatilizes in fumes, but without blackening. Probably an ordinary salt of a volatile metal, such as NH^, Hg, As, Sb, etc. VOL. II. I QUALITATIVE ANALYSIS. F. Neutral or slightly acid, leaving a residue, which on heating blackens and volatilizes in fumes. Probably an organic salt of NH4, Sb, or other volatile metal. G. Neutral or slightly acid, leaving a residue, which on heating changes colour as follows : — Yellow while hot, white on cooling, Probably salt of Zn. Deep yellow while hot, yellow on cooling. Probably salt of Pb. Yellowish-brown while hot, dirty light-yellow on cooling. Pro- bably salt of Sn^'\ ^ Orange or red while hot, dull-yellow on cooling. Probably salt of Bi. Red while hot, reddish-brown on cooling. Probably salt of Fe or Ce. Permanent brownish black. Certain salts of Mn. H. Neutral or slightly acid, leaving a white residue, which blackens on heating, burns, and leaves a black or greyish mass. Pro- bably an organic salt of a fixed metal. In this special case, proceed as follows : Moisten the residue with a little water, and touch it with reddened litmus paper. If alkaline, the original substance was an organic salt of K, Na, or Li, in which case proceed by {a). If not alkaline, proceed by {b). {a) Boil the ash with the smallest possible quantity of water, filter, acidulate with HCl till effervescence ceases ; dip a perfectly clean platinum wire in the solution, and try the flame test. If crimson, Li. Bright yellow, Na. Violet, K. Note . — The latter flame not being very easily seen in daylight, it is ad- visable to add to the solution PtCl4 and CgHgO. Shake well and cool. Yellow crystalline precipitate of potassium platino- chloride (PtCl42KCl). {b) The ash is covered with water and treated with HC2H3O2. If effervescence takes place, the original substance was probably an organic salt of Ba, Sr, or Ca ; and these metals may at once be tested for in the acetic acid solution. I. Neutral or slightly acid, leaving a residue which takes fire and continues to burn even after removal from the flame, giving • off clouds of white fumes and leaving a fixed white or pinkish residue. Probably a hypophosphite ; which fact should be noted as an aid to future information as to acidulous radicals. K. Strongly alkaline, leaving a fixed white residue, also alkaline. A hydrate, carbonate, bicarbonate, or sulphide of a fixed alkaline metal, or a hydrate or oxide of Ba, Sr, or Ca. In this case ' proceed as follows : — Acidulate a portion of the original solution with HCl. {a) If it effervesces without smell, and is therefore a carbonate or bicar- bonate, test at once by the flame for K, Li, Na, and also another portion of the original solution with HgCl2. If red, a carbo- nate ; if not, a bicarbonate. ip) Effervesces with smell of H2S. In this case it is a sulphide ; and if a deposit of S also takes place, a polysulphide. Add to a fresh portion of the original solution excess of HCl, boil till H2S is expelled, filter, if necessary, and test the solution for all metals of fourth and fifth groups. DETECTION OF UNKNOWN SALTS. ns (c) It does not effervesce. In this case add to a fresh portion of the original solution, AgNOg. If a brownish-black precipitate be formed, it is a soluble hydrate. A portion of the original solu- tion should be neutralized with HCl, and then examined for all metals of fourth and fifth groups. Nofe . — If AgNOg with original solution gives a yellow, a white, or a brick- red precipitate, the presence of a phosphate, borate, or arseniate of K or Na may be suspected. In the case of a complex solution in which a salt of some other metal is given dissolved in excess of an alkali, an intimation of the fact will be obtain ed- on cautiously adding the HCl, as, at the moment of neutraliza- tion, the dissolved substance appears as a precipitate before again dissolving in the excess of HCl. Basic plumbic acetate has an alkaline reaction. Step 2. Dip a clean platinum wire in the solution, and heat in the inner Bunsen or blowpipe flame. The outer flame is coloured as under : — Violet . Golden-yellow Yellowish green Crimson Orange-red Green . Blue Potassium. Sodium. Barium. Strontium or Lithium. Calcium. Copper or Boracic Acid. Lead, Arsenic, Bismuth ; also Copper as chloride. Case II. THE SUBSTANCE GIVEN IS A SOLID. Step 1. Heat a little of the substance to redness on platinum foil. A. It fuses and gives off steam, probably water of crystallization. B. It fuses and gives off the odour of ammonia, and leaves an acid residue, probably the ammoniacal salt of a fixed acid as (NHJ^HPa. C. It volatilizes without blackening, probably an ordinary salt of NH^, Hg, As, Sb. NoU . — SbgOg fuses to a yellow mass before volatilizing. Many iodides also fuse and give off iodine in violet fumes, especially Pbig and Cdl^. D. Blackens, burns, and volatilizes. A free organic acid, or an organic salt of NH4, Hg, As, or Sb. Nofe. — Oxalates, although organic, do not blacken to any extent. If carefully observed, however, a slight greyish' tint, followed by a distinct glow running through the mass, will be noticed at the moment of decomposition. To make certain, it is well to place a little of the original powder in one tube, and the residue, after ignition, in another; cover them both with water, and add a drop of acetic acid to each. If the residue effervesce, and the original powder does not, strong presumptive evidence is ob- tained of the presence of an oxalate of the alkaline or earthy metals. E. Blackens, burns, and leaves a fixed residue, an organic salt of a fixed metal. Examine residue as per Case I. Step 1, N. E. The substance does not blacken, but changes colour. See Case I, Step I. G. ii6 QUALITATIVE ANALYSIS. Step 2. Heat a little of the substance on charcoal before the blowpipe. Ordinary alkaline salts fuse and sink into the charcoal. Some decre- pitating (example NaCl, etc.), others deflagrating (as KNO3, KCIO3, etc.), but no sufficiently characteristic indications are usually obtained, except in one of the following cases : — ■ A. A white luminous residue is left. Moisten it when cold with a drop or two of cobaltous nitrate, and again apply the blowpipe, ' observing any change of colour as follows The residue becomes blue, indicating Al, Silicates, or Phos- phates. „ „ „ green, „ Zn. „ ,, „ pink or flesh-coloured, indicating Mg. jB, a coloured residue is left. Prepare a borax bead, and heat a litttle of' the substance in it, both in the reducing and oxidizing flame, and note any colours corresponding with the following list. Metal. In Oxidizing Flame. In Reducing Flame. Cu Green (hot). Blue (cold). Red (cold). Co Blue. Blue. Cr Green. Green. Fe Red (hot). Yellowish (cold). Bottle-green. Mil Amethyst. Colourless. Ni Reddish-brown (hot). Yellow (cold). Same as oxidizing flame. C. A metallic residue is left, with or without incrustation surrounding it. Mix a little of the substance with KCy and Na2C03, and ex- pose on charcoal to the reducing charcoal flame. (a) Metallic globules are produced without any surrounding incrustation of oxide. This occurs with Ag, Au, Cu, Fe, Co, and Ni, all easily recognisable. (Z») Metallic globules are produced with a surrounding incrustation of oxide. This occurs with Sn, Bi, Pb, and Sb. The incrustation having the characteristic colours already described in Case I., Step 1, G. Note. — Sb often forms a white and distinctly crystalline crust. idj The metal volatilizes, and only leaves an incrustation of oxide. This occurs with As (garlic smell and white incrustation), Zn (yellow [hot], white [cold]), and Cd (reddish-brown). Step 3. Dip a clean platinum wire in HCl, then in the substance, and heat in the inner Bunsen or blowpipe flame ; and observe effects already noticed in Case I., Step 2. DETECTION OF UNKNOWN SALTS. 17 II. PREPARATION OF THE SOLUTION FOR ANALYSIS FOR METALS, IF THE SUBSTANCE BE NOT ALREADY DISSOLVED. 1. Take a minute portion of the substance and boil it with water in a test'tube ; should it dissolve, then take a larger portion and dissolve for testing. 2. Should the salt prove insoluble, take another small portion and heat with HCl, and add a little water and again heat. If it now dissolves, prepare a larger quantity of the solution for use in the same manner. 3. Should it resist HCl, try another small portion with HNO3 Seat- ing, and then adding water. If this dissolves it, make up a larger quantity of a similar solution for testing. 4. Should HNO3 another small portion with two parts HCl and one part HNO3, warming and diluting as before ; and if it succeeds, make up a larger amount of solution in the same manner. 5. If all acids fail, then take another portion of the substance, mix it with several times its bulk of a perfectly dry mixture of sodium and potassium carbonates (prepared by heating Rochelle salt in an open crucible until the residue thoroughly ceases to evolve any gases, then extracting with distilled water, filtering, evapo- rating to dryness, heating the residue to redness, and preserving for use in a stoppered bottle. This reagent will hereafter be shortly described as fusion mixture). Place the whole in a platinum crucible, and fuse at a bright-red heat; when cold, boil with water and save the solution thus obtained for acidulous radicals. The insoluble matter is then to be drenched with strong HCl, slightly diluted and boiled, and the solution used for testing for the metal. Any insoluble white gritty matter still remaining is put down as silica. III. DETECTION OF THE METAL. The processes to be applied vary according as the substance under exami- nation is a simple salt or a mixture of salts ; and the following tables are to be used accordingly. ii8 < S O o o o g S s > rt ^ QUALITATIVE ANALYSIS. W T3 .3 _ ^ O dj i_ CG rt (U >~> o, os ^ W) I— ( ^ c H4 'C' 4J 'G ><. G C S P oi o . ^ o 4} W -z A I 0) C Cu 8'|. S I o ^ 3 ^ Q -Q O s E b ’S (U 43 -Q ^ .b >^<5 ^ 8 (U A b ^ o .: tC U W . O4J O O hcv o (/3 b H.O ^ 4 ) *c-^ £3 ^ II a il g-S'^SK ^ ^ rt b 15 bj A * ,0 rt t 3 jj tH .b •• IhC o ^ O 2 9 !jgs- 2 s^r SV, o cc w O M t” *.-•>« g 2 1 = ” s « ^ ^ ^ o'X ^A O +3 >.A «J 5- 'T3 rt •— ' .0 rt e „ hO N] (u .. H-> .-H >0 Oh S 'o -<>r c 0 T3 rt G 0 . , b A G g < cb > «j CO Oh ' „< io II jZ.S ; bj3 cs i< ■«>H „ X . ta , -G < % As Mn may sometimes precipitate through the solution absorbing oxygen, it is always advisable to filter out a little of this precipitate and fuse it with KHO and KNO3 : — ereen residue=:Mn. 120 QUALITATIVE ANALYSIS. Ph o o o H 52? CO o ;z; o H <1 Ph w s B i W - c ” to ^ < 1 ^ S ^ g ffi rt ^ a °o 5,^5 8 ^^ 1 -s :: ^2^ux « a ^ 3 kTkh' ^ ^ ^ y=i „• ( 2 ; ^ cj S rt c3 ^ O >1 ^V ;.2 ^ g s g y 'S ^ -5 ^ a.?:; 75 ^ u bJ3 75 Co S 25 •S o |zi 70 — Oh' e C rt O ^ ,_ ^ rt rt OO '2 o o”o”o”^ m C/3U TO -t; bjO Cl, ^ .2 i g I c^‘ yj -rH O C ,-H c g o t/I > g o n:j H-» ^ c3 o c ^ -g' C '►•' o lh t/3 7 :> 7 O O ^ cS - X! CL, CL, fOTO O t/3 g I* 8 -- 2 ^ w S^ g = - T3 ChCL, 2 o 2 "c pZ 8 o Oco3 (MhH Cj ^Niziu:?!^:^ ^ 2 5 S g 2 5'2 ^ 3 ^ 3 S ^ .2 rC o 2 c! rt X O- S ^ ^ h U lrl 2 ’S"-« -s ^“ 1-^-1 I 52 ^ 32 ^. I o •g .2 ^ (U Ch O a cJ ^ S H-> O c g Vo — . bjO W ^ ,2 § _ CO •<. * !~1 ^„CO CO CO CO a ^ ^73 .hS^ a TJ H o ffip^WUU CO CO ,, imCO c 'Zco CO 4 u) T a o ., . e||^ ^ § C 5 i ^ G o -g ■a "I ^ W G G rP d d 1 r~| 0 +-• 3 c -2 -t-j 4 -> 73 G d 0 d Crt G in d 5-1 Ch-I d Ph l-H d rP 73 d d 0 u ^ 5 h 'B u 0 c /3 15 d Ch-H l—i !>^ 0 S 3 ^ ^3 nd c/3 G d 0 ^-4—1 bO d d 'P 73 73 G *G G d rP d ^ 0 a 5 -h G Ph cp • -H d G 0 d bO .a .2 >^ c/3 rP and too P. N G cp O % “ I K 'c ^ •S S§ § 0^0 K. o 7 , a O S ^ K qj ^ ^ ^ O O 'a ^ rP G S Ph .2 £ ^ ai c« G P P -G ^ t3 o O .a d G O ‘g .^2 S d 5 -h o G d G 73 73 G G CO to w d rP ^ fS u G < d 5 h ^ -P Gh cj >> ^ rP -T3 -H ^ u ffi o" .a u bo G O .12 -K ci cd ^ (L) O § .-a cp d CO bO " .a -2 ^d ^ 73 d *P 3P d G ^ G d S 6 p s I bo 'o .a •'g O c ^ d Note i. — T oo much water added might precipitate any Bi, as Oxy-Nitrate. 2.— If any Cl have been left in the original group precipitate (through inefficient washing) the HgS will dissolve and be lost. DETECTION OF UNKNOWN SALTS, 23 g O ^ o o a, o g G S W ^ G o ^ d O rt'-g u, O >, O U pq h o M 02 M > M P P P o p p p o 02 P < H P P O J 2 J O M H <1 <1 p p CO rt 2 c (u o ^ ^ u O g)c^ &'"l -S O 5-h ^ qj CIh Vi ^ v> U-4 , 2 ^ Q. vt ^ ■ b ^ CJ ^ (U be 2 _ -a ^ U S .S V cj .-b CO 2 c S 60§ O Oh b CJ . W2 4 -. D "b .? 0 b T3 -Q § CO *N a -| I' ^ ^ ^'4-H ^ fl 1 G ^ ° °. 2 ^ "d ^ O b r J ^ S^rb J 2 c3 “z 2'2 tTp c« -d! ^ ^.'b 2 a ^'Sw a s g ° • b ^3 c/3 b b b bq o '-b CO 2 §2 ^ ^ o (U ' ’ '^ bi *- Co rb C\j rb +-> 4:J '-i s ^2 tco'^a Kn 2 d c > > S 2 -b 'S 2 b 2 ^ 2 b g Jb b ^ W 4- c ^ ^ 2 b b g ^ (U bs ^ bb d '-' ^ S cb b 2 t 3 -b ^ b ^ 2 b cej a '^2 ■s u u n & - . * « jj.sy -O^' +3 ij a -b'lz: tC 2 ■'^2 2 cu ^ c b b ^ bq "d b b ai cxi g a •'§ ^ I ^ s, ^1 s •- 5 a P CJ 3 o a 1 •§ b CA! CO g ^ o Zb a 2 .SP a b' ^ d ^ bb b ^ d rb 2 0 a d b _ 2 3 a >^ b b:: 2 . 2 a ga ^ 2 a ^"oo b ^ 2 a 2 d .a 1 — I b ' cj ^3 g 1) o I •'-' U o d a a c2 b ^ ^ r^ R ^ ^ 'd r^4 0 0 0 b in (M 03 P b (— 1 Vi d b ■a 03 P 03 2 P 2 b P 03 b c/3 »-i bXD b r-' 3 b 0 0 03 03 Vi in CO , c\ C/3 .2 CAI 03 p b w P a" 2 0 P d %J d ^ c/3 5 r> b b ^> d b: .bd tJD S b3 b b .;:i >^-2 ° a b ^ CO b 3 I w &0 Ik'"® ^ ^2 b (u o <-; (13 ?-i ■g b ^ B a a 2 o 2 b a r-. d a 2 5^ •a ^ d ^ b d a ^4 b c« o, d qj CAl -b (U d ^ d b3 a bnU „ d CL> rJ=l I VI ^ B b b 2 a 3.S a 3a g g d ^ CJ b >.< S b lC b 8 :§ >sC b B - CO Vi 03 i-i TK "tf ’Tj *-* g 2 2 d as ^ 'b ^ p.a V 44 d . • ■— I fl) cc b - b ;h c/T 3 ^ o£ s >< '"g 3 03 >4 .B< d te >4^b U, 2 0 d-| >4^ S 2 'ij b >^a ^ DO a ‘^2 1 bX) 3 b o 3^1 2 p >> p a' 03 d ^ . oT 4-> t 3 "a _Q b c b 2 O b b 2 .rH ^ rs Cej o S TABLE D. SEPARATION OP METALS OP GROUP III., DIVISION (a). (^Note I.) Wash and transfer to a platinum or silver dish, and fuse with KNaC 03 and KNO 3 . Boil the residue in water and filter. 124 QUALITATIVE ANALYSIS. o oO § o L) f— ' H U oj > ’Eb^ CO |g (U '5.S }_ . u 05 O d PM o • S .4-> rin o § u S o 0 i2 S 05 bo^ ^ ^ S II Ch 0) JrJ (U O . pL^ 'g ^ ^ o o d d > s ^ § - '^*'3 •3 g 3 ^ ^ G O • 'b cj o a ^ in -ti *Ti C3 g O X5 (U o G c/2 G -G ,<1J G r^ ^ ^ “ a s ?l in ^ rG 3 3 Dh^ >>-5 G ?G > ^ gT3'3^'^ ^C/;j"G S3--g .bno/GH ^'T3'G ^ G ■ G G4 'rG G bo G *- o C) G t/3 bO G bO G TABLE E. SEPARATION OP METALS OP GROUP III. (DIVISION a) IN PRESENCE OP PHOSPHORIC Anrn [Note I.) Dissolve precipitate in dilute IICl, add excess of Na 2 HP 04 and then excess of NH 4 C 2 H 3 O 2 and boil. DETECTION OF UNKNOWN SALTS. 125 2 c V O qd ,n , (U ^ :§i ^ -T:j •t' u ^ s Ph II - C C ^ cn S S S 2 - Oh P d 'd • id qd O N • .=■ ..5 - — o t/i U 3 W P •'5 •"O ■idP^ !d (U o ^0 d C-i P-i dd So ^ ©fe . 1^11 M ■5 < .S II cS Vi di d S Tf § ^ n -.2 d 1=1 d 0 13 2 . Ph >.11 ^ dd © (/! © , t 3 d rc5 CJ d >-i ^ © t3 "d .S -fePQ fj _d d ■■" ^ © g|l ® iP ^ o U -f ,^d ^ ii S «j > bil <0 S sIb 'o o ^ .HI .a o 2 " •a l;i rt c"S r- rt ^ d 3 r sc-e T, D G 4 )‘d Ul O U ^ o CS 4J d 3 2 ii •'5 bo .3 O W 4) ., .d d (u c vO ° G « ill till rt g; M-J ,S ^ C ■2 g o ft dr "o _ o 4 ^ ||§| c d « i T3>*-giuft 2 _s3 ^|oi CS .d-- d^-a 2 -d c '2 . rt 1) 2 u .. W ft! hO"" .d ■<-• ^ 2 i. O O (U O 4 , o rt td .2 ^v2 ^ O.S ^ j; O Cfl « 5 c3 y-p | 6 ^ ““ O.'^ ft s d a T 3 -C -2 2.3 d dd 3 i§ I 2 cu**^ M 2 2 3 gS 2 d. S |3 W . 2 i u ^ ^.!2 "ft! . • O S ^ ^ o 3 .■S-S 3 sS.i O o rt c - O CJ .3 S 4 j: 2 ^«'B '3 3 _^g l 3 S 2 .S-. 32 ga •H'd§.^|.| GJ . 3 ^ E E °!iiirips "q(/1 3 ^:g|.s rt'-s - ..g « &.S.S :?:&'2 " 1 ^ ‘I'd 3 d o oj '^ § d ^ 3 4,.- ^ ~ ^ 2-3 ^ O _ ^ la^g-ogsis rh S P CO — iJ 2 d g.3 “"plsll.ll |“■ls|B-^s|| l! 2 g|:S 3 i^«^ i-|i 4 i;till 3 es.9 < 3 « g 4) ts " a-d aao S S.S 23S<3!^-o pL| >> o ^ Oj to c H Cl. cj CJ cj JC (1 cj cu CU U be (u w ^ pd (n o U C3 C! O c^ w bo d § CJ <0 JD <=® C cj C oj '.Bt ^ OCX O O cj ^ “ s c < ;z; Ihe filtrate may contain Co; confirm by evaporating to dryness, and heating SEPARATION OP METALS OP GROUP IV. DETECTION OF UNKNOWN SALTS. [27 O u (M 'TTi d d d U .s ID ^ 3 a M d d c/3 (U ^ %-l ’ 2 a IS D • P ^ 'TJ ^ in D d ■Td n3 d '■a d d o c3 D o H d ^ ^ a d d d C/l (d 8 ^ ^ O rd t:3 d > ^ *2 I •g. m ‘o D J-i P4 >^ d d o o ciT U .d d 4 — > d o o d p ^ c a D ng I Ca. d D a ^ ■M-= d ’T 3 II 0 .IS nj D a ^ in D ■+= r-H cd D d . rd d' rd 1> •Si d 'P ^ a. d .a H .JL, rd -73 ’-I B d d d «d d o P d O D ^ rd ai o O ,D ■u I4-1 ^ ' ■ CJ d ^ S !z; bC o D i-> Pm d < and a little NH4HO (to remove any rated, see that a portion of this filtrate CaS04 accidentally precipitated). . gives no precipitate by warming with White residue giving crimson flame a saturated solution of Ca SO4. SEPARATION OF METALS OF GROUP V. DETECTION OF UNKNOWN SALTS. 129 Having thus ascertained the metals present in the substance under examination, it is now necessary to turn our attention to the examination for acidulous radicals. This is a matter of some nicety, as it is impossible to construct tables for the separation of acidulous radicals so simple and direct as those already considered for metals. Much depends, even with the latter, on continued practice in the laboratory, so that though the tyro may fall into errors, he will soon learn to steer clear of the numerous rocks ahead which are invariably met with. It frequently occurs that two or more substances are mixed together which so completely decompose each other as to render the elucidation of the problem entirely a matter of experience. Let the student therefore seek, to thoroughly grasp the I'easons for the steps he takes, and when he has done so (but not before) let him acquire the habit of thinking for himself, rather than slavishly following any set system to the exclusion of the use of his own brains and experience. VOL. ir. K 130 QUALITATIVE ANALYSIS. m 0 1 o p ►H o o pH 1^— I ^ P5 d hH HH P P pH P o 5b ^ o o ^ Oh ^’o "w ^ ^ c/3 1— t Sh ^ (5 ti o ^ --I Q • ^ •g.2 ^ o ^ ^ c/3 O (1) T3 > (U 0 Co o<3 1 I §i > ^ p: H g) ^ O 1 M ort 5 S d 0 P 1 ^ U ffi.| 0 II p o o w . ■pH.S >-l ^ !? -i 5 , , ^ .2 o t/ ^ S S ^ P ^ (U 'P d o r-H ^ (/3 S 3 « u 3 ^3 W3 (U Oh 2 od o S ^ p Qh o t/3 .p >-, 03^’—'^ CS (U 13 ' 2ll' p ^ w c4 c3 1) o p jjB p ^ d 4_, P P> _§- Cj P S « h c3 *"^ ^ f/i c5 ^ fi, (H O d K 43 P Ph d c/5 d CO 2r* o Ph O P, >> w >% u d PP P d 2 43 43 S o to e s| I S- ii g 43 p d s 43 P o r-i (i> ^ P P P CO CO C3 CH a ffi, <-l-C <-M o o d d s s CO CO p p p 8 Q DETECTION OF UNKNOWN SALTS. 131 CJ • rs 5-» tJ OJ c ° II o" tn o , c5 pin « T3 •“K ■T3 ^ o . ^.2 .2 "2 S V3 2 2 y=l rJ 0 ) in O u '2 ’o < (U o > HH 2-2 s= 2 -2 ^ Q. 0> •B - o C o , d d Tl3 > OJ C (L) ^ d d pH 'p ^ lii S ' 2 '!^ d *" fs g •> 'd CJ C o U ^ bO (Si 1 ° b/3 tJ P d p g -2 K 2 Dh o i-i O o in O! CO pq o CL. (L) 13 d d ' Lh C/3 d b/)g E E d 2 ,p 0 u u E (L> .2 2 a> (j d 55 r V 0 "xi > c d g& P 2 B.52 2 d 2 U 132' QUALITATIVE ANALYSIS. V. PREPAEATION OF THE SOLUTION BEFORE PROCEED- ING TO THE ANALYSIS OF ACIDULOUS RADICALS. ^ I Case I. THE SUBSTANCE IS SOLUBLE IN WATER, OR HAS BEEN GIVEN IN SOLUTION. 1. If any metals other than alkalies have been found, add strong solution of NaaCOs till the whole is just distinctly alkaline, boil and filter any precipitate which forms. By this means the heavy metals are removed, and the acid radicals, being transferred into sodium salts, are then in a proper state for analysis. 2. Divide the solution thus obtained into six parts. (a) One part to be acidulated with HCl, and kept for Step i.' (d) Another part to be acidulated with HNO3, and kept for Step 2. (c) Another part to be acidulated with HC2H3O2, and kept for Step 3. (d) Another part to be rendered just acid with HCl, and then just alkaline with NH4HO, and kept for Step 4. • (e) Another part to be made exactly neutral by boiling and dropping in very diliUe HNO3. If by mistake too much HNO3 be put in we must then work back again with very dilute NaHO till just neutral. This part to be saved for Step 5. (/) The last part to be kept against contingencies. Case II. THE SUBSTANCE IS INSOLUBLE IN WATER, BUT SOLUBLE IN ACIDS. 1. Boil a little of the solid with strong solution of NaHO for some time, then dilute and filter, rejecting the precipitate, and using only the filtrate. 2. Divide the filtrate into six parts, and treat as above directed. Case III. THE SUBSTANCE IS INSOLUBLE IN WATER AND ALL ACIDS. In this case a fusion will have already been performed, for the metal and the acid must be got from the portion of the residue after fusion which was soluble in water. VI. COURSE FOR THE DETECTION AND SEPARATION OF ACIDULOUS RADICALS. Step 1 . Use the portion {a) of the prepared solution, acidulated with HCl. A. To a part of {a) add BaClg. White precipitate, insoluble on dilution with H2O and boiling, and also insoluble in boiling HNO3 = Sulphate, - 5 . To another portion of {a) add FegClg. 1. A deep blue precipitate turned reddish-brown by KHO and blue restored by HCl = Ferrocyanide. 2. A blood-red precipitate bleached by HgClg = Sulphocyanide. 3. „ „ not bleached by HgClg = Meconate. C, To another part of {a) add FeS04. A deep blue precipitate the colour of which is destroyed by KHO and restored by HCl = Ferricyanide. DETECTION OF UNKNOWN SALTS. 133 Step 2 . Use the portion (d) of the prepared solution, acidulated with HNO3, and disregard any precipitate whicl^ does not subside readily in a curdy form on boiling and shaking. To a part of the solution add a drop of AgNOs, and, if it produce a precipi- tate, add excess, warm, and shake well. 1. A curdy-white precipitate, .soluble in strong HNO3 (boiling), and also in NH4,HO = Cyanide (confirm by Iron test). 2. A curdy-white precipitate insoluble in strong boiling HNO3, but instantly soluble in NH4HO = Chloride. 3. A curdy, dirty, or yellowish-white precipitate, slowly soluble in NH4HO = Bromide (confirm by chlorine water and chloroform). 4. A curdy-yellow precipitate insoluble in and turned white by NH4HO = Iodide (confirm by chlorine water and starch paste). SEPARATIONS. A. To distinguish between argentic cyanide and chloride, filter off the precipitate, wash well with boiling water, remove from the filter, and heat to redness in a porcelain crucible. Digest the fused residue in heated HNO3, which will dissolve the Ag left by the decomposition of the AgCy, but will leave the AgCl, if any, untouched as a white residue. The HNO3 will evolve red fumes when dissolving the Ag, and the solution will give a white precipitate with HCl, thus proving the metallic silver, and therefore by inference also the presence of the decom- posable cyanide. If the precipitate be all AgCl, it will simply fuse to a horny mass perfectly unaffected by HNO3. B. To detect AgCl in the presence of Agl. Wash the precipitate well by decantation, and then add some dilute NH4HO (B.P. liquor i in 3), shake up and filter (any Agl remains insoluble). Dilute the filtrate, and add a slight excess of HNO3, and if any AgCl was present, it will separate again as a pure white curdy precipitate. C. To detect AgCl in the presence of AgBr. Remove any Agl, if necessary, by digestion with NH4HO. Filter and reprecipitate with HNO3, then boil the washed precipitate with strong KHO, dilute and filter. Evaporate the filtrate to dryness, and distil the residue with K2C12O7 and H2SO4. If Cl be present, deep red fumes of chlorochromic acid will be formed, which will, when received into very dilute NH4HO, colour it yellow. Note I. — In practice the use of the separations must be governed by what is found previously. For example, if no HCy was given off in the preliminary heating with H2SO4, the ignition of this group need not be resorted to. Again, if, say, neither Cy or Br were found in the preliminary step, of course any silver precipitate soluble in NH4HO must be only AgCl. The best way, if I be found in the preliminary course, is at once to test also for Br, by taking a small portion of the original, adding a drop of starch paste, and then chlorine water until the blue of the iodine is entirely bleached. If now some chloroform be added and the whole shaken, any Br present will colour the chloroform golden red. It is only in the event of Br bring distinctly found in the preliminary (or as just advised) that the distillation of a chloride need be resorted to, and even then only when the silver precipitate looks whiter than AgBr ought to be, and is in part instantly soluble in NH4HO. 134 QUALITATIVE ANALYSIS. Note 2. — A very good rough way of getting at the possible presence of a chloride when a bromide has already been found, is to take some of the solution and add carefully dilute AgN03 till only a part of the whole is precipi- tated, then to filter off, and to once more add AgNOs to the filtrate, this time in excess, and again filter. Compare the colour of the two precipitates, and if both are alike then it is all AgBr, but if the latter portion be whiter than the first, then AgCl is also present. This de- pends on the fact that the Ag combines first with any Br present, and only forms the white AgCl after the AgBr has ceased to be precipitated. The separation of Agl and AgCl is so simple that it should always be done if I can be found. Step 3 . Use the prepared solution (c) acidulated with H2C2H3O2. A. Bring a part of the solution (c) to the boiling point, and drop in CaClg. A white precipitate instantly soluble in HCl = Oxalate. B. Bring another part of the solution {c) to the boil, and drop in FegCle, avoiding excess. White precipitate soluble in HCl = Phosphate, or Arseniate. Distinguish by adding AgNOs to a little of the exactly neu- tralized prepared solution : — 1. Yellow soluble in NH4HO, and also in HNOs= Phosphate. 2. Red „ „ „ „ = Arseniate. C. To a third part of the solution {c) add PbzCaHsOa. Yellow = Chromate. Note 3. — (This test need not be applied unless the original solution was distinctly yellow or orange.) If found, the original solution should be tested for chro 77 iate and bich^'omate by acids and alkalies which change their respective colours from yellow to orange and vice versd. Step 4 . Use the portion of the solution (d) which was neutralized hy HCl and then rendered faintly alkaline with NH4HO; hut do not take this step at all unless the substance was distinctly blackened by heat during the preliminary examination, or unless the presence of boracic acid has been made probable by the flame test. To a portion of the solution {d~) perfectly cold add CaCla in excess, shake well, and let stand for a short time. 1. The original was blackened. If no oxalate has been found, and a crystalline white precipitate entirely soluble after washing in cold KHO is formed = Tartrates. If an oxalate has been already found, collect the precipitate on a filter, wash well with cold water, and percolate with cold KHO. Any calcium tartrate present will dissolve and repreci- pitate on boiling. 2. A gelatinous white insoluble in cold KHO = possibly Borates. (Confirm by turmeric test, but otherwise disregard it, as phos- phates and arseniates may equally precipitate here.) B. To the filtrate from {a) (or, if no tartrate has been found, to the •same solution) add another drop or two of NH4HO, and boil slowly for some time. A white precipitate = Citrate. (This precipitate should be insoluble after washing in KHO). DETECTION OF UNKNOWN SALTS. 135 Step 5 . Use portions of the prepared solution (e) which was exactly neu- tralized. A. Add FcaCle (i) Blue precipitates disregard^ already found. (2) Black, or bluish black = Tannate or Gallate. {a) Add to the original solution KHO, Green gradually becoming brown = Gallate. Rapid- ly becoming brown = Tannate. (Also apply gelatin separation.) (3) Red colour, discharged by HC 1 = Acetates or Pyrogallates. (JI) Add KHO to original solution. Acetates, no colour ; Pyrogallates, black. (Other reds not discharged by HCl to he disregarded.) [ (4) Violet colour = Carholate, Sulphocarholate, alicylate. (Former two have given smell of carbolic acid in preliminary examination, and the latter not). The Sulphocarholate on ignition will leave a sulphate, thus distinguishing it from carbo- late. (5) Pinkish precipitates = Succinates and Benzoates. Distinguished by digestion with NH^HO, filtra- tion, concentration of filtrate and supersaturation with HCl ; when Benzoic Acid precipitates in fine feathery crystals ; while Succinic Acid remains in solution. Step 6. Test for a Nitrate (if not already found in the preliminary course) hy adding FeS04 and strong H2SO4 and getting a hlack ring. If an iodide has been previously found, it must first be separated by digest- ing the solution with Argentic Sulphate and filtering before testing for the nitrate. A rougher method is to introduce some starch paste and to acidulate with HCl and finally drop in some sodium sulphite, which reduces the nitric to nitrous acid ; and this latter, acting on the iodide, will liberate iodine, causing a blue if any nitrate be present in the solution. 136 QUALITATIVE ANALYSIS. c Xi .r- CJ :s s oj s ^ C ^ s o o 5h nzJ w II O 5 bo o> o> o o ;h p< O) u *2 a> rO o E-i o o § ■s o Ph d >- 'T3 iS ^ OJ tn ^ c4 rt i3i rQ C « '•^XX s. oD • .5 o> t/3 > 0^0 Pht^ <» rg P bn rs P3 u 2d 9 o” ^ m (N ^oo p > .oo 1300 w ^ s X y 9 , 13P -*-» o 80 o C3 ^ rP tcJ P^O P ^ o m in CO O oq dd i- o y y ^ y" y « :2oP rt:2 .-P:2:20 OCOU-S.SPU S Sec C/30 OO O S-> P >^2 U 33 o § a 2 c /1 y P, y -pj PU 2 IS PU o Put? o a 2 fi s O OO DETECTION OF UNKNOWN SALTS. "rt ^ in in 137 (U o 'S 'S V OJ in in j-i >-i s9, in" oo g OU^S ^ O .t 3 b (u oO -a PhP 3 ^ rt c/^^^c/^O Og v'A 'A i'u ^ u 'g 3 CL, cl 3 75 ^ ^ 'S 3 3 O c /2 a: O O O ^ CLO o S Pm s_ ci ^ ' (U (U (U -xJ '>< V. hhOO ri MP CL ci go aj (u « ■X3 X3 X3 X3 O XC o ■ ■pi 'PI 'PI 'PI n'PI s- 3 3 3 3 c /2 3 PP 6 u 6 C 3 o o ;0 • 4 -» CM lo" .-in n> 3 O 0 ^ W 1, - rO ^ SC> - ^ ^O •)OjU • fO 000 25 * op^o > i l°.i •pl -p CJ 3 ci cS d CCPC 30 00 O 3 q C 3 c 3 J £ ■go 1 -^ ^2 Cm K 30 I-- ly O Cl ^ o O in 10 33 0^0 o o c/2 • HH CS ^o O - c /2 t— I ^ pi L, IP ^ ^ ^ ^0> ^ ^ (lTO ,,W -0 OO Ll—'r'f - - ^^'■1 oO-bCP OH-13^ oOO 2 O ^ O 2 0 0^0 CJ o MnOo, Pb02, or the positive electrode of a galvanic battery. 14. Brucia {Brucine) is soluble in water, alcohol, and chloroform, but not in ether. The presence of brucine is best recognised as follows : — 1. Strong sulphuric acid turns it red, yellow, and finally green, in rapid succession. Strychnine does not prevent the occurrence of this or the following reaction. 2. Nitric acid strikes a magnificent red colour, which is altered to violet and green by stannous chloride. This latter reaction serves to distinguish it from the morphine red. 3. Potassium iodide gives a kermes-coloured reaction in a solution of -5^-Qo of brucine. ' 15. Y ev 2itvi2i (Veratrine) is insoluble in water, but soluble in alcohol and ether. It is very irritant, and the smallest trace of it inhaled causes violent sneezing. 1. With cold H2SO4 it is not much affected; but warmed, it forms a resinous mass, dissolving to a deep-red fluid. 2. ,With strong HCl it gives no colour ; but on warming becomes deep red. 3. Chlorine water tinges it brown, changing fainter on adding ammo- nium hydrate. 1 6. Atropia {Atropine) is slightly soluble in water, but freely in alcohol, ether, and chloroform. Its reactions are as follows : — 1. It powerfully dilates the pupil of the eye. 2. AuClg produces a precipitate. 3. By heating with strong sulphuric acid till it turns brown. On the addition of a little water, a powerful odour of orange-flowers is evolved. 4. ' By boiling with potassium dichromate and dilute sulphuric acid, a liquid is produced, which, on the addition of excess of potash, gives a smell of herrings. 5. Phospho-molybdic acid yields a yellow precipitate, soluble in ammonium hydrate, and forming a blue solution. 142 DETECTION OF ALKALOIDS. 6. A most characteristic test is the peculiar aromatic odour perceived on placing atropine on a few crystals of chromic anhydride — CrOg — in a porcelain basin and applying a gentle heat till the mixture turns green. 17. Beberia (Be^erine) is soluble in acids, forming a yellow solution which does not form crystalline salts. It is precipitated by potassium and sodium hydrates, and is freely soluble in ether. Heated with HgSO^ and potassium dichromate, it forms a black resinous ’ mass. A curious characteristic is, that by friction with a piece of silk it becomes electrical, and will affect a galvanometer and attract very small pieces of light paper. 18. Aconitia {Aconitine) is only sparingly soluble in water. It is recognised as follows : — 1. By its causing a violet colour when added to phosphoric acid which has been evaporated over the water-bath to the thickness of a syrup. 2. When aconitine is stirred up with concentrated sulphuric acid and a drop of a saturated solution of sugar is added, a fine rose-tint is produced, changing to dirty violet and brown. There is a danger of this test being mistaken for the similar reactions with morphine and codeine ; but morphine is not taken up by ben- zene from its solution in the presence of excess of potassium hydrate, while aconitine and codeine are so dissolved. Again, aconitine is sparingly soluble in water, codeine dissolving easily. 3. AuClg gives a precipitate, but PtCl4 does not. 4. Strong H2SO4 produces first a yellow, and then a fawn-brown. 19. Delphinia is similar to aconitia in most of its reactions, but in addition gives a violet-red with strong H2SO4 and bromine water. 20. Colchicina {Colchicine) is soluble in water and closely allied to veratria, but does not cause sneezing. It is taken up by ether from an acid solutioji. With HNOg it gives a deep violet. SYSTEMATIC COURSE FOR THE DETECTION OF A SINGLE OFFICIAL ALKALOID. All the reactions obtained must be afterwards confirined by the other special tests. 1. Place a little of the alkaloid on a porcelain crucible lid, and add a drop of strong sulphuric acid. {a) Immediate bright-red = Salicin {although not ait alkaloid, yet often present as an adulterant). {b) On heating gently, first yellow, then orange, and finally cherry-red = Veratria. {c) Fawn-brown colour, possibly Aconitia (confirm by syrupy H3PO4). 2. If the H2SO4 gave no colour, place on another part of the lid a minute crystal of potassium dichromate, add to it a drop of strong sulphuric acid, and draw the two drops together with a rod. {a) Evanescent blue-violet = Strychnia. {b) On diluting slightly and warming, a fragrant odour = Atropia. DETECTION OF MIXED ALKALOIDS. 143 3. To a fresh portion of the alkaloid on another lid add a drop of strong nitric acid. {a) Blood-red, decolorized by warming and adding stannous chloride = Morphia. (b) Blood-red, turned violet by warming and adding stannous chloride = Brucia. 4. Dissolve in water by the aid of a drop 01 dilute hydrochloric acid, and add some chlorine water, and then ammonium hydrate in excess. (a) Green-coloured solution = Uuinia ip) Yellowish-white precipitate = Cinchonia. COURSE FOR THE DETECTION OF A MIXED SAMPLE OF ALKALOIDS. 1. Dissolve in water by the aid of a drop of hydrochloric acid, and shake up with ether. ^ This may extract colchicina and a little atropia. Evaporate off the ether, and if it leave a residue, test it. 2. Add an excess of ammonium hydrate, shake up with chloroform, separate, and evaporate small portions of the chloroform solution to dryness at a time, and apply the simple table already given to the different residues thus obtained. All alkaloids may be present, except morphia. 3. Acidulate the liquid which has been shaken with chloroform, with acetic acid, and evaporate it to a low bulk at a ve 7 j gefitle heat. Add excess of a saturated solution of potassium hydrogen carbonate, and shake up with an ethereal solution of acetic ether. Evaporate off the ether almost spontaneously, and test the residue, if any, for morphia. CHAPTER VII. TOXICOLOGICAL ANALYSIS. This subject is one which can only be treated in a comparatively short manner in the present work, as a full notice of all known poisons would be beyond its scope. As good general examples, however, w'e give the following processes for the more common poisons. I. Poisonous Metallic Salts. Acidulate a portion of the contents of the stomach strongly with hydrochloric acid, place the whole in a basin over the water-bath, and drop in crystals of potassium chlorate until the contents of the basin are entirely decolorized. Boil up with the addition of some acidulated water if necessary, and filter, and use this solution for the ordinary separation course for metals, taking care to pass the sulphuretted hydrogen for several hours. II. Mineral Acids are known by the highly-corroded appearance of the viscera and usually strongly acid reaction and free effervescence with sodium hydrogen carbonate. Warm the contents of the stomach with water, filter, and test for the acids. ' III. Arsenic, Antimony, and Mercury. Reinsch’s Test. — This process is performed as follows. The suspected liquid is acidulated with ^ of its bulk of pure hydrochloric acid, boiled, and filtered. The filtrate is boiled with some fragments of bright copper foil, When a coating forms' on the copper. The coated copper is then washed, dried carefully at a gentle heat, cut up into small fragments, and introduced into a small tube of hard glass. The mouth of the tube being lightly closed with the finger, the end containing the copper is strongly heated in the Bunsen or blowpipe flame. Arsenic sublimes as a white crystalline ring of arsenious anhydride, while antimony forms an amorphous sublimate of antimonious oxide, and mercury collects as a minute mass of metallic globules which can be caused to aggregate by rubbing with a glass rod. Should the sublimate possess the characters of arsenious anhydride the tube is filled with distilled water, boiled, and the solution thus obtained tested with argent-ammonium nitrate or cupr-ammonium sulphate. If the sublimate be amorphous and insoluble in water it is dissolved in tartaric acid, and the antimony precipitated from the solution by sulphuretted hydrogen. IV. Arsenic and Antimony on/y. Marsh’s Test. — A gas bottle is fitted up with a funnel tube and a jet, and some fragments of pure zinc are introduced. Dilute sulphuric acid is poured in by the funnel, and when the air has been expelled the hydrogen which issues from the jet is lighted, and a piece of cold porcelain is held in the flame. If no stain be produced on the porcelain, thus indicating that the reagents are perfectly pure, a little of the suspected fluid is added through the funnel tube, and after the lapse of a minute or two the cold porcelain is again held in the flame. If either arsenic or anti- mony be present, a stain will now be formed on the porcelain, for it always must be remembered that both antimony and arsenic produce the same re- ARSENIC— OXALIC ACID— HYDROCYANIC ACID. H5 action. Several of these stains having been procured, they are treated one at a time by the following reagents : — Reagents. Arsenic Stain. ) Antimony Stain. Solution of Calx Chlorata Ammonium Sulphydrate Bromine Vapour . . . Heat (moderate) . . . disappears very slowly affected becomes yellow disappears not affected. ' rapidly dissolves, becomes orange, remains. By another modification, the gas bottle is made to communicate first with a bottle containing plumbic acetate, and afterwards with one containing solu- tion of argentic nitrate. The arseniuretted and antimoniuretted hydrogen having been freed by the lead from any possible contamination of sulphuretted hydrogen, pass into the argentic nitrate, in presence of which the former is decomposed, depositing silver and forming arsenious acid in solution, while the latter deposits as argentic antimonide. The precipitate, having been removed by filtration, is examined for antimony by boiling in solution of tar- taric acid, and subsequent treatment with sulphuretted hydrogen ; while the filtrate, on exact neutralization with dilute ammonium hydrate, deposits yellow argentic arsenite, should arsenic be present. V. Arsenic only. Fleitmann’s Test. — This process differs from Marsh’s inas- much as the nascent hydrogen required to convert the poison into arseniuretted hydrogen is evolved by heating zinc with a solution of potassium hydrate. A flask fitted up with delivery and funnel tubes is charged with the zinc and potassium hydrate, and heat being applied, the gas evolved is tested by ex- posing to its action as it issues from the delivery tube a piece of white filtering paper moistened with a solution of argentic nitrate. Should no stain be pro- duced (indicating purity of reagents) a little of the suspected liquid is intro- duced by the funnel tube, and the process repeated, when, in the presence of arsenic, a dark stain will form on the paper. Further confirmation is obtained by heating the middle of the delivery tube to redness with a small spirit or gas flame, when the arseniuretted hydrogen will become decomposed, and deposit a mirror of arsenic on the cold part of the tube. This mirror may then be examined as already directed for such stains. Fleitmann’s process is not applicable to antimony, as the hydrogen compound of that metal is not produced in presence of an excess of alkali. VI. Oxalic Acid. Clarify the suspected matter by boiling with water, filter, and add plumbic oxy-acetate to the filtrate, collect the precipitate on a filter, wash it, beat it up with water, pass sulphuretted hydrogen through the mixture until it smells freely of that gas, filter, wash the precipitate and expel the excess of the sulphuretted hydrogen from the filtrate by boiling, and concen- trate on the water-bath to a low bulk. The tests for an oxalate are then to be tried upon the clear liquid. VII. Hydrocyanic Acid. This poison is often to be recognized simply by the smell, and is separated by taking advantage of its volatility. The usual way of proceeding is to put some of the suspected liquid into a flask, acidu- lated with sulphuric acid, and having inverted a watch-glass, moistened with the test, over the mouth of the flask, to apply a gentle heat, when the vapour rises, and is absorbed by the reagent on the watch-glass. Another way is to distil the liquid with sulphuric acid, and having con- densed the vapour in a receiver containing a little distilled water, to apply appropriate tests to the distillate. VOL. II. L 146 TOXICOLOGICAL ANALYSIS. These tests are three in number. 1. T/te Silver Test. — A drop of argentic nitrate exposed to the vapour, or added to a solution, of prussic acid, gives a curdy- white precipitate of argentic cyanide. The precipitate is soluble in ammonium hydrate and in strong boil- ing nitric acid, but not in dilute nitric acid ; nor does it blacken on exposure to the light. Dried and heated it darkens, evolving half its cyanogen, leaving a mixture of silver and argentic paracyanide. During the action effervescence is observed, and a bright glow seems suddenly to pass through the mass. 2. The Iron Test. — A drop of solution of potassium hydrate is exposed to the action of the vapour, or an excess is mixed with the solution. To this a mixture of a ferrous and a ferric salt is added, and the whole acidulated with hydrochloric acid. If hydrocyanic acid be present Prussian blue will be formed. 3. The Sulphur Test. — A drop of yellow ammonium sulphydrate is ex- posed to the vapour, or added to a solution of hydrocyanic acid, and the whole evaporated to dryness at a very gentle heat, with the addition of a drop of ammonium hydrate. A residue is thus obtained which strikes a blood-red colour with ferric chloride, not dischargeable by hydrochloric acid, but at once bleached by solution of mercuric chloride. This colour is due to the forma- tion of ammonium sulphocyanide (which takes place when an alkaline sulphide, containing excess of sulphur, is brought into contact with cyanogen) — VIII. Strychnia. The common method of examination pursued in cases of poisoning by strychnine is that of Girdwood and Rogers. The suspected matter is freely acidulated with hydrochloric acid, evaporated to dryness, and the residue thoroughly exhausted by rectified spirit. This solution having been once more evaporated, the residue is treated with water, and the whole again filtered. The watery acid solution thus obtained is treated with a slight excess of ammonium hydrate, and shaken up with chloroform in a long narrow tube. After standing at rest, as much as possible of the chloroform solution of strychnine is drawn off, without disturbing the upper aqueous layer. The chloroform having been driven off by evaporation, the residue is digested for some hours on the water-bath with a few drops of pure strong sulphuric acid, which chars foreign organic matters but does not affect the strychnine. The mass, having been exhausted with water and filtered, is once more rendered alkaline by ammonium hydrate, and shaken up with chloroform, which, on evaporation, will generally leave a residue of strychnine sufficiently pure for testing. Sometimes it is necessary to repeat the digestion with sulphuric acid and subsequent portions of the process before a residue of sufficient purity is obtained. The acid used must be perfectly free from nitrous compounds, and should be tested and purified if necessary. The residue is sufficiently pure for testing when the addition of a drop of strong sulphuric acid causes no tinge of colour. (See tests for Strychnia, page 148.) IX. Opium. The research in cases of poisoning by opium or a morphine salt is best conducted as follows. The suspected matter, having been cut up into small pieces, is, together with the fluid contents, warmed for some time with alcohol acidulated with acetic acid, and filtered. It is then precipitated with excess of plumbic oxy-acetate. The precipitate having been washed and marked A, and the filtrate having been marked B, are then examined sepa- rately as follows : — I. A is mixed up with a little water, and sulphuretted hydrogen is passed through until the whole is decomposed. The resulting black mixture is ' filtered to remove plumbic sulphide, and the clear solution, having been con- centrated until free from sulphuretted hydrogen, is tested with a drop of ferric chloride, when the development of a red colour, not destroyed by dilute hydrochloric acid or by solution of mercuric chloride., indicates the presence of POISONOUS ALKALOIDS. 147 meconic acid, thus leading to the inference that the poison employed was a preparation of opium, 2. B is treated with sulphuretted hydrogen in excess and the precipitated plumbic sulphide is removed by filtration. The solution, having been evapo- rated nearly to dryness on a water-bath, is treated with a few drops of water and filtered. To the filtrate is added an excess of potassium hydrogen car- bonate, and the whole is placed in a long tube and shaken up mth an ethereal solution of acetic ether. The ether solution is then separated by a pipette and evaporated nearly to dryness at a very gentle heat, and finally allowed to dry spontaneously under a desiccator. The residue thus obtained is tested for Morphia. (See tests for Morphia, page 148.) X. Poisonous Alkaloids generally. Sta^s process consists essentially in : — 1. Heating the suspected viscera with twice their weight of absolute alcohol, to which about 30 grains of pure tartaric acid have been added ; filtering when cold, washing with absolute alcohol, and evaporating the solution in vacuo. 2. The residue thus obtained is dissolved in the smallest possible quantity of water, and while still acid is shaken up in a tube with ether. The ethereal solution having been drawn off and preserved (see Table, mfrci) the remaining liquid is placed in a basin and powdered sodium hydrogen carbonate added until effervescence ceases. 3. The solution thus neutralized is again transferred to the tube and shaken up with five times its bulk of pure ether, and when all has settled clear, a little of the ether is evaporated, and the residue examined, to ascertain if the alkaloid be fixed or volatile; (i) by observing if it be in oily streaks, and (2) by warming very gently to about 100° F., and ascertaining whether or not any irritating fumes are driven off, in which case it is volatile. Case A . — The alkaloid is apparently volatile and fluid. Some strong solution of sodium hydrate is added to the contents of the flask, and the whole having been again shaken and allowed to settle, the ether is removed by a pipette, and the process of shaking repeated several times with fresh ether. The ethereal solutions having been united are shaken with a little dilute sulphuric acid (i of acid to 4 of water) which causes the alkaloid to become a sulphate, in which state it is insoluble in ether, and consequently passes into the water. The ether having been poured away, the acid solution is treated once more with excess of sodium hydrate and ether as before, and the ethereal solution by careful spontaneous evaporation leaves the pure alkaloid. Case B . — The alkaloid is flxed and solid. The contents of the flask are treated, as in the last case, with sodium hydrate and ether, and the ethereal solution evaporated. A little alcohol is added to the residue to dissolve the alkaloid, and the solution thus obtained again evaporated. The residue is then converted into sulphate, and dissolved by adding a little water slightly acidulated with sulphuric acid. The solution thus obtained having been con- centrated in vacuo over sulphuric acid to three-fourths of its bulk, is treated with pure potassium carbonate in slight excess and the mixture exhausted with absolute alcohol, which on evaporation leaves the alkaloid in a pure state. The alkaloids thus obtained may be then separated by the following table devised by Brunner. BRUNNEE’S ALKALOID SEPARATION TABLE. ^If i| c| j: g O g C/) 4_x 2 2 c! CJJ2 2.2.i2 u) o g.t: c n C ' g- I I ^ !'«•?! I pT. W40 ,'a.'2.'5;g 4, g I ’^>2 2-2 I d o Ofl j-i|0 1. O'^ •» Igl'slgti-^ 2'^- ^■|g| «.o g ^'^•D' 1 :§ ^ > biO.SrX^ rt OJ rt S ^ . ^ ^-£ O ^;2 g g J 8 S 8 5 8 ft 3 ^ O S o« ^ 2 d O^ rt . V. "O 2 ^ « diJ-.^ eIII d3 rt 1) 2 y i « go ^ 3 dftt:^E«o«o-- 2 ftO bO E ^ 33-d-3 (U g ' ■ I/) r/ tZ ‘dOC^ « sO.^' o55g||3^g49^^-|^ 8 ft^toW^ u O O ft-2 , 20 '3 S Et3 , d P '0 '•«—’>' coajCJ ^.s 2 'g gKc° " 2c« rt^g.O.'oS‘="^C o p2-.CKrra«° Ssisg a,'^g5^g^8^;a.s6^ K>i ^.iSjo.S ^^ d'O o 5 " bX) P 111^‘NI VO d'^.'S^ 8 ^ fio^OOCP,« 043 Ci O 043’^ v-ppi P'^' 4 d 3-n d ^43 3 2 2 p y ^'O '^Eis^l ii P S o §;> ^ bi) - o ^ .5 2-243 ^ ^ |*i i.2 2 3a‘8 •5>3^ . •|a ^ S.-H ~ p § .2 § ^.2 i'^lj 13 ^ 0-2 ^o -g c/, •'-2.i2'^ 8 c/5 |"Po "ortc^S^.S rb ^ 3^ g’-^-o'^ ft 'g^’S'o'S'S^ ^ p o ^ ° ft 0 ^ -p o -S.g bog '-> 2 d 2„« . “ d-g-2 bo c .2-3 p C.2 P 3 3 iH 33 V2 £-2 G -g^ C3 O P ,„r- O CS 3 . O' d E i cci;3Ct_ o (J . C Q o |^"H 1 '.^§3'o8 gSiSgcr Qo‘"’o2 0 ft<43 ?: -43 O 3 i E 3 ■rl: G '0 3.43 G'bS.i" .0 P rt.d 3 ^ l.aa ^ . • o-g rijsip '§.is is §, SONNENSCHEIN’S PROCESS. 149 The complexity of Stas’s process, and the facts that (i) conine is frequently lost by evaporation with the ether, and ( 2 ) that morphine, unless treated instantly and rapidly, refuses to dissolve in ether, has caused the proposition of many other processes. The best of which, as well as the most modern, is Sonnenschein’s process, which depends on the fact that all ammonia deriva- tives are more or less easily precipitated by sodium phospho-molybdate in solution with nitric acid, which reagent is thus prepared. A solution of ammonium molybdate in water acidulated with nitric acid is precipitated by sodium phosphate. The resulting yellow precipitate, having been washed, is dissolved by heating with sodium carbonate. The solution is evaporated to dryness, ignited, moistened with a little nitric acid, and again ignited. The residue is dissolved in ten parts of water strongly acidulated with nitric acid, and kept for use in a stoppered and capped bottle to prevent any chance of the access of ammoniacal vapours. The whole of the organic matter to be examined is repeatedly exhausted with very dilute hydrochloric acid : the extract is evaporated at a heat of 86° F. to the consistence of a thin syrup, then diluted, and left for some hours in a cool place before filtration. The filtrate is precipitated by excess of the above reagent, the precipitate collected on a filter, thoroughly washed with water containing the reagent, and introduced while moist into a flask. Barium hydrate is added, to a distinctly alkaline reaction ; and the flask having been fitted with a delivery-tube which is connected with a bulb apparatus contain- ing hydrochloric acid, heat is gradually applied, when the volatile alkaloids distil over, and are collected in the hydrochloric acid. The residue in the flask (containing the fixed alkaloids) is freed from excess of barium hydrate by a current of carbonic anhydride, carefully evaporated to dryness, and extracted with strong alcohol. On evaporating the alcoholic solution, the alkaloids are commonly obtained in a state of such purity that they will at once exhibit their characteristic reactions ; occasionally, however, they require to be further purified by recrystallization from alcohol or ether. I CHAPTER VIII. I VOLUMETRIC QUANTITATIVE ANALYSIS. I. GENERAL PRINCIPLES. In performing this variety of quantitative analysis the results are obtained by finding the quantity of any reagent capable of producing a given reaction. For example, supposing we take the equation, — AgNOg + NaCl = AgCl + NaNOg it is evident that one molecular weight of AgNOg (170) will exactly turn one molecular weight of NaCl (58*5) into insoluble argentic chloride. If, therefore, to a solution of sodium chloride we added slowly 170 grains of argentic nitrate dissolved in water, and the precipitation ceased just as the last drop fell in, it is plain that we must have had exactly 58’ 5 grains of sodium chloride in solution ; or, supposing that a less quantity of argentic nitrate had been found necessary (say 10 grains), then the amount of sodium chloride present would be found by simple proportion, thus — IQ X 5^’5 170 170 : 58-5 :: to = 3-441 grains NaCl actually present in the solution. The necessity of weighing out the reagent every time is avoided by the use of what are called standard solutions y\\\2X is, solutions of known strength. These are usually made on the metrical system by dissolving a certain number of grammes in one litre (1000 grammes) of water ; when, however, the grain system is employed, ten times the quantity of both reagent and water are taken, because 1000 grains would be so small an amount of solution as to be not worth making. Standard solutions receive special names according to their strength, as follows : — 1. A normal solution contains one molecular weight in grammes dissolved in one litre of water, or ten molecular weights in grains dissolved in 10,000 grains of water. 2. A semi-normal solution contains half a molecular weight in grammes dis- solved in one litre of water, or ten times the amount in grains dissolved in 10,000 grains of water. 3. Deci-normal or centi-normal solutions contain, respectively, or -^60 of the molecular weight in grammes. in a litre, or ten times these amounts in grains in 10, coo grains of water. II. APPARATUS USED. These are very simple, and consist : — I. Of a graduated tube, usually constructed to contain 100 cubic centimetres of water and marked at each c.c., or to contain 1000 grains of water and marked at each 10 grains, this latter space being usually called a test STANDARD SOLUTIONS. T51 measure. The instrument is called a burette, and is supported on a proper stand and provided at the bottom with a pinchcock, by pressing which the fluid can be allowed to pass out rapidly or in drops at will. The burette is provided with a small tube which just fits into it and is closed at both ends, and marked by a line running round the middle. Previously to sealing the top end, a little mercury is introduced, so as to weight the tube and cause it to float upright just under the surface of water. This appliance is called Erdmann’s Float, and the line on it enables the reading of the amount of fluid expended from the burette to be made very accurately. 2. Of a long tube on a foot, closed with a glass stopper and made to contain I litre or 10,000 grains of water, according to the system of weight fol- lowed. It is graduated in spaces of 10 c.c. or 100 grains, and is used for mixing the solutions, being called a test mixer. 3. Of several flasks called measuring flasks, with marks on their necks, hold- ing, when filled up to these marks, definite volumes of water, such as too c.c. or 1000 grains. 4. Of a set of pipettes, which are tubes with bulbs near the middle, drawn out to a jet at the lower end, and so constructed as to deliver fixed quanti- ties of liquid, such as 10, 50, or 100 c.c., or 100, 500, or 1000 grains. The distinction between the use of the measuring flask and the pipette must be steadily kept in view — the former being only for containing fixed volumes^ while the latter is for delivering the same into any other vessel. III. PREPARATION OF THE STANDARD SOLUTIONS. 1. Standard Solution of Oxalic Acid. This is a semi-normal solution made by dissolving 63 grammes of crystallized oxalic acid — H2C2O4.2H2O — in one litre of distilled water at 60°, or 630 grains in 10,000 grains of water. Al- though official, it is in many ways an objectionable solution, notably because it is so nearly saturated that in cold weather the oxalic acid will refuse to entirely dissolve, or, if dissolved by warming, it will separate out. It is therefore preferable to make the solution quadri-normal (/.^., 31*5 grammes per litre), and then to divide the number of cubic centimetres used by two before calculating. In practice, most analysts prefer to use a standard solution (semi-normal) of sulphuric acid instead of the above. One c.c. of Oxalic Acid solution contains *063 gramme pure H2C2O4.2H2O. 2. Standard Solution of Sodium Hydrate. This is normal, and contains 40 grammes per litre of real NaHO (or 400 grains in 10,000 grains). As, however, sodium hydrate can never be obtained absolutely free from moisture and impurities, it is made indirectly as follows : — The ordinary liquor sodce of the shops is taken, and a burette is filled with it. 100 c.c. of standard solution of oxalic acid is placed in a beaker, a few drops of solution of litmus added, and the solution is run in from the burette until the red colour is just changed to a pale purple-blue. The number of cubic centimetres of sodium hydrate solution used is then read off from the burette, and ten times this a 77 iount of the liquor sodce having bee 7 i placed m the test 77 iixer, distilled water is added till the whole 7 neasures 07 ie litre. If the process has been carefully conducted, 50 c.c. of this solution will exactly neutralize 50 c.c. of the oxalic acid solution : because by the equation — H2C2O4.2H2O + 2NaHO = Na2C204 + 4H2O we see that 126 of H2C2O4.2H2O exactly neutralizes 80 of NaHO, and consequently — as 126 : 80 :: 63 to 40 152 VOLUMETRIC QUANTITATIVE ANALYSIS. Therefore i c.c. of normal NaHO is exactly neutralized by i c.c. of semi- 7 iormal HgCgO^. One c.c. of Soda Solution contains *04 pure NaHO. 3. Standard Solution of Argentic Nitrate. This is deci-normal, and is pre- pared by dissolving 17 grammes (AgN03= 170) of argentic nitrate in one litre of distilled water, or 170 grains in 10,000 grains. It should be kept in the dark. One c.c. of Silver Solution contains '017 pure AgNOg. 4. Standard Solution of Iodine. This is also deci-normal, and is prepared by dissolving 12 '7 grammes (1 = 127) of Iodine in about 400 c.c. of distilled water by the aid of 18 grammes of potassium iodide and then making up to I litre with distilled water (or 127 grains in 10,000 grains with 180 grains of KI). The potassium iodide has nothing to do with the real strength of the solution ; and provided sufficient be used to thoroughly dissolve all the iodine, the quantity is quite immaterial. One c.c. of Iodine Solution contains *0127 pure I. 5. Standard Solution of Sodium Thiosulphate {Hyposulphite). This is also deci-normal, and is made so as to exactly balance the iodine solution. It contains 24-8 grammes (or 248 grains) of Na2S203.5H20 in one litre (or 10,000 grains) of water. As, however, the commercial salt is never pure the solution has to be made, like the sodium hydrate, indirectly. About 28 grammes of commercial sodium hyposulphite are dissolved in a litre of water and a burette is filled with the resulting liquid. 100 c.c. of standard solution of iodine are then placed in a beaker, and the solution from the burette is added slowly until the colour begins to lighten. A few drops of mucilage of starch are then stirred in and the cautious addition of the hyposulphite continued until the blue colour is just discharged. The number of cubic centimetres used is then read off, and ten times this a^noimt havmg been placed in the test mixer, water is added till the whole measures one litre. If the process has been carefully done, the equation — • 2Na2S203.5H20 + I2 = 2NaI + Na2S40g + 5H2O. proves that 248 of real sodium thiosulphite decolorizes 127 of Iodine, and therefore, 12-7 of I represents 24*8 of Na2S203. If, therefore, the solution is correct, it will decolorize the iodine solution exactly c.c. to c.c. ’ One c.c. of Hypo sulphite Solution represents '0127 pure I. 6. Standard Solution of Potassium Dichromate. This is viginti-normal, and is made by dissolving 14*75 grammes of KgCrgO^ in one litre of water (or 147*5 grains in 10,000 grains). It should be carefully checked as described further on. (See estimation of Fe.) One c.c. of Dichromate Solution contains *01475 pure K 2 Cr 207 . IV. CALCULATION OF EESULTS. After the process is complete, the results may be calculated in two ways, either by full calculation or by the use of equivalents. A. The full calculation is conducted as follows : — 1. Multiply the number of c.c. used by the strength of the standard solution in each c.c. = {a). 2. Draw the equation for the reaction, and by simple proportion calcu- late {a) from what it is, to what you want to know = (b). CALC C/LA TION OF RESULTS. 153 3. Multiply (^) by 100, and divide by the 'quantity weighed out for analysis, and the answer (x) will give the percentage of the real article present in the sample. For example, let us suppose that we took 4 grammes of commercial soAa caiisFca, to ascertain how much real NaHO it contained. On finishing the proper process, we found that we used 90 cubic centimetres of oxalic acid solution. 1. '90 X *063 = 5 ’67 solid oxalic acid actually added. 2. H3C2O42H2O + 2NaHO = NagCgO^ + 4H2O. Therefore as— 3 - H2C3O42H2O : 2NaHO : : 5-67 . 126 : 80 : : 5’67 Or, 5’67 X 80 126 3*60 X TOO 4 - 3'6o real NaHO in the amount taken for analysis. per cent, real NaHO in the sample of commercial soda caustica analysed. B. The short method by equivalents. The term equivalent is used in volu- metric analysis to represent the amount by weight of any body which corresponds to a given amount of the reagent, as shown by the equation. Thus, taking the same case as already illustrated, the equation — H2C2O42H2O + 2NaHO = NaoC204 + 4H2O shows that 126 (or i molecule) of oxalic acid requires 80 (or 2 molecules) of sodium hydrate for complete neutralization. But our standard solution of acid is semi-normal, and consequently contains only half a molecule per litre ; and therefore it would only neutralize one molecule of NaHO, be- cause — as 126 : 80 :: 63 to 40. 63 grammes of oxalic acid used in any analysis will therefore represent 40 grammes of real NaHO. Taking now the following scale of strengths : — 1000 c.c. (i litre) of oxalic acid contains 63 and represents 40 of NaHO 100 c.c. do. do. 6-3 do. ' 4-0 do. 10 c.c. do. do. *63 do. •40 do. I c.c. do. do. •063 do. •04 do. The equivalent of NaHO in volumetric analysis by oxalic acid is, therefore^ •04 gramme for each c.c. of acid used. The rule then follows : — Note the number of c.c. used, and simply multiply that by the equivalent value for i c.c. of the substance analysed. Thus, in the example already studied, 4 grammes of soda caustica to 90 c.c. of oxalic acid; therefore — 90 X ‘04 = 3‘6o amount of real NaHO in the 4 grammes of soda caustica^ and .r = 90 per cent, real NaHO in the sample. For the full carrying out of this simple method, it is necessary to commit to memory the equivalent values as hereafter given for each analysis. V. ESTIMATION OF ALKALINE HYDRATES. A convenient quantity having been weighed out (taking care that the amount used cannot require more than 100 c.c. of the reagent) is diluted, if a liquid, or dissolved, if a solid, and a few drops of solution of litmus are added. 54 VOLUMETRIC QUANTITATIVE ANALYSIS. The beaker containing this liquid is then brought under the burette containing the standard oxalic acid, and the latter is run in until the blue colour changes to reddish purple. The number of c.c. used is then read off from the burette and calculated. The proper amounts to take for analysis are thus given in the B.P. - Liquor ammonias . . . . . 8 ’5 grammes fort. Liquor calcis . 438-00 „ ,, sacchar. 46-02 Liquor potassse . 46-29 ' „ ,, sodae 45-80 Potassa caustica . 5 ‘ 6 o Soda caustica 4-00 „ equivalent values of the alkalies for i c.c. of acid are as follows : — I c.c. of oxalic acid solution represents -017 NH3 I c.c. do. „ do. -028 Cab I c.c. do. ,, do. -056 KHO I c.c. do. „ do. -040 NaHO 5'23 VI. ESTIMATION OF ALKALINE CARBONATES. Owing to the fact that the liberation of carbonic acid during the neutraliza- tion of a carbonate communicates a spurious acidity, and turns the litmus red before the proper point, it is necessary in this case to proceed as follows ; — Weigh out and dissolve the carbonate, then add the litmus, and run in from a burette a considerable excess of oxalic acid, carefully noting the amount used. Roil the liquid in the beaker for some minutes, and see that it retains its red colour after boiling, because, if it does not, excess of acid has not been added. Now bring the whole under another burette charged with standard solution of sodium hydrate, and carefully add it until the liquid changes pale violet. Note the number of c.c. used, and deduct it from the total acid first added, when the difference will represent the true number of c.c. of standard acid used in neutralizing the carbonate, which is then to be calculated as usual. The proper quantities of the B.P. carbonates to be taken for analysis are : — Ammoniae carbonas Potassae carbonas „ bicarbonas Sodae carbonas „ bicarbonas 5 ‘9 grammes. 8*3 5‘o n 14-3 ■ 8 '4 jj I c.c. do. „ do. 5 ? I c.c. do. „ do. I c.c. do. „ do. I c.c. do. „ do. The equivalent values of the alkaline carbonates for each c.c. of acid are as follows : — I c.c. of standard oxalic acid represents . . *059 N^H^^CgOg •143 Na.XO;^ioHoO •084 NaHCbg •069 K0CO3 *IOO KHCO3 By using solution of cochineal as an indicator instead of litmus, the alkaline carbonates may be liberated directly just like the hydrates, as the presence of free COg does not affect the colour of cochineal. VII. ESTIMATION OF ORGANIC SALTS OF POTASSIUM AND SODIUM. A weighed quantity of the substance is ignited in a small platinum crucible until fumes cease, by which it is reduced to the carbonate mixed with finely- divided carbon. The residue is dissolved in warm water, and a little litmus SALTS OF LEAD— FREE ACIDS. 155 having been added, it is treated with excess of standard oxalic acid, boiled, and checked back by standard sodium hydrate exactly as already described for the analysis of alkaline carbonates. Convenient quantities to take, according to the B.P., are : — Potassse tartras . „ „ acida Soda tartarata . 11*30 grammes i8*8o ,, 14*10 The equivalent values of the salts for each as follows : — I c.c. of standard oxalic acid represents I C.C. do. do. I c.c. do. do. c.c. of oxalic acid solution are . *113 K2C4H4O6 . *094 KHC4H40g . *i4iKNaC4H4064H20 VIII. ESTIMATION OF SALTS OF LEAD. This is also conducted by means of standard oxalic acid, which is simply carefully run in until the precipitation of plumbic oxalate ceases. . Convenient quantities are : — Plumbi acetas . . . , . 3*80 grammes Liquor plumbi subacetatis . . . 4i'33 ,, The equivalent values for each c.c. of standard oxalic acid are : — I c.c. of standard oxalic acid represents . ’1855 Pb2C2Hg023H20 I c.c. do. do. . *137 Pb202C2H302 The oxalic acid solution is also used to take the alkalinity of borax and the strength of the' effervescing liquors of potash and soda. The following are the empirical strengths they should exhibit : — 19*10 grammes of borax should take 100 c.c. oxalic acid 438*0 „ liq. potass, effervesc. „ 15 c.c. „ 438*0 „ liq. sodse effervesc. „ 17*8 c.c. „ IX. ESTIMATION OF FREE ACIDS. This is performed by simply adding a few drops of solution of litmus, and running in standard solution of sodium hydrate until the red colour just changes to pale violet, then noting the number of c.c. used, and calculating. The following are the quantities ordered to be taken for analysis by the B.P. Acetum Acid. Acetic. J) 5) „ dil. „ _ glacial Citric Hydrochloric dil. Nitric ,, dil. Nitro-hydrochlor. di' Sulphuric }) Tartaric aromat. dil. 44*54 grammes 18*20 44*00 j) 6*00 7*00 1 1*48 >> 34-50 9*00 )f 36-13 }} 35-24 5*06 30*42 }f 35 ' 9 o 7-50 156 VOLUMETRIC QUANTITATIVE ANALYSIS. The equivalent values of the respective acids for i c.c. of the sodium hydrate solution are as follows : — Acetic acid Acetic acid (anhydrous) Citric acid Hydrochloric acid Nitric acid Nitric acid (anhydrous) Sulphuric acid . Sulphuric acid (anhydrous) Tartaric acid •060 HC2H3O2 •051 C4Hg03 •070 0 , 11,0 •0365 HCl •063 HNO3 •054 N2O5 •049 H2SO4 •040 SO3 •075 H2C4H4O6 X. ESTIMATION OF HYDEOCYANIC ACID. A suitable quantity of the sample (27 grammes) is weighed out, and ren- dered distinctly alkaline with the liquor sodce. It is then brought under the burette containing the standard solution of argentic nitrate, and the latter is cautiously run in with constant stirring, until a faint, permanent, white cloud is produced in the liquid. When the silver solution is first added to the cyanide no precipitate is produced, owing to the formation of a soluble double cyanide of silver and sodium : 2 N aCy + AgN O3 = AgCy NaCy -f- NaN O3. On continuing to add the silver, a time arrives when, the double compound having been fully formed, it is in turn decomposed by excess of silver, and a white cloud of argentic cyanide is produced. AgCyNaCy + AgN03 = 2AgCy 4- NaN03. At the moment, therefore, when the precipitate appears, sufficient silver has been added to combine with one half of the cyanogen present in the sample., as is shown by the formula AgCyNaCy. It now only remains to read off the number of c.c. of silver used, and apply the calculation : — , (c.c. used X 017) X 54 _ present in the amount taken for analysis. 170 Or, by the short method, the number of c.c. of silver solution used is multi- plied by the equivalent value in HCN, which is *0054. ESTIMATION OF CHLOEIDES, BEOMIDES, AND IODIDES. The chloride is weighed out, dissolved in water, and placed in a beaker over a sheet of white paper, and brought under the burette charged with the stan- dard solution of argentic nitrate. Two drops of a solution of potassium chromate are then added, and the silver solution is veiy carefully run in, with constant stirring, until the solution in the beaker just changes from yellow to red. This indicates that all the chloride has been precipitated as argentic chloride. The red-coloured argentic chromate will not form until all the ^ chlorides have been removed ; but whenever this is attained, the least excess of silver solution turns the chromate red. Each c.c. of decinormal silver solu- tion used will indicate ’00355 chlorine. Bromides and iodides may be treated in the same way, or the silver solution may simply be added with constant stirring till precipitation ceases. The B.P. only values potassium bromides by this process, and directs the use of I gramme, which should take 84 c.c. The equivalents for i c.c. of silver solution are 'ooS Br. and ’0127 I. ARSENIATE OF SODA—ARSENIOUS ACID. 157 XII. ESTIMATION OF COMMERCIAL ARSENIATE OF SODA. Dry some of the commercial salt at a temperature of 300° Fah., when it should lose 40 '3 8 per cent, of its weight. Take one gramme of the dried residue, dissolve it in water, and add 5 '3 cubic centimetres of standard solution of sodium hydrate. Into this prepared liquid run, from a burette, the standard solution of argentic nitrate, until the brick-red precipitate of argentic arseniate ceases to form. With regard to the volumetric test mentioned above, the reason for adding sodium hydrate solution previously to running in the argentic nitrate, is to ensure the precipitation of triargentic arseniate without any acid being set free, as would otherwise happen. It is necessary to secure the non-liberation of acid, because it would dissolve the argentic salt. With sodium hydrate the reaction is — Na2HAs04 -t- 3AgNOg + NaHO = Ag3As04 + 3NaN03 + FI2O ; which shows that 3 AgN 03(510) represents Na2HAs04 (i86) or Na2HAs047H20 (312) or Na2HAs04i2H20 (402). The number of c.c. of silver used should therefore be multiplied by the equivalent value of Na2HAs04= '0062. XIII. ESTIMATION OF ARSENIOUS ACID. This is performed by the standard iodine solution, which acts as an indirect oxidizer, the following reaction occurring : — AS2O3 4 - 5H2O -h 2I2 = 2H3ASO4 + 4HI. Thus it is plain that one molecular weight of arsenious acid represents four atomic weights of iodine ; and therefore the calculation will require that the number of grain-measures of volumetric solution of iodine used be multiplied by *0127 and 198 (the molecular weight of AS2O3) and divided by 508 (four times the atomic weight, 127, of iodine). The mode of estimation is very simple. Four decigrammes of arsenious anhydride are rubbed with about eight decigrammes of sodium hydrogen carbonate and a few drops of water in a beaker. The mixture is heated for a few minutes, and, an ounce or more of water having been added, the whole is boiled until complete solution is effected. The solution is allowed to become perfectly reduced to the ordinary atmospheric temperature, a little starch paste is added, and the iodine solution is run in until a slight permanent blue colour is produced. The number of c.c. of iodine used is read off, and the calculation made as follows : — (No. of c.c. used X *0127) x 198 _ ( amount of AS2O3 in the 4 decigrammes 508 C taken. Or more simply by multiplying the number of c.c. used by '00495, which is the amount of AS2O3 equivalent to i c.c. of the iodine solution. 44*15 grammes of liquor arsenicalis and liquor arsenici hydrochloric! thus treated should respectively take 80 *8 and 81*0 c.c. of iodine solution. XIV. ESTIMATION OF SULPHUROUS ACID. When sulphurous acid is treated with iodine in the presence of water, it decomposes the latter, forming sulphuric acid and hydriodic acid H2SO3 + I2 + H2O - 2HI + H2SO4. The B.P. therefore uses standard solution of iodine for ascertaining, volu- 158 VOLUMETRIC QUANTITATIVE ANALYSIS. metrically, the strength of sulphurous acid, by adding it to a weighed quantity (3 ‘47 grammes) of sulphurous acid, mixed with a little starch paste, until a permanent blue colour is produced (showing the presence of undecomposed iodine). The following calculation is then employed : — (No. of c.c. used x *0127) x 82 ^ J amount of H2SO3 in weight of sample 254 ( taken. (c.c. used X *0127) X 64 r ^ 1 ^ — ^ — amount of SOo in weight taken. 254 Or the number of c.c. used may be multiplied by '0032, which is the equiva- lent value of SO2 for i c.c. of iodine solution. XV. ESTIMATION OF AVAILABLE CHLORINE Is conducted in calx chlorata by the use of the standard solution of sodium hyposulphite. Weigh out 10 grammes of the sample of calx chlorata., and having rubbed it in a glass mortar with a little distilled water to a creamy con- sistence, wash the whole carefully into a large stoppered bottle or flask, and make up with water to one litre. Shake well for some time, and set it aside to settle. When clear,' draw off with a graduated pipe the 100 c.c. for analy- sis, into a clean beaker. Thus you have of the whole soluble and active portion of 10 grammes ( = i gramme) in the beaker. To this add 3 grammes of potassium iodide, and acidulate with 10 c.c. of hydrochloric acid, adding a few drops of starch paste. The hydrochloric acid acts on the chlorinated lime to liberate the available chlorine. CaCl2Ca2C10 + 4HCI = 2CaCl2 + CI2 + 2H2O. The chlorine then displaces an equivalent amount of iodine — 2KI + Cl2 = 2KCl + l2, which instantly strikes a blue with the starch paste. The blue liquid is now to be brought under a burette charged with the standard hyposulphite of soda solution, which is to be carefully run iri, until the colour is just discharged. This occurs by the formation of sodium iodide and sodium tetra-thionate : — 2 Na 2 S 203 I 2 = 2NaI + Na2S40e. As the hyposulphite solution represents ’0127 of iodine to each c.c., it follows that, 127 of I having been displaced by 35’5 of chlorine, nothing remains to be done but simply to multiply the number of c.c. of hyposulphite used by ’00355 the equivalent value in Cl for each c.c. By the same process : — 6 grammes of liquor calc, chloratae should take 50 c.c. hyposulphite. 7 » sodce_ „ „ „ 50 c.c. „ 43’9 ,, ,, chlori should take . . 75 c.c. „ Good samples of calx chlorata should show 33 per cent, of available chlorine ; but the B.P. considers it saleable so long as it shows 30 per cent. XVI. ESTIMATION OF FERROUS SALTS ’ Is performed by means of the standard solution of potassium dichromate, which is a powerful direct oxidizer, and in presence of excess of acid raises iron from the ferrous to the ferric state. One molecule of this salt has the power in this manner to convert six atoms of ferrous iron. Thus with ferrous chloride and hydrochloric acid : — flFeClg + 14HCI + - sFcgCls + Ct^CIq + 2KCI + 7H2O. FERROUS SALTS— GLUCOSE— LACTOSE. 159 Or, with sulphate and sulphuric acid - dFeSO^ + 7H2SO4 + KgCrgOy = 3Fe23S04 + Cr23S04 + K2SO4 + yHgO. The standard solution being made, as already shown, by dissolving of a molecular weight (= 1475 grammes) in one litre of water, each c.c. therefore contains '01475 grammes of potassium dichromate, and is equal to 'oi 68 grammes of iron of 6Fe). The process is conducted as follows : Four ounces of water are introduced into a ro-ounce basin, placed over a lamp, and half an ounce of strong hydro- chloric acid is added. When the whole is hot (not boiling), a weighed quan- tity of the iron compound is introduced, and as soon as it is dissolved the dichromate solution is run in, with constant stirring, until a drop taken from the basin on the end of the stirring-rod fails to produce a blue colour when touched against a drop of potassium ferricyanide ; thus proving that the iron has been fully converted to the ferric state. Before commencing the experi- ment, a white porcelain slab should be covered with drops of the ferricyanide solution freshly made, and after each little addition of dichromate, a drop is to be taken out on the end of the rod, and tested on the slab. This is most important, and so is the rapidity of working and application of the heat. In treating of this process it frequently happens that mention is not made of heat \ but the Author, who was educated under the late Professor Penny (the inventor of the process), learnt to work exactly as above directed. It is also important to remember that when the blue begins to lighten in colour, the dichromate must be added very carefully, as two or three drops are often sufficient to overdo and spoil the accuracy of the determination. The number of c.c. used are read off, and having been multiplied by *01475, the product is multiplied by as many molecules of the salt under analysis as will contain 6 atoms of iron, and divided by the molecular weight of potassium dichromate. By the shorter method the number of c.c. used is multiplied by one ot the following equivalent values, — I c.c. of standard K2Cr20y (*01475) convert *0834 gramme FeS047H20 do. do. do. •0348 FeCOg do. do. do. •0358 Fe 23 P 04 do. do. do. *0446 Fe 33 As 04 do. do. do. •0216 Fe0(inFe304) 5 ) do. do. do. ■ *0168 It Fe XVII. ESTIMATION^ OF SUGAR. To perform this operation, the following special solutions are requisite : — I. A solution of the substance in which the glucose is to be estimated, con- taining about *5 per cent, of that substance. This may conveniently be made by dissolving 5 grammes (of a syrup or any compound believed to contain 70 per cent, or more of glucose or lactose) in one litre of water. II. Fehlin^s solution of cupric tartrate in potassium hydrate, made by dis- solving 35 grammes of pure crystallized cupric sulphate, reduced to powder, and pressed between bibulous paper till absolutely free from extraneous moisture, in a little distilled water, and adding 173 grammes of sodium potas- sium tartrate (Rochelle salt), then introducing 60 grammes of pure potassium hydrate, dissolved in the smallest possible quantity of water, until the deep blue precipitate of cupric tartrate is entirely dissolved, using more of a ten per cent, solution of potassium hydrate, if necessary. The liquid must then be made up to one litre, and immediately introduced into a well-stoppered bottle, as the carbonic anhydride of the air causes rapid deterioration. Previously to i6o VOLUMETRIC QUANTITATIVE ANALYSIS. every determination in which this solution is employed, it is necessary to boil a few drops with a quantity of pure water, and if any red precipitate is formed, the solution must be rendered incapable of producing such (when boiled with pure water) by the addition of solid potassium hydrate free from carbonate. Thus made, Fehling’s solution should represent '05 gramme of glucose or •0475 sucrose for each 10 c.c. III. A solution of i gramme of pure glucose, or *95 gramme of pure lactose, in 200 c.c. of water. This solution, which is used for checking the Fehling’s solution, must be made very exactly and carefully, as upon its accuracy the whole process depends. The modus operandi is as follows : — 10 c.c. of Fehiing’s solution are put into four ounces of water contained in a porcelain basin, and the liquid is raised to the boiling point. The solution of sugar having been introduced into a burette, placed immediately over the basin, is then run in until the cupric solution, after five minutes’ boiling, loses its colour. A drop of the solution is taken out with a glass rod, and let fall upon a piece of bibulous paper, placed over a beaker containing ammonium sulphide. If a black colour be produced, more sugar solution must be carefully added until this no longer occurs, which takes place when all the copper is thrown down as cuprous oxide. Between every two or three drops, the liquid must be boiled for three or four minutes before it is tested. The number of c.c. of sugar solution employed having been read off, the following statement is made ; — As the number of c.c. | ^ { The number of c.c. of Fehling’s ) used j ‘ 1,000 . . I solution taken (=^10) j ’ Multiplying by the amount of sugar to which a c.c. of the Fehling’s solu- tion corresponds, the product gives the total quantity of pure glucose in the litre of solution. If it be 5 grammes (the amount dissolved in the litre of water originally) the glucose taken for analysis is pure. If it be less, the quo- tient obtained by division by '5 (viz., multiplication by 2), gives the percent- age. If it be more (than 5 per 1000), which may occur when the check is made, the Fehling’s solution must be too weak. In this case then the ratio of the amount employed to 5 is that which must be taken to reduce the volume of Fehling’s solution to the true volume, that is, to the volume which would have been taken had it been of accurate strength. Both the check and the actual estimation are carried out as above detailed. When cane sugar is to be estimated, it must be first “ inverted ” by boiling for some hours with a few drops of dilute sulphuric acid, and then neutralized with sodium hydrate before using ^^FehlingJ^ XVIII. ESTIMATION OP BREA. The best way of estimating the amount of urea in urine is by means of mercuric nitrate, with which it causes a precipitate. The process is of some importance to pharmacists, and is thus performed : — 1. A solution of-mercuric nitrate is prepared by dissolving 77^2 grammes of perfectly pure mercuric oxide in the smallest possible quantity of nitric acid ; evaporating to get rid of all free acid, and diluting to one litre (if a precipitate of yellow basic nitrate should form, it may be redissolved by the addition of a drop of free nitric acid). This solution is so constructed that i c.c. will pre- cipitate ’oi gramme of urea. 2. A mixture of two volumes of cold saturated solution of barium hydrate with one volume of a similar solution of barium nitrate. 3. Solution of sodium carbonate. 50 c.c. of the urine to be tested are mixed with 25 c.c. of the solution No. 2, which removes, by precipitation, all the phosphates and sulphates, and the whole is filtered. 15 c.c. of the filtrate (=10 c.c. of the original urine) are PHOSPHORIC ACID. i6i then put into a beaker, and brought under the burette containing the mercuric solution. The latter is now carefully run in, until all the urea is precipitated, which is known when a drop taken out of the beaker on a glass rod strikes a yellow colour with a drop of the sodium carbonate solution, placed upon a glass slab, over a piece of black paper to show the colour better. The num- ber of c.c. of mercurial solution used are then read off, multiplied by ’oi, which gives the urea in lo c.c., and that x lo = percentage. In urine analysis it is more common, however, to state results in parts in looo, instead of in percentages. The mercuric solution should always be tested by a solution of lo grammes of pure artificial urea in i litre of water, of which each c.c. will equal ‘oi urea, and which should exactly balance the former, c.c. to c.c. There are certain difficulties which might sometimes occur, for which we must refer the student to Sutton's Volumeti'ic Analysis ; but we may mention that should the urine contain albumen, it must be first removed by boiling loo c.c. with 4 drops of acetic acid, letting the coagulated albumen settle, and taking 50 c.c. of the clear urine for analysis. XIX. ESTIMATION OF PHOSPHORIC ACID Is performed by means of a standard solution of uranic nitrate in the pre- sence of sodium acetate. The necessary solutions are, — 1. Standard solution of uranic nitrate, made by dissolving 70 grammes in 900 c.c. of water, and then, after ascertaining its strength by performing an analysis on 50 c.c. of the standard phosphate solution, diluting with water so that 50. c.c. v^ill correspond exactly to 50 c.c. of that solution. If abso- lutely pure uranic nitrate were obtainable, theory requires the solution of 71 grammes in one litre of water to yield a solution which will balance the standard phosphate (each i c.c. = i gramme of P2O5). 2. Standard phosphate solution, made by dissolving 50*42 grammes of perfectly pure disodium hydrogen phosphate in one litre of water, when each c.c. will equal *i gramme of P2O5. 3. A solution of 100 grammes of sodium acetate and 100 grammes of acetic acid in water, and the whole diluted to one litre. 4. Finely powdered potassium ferrocyanide. To perform the process, the solution of the phosphate in about 50 c.c. of water, is placed in a basin on the water bath, mixed with 5 c.c. of solution No. 3 (sodic acetate), and No. i (uranic nitrate) is run in from a burette, until a drop taken from the basin on to a white plate just gives a brown colour when a little powderd ferrocyanide is cautiously dropped into its centre. The number of c.c. of uranic solution used having been noted, the usual calcula- tions are to be applied. After repeated trials upon 50 c.c. of the standard phosphate solution, so as to thoroughly adjust the strength of the uranic solution, and at the same time accustom the eye to observe the exact moment of the appearance of the brown coloration, the process may be practically applied to Manures. The best method of preparing the solution of the manure, is to heat 10 grammes to dull redness for 1 5 minutes, and when cold to reduce it to a fine powder in a mortar, and add gradually 10 grammes of sulphuric acid diluted to 200 c.c. with water. Rinse the whole into a stoppered bottle, and make up with water to one litre. Shake up occasionally for an hour, and having then let all settle for three hours, draw off 100 c.c. ( = i gramme manure) for analysis. To this add a little citric acid (10 drops of a cold saturated solu- tion), and slightly supersaturate with ammonium hydrate. Again acidify with acetic acid, add 10 c.c. sodium acetate solution, and then use the uranic solu- VOL. II. M i 62 VOLUMETRIC QUANTITATIVE ANALYSIS.- tion as usual. If all these quantities be rigorously adhered to, each c.c. of uranic solution used can, without further calculation, be taken as indicating one per cent, of tricalcium phosphate in the manure. This process is highly recommended by Mr. Sutton, of Norwich, and elabor- ate details will be found in his work on Volumetric Analysis. "XX. VALUATION OF MANGANESE PEROXIDE. When manganic peroxide is treated' with oxalic acid and sulphuric acid, it dissolves, forming manganous sulphate, converting the oxalic acid entirely into carbonic anhydride and water : — H2C2O4 + MnOa + H2SO4 = MnS 04 + 2CO2 + 2H2O. This reaction is taken advantage of to estimate the value of> samples of the ore. The solutions required are, — 1. The B.P. volumetric solution of oxalic acid, made by dissolving 63 grammes of oxalic acid in one litre of water, each c.c. of which contains ’063 gramme oxalic acid. 2. A solution of potassium permanganate, of about the colour of strong port and water. 10 c.c. of the oxalic acid are introduced into a beaker, diluted to 200 c.c. with water, and acidulated with 5 c.c. of strong sulphuric acid. The permanganate is then run in carefully from a burette, until its colour ceases to ' be destroyed, and the contents of the beaker exhibit a faint permanent pink colour when viewed over white paper. The number of c.c. of permanganate used is carefully noted, and its relation to the oxalic acid thus ascertained. We will suppose, for example, that 40 c.c. were required, then 40 c.c. of permanganate will represent to c.c. of oxalic acid. Having obtained the strength of our permanganate (which spoils by keeping, and therefore must be titrated and standardized every time), we proceed as follows : — ' Weigh out 2 grammes of the sample to be analyzed, transfer it to a beaker, run in 50 c.c. of oxalic acid, and acidulate with 5 c.c. of strong sulphuric acid. The reaction immediately sets in, and carbonic anhydride is evolved with effervescence. The manganic peroxide dissolves, and in so doing decomposes an equivalent quantity of oxalic acid. The action is assisted at the last by gently heating, till no more gas is evolved, and the ore is all dissolved. The solution is diluted to 200 c.c., and 5 c.e. of sulphuric acid having been added, permanganate is run in until it ceases to be decolorized. The number of c.c. of permanganate used are calculated for the amount of oxalic acid they have been found to represent, and thus the quantity which has been decom- posed by the ore is ascertained. Example. — 2 grammes of ore, treated with 50 c.c. of oxalic acid, took, after solution, 20 c.c. of permanganate. Now, as 40 c.c. of the latter were found to be equal to 10 c.c. oxalic acid, 20 must be equal to 5. Then 50 - 5 = 45 c.c. of oxalic acid decomposed by the ore. 45 c.c. x *063 = 2*835 oxalic acid, decomposed by 2 grammes of ore. Then from the equation already given, 2 835 ^ ^7 _ pure peroxide in two grammes of ore; 126 and i_9.57 ^ 100 _ p^j- Qgut. peroxide in ore analyzed. 2 For all the other many processes of volumetric ^analysis, the student is referred to any standard work upon the subject. CHAPTER IX. GRAVIMETRIC QUANTITATIVE ANALYSIS. L PRELIMINARY REMARKS. Before giving the processes for the quantitative estimation of the various metals, we must first say something about the preparation of filters, and the washing, drying, and weighing of precipitates. 1. THE PREPARATION OF FILTERS. Ready-cut filters may be procured from the dealers in chemical apparatus. The kind known as Swedish is the best for all cases where the precipitate is finely divided or pulverulent. For gelatinous precipitates, such as ferric hydrate and calcium phosphate, the white English filters are preferable ; but they should never be used, say, for barium sulphate or calcium oxalate, as those bodies would very likely pass through the pores of the filter, and so cause a loss in the analysis. The only drawback to Swedish papers is their filtering rather slowly. Whatever paper be used, the size for quantitative operations is, for the larger sort, six inches in diameter, for the smaller, about two inches. The small sort is used where we have to deal with traces of precipitate only, or when a small quantity of fluid has to be filtered. The paper should yield nothing to dilute acids, and if the ash exceed one milligramme per large filter it will in most cases be remedied by placing, say, loo cut filters for some hours in a basin filled with a mixture of one volume of HCl and eight volumes of water. They must then be repeatedly washed with distilled water till quite free from acidity, otherwise they \yould crumble to pieces when being folded. The washing is a very tedious operation indeed, and having been completed, the basin is put on to a water-bath till the filters are perfectly dry, when they are taken out and their ash estimated. This is most conveniently done by folding ten filters into a small compass, twisting a long platinum wire round the packet so as to form a cage, holding the free end in the hand and the paper over a previously weighed platinum crucible while touching it with the flame of a Bunsen burner. The paper burns and the ash drops into the crucible, while any particles of carbon which have escaped combustion are quite consumed by exposing the crucible for some time to a red heat till the ash gets perfectly white. The crucible after cooling is re weighed, and its increase is the ash of ten filters. Divided by ten, we get the ash of one filter ; and in every case where both filter and pre- cipitate are burned, the ash of the -filter thus found must always be deducted from their total weight, and the difference is then the actual weight of the precipitate. ' 2. THE WASHING OF PRECIPITATES. When the precipitate has been fully formed and the supernatant fluid has become quite clear, the latter is poured on the filter, care being taken not to GRAVIMETRIC QUANTITATIVE ANALYSIS. 164 disturb the precipitate. After thus pouring off as much as practicable, the pre- cipitate remaining in the beaker is treated with water and well stirred. When the whole has once more settled, the clear fluid is again passed through the filter. This operation having been repeated three or four times, the precipi- tate is allowed to pass on to the filter, any particles which stick to the sides of the beaker being removed with a feather ; and the whole having been thus collected, the washing is continued by means of a washing-bottle, till the pre- cipitate is quite freed from its soluble impurities. For instance, in estimating sulphuric acid, the barium sulphate is washed till the filtrate no longer gives a turbidity with argentic nitrate. Many bodies, as ferric and aluminic hydrate, most phosphates, barium sul- phate, and some of the carbonates are best washed with boiling water. Others, on the contrary, must be washed with cold water, such as plumbic sulphate, for which we use cold water acidified with some HgSO^; magnesium ammonium phosphate, for which cold dilute ammonium hydrate is used, etc. 3. DRYING OF PRECIPITATES. After the precipitate has been thoroughly washed, the funnel containing it is loosely covered over with filter paper and then put into an air-bath. Most precipitates require a temperature of 212° F., but some of them, as mag- nesium ammonium arseniate, require a temperature of 220° F. before becoming constant in weight ; while palladious iodide must be dried at a temperature not exceeding 200° F. Prolonged and repeated drying is only necessary when the precipitate is weighed on the filter. 4. IGNITING AND WEIGHING OF PRECIPITATES. Most precipitates must first be ignited before they can be weighed. This is to drive off water which they may still retain after drying at 212° F., or carbonic anhydride and water. For instance, zinc is best weighed as oxide, and therefore the precipitate, consisting of oxycarbonate, is first ignited. Iron is precipitated as hydrate, but the composition of that body not being constant it is'ignited and so made into pure oxide before weighing. As soon, there- fore, as the precipitate appears dry it is carefully detached from the filter and put into a previously ignited and weighed crucible, the filter is burned on the lid (which has been weighed together with the crucible), the ash is thrown into the crucible, and the latter covered with the lid. The crucible is now supported by a pipe-clay triangle, and gently ignited at first to prevent spurt- ing from the sudden evolution of steam or other gases. The lid is now taken off, and the crucible inclined a little so as to give a free access of air. The ignition is continued for some minutes, and the crucible, having been again covered with the lid, is allowed to cool and weighed. For accurate estima- tions it is best to let it cool under a desiccator. The heat of an ordinary Bunsen burner is generally sufficient for all pur- poses ; but the conversion of calcium carbonate into oxide requires the aid of a gas blowpipe ; while argentic chloride must be heated with a rose Bunsen or spirit lamp until it just begins to fuse. The filters are, as already shown, burned separately, to prevent any reduction of the precipitate by the carbon of the filter. Some precipitates are not ignited but weighed on a previously tared filter. Before weighing the filter (for which purpose it is placed between two closely- fitting watch-glasses provided with a clamp to hold them together) it must first be dried for fifteen minutes at 2 1 2° F. After drying the precipitate, the filter is again placed between the glasses and reweighed ; the increase shows, of course, the weight of the substance. It is well to replace the filter SILVER— LEAD. 165 in the bath for, say, half an hour, and to weigh again. Should the weight be considerably less, it must be once more put into the bath and reweighed. ^ As examples of precipitates weighed in this manner, we mention the sulphides of mercury and arsenic, which cannot be ignited because they would volati- lize ; magnesium ammonium arseniate, which would suffer a loss of arsenic in ignition ; and potassium platino-chloride, which would partly decompose. Silver is most conveniently weighed as chloride, because this body is per- fectly insoluble in water and dilute acids, and separates readily. The silver solution to be estimated is strongly acidified with nitric acid, which, for phy- sical reasons, promotes the separation of the chloride, and a slight excess of hydrochloric acid is added. It is best to have the solution slightly warm, and to stir till the supernatant liquid has got perfectly clear. A little more hydro- chloric acid is added, to make sure that all the silver is precipitated. The clear fluid is now poured off, but best through a filter, lest some particles of chloride should be accidentally carried away. The chloride, which must be kept from the light, is then washed by decantation with boiling water till every trace of acid is removed, the water poured off as completely as pos- sible, and the chloride transferred into a weighed porcelain dish, dried, heated till it just commences to fuse,, and weighed. The filter is burned on a lid ; and should any excess of ash be obtained, this must be considered as metallic silver, because the traces of chloride are reduced by the filter-paper. Or the ash may be treated with a drop of aqua regia, the resulting chloride dried, and its weight added to the other weight. The following calculation is now applied : — If silver is required to be estimated in organic salts, and other bases are absent, the analysis is performed by igniting a weighed quantity of the salt, and weighing the ash, which will consist of pure metallic silver. Lead is usually estimated in this form. The solution containing the sub- stance to be analyzed is precipitated with ammonium carbonate in the presence of a little ammonium hydrate. The precipitated plumbic carbonate is then collected on a small filter, washed, and dried. The dry precipitate is re- moved as completely as possible from the filter-paper, and introduced into a weighed porcelain crucible. The filter having been burned on the lid, and its ash added to the contents of the crucible, the whole is ignited, cooled, and weighed. By ignition, the oxide is formed ; and after deducting the weight of the crucible, the following calculation is applied : — Weight of precipitate x 20; weight of metallic lead in II. GRAVIMETRIC ESTIMATION. OF METALS. ESTIMATION OF SILVER. {a) As Argentic Chloride. Weight of chloride x 108 1 43 '5 = silver in the amount taken for analysis. (/;) As Metal. ESTIMATION OF LEAD. {a) As Plumbic Oxide. amount of sample analyzed. 223 1 66 GRAVIMETRIC QUANTITATIVE ANALYSIS. Great care must be taken in the removal of the precipitate from the filter, as the carbon of the paper is apt to reduce the oxide to metallic lead, and thus cause loss of weight. The oxide must be completely soluble in warm acetic acid. Any insoluble substance may be metallic lead. {b) As Plumbic Sulphate. Lead is estimated as sulphate when it has to be separated from other metals which are not precipitated by sulphuric acid. The solution, — for instance, a weighed quantity of an alloy, — dissolved in nitric acid is mixed in a glass basin with a slight excess of sulphuric acid. As plumbic sulphate is slightly soluble in nitric acid, the whole is evaporated in the water-bath till acid fumes cease to be evolved. The sulphate is now washed by decantation with very dilute sulphuric acid, to remove other metals, then brought on the filter, and finally washed with spirit^ of wine. The sulphate is slightly soluble in water, but in- soluble in dilute sulphuric acid, and altogether so in alcohol. The filter is now dried, the sulphate having been detached from it, the latter is put into a weighed porcelain crucible, ignited, and weighed. The filter is burned sepa- rately (best in another weighed crucible) the ash is treated with a drop of nitric acid and a drop of sulphuric acid, dried, ignited, and reweighed. The treatment with acid is necessary, because the s.ulphate is almost completely reduced to metallic lead or sulphide of lead by the carbon of the burning filter. The total weight of sulphate having been got, the following calcu- lation is applied : — Weight of piecipitate X 207 ^ quantity taken for analysis. 303 ESTIMATION OF MERCURY. (a) As Mercurous Chloride. Compounds of mercury insoluble in Water are dissolved in cold dilute HCl, and if this fails, they are treated with potassium hydrate solution, and chlorine gas is passed through the liquid till perfectly saturated. The excess of chlorine is expelled by gentle boiling. If mercury compounds were boiled with hydrochloric acid and potassium chlorate, a little of the mercury would volatilize. To the solution some hydrochloric and phosphorous acids are added ; and after standing for 12 hours in a warm place, the precipitated mercurous chlo- ride is collected on a weighed filter, washed, dried at 212° F., and weighed. Weight of precipitate x 200 _ J amount of mercury in the 235-5 '■ taken for analysis. (b) As Mercuric Sulphide. Through the solution of the mercuric salt a current of HgS is passed till the liquid is saturated. It is necessary the mercury should be all in the mer- curic state, and not contain other metals precipitable by H^S. The precipitate is collected on a weighed filter, washed first with water, then with absolute alcohol, and finally, to remove any free sulphur, with a mixture of equal parts of ether and carbon disulphide. After drying at 212° F. and weighing, the following calculation is applied : — m Weight of the sulphide x 200 _ ( mercury in the sample taken for analysis. 232 CADMIUM— COPPER. 167 ESTIMATION OF CADMIUM. {a) As Cadmium Oxide. The solution containing the metal is mixed with excess of sodium carbonate and boiled. The precipitated cadmium carbonate is collected upon a filter, washed with hot water, and dried. It is of the utmost importance, to have a very thin filter, and to detach the precipitate as completely as possible from it. The filter is moistened with a little strong solution of ammonium nitrate, and dried ; and a platinum wire having been twisted round it, it is then burned, the ash being allowed to drop into the crucible. The nitrate will cause a more speedy and complete oxidation of the carbon of the filter, and so pre- vent reduction of the oxide and volatilization of metallic cadmium. Yet, notwithstanding this precaution, a little loss is unavoidable. The crucible is now heated to redness, and after cooling the residual oxide is weighed. The weight of oxide x 112 _ f cadmium in the quantity ~ taken for analysis. {U) As Sulphide. The solution is precipitated with ammonium hydrate and ammonium sul- phide. The cadmium sulphide is collected in a weighed filter, washed, dried at 212° F., and weighed. This process is only applicable in the absence of metals also precipitable by ammonium sulphide. In the presence of metals of the fourth group, the solution must be slightly acidified with hydrochloric acid and precipitated by a current of sulphuretted hydrogen. Weight of sulphide x 112 144 cadmium in the amount taken for analysis. ’ ESTIMATION OF COPPER. {a) As Cupric Oxide. Copper is frequently estimated in this form. The solution (freed from other metals if necessary) is boiled with a slight excess of sodium hydrate. The precipitate is filtered out, washed, and dried. It is then carefully removed from the paper to a weighed crucible, and the filter having been burned on the lid, and the ash added to the contents of the crucible, the whole is well ignited, cooled in a desiccator, and weighed rapidly, because cupric oxide is very hygroscopic. To make sure that the oxide contains no suboxide, it is, however, generally moistened with a little fuming nitric acid, dried with the lid on and ignited for ten minutes, and then re-weighed ; but - this operation requires great care, and is liable to involve a loss on account of spurting. Y eight of oxide x 63 5 _ (^Qppgj. quantity of substance analyzed. {b) As Metallic Copper. The solution, which must be free from metals precipitable by zinc, is intro- duced into a weighed and very clean platinum basin. A small piece of zinc is introduced, and the crucible covered with a lid to prevent spurting. The solution must contain a slight excess of hydrochloric or sulphuric acid, but on no account nitric acid. After the fluid has become quite colourless and the basin has become coated with metallic copper, a little more hydrochloric acid is added, to dissolve out the excess of zinc, which will have disappeared when the liquid has ceased to ‘effervesce. The fluid is now poured off, and the i68 GRAVIMETRIC QUANTITATIVE ANALYSIS. copper repeatedly washed with boiling water till all acidity is rentioved. The basin is finally rinsed with absolute alcohol, quickly dried, and weighed. This process gives excellent results when pure zinc is at disposal ; but it must be borne in mind that so-called pure zinc in rods frequently contains traces of lead insoluble in hydrochloric acid. ESTIMATION OF BISMUTH. (a) -As Bismuth Oxide. Bismuth is estimated in this form. The solution for analysis (freed, if necessary, from other metals) is diluted with water, and precipitated with a slight excess of ammonium carbonate. The precipitated bismuthous oxy- carbonate is collected, washed, and dried. It is then separated from the filter paper, and the latter having been burned on the lid of a weighed crucible, the whole is introduced into the crucible, and ignited, cooled, and weighed. The weight of the crucible having been deducted, we say, — Weight of precipitate x 416 _ | weight of bismuth in the quantity 464 X of substance taken for analysis. As Bismuth Sulphide. Bismuth is sometimes estimated as sulphide ; but this process cannot be much recommended, as the sulphide is apt to increase in weight on drying, owing to the absorption of oxygen. When following this method, a current of sulphuretted hydrogen is passed through the acid bismuth solution; the result- ing sulphide is collected on a weighed filter, dried at 2i2°F., and weighed. Weight of the sulphide x 416 _ | amount of bismuth in the ^12 ~ X sample taken for analysis. ESTIMATION OF GOLD. (a) As Metallic Gold, by Precipitation. The solution is boiled with excess of ferrous sulphate or oxalic acid, and, to prevent iron compounds or oxalates from precipitating, some hydrochloric acid is also added. If oxalic acid is used, a slight effervescence will be noticed, so it is advisable to cover the beaker with a glass. The precipitated gold is washed on a filter, dried, ignited, and weighed. This method gives accurate results, providing the gold exists as trichloride. (d) By Cupellation. Gold solutions containing potassium cyanide are treated as follows : A known portion is evaporated with a few grammes of red lead. When dry, the crucible is covered and heated to redness. The result is a button of lead containing the gold, from which the latter is readily separated by cupellation, and can then be weighed. ESTIMATION OF PLATINUM. As Metallic Platinum. Platinum is usually estimated in this form. The solution, which must contain the platinum as trichloride, is concentrated and precipitated with excess of ammonium chloride. As ammonium platino-chloride is slightly soluble in water, four times its bulk of absolute alcohol is added to the fluid, which, after standing for several hours, is filtered. The precipitate is well washed with spirit of wine, dried, ignited, and weighed, as metallic platinum. TIN— ANTIMONY. 169 Sometimes it is useful to wash the platinum on a filter with hot water, and to again dry and weigh. The results are accurate. ESTIMATION OF TIN. {a) As Stannic Oxide. ' Alloys containing tin, but free from antimony or arsenic, are treated with nitric acid, which converts the tin into oxide, and other metals into nitrates. The acid fluid is evaporated nearly to dryness, the residue taken up with water and a little nitric acid ; the oxide is washed by decantation, collected on a filter, completely washed and dried. It is then as completely as possible detached from the filter, the latter is burned on a lid, the ash added to the contents of the crucible, and the whole ignited. After cooling the oxide is moistened with a little nitric acid, dried (with the lid on), and again ignited, when, after cooling, it is ready for weighing. Where we have to deal with tin in solution, the following method is, applied : — The solution, which must be free from metals of the first three groups, is precipitated with sulphuretted hydrogen, the resulting sulphide is washed with solution of acetate of ammonium, which will prevent the stannic sulphide from passing through the filter. After drying, the sulphide is transferred to a weighed crucible, the filter burned on the lid, its ash added to the contents of the crucible, and the whole ignited, at first very gently., until fumes of sulphurous anhydride cease, and then at a very high temperature, with the addition of a fragment of ammonium carbonate. The whole having been cooled, weighed, and the weight of the crucible deducted, we say, — ^ Weight of precipitate x 118 _ ( amount of metallic tin in the quantity ( of substance taken for analysis. This process depends on the conversion of the sulphide into S11O2 by ignition ; but it must be conducted with care, as a too rapid application of heat would cause the change to take place suddenly, and the whole would ignite. {b) As Metallic Tin. This process, which is only applicable to tin stone, consists in fusing a known quantity of the pulverized ore with potassium cyanide in a porcelain crucible, when a small button or granules of metallic tin will be obtained on treating the mass with water. The tin is washed, dried, and weighed. ESTIMATION OF ANTIMONY. {a) As Metallic Antimony. In the solution, which must contain some excess of hydrochloric acid, a slip of tin is introduced, which will soon precipitate all the antimony as a black powder. The excess of tin is best removed by pouring off the greater part of the liquid and boiling the precipitate with moderately strong hydrochloric acid. When no more evolution of hydrogen is visible, the metal is washed till free from acidity, then again washed with alcohol, collected on a weighed filter, dried, and weighed. Or what is left frorh the tin may be taken out and care- fully freed from the adhering antimony, when boiling with acid is superfluous. {b) As Antimonious Antimonic Oxide. The acid solution is precipitated with sulphuretted hydrogen, the sulphide collected on a weighed filter, dried at 2 2o°F., and weighed. The total w’eight 170 GRAVIMETRIC QUANTITATIVE ANALYSIS. being known, a weighed portion of it is taken for conversion into the oxide, when it can be easily calculated how much oxide the whole of the sulphide would have yielded. The conversion of the sulphide into oxide is best done by mixing it with forty times its weight of pure mercuric oxide and heating gently at first and very strongly' afterwards, to drive off the mercury. The remaining SbOg is weighed. A platinum crucible may be used, but must first be lined with some mercuric oxide before introducing the mixture. The following calculation js now applied : — Weight of oxide x 122 j amount of antimony in the 1^4 “ I sample taken for analysis.^ Another process for the conversion of the sulphide into oxide consists in evaporating a known quantity of the sulphide in a porcelain dish with fuming nitric acid. When dry, the residue is ignited, cooled, and weighed. ESTIMATION OF ARSENIC. {a) As Arsenious Sulphide. The solution must contain the arsenic as arsenious acid. After adding some HCl, a current of sulphuretted hydrogen is passed through the liquid till * the latter acquires a strong smell. The excess of gas is now removed by warming the fluid and passing a current of carbonic anhydride through it. The sulphide is collected on a weighed filter, washed, dried at 212° F., and weighed. The following calculation is then applied : — Weight of sulphide x 150 _ J amount of arsenic in the ^^6 1 sample taken for analysis. {b) As Magnesium Ammonium Arseniate. Arsenious acid is dissolved in some hot solution of sodium carbonate, excess of hydrochloric acid is added, and the fluid gently heated with potassium chlorate till it smells distinctly of chlorine, even after half an hour. Arsenic sulphur compounds are dissolved in hot potassium hydrate and treated with ex- cess of chlorine gas to convert them into arsenic acid. The solution of arsenic , acid thus obtained by either of the foregoing methods is mixed with large excess of ammonium hydrate, and, after being allowed to cool, precipitated with magnesia mixture (a fluid prepared by adding ammonium hydrate to a solu- tion of magnesium sulphate and re-dissolving the precipitate with ammonium chloride). After standing for at least twelve hours, the precipitate is collected on a weighed filter, washed with a mixture of one volume of arnmonium hydrate and three volumes of water till free from chlorine, dried for three hours at 2 20°F. and weighed. If only dried at 212° F. the drying will occupy a considerably longer time. The results are usually a trifle too low. The following calcu- lation is applied : — Weight of precipitate x i5o_ ( amount of arsenic in the 280 ( sample taken for analysis. ESTIMATION OP COBALT. As Potassium Cobaltous Nitrite. Cobalt is most accurately estimated in this form. The solution is concen- trated to a small bulk, the excess of acid is neutralized with potash, and excess of potassium nitrite and a little acetic acid (to keep the solution slightly acid to test-paper) are then added. After the lapse of twenty-four hours, all the cobalt will have crystallized out as potassium cobaltous nitrite. This salt is NICKEL— MANGANESE— ZINC— IRON, 171 quite insoluble in the mother liquor, but slightly so in pure water. For the washing, a 10% solution of potassium acetate is used, wherein the salt is also insoluble, and the acetate is afterwards removed by washing with alcohol. A weighed filter is used and after drying and weighing, the following calculation is applied : — Weight of precipitate X ny6_ j amount of cobalt in the 86y6 i sample taken for analysis. ESTIMATION OF NICKEL. As Metal. The solution is precipitated with excess of sodium hydrate and boiled. The precipitate is washed with boiling water, dried, ignited, and weighed. The ignited residue, or a known portion of it, is now introduced into a weighed glass tube and reduced at red heat by a current of hydrogen. The reduced metallic nickel is afterwards weighed. ESTIMATION OF MANGANESE. As Manganoso-manganesic Oxide. Manganese is best estimated in this form. The solution for analysis, if strongly acid, is neutralized with ammonium hydrate and precipitated by am- monium sulphide. The precipitated manganous sulphide is washed with water containing ammonium sulphide, and dissolved in acetic acid. Chlorine gas is passed through the liquid until all the manganese precipitates as manganic peroxide, which is then collected, washed, and calcined in a weighed crucible to bright redness. This forms Mng04 ; the crucible and the contents having been cooled and weighed, the weight of the crucible itself is deducted, and the following calculation employed : — • Weight of precipitate x 16 5 ^ c weight of manganese in the am.ount of 229 ( substance taken for analysis. ESTIMATION OF ZINC. As Zinc Oxide. The solution of the zinc salt (freed from other metals if necessary) is pre- cipitated boiling with sodium carbonate, and the solution boiled well. The precipitate is allowed to settle, washed by decantation with boiling water, filtered out, and dried. It is then introduced into a weighed crucible, ignited for some time at a bright red heat, cooled, and weighed. The ignition changes the precipitated zinc carbonate to oxide, and it is weighed as such. Or the solution is precipitated with ammonium sulphide, the zinc sulphide collected on a filter, washed with dilute ammonium sulphide, dried, ignited, and finally weighed as oxide. This process is useful when only small quan- tities of zinc are present. The calculation is as follows : — Weight of precipitate x 65 _ f weight of zinc in the quantity 81 ( taken for analysis. ESTIMATION OF IKON. {a) As Ferric Oxide. The solution (freed if necessary from other metals, phosphates, and organic matter) is boiled with a few drops of nitric acid to insure that the whole of the iron is in the ferric state. Excess of ammonium hydrate is added, the whole boiled, and rapidly filtered. The precipitated ferric hydrate is 72 GRAVIMETRIC QUANTITATIVE ANALYSIS. washed with boiling water, dried, and ignited in a weighed crucible for some time. The crucible and contents are weighed, and the weight of the crucible having been deducted, the following calculation is applied : — Weight of precipitate x 112 _ j weight of iron in the quantity of 160 \ substance taken for analysis. In the presence of organic matter such as citric or tartaric acids, the iron must first be separated by precipitation with ammonium sulphide, the precipi- tate washed with dilute ammonium sulphide, redissolved in hydrochloric acid, boiled, oxidized by potassium chlorate, and then precipitated with ammonium hydrate, as directed. Indirect Estimation by means of Metallic Copper. When an iron solution is free from metals acted upon by copper, such as cupric, arsenic, and mercury salts, it is first of all, if necessary, completely oxidized with hydrochloric acid and potassium chlorate, and the free chlorine is entirely expelled by prolonged boiling. The solution is now introduced into a flask, and the latter is fitted with a perforated cork provided with a long narrow open glass tube. Before closing the flask a few clean and weighed pieces of metallic copper are introduced. The liquid is now boiled till almost quite colourless (not till faint greenish blue, as said in some works). The solution is then poured out of the flask, and the copper, having been rapidly washed with boiling water, is taken out and rinsed with absolute alcohol. On no account must it be rubbed, notwithstanding it may appear blackish. After drying it is weighed, and the loss calculated to iron : — Loss X 56 63 '5 amount of iron in the sample taken for analysis. This process is based upon the fact that ferric chloride, boiled with hydro- chloric acid and copper, yields ferrous and cuprous chlorides. This process is not available in the presence of nitric acid. ESTIMATION OF ALUMINIUM. As Aluminic Oxide. It is in this form that aluminium is always estimated. The solution con- taining the alum or other salt of the metal (which must be free from iron and earthy phosphates) is precipitated with a slight excess of ammonium hydrate, and boiled until it only smells very faintly of ammonia. The precipitated aluminic hydrate thus obtained is filtered out, washed with boiling water, and dried. The dry filter and its contents are transferred to a weighed platinum crucible, and ignited to bright redness for some time, allowed to cool, and weighed. The weight of the crucible having been deducted, the following calculation is then applied : — Weight of precipitate x 55 _ / weight of aluminium in the quantity ( of substance taken for analysis. ESTIMATION OF CHROMIUM. As Chromic Oxide. Salts of chromium are at once precipitated with ammonium hydrate and the precipitate washed, dried, ignited, and weighed as Cr203- Soluble chromates are first reduced by means of hydrochloric and sulphurous acids, or, instead of the latter, spirit of wine may be used. The following is the process used for the estimation of chromium in the native chrome-iron ore : — The ore is CHROMIUM— BARIUM— CALCIUM. 173 reduced to powder, which cannot be done too thoroughly, as a correct analysis will be secured if it be carefully pulverized, and dried at the heat of boiling water. Place in a good-sized platinum crucible 5 grammes of the powdered ore, with 6 grammes potassium acid sulphate ; heat for a quarter of an hour, at a temperature slightly in excess of the fusing point of the latter substance ; after which (for 20 minutes) increase the heat until the crucible becomes reddened, when sulphuric acid fumes will be evolved. By increasing the temperature still more, the remainder of these fumes will be driven off, and the ferrochromic sulphate partly decomposed. Three grammes pure sodium carbonate must now be added. Fuse, and add, in small portions at a time, 3 grammes potassium nitrate, maintaining for an hour a dull. red heat; but for the last fifteen minutes a higher temperature may be allowed. Cool the mass, treat it with boiling water, filter, wash the residue with hot' water. (This residue should be tested by digestion in heated hydrochloric acid, and any insoluble portion remaining must be again treated as before). The alkaline solution, which frequently contains, in addition to chromic acid, silicic, titanic, and manganic acids, besides aluminium, must be evaporated on a water-bath nearly to dryness in the presence of ammonium nitrate in excess, until all free ammonia is driven off. After water has been added, the silicic and titanic acids, with the aluminic and manganic oxides, will remain insoluble ; but the chromic acid is dissolved, and is to be treated as follows : — The filtrate is acidulated by HCl, mixed with sulphurous acid in excess, and slowly heated to ebullition. Ammonium hydrate being added in slight excess, boil again for a little time, wash the precipitated chromic hydrate repeatedly on a filter, until the washings are entirely free from sulphuric acid. Dry the precipitate, and ignite ; when it will be found to contain alkaline chromate, owing to the washing not having removed the whole. Before weighing, boil with water ; add a few drops of sulphurous acid, then ammonium hydrate, filter again, dry, and finally ignite in a weighed crucible. The weight of chromic oxide, thus yielded by the amount of the ore taken for analysis, calculated to percentage, gives the value of the sample for com- mercial purposes. ESTIMATION OF BAEIUM. As Barium Sulphate. Barium is estimated by weighing out a known quantity of the sample, dis- solving in boiling water, and adding excess of sulphuric acid. The whole is then boiled rapidly for a few minutes, and set aside to settle. The clear liquor is poured off as closely as possible, and the precipitate collected on a filter of Swedish paper., and washed with boiling water. The filter and precipitate are next dried and ignited in a weighed platinum crucible (the precipitate being removed as perfectly as possible from the paper, and the latter first burned separately on -the crucible lid, and the ash added to the contents of the crucible, to avoid the reduction of BaSO^ to BaS, by the carbon of the paper). The crucible and its contents having been weighed, and the weight of the crucible deducted, the difference equals the BaSO^, which is now to be calculated for barium, thus : — Differenc e _ x j 3 7 ^ weight of sample taken for analysis. 233 ESTIMATION OF CALCIUM. As Calcium Carbonate or Calcium Oxide. The solution of the lime salt is mixed with ammonium chloride, and is then made strongly alkaline by ammonium hydrate. Should any precipitate (for ^74 GRAVIMETRIC QUANTITATIVE ANALYSIS. instance, calcium phosphate) form, it is redissolved by means of acetic acid, and any insoluble residue is removed by filtration. Ammonium oxalate is now added in excess. The precipitated calcium oxalate is boiled for a few minutes, filtered, the precipitate washed until free from oxalates ; the filter and contents are dried at 212° F. The precipitate is now carefully trans- ferred to a tared platinum crucible, and heated gently at first, but afterwards more strongly, the filter being burnt on the lid until the ash is white, and then jdaced in the crucible. Finally, the whole is ignited strongly in the blowpipe flame for half an hour, cooled, and weighed. The contents of the crucible are calcium oxide ; the oxalate producing first carbonate and then oxide when ignited. The blowpipe flame is requisite to ensure the complete reduction of the carbonate to oxide. Some chemists prefer to moisten the calcium car- bonate with a solution of pure ammonium carbonate, evaporating to dryness, heating until no more fumes are evolved, and then weighing as carbonate. The great amount of loss relative to the weight of the precipitate which would accrue if a portion of the carbonate were to become accidentally re- duced to oxide, inclines us to prefer the former method. The following cal- culation is now applied : — Weight of precipitate x 40 , . . ^ ^ , r , • ° ^ -- calcium in the amount taken for analysis. looCaCOg, or 56CaO ESTIMATION OF STRONTIUM. As Strontium Carbonate. The solution containing the strontium compound is precipitated with ammonium carbonate and boiled. The carbonate is collected on a filter, washed with hot water, dried, ignited, and weighed. Acids, such as phos- phoric, which form with strontium compounds insoluble in dilute ammonia, must be first removed. The following calculation is applied : — Weight of the carbonate x 87'5 _ J weight of strontium in the i47~5 i sample taken for analysis. ESTIMATION OP MAGNESIUM, As Magnesium Pyrophosphate. The solution, which must not be over-diluted, is mixed with some ammo- nium chloride, and then with one-third of its bulk of ammonium hydrate. Should the solution be very acid, the excess of acid must first be neutralized by ammonium hydrate. When the solution has entirely cooled, excess of di-sodium hydrogen phosphate is added, and the whole allowed to stand for twelve hours. Care must be taken not to touch the sides of the beaker with the stirring rod, as otherwise particles of the triple phosphate will adhere to them so tenaciously that they can only be removed with great difficulty. The precipitate is collected on the filter and washed with a mixture of one volume of ammonium hydrate and three volumes of water, till the washings are free from chlorine and dried. The precipitate is now detached from the filter and put into a weighed platinum crucible, the filter is burned in the lid, the ash added to the contents of the crucible, and the whole ignited by means of a Bunsen burner ; and when a large quantity of phosphate has been obtained, finally ignited before the blow-pipe. After weighing, the following calculation is applied : — Weight of the phosphate x 48 _ | amount of magnesium in the ( sample taken for analysis. POTASSIUM. 175 It sometimes happens that the phosphate, even after prolonged ignition, is very black. In that case it is, after cooling, thoroughly moistened with nitric acid, carefully dried, and re-ignited, when it will be found to be perfectly white. ESTIMATION OF POTASSIUM. {a) As Potassium Platino-Chloride. The solution, which must be free from other metals, but may contain calcium, magnesium, and sodium compounds (as their presence does not interfere with the process), is first of all precipitated with excess of barium chloride, which throws down sulphuric, phosphoric, etc., acids. Barium hydrate or some milk of lime is now added in slight excess, when any magnesia will also be thrown' down. To the filtered liquid excess of ammonium carbonate is added, the precipitate is separated by the filter and the fluid evaporated in a platinum crucible to dryness, best on the water-bath. When quite dry it is covered with a platinum lid and gently heated as long as white ammoniacal fumes are visible. The residue, which will now consist of potassium chloride, together with perhaps sodium chloride, is however not quite fit for weighing, and must be purified. This is done by redissolving in water and adding a little ammonium carbonate, when a slight precipitate will form. After filtering, the fluid is evaporated, this time in a weighed platinum basin covered with a weighed. lid on the water bath, and when dry the residue is gently heated to faint redness for a minute, and cooled. When no sodium is present it will now be pure potassium chloride and may be weighed as such, and the following calculation applied : — Weight of chloride x -20 , . . . 1 . i r 1 • — ^ = potassium in the sample taken for analysis ; but should it contain sodium chloride it is dissolved in the smallest amount of water, transferred to a small porcelain basin, and mixed with a good excess of solution of platinic chloride. The whole is evaporated to dryness on a water-bath kept at a temperature of about 2oo°F. When quite dry it is again digested with a few drops of platinic chloride solution, to make sure that all the sodium will be in the state of sodium platino-chloride. This sodium compound and the excess of platinic chloride are now removed by spirit of wine of 60 O.P., the precipitate is collected on a weighed filter, washed with alcohol till the washings appear quite colourless, dried at 2i2°F., and weighed. The following calculation is now applied : — Weight of potassium platino-chloride x 78 _ ( weight of potassium in the 4^9 I sample taken for analysis. {b) As Sulphate. This method is applicable where we' have to deal with a potash salt contain- ing a volatile acid. The solution is mixed with excess of sulphuric acid and evaporated in a weighed platinum basin. When fumes of sulphuric acid become visible, the basin is covered over with a lid or foil which has been weighed together with the crucible, and gradually heated till fumes cease. While red-hot the foil is lifted up a little, and a small lump of ammonium carbonate put in the crucible, which operation is repeated after a few minutes. The object of introducing the ammonium carbonate is to remove the last traces of free sulphuric acid. After weighing, the following calculation is applied : — Weight of the sulphate x 78 _ ( potassium in the sample fTT taken for analysis. 176 GRAVIMETRIC QUANTITATIVE ANALYSIS. ESTIMATION OF SODIUM. (a) As Sodium Chloride. Proceed in the same way as for potassium. Weight of sodium chloride X 2^ • w r j- • i i 2 ^ = weight of sodium m the sample. (d) As Sodium Sulphate. As for potassium. Weight of the sulphate x 46 , — = sodium m the sample. 142 ESTIMATION OF AMMONIUM. As Ammonium Platino-Chloride. If the solution contains other basylous radicals, a known quantity of it is distilled with some slaked lime in a suitable apparatus, and the distillate received into dilute hydrochloric acid. About , three-fourths is distilled over. The distillate is then evaporated to dryness with excess of pure platinic chloride (free from nitro-hydrochloric acid). The dry residue is now treated with a mixture of two volumes of absolute alcohol and one of ether, collected on a weighed filter, washed with the said ether mixture, dried at 2i2°F., and weighed. The following calculation is now applied : — Weight of the double chloride x 36 _ J ammonium in the quantity ( taken for analysis. III. GEAVIMETEIC ESTIMATION OF ACIDULOUS EADICALS. 1. HYDROCHLORIC ACID AND CHLORIDES. The solution containing the acid or h chloride is precipitated with argentic nitrate. Nitric acid is then added, and the whole warmed and stirred till the liquid is perfectly clear. The precipitate is now treated as directed (see Silver), p. 165. After weighing the chloride, the following calculation is applied : — Weight of the argentic chloride x 36'5 _ j hydrochloric acid in the 143-2 t sample taken for analysis. 2. HYDRIODIC ACID AND IODIDES. 3. HYDROBROMIC ACID AND BROMIDES. 4. HYDROCYANIC ACID AND CYANIDES. The process for each of these acids is practically the same as for hydro- chloric acid. The argentic cyanide is, however, collected and weighed upon a weighed filter. The argentic iodide and bromide are treated like the chlo- ride ; but if a filter is used, it must be a weighed one. The filter is afterwards reweighed, and the increase in weight is the amount of argentic iodide or bromide lost during the washing by decantation. The following calculations are respectively applied : — For the hydriodic acid — Weight of the iodide x 128 _ ( weight of hydriodic acid in fit ( the sample taken for analysis. CHLORINE— BROMINE— IODINE-SULPHIDES. 177 For the hydrobromic acid — Weight of the bromide x 81 _ J hydrobromic acid in the ^88 ( sample taken for analysis. For the hydrocyanic acid — Weight of the argentic cyanide x 27_ J hydrocyanic acid in the I sample taken for analysis. 5. ESTIMATION OF AN IODIDE IN THE PRESENCE OP A CHLORIDE AND A BROMIDE. By palladium. The solution, slightly acidified, is precipitated with excess of palladious chloride or nitrate. The whole is then allowed to stand in a warm place for twentyTour hours, so that the precipitate may thoroughly settle. The supernatant liquor is poured off, and the precipitate having been collected on a filter, and washed, is placed in a weighed platinum crucible and ignited. The whole is then again weighed, and the weight, less that of the crucible, equals the amount of metallic palladium left after ignition. Now 100 parts of the metal combine with 239-6 parts of iodine in the precipitate, therefore the weight of the metal left after ignition x 2*396 = the amount of iodine in the weight of the sample taken for analysis. 6. MUTUAL ESTIMATION OF Cl, Br, AND I IN THE PRESENCE OF EACH OTHER. Observation has revealed, that although argentic bromide is converted into the chloride by hydrochloric acid, and the iodide into the bromide by hydro- bromic acid, yet the potassium salts of hydriodic acid will decompose, not only argentic bromide, but also argentic chloride ; and that potassium bromide also reacts upon argentic chloride. This being recognised, and a solution of a known quantity of the mixed salts being made, divided into three equal volumes, and slight excess of argen- tic nitrate added to each, three precipitates are obtained, which are to be washed till free from soluble matter. The first of ^lese must then be dried and weighed. The second digested with KBr, washed, dried, and weighed. The third digested with KI, washed, and also, after being rendered free from moisture, weighed. From these three results the amounts of Cl, Br, and I are to be deduced by a calculation based on the difference of the molecular weight of AgCl, AgBr, and Agl. The first weighing is — AgCl + AgBr + Agl. The second is — AgBr + Agl, and is consequently increased as 35*5 is to 80. The third is entirely Agl, and is consequently increased as 80 is to 127. 7. SULPHIDES Are best analyzed by fusion with a large excess of a mixture of potassium nitrate and carbonate, extracting the fused mass with water, filtering,- acidu- lating with hydrochloric acid, adding excess of barium chloride, and proceeding as for a sulphate ; but calculating at the last to sulphur instead of sulphuric acid. Some sulphides 'can be dissolved in nitric acid or in aqua regia, both of which convert the sulphur into sulphuric acid, but the fusion is always the most accurate method. VOL. II. N 178 GRAVIMETRIC QUANTITATIVE ANALYSIS. 8. SULPHURIC ACID AND SULPHATES. , As Barium Sulphate. To the solution of the sulphate hydrochloric acid is added, then excess of barium chloride, and the whole boiled. When quite clear, a little more barium chloride is added, to ascertain whether all the sulphuric acid has precipi- tated. The precipitate is now treated precisely as in the barium estimation and the following calculation applied : — Weight of precipitate x 8o _ f weight of sulphuric anhydride in 233 ~ \ the sample taken for analysis. 9. NITRIC ACID. ' (a) In Alkaline Nitrates. If nitric acid be required to be estimated in, say, ordinary nitre, the sample must first be heated to fusion to remove moisture, and then be quickly powdered. A known quantity of it is now mixed in a platinum crucible with .(exactly) 4 times its weight of plumbic sulphate. The mixture is ignited till it ceases to lose weight, and the loss will just represent the amount of nitric anhydride in the sample taken for analysis. If plumbic sulphate is used, the reaction is represented by the following formula : — PbSO^ + 2KNO3 = PbO + K2SO4 + 2NO2 + O. (I) By Conversion into Ammonia. The nitrate is converted into ammonia by the action of nascent hydrogen, thus — HNO3 + 4H2 - NH3 -I- 3H2O. The nascent hydrogen may be applied in various ways, as follows : — 1. By distillation with sodium hydrate and metallic aluminium, and receiving the evolved ammonia into a known volume of standard acid. 2. By acting on the nitrate for 12 hours with zinc or iron and dilute sulphuric acid, and then adding excess of sodium hydrate, and distilling off the ammonia into a known volume of standard acid. In any case, the standard acid used is then volumetrically checked back by standard sodium hydrate, and the excess of acid used over that of alkali gives the amount of standard acid neutralized by the ammonia. This amount, having been multiplied by the strength of the acid in each c.c., is calculated to ammonia. Then — Ammonia found x 54_ J amount of anhydrous nitric acid in Yj ( the quantity taken for analysis. 10. PHOSPHORIC ACID AND PHOSPHATES. This acid is always weighed as magnesium pyrophosphate ; but several cases may occur. PHOSPHORIC ACID— PHOSPHATES. 179 (a) Alkaline Phosphates. They are at once precipitated with ammonium hydrate and magnesia mixtitre., and the precipitate is treated as directed under Magnesium. Should they contain the acid as meta- or pyro- acid, they must first either be boiled with strong nitric acid for one hour, or be fused with potassium sodium car- bonate. After the weighing of the magnesium pyrophosphate the following calculation is applied : — Weight of precipitate x 142 _ f phosphoric anhydride in the 2 2 2~ ~~ L sample taken for analysis. (if) Phosphoric Acid in the Presence of Lime and Magnesia. The solution (which must contain orthophosphoric acid, or, failing that, should be boiled with HNO3 as above) is precipitated with ammonium hydrate, the precipitate re-dissolved in the smallest amount of acetic acid, the lime precipitated with ammonium oxalate, and the phosphoric acid pre- cipitated in the filtrate by adding ammonium hydrate and magnesia mixture. Before precipitation this filtrate should be evaporated to a bulk of 3 ounces. This process is suitable for determining the ‘‘ soluble phosphates ” in an artificial manure. (c) Phosphoric Acid in the Presence of Iron and Aluminium. The solution is mixed with excess of ammonium acetate, boiled, and ferric chloride added till a dark-brown precipitate forms. This is washed with boiling water and redissolved in a small quantity of dilute HCl. About five grammes (or more) of citric acid are now added, and when quite cool a few c.c. of the solution are mixed in a test-tube with excess of ammonium hydrate. Should this give a lemon colour, it is all right; but should the colour be brownish, it is a sign that sufficient citric acid has not been added. In that case supersaturate the ammoniacal solution with HCl, mix it again with the bulk of the liquid, and add more citric aCid, when the same test is to be again applied. If satisfactory, the tested portion js added to the main liquid, and ammonium hydrate is added to the whole in large excess, and, after cooling, magnesia mixture. (d) Separation from All Metals. If necessary, the acid solution is heated and precipitated with H2S to remove arsenic. The excess of H3S is boiled off, and large excess of nitric acid is added. An excess of ammonium molybdate dissolved in nitric acid is now poured in, the liquid boiled, and finally allowed to stand for at least twelve hours in a warm place. The precipitate is filtered off, washed with water containing a little molybdate solution, redissolved in dilute ammonium hydrate, and the phosphoric acid precipitated by magiiesia mixture. This process is the best for determining the total phosphoric acid in manures, coprolites, etc. 11 . ARSENIC ACID AND ARSENIATES Are estimated precisely like phosphates ; but the precipitate of ammonium magnesium arseniateis dried at 220° F. on a weighed filter, as already directed under arsenic. The precipitate thus dried is 2(MgNHj^As04).H20 ; or, for simplicity of calculation, MgNH4As04.|H20. i8o GRAVIMETRIC QUANTITATIVE ANALYSIS. 12. CARBONIC ACID. Direct Estimation in Carbonates. A carbonate is estimated by the loss of weight it undergoes by the dis- placement of its carbonic anhydride by an acid. A small and light flask is procured, and fitted with a cork through which passes a tube containing fragments of calcium chloride. A weighed quantity of the carbonate is introduced into the flask with a little water, and a small test-tube about two inches long is filled with sulphuric acid and dropped into the flask, so that, being supported in an upright position, none of the acid shall mix with the carbonate. The cork is put in, and the weight of the whole apparatus having been carefully noted, it is inclined so as to allow the acid to run from the small tube into the body of the flask. Effervescence sets in, the carbonate is dissolved, and the COg escaping through the calcium chloride tube, is deprived of any moisture it might carry with it. When all action has ceased, and the whole has cooled, it is once more weighed. The difference between the two weights gives the amount of CO2 evolved, and then loss in weight x 6o radical in the weight of sample taken. 44 13. OXALIC ACID. (a) As Calcium Carbonate. The solution containing the acid, or its potassium or sodium salt, is made alkaline with ammonium hydrate, and precipitated with calcium chloride. The precipitate is washed till free from chlorides., dried, ignited, and finally weighed as carbonate. (See Estimation of Calcium.) Weight of the carbonate x 126 _ ( oxalic acid in the sample “ ( taken for analysis. 14. TARTARIC ACID. As Calcium Oxide. The solution (which must contain no Other bases than Ka, Na, or NH^) is made faintly alkaline by ammonium hydrate, and precipitated by excess of calcic chloride. The precipitate is washed, dried, ignited (with the blow- pipe) and weighed as calcic oxide. Weight of lime x 150 sample taken for analysis. 15. SILICIC ACID. (^r)vln Soluble Silicates. By soluble silicates are meant those which are either soluble in water or in hydrochloric acid. The solution (which must contain some free HCl) is evaporated to dryness on the water-bath, and the residue dried for an hour at 248° E. After cooling, the mass is moistened with strong HCl, and then boiled with water, thus leaving an insoluble residue of pure silicic acid, which is collected on a filter, washed, dried, ignited, and weighed. (h) In Insoluble Silicates. These bodies must be decomposed by mixing a weighed quantity of the finely powdered substance with four times its weight of sodium potassium carbonate, and fusing the whole for about half an hour. When alkalies have also to be estimated, barium hydrate is used instead of the double carbonate. The crucible must be well covered during fusion. After cooling, the residue will be found soluble in dilute and warm HCl ; if, however, much silica be present, a jelly will form. The whole is now evaporated to dryness and treated as before. CHAPTER X. ULTIMATE ORGANIC ANALYSIS. I. ESTIMATION OF CARBON AND HYDROGEN. This process is performed by heating a weighed quantity of the substance in a tube with some easily reducible body, such as cupric oxide or plumbic chro- mate, by which the hydrogen and carbon of the organic body are respectively oxidized into water and carbonic anhydride. These products are passed first through a previously weighed tube containing calcium chloride, which retains the water, and then through a bulb apparatus containing potassium hydrate, which absorbs the carbonic anhydride and has also been previously weighed. After the experiment is finished, the increase in weight of the tubes is calcu- lated thus : — As HgO : Hg : : increase in CaClg tube. As CO2 : C : : increase in KHO bulbs. The operation takes place in a furnace specially constructed, and known as a combustion furnace. It consists of a series of gas burners by means of which a bright red heat can be gradually applied to the whole length of the tube, which rests in and is enclosed by a bed of fire-clay. The details of the actual process are as follows : — Cupric oxide is prepared by heating cupric nitrate to bright redness in a crucible ; it is reduced to powder while still warm, and preserved in a well- stoppered bottle. A tube of hard Bohemian glass (which does not soften at a red heat) is procured, having a bore of about half an inch and a length of fifteen to eighteen inches. It is closed at one end by heating in the blowpipe flame and drawing it outwards and upwards to a point, sufficient, cupric oxide to fill it is measured out, heated to expel any moisture (as it is very hygroscopic) and placed m a well-corked flask to cool. When cold, a little oxide is introduced into the tube ; and the organic substance, having been weighed out, is rubbed up in a warm mortar with enough cupric oxide to half fill the tube, and the mixture is quickly transferred to that apparatus, sufficient cupric oxide to nearly fill the tube is then introduced, and lastly a few bright copper turnings are put in. To this charged tube is then attached by means of a good cork, a previously weighed tube containing fragments of dry calcium chloride, and to this is in turn fixed by an indiarubber joint a bulb apparatus also previously weighed and containing solution of potassium hydrate of I'zy specifc gravity. The tube is now placed in the furnace, and the glass attachments supported outside of it by appropriate stands. A little air is sucked out by applying the lips to the end of the potash bulbs, and if the alteration of level thus caused in the liquid is maintained for some time the joints are all perfect; but if not, they must be re-made until perfectly air-tight. Heat is now applied to the front portion of the tube by lighting the first five or six burners, and when that part is quite red-hot the next burner is turned on. The heat is thus applied ULTIMATE ORGANIC ANALYSIS. 182 gradually, taking care that it is so regulated as to produce a regular slow passage of the evolved gases, so that the bubbles may be distinctly counted as they pass. When the whole tube is heated from end to end and all action has ceased, the drawn-out point is broken, a little perfectly dry air is drawn through the whole to carry the last traces of moisture and carbonic anhydride into the bulbs, which are then detached, weighed, and the increase in weight of each noted. The following example of the results of the combustion of a little pure sugar will show the calculation : — Weight ot sugar taken . . . . . *475 gramme. Potash bulbs after combustion weighed „ „ before Difference, due to COg 7 9 ’IIS grammes. 78-382 731 Calcium chloride tube after combustion weighed . ,, ,, before ,, ,, . Difference, due to HgO . 23*605 grammes. 23’33o '275 (C) 12 X -731 (CO2) 44 = *1994 carbon (Hg ) 2 X *27 5 (HgO) 18 = '03056 hydrogen. Total sugar taken . . . . . . *475 Total C and H found ..... '22996 Difference, due to oxygen . '24504 Or, in percentage — Carbon Hydrogen Oxygen . 4i'98 6*43 • 5^’59 100*00 When the organic matter is a liquid, it is weighed in a small hermetically sealed tube, and a little oxide having been first put into the combustion tube, the sealed one is dropped in, its end broken by a wire, and the whole of the rest of the oxide poured in. The heat is applied till six or seven inches of CuO are bright red, and then the burner underneath the spot where the tube with the liquid lies, is cautiously applied, so as to volatilize the vapour and cause it to pass over the red-hot cupric oxide and so suffer combustion. Fats and other bodies which cannot be mixed with the oxide are weighed in a small platinum boat, which is dropped in and treated like the. tube of liquid already referred to. Substances which are very carbonaceous and difficult to burn are best mixed with a little plumbic chromate and then the rest of the tube filled with the cupric oxide. Another method is, to produce at the last a stream of pure oxygen by putting a little pounded and perfectly dry potassium chlorate (mixed with a little pure sand to divide it) into the closed end of the combustion tube, then some pure CuO, then CuO plus the substance, and fill up as usual. When the last burner is lit, the potassium chlorate gives off sufficient oxygen to clear the tube of other gases and to aid in the combustion of the last particles. NITROGEN ESTIMATION 183 II. ESTIMATION OF NITROGEN. The estimation of nitrogen in all compounds, not being nitrites or nitrates, is conducted as follows : — ia) The method of Varrentrapp and Will. This depends for its success on the fact that when nitrogenous substances are strongly heated with sodium hydrate, 'they are decomposed, forming a carbonate and oxide with the oxygen from the hydroxyl, and liberating hydrogen, which then combines with the nitrogen to form ammonia. When substances very rich in nitrogen and carbon are analyzed, cyanogen compounds are formed ; but they are in turn entirely decomposed in the presence of a free excess of the alkali and a very high temperature. 2CN + 4H2O = 2CO2 + 2NH3 + Hg. The excess of hydrogen usually combines with part of the carbon to form volatile hydrocarbons. The process itself is conducted as follows : — Slake five parts of calcium oxide with two parts sodium hydrate, and after this mixture is dried in an iron pot, let it be made red-hot in a Hessian crucible, then turned, still hot, into a warm mortar, where it must be reduced to powder, and retained for after use in a closely-stoppered bottle, labelled “ soda-lime.” About five to eiglit decigrammes of the nitrogenous substance to be investi- gated must be dried and weighed exactly, rnixed with soda-lime in a warm wedgwood mortar, sufficient to fill about three-quarters of a combustion tube ; rinse the mortar with a little more soda-lime, and in order to thoroughly cleanse it, rub round the inside with powdered glass which can be put into the combustion tube. More soda-lime can bo put into the tube, until it is filled to within two inches of its open end, and then an inch of asbestos in shreds packed loosely in front of all, so as to prevent the passage of fragments of lime along with the evolved gases. A three-bulb apparatus, specially con- structed, and containing a little tolerably strong hydrochloric acid, is carefully adapted to the mouth of the combustion tube by means of a well-fitting cork, and the tube thus disposed is placed in a properly arranged combustion furnace, so that the bulbs and about an inch of the tube project outside, while the remainder can be exposed to the heat. A few front burners having been lighted, and the free part of the tube having become red-hot, the heat is gradually applied until the whole of it has been heated to bright redness. When this point is attained, and bubbles of gas cease to pass through the acid in the bulbs, the end of the tube is broken off, and some air sucked through the apparatus by means of a small tube attached to the outer end of the bulbs. The contents of the bulbs are then transferred into a small basin, the bulbs washed out into it, first by means of a little alcohol, and afterwards repeatedly with distilled water. An excess of platinic chloride is then added, the whole evaporated to dryness in a water bath, and the precipitate, having been moistened with a little alcohol, is washed on, to a weighed filter. The washing with alcohol is continued until it passes colourless, and the precipitate is dried at 212° and weighed. The weight of the filter having been deducted the balance is PtCl42NH4Cl, which is then calculated to Ng. A more simple plan, adapted to the estimation of nitrogen in manures and other commercial products, may be thus followed out : — The ammonia is received into a known volume of a volumetric solution of sulphuric acid, which is placed in the bulb apparatus. The ammonia which passes into the bulbs during the combustion neutralizes a portion of this acid, and at the conclusion of the operation the amount of acid still remaining free ULTIMATE ORGANIC ANALYSIS, 184 is ascertained by means of a volumetric solution of sodium hydrate. The difference between the amount of acid originally placed in the bulbs and that remaining free as thus ascertained, evidently corresponds to the amount of sul- phuric acid neutralized by the ammonia produced during the combustion. The strength of the acid being known, a simple calculation enables us to ascertain the amount of the nitrogen evolved in the form of ammonia. The following is a practical example : — Let an acid be prepared containing 2 grammes of pure hydrogen sulphate (HgSO^) in 100 C.C., then 20 c.c. of this acid (the quantity introduced into the bulbs) will correspond to ’138 gramme of ammonia, or ‘iiq gramme of nitrogen. Let an alkaline solution be so graduated that 100 c.c. will exactly neutralize the 20 c.c. of the standard acid. If we now find that the acid which was in the bulbs after the combustion, requires only 70 c.c. of the alka- line solution, it is evident that = 6 c.c. were saturated by the ammonia, and the quantity of nitrogen is obtained by the proportion ~ °342 gramme of nitrogen. (d) The process of Dumas. This consists in measuring the amount of pure nitrogen evolved, and is suitable for certain organic bases and for com- pounds containing nitrosyl (NO) or nitryl (NOg) in which the soda-lime fails to convert all the nitrogen into ammonia. The combustion tube (which in this case is twenty-six to twenty-eight inches long) is packed (i) with six inches of dry sodium hydrogen carbonate ; (2) with a little pure cupric oxide ; (3) with the weighed substance mixed with CuO ; (4) with more pure CuO; and lastly with a considerable length of pure spongy metallic copper, and the whole is closed by a good cork through which passes a bent delivery tube dipping under the surface of mercury in a small pneumatic trough. Heat is first applied to the very end portion of the NaHCOg until sufficient COg has been given off to entirely drive all the air out of the apparatus, which is ascertained by collecting a little of the gas passing off and seeing that it is entirely absorbed by solution of potassium hydrate. A graduated glass jar is then filled, one-third with strong solution of KHO, and the remainder with mercury, and carefully inverted into the mercury trough so that no air is admitted, and placed over the mouth of the delivery tube. Combustion is now commenced at the front of the tube and gradually carried backwards as usual. The gases evolved are COg and N, the former of which is absorbed by the KHO and the latter collects in the graduated jar. When the heat reaches the back of the tube the remainder of the NaHCOg is decom- posed, and the carbonic anhydride given off chases any trace of nitrogen out of the tube. It only remains to read off the volume of nitrogen, notice the temperature and pressure, calculate to 0° C and 760 mm. bar, and then reduce the volume found to weight. III. ESTIMATION OF CHLORINE. In the ordinary combustion of chlorinated compounds it is better to use plumbic chromate than cupric oxide, because in the latter case a volatile cupric chloride would be formed. Chlorine itself is estimated by combustion of the substance in a tube filled with pure calcium oxide, when it displaces oxygen and turns part of the oxide into soluble calcium chloride. After combustion the contents of the tube are digested in water, filtered, excess of argentic nitrate added, and the precipitate washed, dried, and weighed as already directed (see Gravimetric Estimation of Chlorine). SULPHUR AND PHOSPHORUS ESTIMATION. 85 IV. ESTIMATION OF SULPHUR AND PHOSPHORUS. ’ When substances contain either of these elements, it is best to use plumbic chromate for the estimation of the C and H j or, if cupric oxide be used, then to place a little plumbic oxide in the front of the tube. The sulphur and phosphorus themselves are estimated by fusing in a silver crucible with twelve times the bulk of pure potassium nitrate, a little mixed carbonate and nitrate being first put into the crucible, heated to fusion, and the mixture added a little at a time, waiting between the additions till action ceases. After fusion the sulphur and phosphorus, which have been converted into sulphuric and phosphoric acids respectively, are estimated by dissolving the residue in water and proceeding by precipitation as barium sulphate and magnesium ammonium phosphate respectively. (See Gravimetric Estimation of Sulphuric and Phos- phoric Acids.) CHAPTER XL SPECIAL PROCESSES IN-ANALYSIS, Under this head it is proposed to give the analysis of some ordinary articles likely to come prominently under the notice of Pharmaceutical Chemists. I. POTABLE WATER. The Analysis of Waters Suspected to he Sources of Disease is daily becoming a more important matter, owing to the rapid enlightenment of the public on sanitary questions. It is an operation which every pharmacist should be able to perform. The following is a sketch of a method of sanitary water analysis which will be found easy to conduct, and is based upon the researches of Messrs. Wanklyn and Chapman, who have contributed much to our knowledge on this subject. The apparatus and reagents required consist of — I. A tubulated stoppered retort, to hold about 30 ounces, adapted with a piece of indiarubber tubing to a Liebig’s condenser. . 2. A non-tubulated retort, to hold about 10 ounces, also adapted to a con- denser. 3. A burette to contain 10 c.c. graduated in Lo 4. A Sink’s burette, to hold 1000 grains, graduated in |-decems. 5. A wide-mouth stoppered bottle, of 8 oz. capacity, graduated to hold 1000 grains of water. 6. A platinum evaporating dish, to hold 4 ounces of water without running over. 7. A water and air bath fitted with a centigrade thermometer. 8. A good balance to show of a milligrame. 9. A. standard solution of lime, made by dissolving 16 grains of perfectly pure calcium carbonate in dilute hydrochloric acid, evaporating to dryness, again moistening with water, once more drying, and finally dissolving in one gallon of pure distilled water. . 10. A standard solution of argentic nitrate, made by dissolving *479 gramme of the pure salt in a litre of water, each c.c. of which will be equal to of a milligramme of chlorine. II. A perfectly neutral solution of pure potassium chromate. 12. A solution of 100 grammes pure sodium hydrate, in one litre of water. 13. A cold saturated solution of sodium carbonate which has been boiled for some time. 14. A solution of 8 grammes potassium permanganate, in a litre of water, with 200 grammes of potassium hydrate. The whole is boiled for about an hour, and when cold, made up to one litre with pure distilled water. 15. Some fragments of sheet aluminium, about this size POTABLE WATER. 187 16. A standard solution of potash soap {sapo mollis, B.P.) in proof spirit of such strength that 32 decerns. (320 grains) delivered exactly from the Sink’s burette, produce a permanent froth or lather that lasts five minutes when well shaken, in the wide-mouthed bottle, with 1000 grains of the standard lime solution. The points to be noticed in the sanitary analysis of water are — Total Hardness, Permanent Hardness, Chlorine, Nitrogen as Nitrates and Nitrites, Free Ammonia, Albufninoid Ammonia, Total Solid Residue, and these we will consider seriatim. I. Total Hardness is supposed to represent the whole amount of lime and other salts which render a water hard and unfit for use for culinary and cleans- ing purposes. It is measured by the quantity of soap which can be rendered insoluble in water by conversion into a lime soap. {See Oleates.) The presence of undecomposed soap in watery solution is always recognisable by the per- manent white froth which is produced on the surface of the liquid by violent shaking and then setting at rest. If a spirituous solution of soap be added to water containing lime, a compound is formed between the lime and the fatty acids of the soap, which, being insoluble in water, floats^ to the surface in white flakes, and no permanent froth can be produced until enough soap has been added to thus precipitate all the lime. 1000 grains of the water to be tested are mtroduced into the wide-mouthed stoppered bottle, and some soap solution is added from the burette. The bottle is closed, and well shaken ; and the addition of soap is continued, shaking each .time, until a permanent lather is produced which lasts five minutes. The number of test measures (decerns of. 10 grains of water, as indicated on the burette) of soap solution thus used is then read off, and the following table is referred to as therein directed. After each shaking, the carbonic anhydride which collects in the bottle should be sucked out by means of a glass tube. In cases where a water takes more than 32 measures of soap, 500 grains only must be employed and diluted to 1000 with distilled water before use ; the result obtained being multiplied by 2. Dr. Clarke’s Table for taking the Hardness of Water. Degrees of Hardness. 0 1 Test Measures used. Difference. I ‘4 . . . . . 1-8 3‘2 . . . . . 2'2 2 . . . . . 5’4 . . . . . 2-2 3 7‘6 2-0 4 • • . . . 9‘6 . . . . .2-0 5 . . . . . ii ’6 . . . . . 2-0 6 . . . . . i 3'6 . . . . . 2 'o 8 i 7’5 i ’9 9 • . . . I 9’4 I ’9 10 21-3 1-8 11 .... . 23-1 ..... 18 12 24-9 . . . . .1-8 13 • • . . . 267 ..... 1-8 14 • • • . . 28-5 . . . . .1-8 15 30-3 17 10 . . . . .320 Should the number of test measures u^ed { = n) coincide with any number in the second column, the hardness is seen by glancing at the corresponding 88 SPECIAL PROCESSES IN ANALYSIS. number in the first column. If, however, n should come between two numbers, the lower of the two must be deducted from n., and the difference so obtained divided by the number in the third column opposite to the higher of the two. The quotient thus arrived at is to 'be added to the number in the first column corresponding to the lower of the two numbers, and the sum will be the hardness. Example. — Measures used = 20, which falls between 19 "4 and 21*3, then 20 - 19*4 = ‘6 ; and — = '33 ; lastly, *33 + 9 = 9-33 degrees of hardness. I '8 2. Permanent Hardness indicates the amount of calcic and magnesic salts in a, state other thah carbonate. The calcic and magnesic carbonates are held in solution in water by the carbonic anhydride (carbonic acid gas) dissolved in the fluid. On boiling, this gas passes off, and the carbonates are conse- quently precipitated, while all other salts remain unaffected. High permanent hardness is bad, because it is an indirect confirmatory evidence of sewage contamination, as showing the presence of sulphates and chlorides, both of which might be derived from such a source. Moreover, it would be impossible to render such a water potable by boiling. 1000 grains of the sample are introduced into a small flask, and a mark made with a file at the surface of the water. It is then briskly boiled for twenty minutes, and made up, when , cold, to the mark, with distilled water. The sample thus prepared is put into the bottle, and treated with soap solution, as already directed, and the result noted as permanent hardness. 3. Chlorine present as Chlorides is important, as also being a product of the decomposition of sewage matters. It is estimated as follows : — 70 c.c. of the water to be tested are placed in a beaker over a sheet of white paper, and brought under the 10 c.c. burette, charged with the standard solution of ■argentic nitrate. Two drops of the solution of potassium chromate are then added, and the silver solution is very carefully run in, with constant stirring, until the solution in the beaker just changes from yellow to red. This indi- cates that all the chlorides have been precipitated as argentic chloride. The red-coloured argentic chromate will not form until all the chlorides have been removed ; but whenever this is attained, the least excess of silver solution turns the chromate red. Each c.c. of silver solution used will indicate (if 70 c.c. be taken for analysis) of a grain of chlorine per gallon of water. The solutions, both of argentic nitrate and potassium chromate, must be perfectly neutral. 4. Nitrogen existing as Nitrates and Nitrites is very important, because when sewage decomposes, it produces nitrates as one of the ultimate products of its oxidation. Some waters from chalk soils contain nitrates naturcilly.^ and therefore, taken by themselves, an excess should not condemn a water \ but when coupled with high chlorides and free ammonia and a fair quantity of albuminoid ammonia, they may be taken as an index of previous sewage con- tamination. Such a water should always be examined again after a heavy rainfall, when it is more than probable that active present contamination will be discovered. 100 c.c. of the sample are introduced into the non-tubulated retort with 100 c.c. of the sodium hydrate solution, and the whole is distilled until a phialfiil of the distillate ceases to give a colour with i-| c.c. of Nessler’s solution. (See Mercuric Iodide.) The retort and its contents are allowed to cool, a fragment or two of sheet aluminium is dropped in, and the neck of the retort closed by a cork, through which passes a V shaped tube, filled with fragments of recently ignited clay tobacco pipe, moistened with hydrochloric acid. After standing for the night, during which the nitrates are reduced to POTABLE WATER. ammonia by the nascent hydrogen produced from the aluminium and the sodium hydrate, the retort is once more attached to the condenser, and gently distilled until the distillate comes over free from ammonia. The ammoniacal distillate is then made up to a definite bulk, say 500 c.c., with pure “ ammonia- free ” distilled water, and the ammonia is estimated by Nessler, as hereafter shown. (See No. 8.)' The number of milligrammes of ammonia found is multiplied by 14 and divided by 17, which gives the quantity of nitrogen as nitrates in the 100 c.c. of water examined. This result, multiplied by 10, gives milligrammes per litre, or parts in 1,000,000 parts of water. 5. Free Ammonia is a matter which, when in excess, renders a water ques- tionable, especially if it be accompanied by much nitrogen, as nitrates and high chlorides. Under this head is also included the ammonia derived from some very readily decomposable bodies, such as urea, as well as that really present in the state of ammonium salts. A little distilled water is introduced 'into the tubulated retort, and the condenser having been attached, the heat of a large nakecUBunsen burner is applied, and distillation continued until the distillate no longer gives a colour with Nessler. The retort is then emptied out, and 500 c.c. of the water to be tested is introduced, with 10 c.c. of the solution of sodium carbonate. Distillation is then resumed, and continued until the water comes over ammonia-free by Nessler. The distillate is made up to a known bulk, say 500 c.c., and the number of milligrammes of ammo- nia estimated in it in the usual manner. The result, multiplied by 2, gives milligrammes of free ammonia per litre of water (parts in 1,000,000). 6. Albuminoid Ammonia. When nitrogenous organic bodies are heated with a strongly alkaline solution of potassium permanganate, they undergo a limited oxidation, and a portion of their nitrogen is obtained as ammonia. This yield of ammonia has been found to be fairly constant, and is therefore made the measure of actual present sewage or other active deleterious organic contamination. The residue remaining in the retort, after the estimation of the free ammonia, is treated with 50 c.c. of the permanganate solution, and distillation is resumed and carried on until the distillate comes over ammonia free. The distillate is made up as before to 500 c.c. with pure distilled water, and the ammonia estimated in it by Nessler. The number of milli- grammes thus found, when multiplied by two, gives milligrammes per litre (parts in 1,000,000).* 7. Total Residue. The platinum dish is washed, dried, and heated to red- ness. It is then placed in the air bath at 120° C. for a few minutes ; taken out, and quickly cooled in a desiccator, or by placing it on a thick slab of cold iron. After cooling it is quickly and accurately weighed, and 70 c.c. of the water having been introduced it is placed on the water bath, and evapo- rated to dryness. When dry it is placed in the air bath, heated to 120° C. for an hour, cooled as before, and weighed. It is then returned to the bath for half an hour, cooled, and again weighed j and this is repeated until two successive weighings come out alike. The weight of the empty crucible having been deducted, the difference gives the residue, each milligramme of which represents one grain per gallon. As a specimen of the mode of stating the results of analysis, and also to show the distinctive characters of a good and a bad water, the following two analyses are appended : — * The processes, Nos. 4, 5, and 6, should be all first performed with pure distilled water, and the amount of ammonia found be marked on the solution bottles as a cheeky to be deducted afterwards from the results of each actual analysis. 190 SPECIAL PROCESSES IN ANALYSIS. A Good Ordinary A VERY Bad Water Drinking Water. FROM Kingston. Total residue i8’84 1 Chlorine .... •84 . . 1213 1 , Grains per Total hardness . lO'I • 4o'o 1 f gallon. Permanent hardness 2'I . i8-8 J 1 Nitrogen, as Nitrates, etc. . Free ammonia •82 'OI • 439 ‘ 35 ^ . ' . i-i8 ' Parts per Albuminoid Ammonia .' •08 . . -20^ L 1,000,000. 8. Manufacture and Use of Nessler’s Solution. This solution is thus pre- pared : — 50 grammes of potassium iodide are dissolved in a small quantity of boiling distilled water, in a basin placed on a water bath. Hot saturated solution of mercuric chloride is then added, with constant stirring, until a slight pe 7 'manent red precipitate is produced. The solution thus obtained is filtered and mixed with 200 grammes of potassium hydrate dissolved in the smallest possible quantity of distilled water. When the whole is quite cold, it is made up with cold distilled water to the bulk of one litre ; and 5 c.c. of a cold saturated solution of mercuric chloride having been added, the solution is well shaken, and then left to settle. Lastly, the clear portion is decanted and kept for use. To use the solution we require — 1. A standard solution of ammonium chloride, made by dissolving *315 gramme of the pure and dry salt in a litre of distilled water free from ammo- nia. 2. Two tall cylinders, of clear colourless glass, to contain about 150 c.c. each, and graduated at 100 c.c. ; or a pair of perfectly clear long narrow 4-oz. phials will serve the purpose, which can be graduated by pouring in 100 c.c. of water, and scratching with a file. 3. A pipette graduated to deliver c.c. 4. Some distilled water, perfectly free from ammonia, prepared by redistil- ling ordinary distilled water until a phialful of the distillate ceases to give a colour with i J c.c. of Nessler, and saving the rest of the water remaining in the retort. 5. A sheet of white paper, on a table, placed in a good light near a window without any highly-coloured hangings or decorations. The solution containing the ammonia (usually a distillate in water analysis) is to be diluted to a definite bulk (say 500 c.c.), with the pure water, till it ceases to give any precipitate, but only a colour, with Nessler. One of the cylinders or phials is to be filled to the mark (100 c.c.) with the solution, and 1 1 c.c. of Nessler added by means of the pipette. The colour is to be noted, after five minutes, by lookmg down through the column of liquid held over the white paper. A little (say 2 c.c.) of the standard ammonia is to be added from the burette to the other phial or cylinder, which is to be filled up to the mark with the pure water; and ij c.c. of Nessler having been added, the colour is to be observed as before. If the two colours correspond, the amount of ammonia is equivalent to 2 c.c. of the standard solution. If not, the second phial is to be emptied, and another trial made, with more or less standard ammonia, as the colour produced is fainter or darker than that in the first phial. When by repeated experiment the two colours are obtained exactly equal, then the number of c.c. of ammonium chloride solution used in the final attempt is to be read off and multiplied to the total volume of the water distillate. The amount thus obtained is then calculated from the quantity of water taken for analysis to one litre. CINCHONA ALKALOIDS. 191 II. ANALYSIS OF CINCHONA BARKS. {a) For Quinine only. ' {B.P. Process for Yellow Bark.) Test . — Boil 100 grains of the bark, reduced to very fine powder, for a quarter of an hour in a fluid ounce of distilled water acidulated with ten minims of hydrochloric acid, and allow it to macerate twenty-four hours. Transfer the whole to a small percolator, and after the fluid has ceased to drop add at intervals about an ounce and a half of similarly acidulated water, or until the fluid which passes through is free from colour. Add to the per- colated fluid solution of subacetate of lead, until the whole of the colouring matter has been removed, taking care that the fluid remains acid in reaction. Filter and wash with a little distilled water. To the filtrate add about thirty- five grains of potassium hydrate, or as much as will cause the precipitate which is at first formed to be nearly re-dissolved, and afterwards six fluid drachms of pure ether. Then shake briskly, and, having removed the ether, repeat the process twice with three fluid drachms of ether, or until a drop of the ether employed leaves on evaporation scarcely any perceptible residue. Lastly, evaporate the mixed ethereal solutions in a capsule. The residue, which consists of nearly pure quinine, when dry, should weigh not less than two grains, and should be readily soluble in diluted sulphuric acid. {h) For Mixed Alkaloids. 1 1. In Cincho 7 ia pallida (B.P. process). 200 grains of the bark, treated in the manner directed in the test for yellow cinchona bark, with the substitution of chloroform for ether, should yield not less than one grain of alkaloids. 2. In Cincho 7 ia rubra (B.P. process). 100 grains of the bark, treated in the manner directed in the test for yellow cinchona bark, with the substitution of chloroform for ether, should not yield less than i’5 grain of alkaloids. if) Complete Analysis of Cinchona Bark for Alkaloids. The following is a more complete process than the official one, and has the additional advantage of rapidity when only pursued as far as the obtaining of the total mixed alkaloids. The second part, involving separation, is more tedious. Mix 300 grains of powdered bark, dried at 212° F., with milk of lime (75 grains of slaked lime to 750 grains of water). Dry the mixture slowly and then boil it with 7 fluid ounces of rectified spirit. Pour off the clear liquid ; boil again with half as much more alcohol ; filter, and wash the powder with ounces more alcohol. From the mixed liquors precipitate the calcium as sulphate by a few drops of diluted sulphuric acid. Filter; distil off the spirit, and pour the residual liquid into a capsule, and heat it on a water-bath, until the spirit is wholly expelled. Filter the remaining liquor, which contains all the alkaloids in the form of acid sulphates, and wash the residue (quinovic acid and fatty matter) with water, slightly acidulated with sulphuric acid. The filtrate and washings, reduced to about | fluid ounce, are now treated, while still warm, with caustic soda in slight excess. Wash the precipitate with a very little water ; press it between folds of blotting paper, and dry on a water-bath. The weight, divided by three, gives the percentage of the total alkaloids. Five grammes at least of the residue thus obtained is pulverized, digested in 50 grammes of ether, and filtered, whereby the alkaloids are separated into two groups. 192 SPECIAL PROCESSES IN ANALYSIS. (a) Soluble in ether . . Quinine, Quinicine. (/ 3 ) Insoluble in ether . . Cinchonine, Cinchonidine, and Quinidine. (a) PaN soluble m Ether . — The ether is evaporated, the residue dissolved in lo parts of proof spirit, acidulated with one-twentieth of sulphuric acid, and alcoholic iodine added until a precipitate is no longer formed. The quinine is thus precipitated as herapathite. One part of herapathite washed, and dried at ioo°, represents o’565 parts of pure quinine. The liquid separated from the herapathite is mixed with an alcoholic solution of sulphurous acid, then neutralized with caustic soda, heated on a water-bath to expel alcohol, and mixed with an excess of soda. The precipitate consists of quinicine, with perhaps traces of quinidine and cinchonidine. ip) Part insoliible in Ether . — The insoluble alkaloids are dissolved in 40 parts of hot water with the aid of a little dilute sulphuric acid, the acid being so adjusted that the solution shall preserve a faint alkaline reaction. To this liquid a solution of Rochelle salt is added, and the whole allowed to remain for twelve hours. The cinchonidine will be found separated as tartrate, which may be. collected and dried at 100°. One part of this tartrate represents o’8o 4 parts of cinchonidine. The filtrate is mixed with a solution of potas- sium iodide, which precipitates- the quinidine as a sandy crystalline powder, provided that the quinidine be not very small in quantity relatively to the cinchonine ; otherwise the preciptitate is often resinous. One part of the hydriodide dried at 100° represents 0718 parts of anhydrous quinidine. The liquid separated from the quinidine is precipitated by caustic soda whereby the cinchonine is obtained; it is collected and dried as in the previous instances. III. VALUATION OF A SAMPLE OF OPIUM. This is dependent on the amount of morphine it contains, and is conducted according to the B.P. process as follows : — Take of opium 100 grains, slaked lime too grains, distilled water 4 ounces. Break down the opium, and steep it in an ounce of the water for twenty-four hours, stirring the mixture frequently. Transfer it to a dis- placement apparatus, and pour on the remainder of the water in successive portions, so as to exhaust the opium by percolation. To the infusion thus obtained, placed in a flask, add the lime, boil for ten minutes, place the un- dissolved matter on a filter, and wash it with an ounce of boiling water. Acidulate the filtered fluid slightly with diluted hydrochloric acid, evaporate it to the bulk of half an ounce, and let it cool. Neutralize cautiously with solu- tion of ammonia, carefully avoiding an excess ; remove by filtration the brown matter which separates, wash it with an ounce of hot water, mix the washings with the filtrate, concentrate the whole to the bulk of half an ounce, and add now solution of ammonia in slight excess. After twenty-four hours collect the precipitated morphia on a weighed filter, wash it with cold water, and dry it at 212°. It ought to weigh at least from 6 to 8 grains. In addition to this official process several others have been proposed, but none without a drawback of some kind. The following is good, if carefully performed : — Take 100 grains of opium, previously dried at 212° F., rub it in- timately with three times its weight of coarsely-powdered pumice-stone, and percolate with boiling ether to remove narcotine, colouring matter, and wax. Just moisten with a little spirit, and then extract with water slightly acidulated with acetic acid. The amount of water employed should not, if possible, exceed 5 ounces. Ammonia is now added in the slightest possible excess, and the whole set aside for forty-eight hours, when the morphia will be deposited in crystals on the sides of the glass. The mother liquor is to be poured away, the EMETINE-ELATERIN—SCAMMONY RESIN. 193 morphia purified by re-crystallization from boiling alcohol, and the crystals dried and weighed. In addition to the assay for morphia, the amount of water should always be determined in a sample of opium, by taking a weighed portion of thin slices, and drying over the water-bath until it ceases to lose weight. Besides these points, the dried opium should be exhausted with cold water, and the residue collected on a weighed filter, and again dried at 212° F. The amount of this residue should not exceed 45 per cent. The addition of gum arabic may be detected by precipitating a solution of opium with normal plumbic acetate, concentrating the filtrate to a low bulk, and precipitating out the gum arabic with alcohol. Genuine opium should contain no starch or tannic acid. Lastly, a portion of opium dried at 212° should be weighed and freely incine- rated, when the amount of ash left should not exceed 8 per cent. IV. ESTIMATION OF EMETINE IN IPECACUANHA Is very readily performed by volumetric analysis as follows, using a standard solution of mercuric iodide in excess of potassium iodide : — The test solution is prepared by dissolving 135 "46 grains of pure mercuric chloride and 498 grains of potassium iodide in 10,000 grains of water. Each decern (10 fluid grains) of this solution will precipitate o i oo of the molecular weight of emetine, and is thus applied : — 150 grains of ipecacuanha are treated with 15 drops of dilute sulphuric acid, and sufficient rectified spirit of wine added to make the whole bulk up to 1500 grains. The whole is allowed to stand for 24 hours, and 1000 grains are decanted off for analysis. The liquid is evaporated until all the alcohol is driven off, and then brought under the burette containing the test solution, which is run in until it ceases to give a precipitate. The final point of the reaction is ascertained by filtering off a drop or two into a watch-glass placed on black paper, and adding a drop of the reagent, when, if no cloudiness appear, the precipitation of the alkaloid is complete. The number of grain- measures of the test used multiplied by '0189 gives the amount of alkaloid in 1 00 grains of the sample. V. ESTIMATION OF ELATERIN IN ELATERIUM. (a) B.P. Process . — Boil 25 grains of elaterium with rectified spirit until ex- hausted, and filter. Concentrate the solution to a low bulk, and pour it into an excess of warm liquor potassce. When quite cold, filter out the crystals of elaterin which have formed, dry, and weigh, when at least 5 grains should result (20 per cent.). ip) Improved Process . — Exhaust i gramme of elaterium by percolation with chloroform in a small funnel tube, and then add to the solution an excess of ether. Allow the whole to settle, pour off as completely as possible from the crystals of elaterin, and wash them by decantation with pure ether, collect, dry at a very gentle heat, and weigh. VI. ESTIMATION OF SCAMMONY RESIN IN SCAMMONIUM. Take 25 grains (or 2 grammes) and dry in a water-bath until the weight is constant (loss of weight = moisture). Place the dried residue on a weighed filter in a small funnel, and percolate with ether until a portion of the ether on evaporation leaves no residue. Dry the filter and its contents at 212°, and weigh and deduct the weight of the filter. Then deduct the weight of the in- soluble matter thus obtained from that of the dried residue, and the difference VOL. II. o 194 SPECIAL PROCESSES IN ANALYSIS. is scammony resin. The residue is to be then examined for starch and mineral matter. VII. ESTIMATION OF THE ALCOHOLIC STRENGTH OF SPIRITS, WINES, AND TINCTURES. If the sample be simply a dilute spirit which leaves no residue upon evapo- ration, the percentage may be ascertained by taking the specific gravity, thus : A flask is taken, capable of holding exactly looo grains of distilled water at 6o° F., and after being carefully and exactly counterpoised in a balance, is filled with the spirit previously brought to a temperature of 6o° F. If a spe- cific gravity bottle, as generally used in analysis, be employed, it must be filled perfectly, and when inserting the stopper, it should be allowed to sink by its own weight ; then, after careful examination to see that no air bubbles remain, the flask is wiped dry and the weight taken. Immediately this is done, the temperatilre of the contents must be determined, and if not 6o° F.j the flask must be refilled, placed in a vessel of water at 6o° F. for a few minutes, the stopper inserted, and the weight of the dried flask and contents determined as before. When the weight at 6o° F. is known, reference is made to the following table, to ascertain the corresponding percentage of alcohol. In taking such specific gravities it is of great importance to perform tlie operation say three times, and take the average of the three determinations, as a very small error makes a great difference in the commercial value of the sample under examination. If the sample be a wine or tincture containing matters in solution, the fol- lowing course must be adopted : — 2000 grains must be weighed out, rendered neutral by sodium carbonate, if acid, and immediately transferred to a retort. This must be adapted (in any convenient manner so as to render the joint air-tight) to a Liebig’s condenser, and the heat of a water-bath being applied, the spirit distilled over into a previously weighed flask, the condenser being kept cool by a constant slow stream of cold water passing through it. When about nine-tenths of the liquid in the retort have distilled over, the flask and contents are weighed, and the weight of the flask deducted. The temperature of the spirit having been rendered correct (60° F.), the specific gravity must be determined as above. The corresponding percentage of alcohol having been ascertained from the tables, the calculation is as follows : — Percentage of alcohol in distillate x weight of distillate 2000 percentage by weight of alco- hol in sample. Example. — 2000 grains of sherry {vmtim Xericuni) taken and distilled. The distillate weighed 1772*8 grains, and the specific gravity was *9711, an- swering to 20*4 per cent, by weight of alcohol. 1772*8 X 20*4 _ I 18*08 per cent, of absolute alcohol by weight in 2000 C sample, which is too high for a natural sherry. Then, PERCENTAGE WEIGHT OF ALCOHOL. 195 Table of the Proportion by Weight of Absolute or Real Alcohol in 100 parts of Spirits of different Specific Gravities (Fownes). Sp. Gr. at 60“ F. bs's'’ c.) ! Per- centage OF REAL i Alcohol. i Sp, Gr. at 6o° F. (15-5° C.) Per- centage OF REAL Alcohol. Sp. Gr. at 6o“ F. (15-5° C.) Per- centage OF REAL Alcohol. 0-9991 0-5 O-951I 34 0-8769 68 0-9981 I 0-9490 35 0-8745 69 0-9965 2 0-9470 36 0-8721 70 0-9947 3 0-9452 37 0-8696 71 0-9930 4 0-9434 38 0-8672 72 0-9914 5 0-9416 39 0-8649 73 0-9898 6 0-9396 40 0-8625 74 0-9884 7 0-9376 41 0-8603 75 0-9869 8 0-9356 42 0-8581 76 0-9855 9 0-9335 43 0-8557 77 0-9841 10 0-9314 44 0-8533 78 0-9828 II 0-9292 45 0-8508 79 0-9815 12 0-9270 46 0-8483 80 0-9802 13 0-9249 47 0-8459 81 0-9789 14 0-9228 48 0-8434 82 0-9778 15 0-9206 49 0-8408 83 0-9766 16 0-9184 50 0-8382 84 0-9753 17 0-9160 51 0-8357 85 0-9741 18 0-9135 52 0-8331 86 0-9728 19 0-9113 53 0-8305 87 0-9716 20 0-9090 54 0-8279 88 0-9704 21 0 -9069 55 0-8254 89 0-9691 22 0-9047 56 0-8228 90 0-9678 23 0-9025 57 0-8199 91 0-9665 24 0-9001 58 0-8172 92 0-9652 25 0-8979 59 0-8145 93 0-9638 26 0-8956 60 O-8118 94 0-9623 27 0-8932 61 0-8089 95 0-9609 28 0-8908 62 0-8061 96 0-9593 29 0-8886 63 0-8031 97 0-9578 30 0-8863 64 o’8ooi 98 0-9560 31 0-8840 65 0-7969 99 0-9544 32 0-8816 66 0-7938 100 0-9528 33 0-8793 67 VIII. EXAMINATION OF A TINCTURE FOR THE PRESENCE OF METHYLATED SPIRIT. The process usually adopted by pharmacists' is that proposed by Mr. Miller. , For the purpose of testing tinctures, they must first be distilled until the greater part of the spirit has passed over. The distillate is treated as follows : — A small flask is fitted with a cork and a tube having two right angular bends, and in it is put, — 1. About half a drachm of the spirituous liquid required to be tested. 2. An equal quantity of potassium dichromate, and of pure sulphuric acid. 3. Four or five times as much water. The mixture, after standing for twenty minutes, is distilled at a gentle heat, until nearly the whole has passed over. Sodium carbonate having been added to the distillate till it is slightly alkaline, the liquid is evaporated in a porce- lain basin to about half its bulk, and having been acidulated slightly by acetic acid, is transferred to a test-tube, heated gently with twenty drops of a five per 96 SPECIAL PROCESSES IN ANALYSIS. cent, solution of argentic nitrate for a fe\y minutes, when any decided opacity (due to the discoloration of the fluid and the separation of a blackish precipi- tate of metallic silver), indicates the presence of methyl hydrate in the sample thus tested. In the oxidation of ordinary alcohol a mere trace of formic acid is formed by secondary decomposition, consequently a distinct precipitate must be obtained before the spirit can, with certainty, be pronounced to be methylated. The operation of the above process depends on the fact that by oxidation with sulphuric and potassium dichromate, aldehyds and acids are produced, which, by being boiled with sodium carbonate, yield sodium acetate and formate, the former from the ordinary “ alcohol and the latter from the wood spirit. Upon the addition of argentic nitrate, argentic formate is produced, which is easily reduced by boiling to metallic silver, while argentic acetate is not so affected. When this process has to be applied to sweet spirit of nitre, the ethyl nitrite must be first got rid of, as follows : — Take a little of the spirit and place it in a bottle with some dry potassium carbonate, and shake up. Let it settle, and take about two drachms of the strong spirit which separates. Saturate this with calcium chloride, and distil on a water-bath, rejecting the distillate (ethyl nitrite, etc.). Add a little water to the contents of the retort and distil again, when the pure spirit will come over, and a portion may then be tested as above directed. IX. ESTIMATION OF FREE SULPHURIC ACID IN VINEGAR. (a) B.P. Process . ten minims of solution of barium chloride be added to a fluid ounce of the vinegar, and the precipitate, if any, be separated by filtration, a further addition of the test will give no precipitate (absence of more than per cent, of sulphuric acid). {b) Improved Method . — The official test given above is entirely valueless in the case of vinegars containing much sulphate, from being made with water rich in that ingredient ; it is therefore necessary, if the vinegar appear to be adulterated when thus tried, to proceed as follows : 50 c.c. of the vinegar are mixed with 25 c.c. of volumetric solution of sodium hydrate, made decinormal by diluting the official volumetric solution to ten times its bulk with water. The whole is evaporated to dryness, and incinerated at the lowest possible temperature. 25 c.c. of decinormal solution of sulphuric acid (made to exactly balance the sodium hydrate solution) are nbw added to the ash, the liquid heated to expel COg, and filtered. The filter is washed with hot water, and the washings having been added to the filtrate, litmus solution is added, and the amount of free acid ascertained by running in decinormal soda from a burette. The number of c.c. of soda thus used multiplied by ’0049 gives the amount of free sulphuric acid in the vinegar. This process depends on the fact that whenever the ash of vinegar has not an alkaline reaction^ free 7 nineral acid was undoubtedly added. X. ANALYSIS OF URINE. The following are the chief points on which information is usually required by the physician who submits a urine for examination to a chemist ; — 1. Take the specific gravity, which should range from I’oi^ to 1*025 at6o°F. Note . — In diabetes the gravity is too high, sometimes reaching i*o6o, while in albuminuria it is abnormally low, even occasionally falling to 1*005. 2. Examine the reaction, which should be very faintly acid. URINE ANALYSIS. 197 3. Set a portion to settle in a long glass, and examine the deposit under the microscope for calcium oxalate or phosphate, uric acid or urates, pus, casts of kidney tubes, etc., etc. Nofe. — The nature of the deposit may also be confirmed chemically as follows : — (a) Warm the urine containing the sediment, when, if the latter should dissolve, it consists entirely of urates. In this case let it once more crystallize out, and examine it by the ordinary course for Ca, Na, and NH4, to ascertain the bases. (R) If the deposit be not dissolved by heating, let it settle, wash once , by decantation with cold water, and warm with acetic acid. Phosphates will dissolve, and may be reprecipitated from the solution by excess of NH^HO, filtered out, well washed with boiling HgO, dissolved in HC2H3O3 'and examined for Ca or Mg by the usual course for these metals in presence of PO4. {c) If the deposit be insoluble in acetic acid, warm it with HCl. Any soluble portion is calcium oxalate, which may be reprecipitated by NH4HO. {d) If the deposit be insoluble in HCl it is probably uric acid. In this case apply the murexid test as follows. Place it in a small white dish, remove moisture by means of a piece of bibulous paper, add a drop or two of strong HNO3 and evaporate to dryness at a gentle heat. When cold add a drop of NH4HO, which will produce a purple colour deepened to violet by a drop of KHO. 4. Test for albumen, as follows : — {a) Take a drachm of the urine and add from 10 to 15 drops of strong 'nitric acid, when any albumen present will be coagulated, and form a distinct cloud. (JI) MillofCs Mercurial Colour Test. — Take equal parts by weight of Hg and strong HNOg and dissolve by gentle heat, adding after- wards 2 parts of hot HgO. Set the whole aside to crystallize, pour off the mother liquor and keep it for use. The solution added to albuminous urine turns it red, and the colour deepens by warming nearly to boiling. {c) Bodeker's Method. — Take a drachm of the urine, acidulate it with acetic acid, and add some potassium ferrocyanide drop by drop till a clear excess has been added. If during the addition a precipitate forms, albumen is to be suspected. Note.— Of these three methods, {a) is decidedly the most reliable. - {d) If the result of {a) shows the presence of albumen, take a weighed quantity of the urine, and allow it to drop into boiling water acidulated with acetic acid. Collect the precipitate on a tared • filter, wash with boiling water, dry at 2 1 2°, weigh, and deduct the weight of the filter, when the balance = albumen in the weight of urine operated upon. 5. Test for grape sugar, as follows : — {a) Moore's -Acidulate with acetic acid, boil, and filter out any albumen if necessary. Then mix the filtrate with equal parts of liquor potassce and heat to boiling, when ordinary urine will turn brownish-red, but saccharine urine will become dark brown or black. {b) Trommer's Test. — Add to some urine in a test-tube 5 to 10 drops of solution of cupric sulphate (gr. x. in ^i.), then add solution of 198 SPECIAL PROCESSES IN ANALYSIS. KHO until the precipitate first formed is redissolved. Slowly heat the solution till nearly boiling, when, if sugar be present, a brick-red precipitate of cuprous oxide forms. (c) Fehlin^s Test. — Render the urine alkaline with potassium hydrate, and filter to remove any phosphates, etc., which may precipitate. Boil the filtrate with Fehling’s solution of copper (see page 159), and if a red precipitate should form, sugar is present. {a) If the presence of sugar be thus ascertained, estimate its amount by taking 10 grammes of the urine and diluting it with water to 100 c.c. Place this solution into a burette, and run it gradually into 10 c.c. of Fehling’s solution, kept boiling in a basin as directed under the volumetric analysis of sugar, page 160. The number of c.c. of urine used will contain *oi of grape sugar, and then = sugar in the 10 grammes of urine taken, c.c. used 6. Test for Bile, as follows : — (a) Gmelm's Test for Bile Pigments. — Place a drachm of nitric acid in a test-tube and cautiously pour upon it an equal volume of the urine. In the presence of bile a play of colours from green to violet, blue, and red will be observed where the liquids touch. {b) Pettenkofer's Test for Biliary Acids. — Mix equal parts of urine and sulphuric acid, add one drop of saturated syrup, and apply a • gentle heat. If biliary acids be present, the colour will change from cherry-red to deep purple. Note. — Bilious urine is usually of a brownish-green colour. 7. Test for Urea, as follows : — , (a) Separate any albumen (as directed in Moore’s test) if necessary, and evaporate an ounce of the urine to a syrupy consistence on the water-bath. When cold add nitric acid, drop by drop, till crystals of nitrate of urea cease to deposit. (d) Estimate the amount of urea by mercuric nitrate as directed at page 160, or, if inconvenient, ascertain roughly whether the urea is in excess as follows : Take a drop of the clear urine, place it on a glass slide, add a drop of nitric acid, and place under the microscope. If flat rhombic or hexagonal plates of nitrate of urea be thus formed, without concentration of the urine, then the urea is in excess of the natural amount. 8. Test for Uric Acid by mixing one ounce of the urine with one drachm ot hydrochloric acid in a beaker, and set aside for some hours. The uric acid will be deposited in reddish-brown crystals, which may, if desired, be weighed and proved by the mui'exid test (page 197.) ' 9. Test for Phosphates, as follows : — , {a) Add to one ounce of the urine a slight excess of ammonium hydrate, and boil. Ca32P04 and MgNH^PO^ will both be precipitated, and the precipitate, if more than a distinct cloud, should be filtered out, dissolved in HCl, and analyzed by the ordinary process already given for phosphates. {b) After filtering out the earthy phosphates as above, alkaline phos- phates may be tested for by adding magnesia mixture to the filtrate and getting the usual precipitate of MgNH4P04 after standing some hours in a cold place. This may be estimated if required as usual. URINARY CALCULI. 199 10. Test for Sulphates, as follows : — Acidulate a weighed quantity of the urine with HCl, warm, and add excess of BaClg. If the precipitate appear too copious, estimate as usual. ' II. Test for Chlorides^, as follows : — Acidulate a little of the urine with HNO3 and add excess of argentic nitrate. If the precipitate thus produced looks very large, a weighed quantity of the urine should be mixed with some potassium nitrate, evaporated to dryness, and fused. The residue is then to be dissolved in water and the chlorine estimated volumetrically by argentic nitrate with potassium chromate as the indicator. 12. Blood is best seen under the microscope ; but urine containing it has always a very characteristic smoky appearance. A test for blood is to add tincture of guaiacum and ethereal solution of hydrogen peroxide, which pro- duce a sapphire blue ; but such colour of itself should not be taken as positive proof without the blood discs being also visible under the microscope. XI. ANALYSIS OF URINARY CALCULI. The following table will show at a glance the composition and methods of proving the various calculi. I. Calculi, fragments of which, heated to redness on platinum, entirely hum away. Name. Physical Characters. Chemical Characters. Uric Acid C5N4H4O3 Brownish-red ; smooth or tuberculated ; concentric laminae Insoluble in water ; soluble in KHO by heat, but evolves no NH3 ; Dis- solves with effervescence in HNO3 (common) and the residue on evaporating the solution is red and gives the murexici test. Ammonium Urate C lay -coloured ; usually smooth, and rarely with fine concentric laminae (uncommon) Soluble in hot water ; soluble in heated KHO, evolving NH3. Behaves with HNO3 like uric acid. Cystine C3H7NSO2 Brownish-yellow, semi-transparent and crystalline (very uncommon) Insoluble in H2O, alcohol, and ether. Soluble in NH4HO and depositing, when allowed to evaporate spon- taneously, hexagonal plates. When heated, gives off odour of CS2. Xanthin C5H4N4O0 Pale polished brown surface (very uncommon) Soluble in KHO; soluble in HNO3 'without effervesceiice, and the solu- tion leaves on evaporation a deep yellow residue. 200 SPECIAL PROCESSES IN ANALYSIS. II. Calculi, fragments of which, heated to redness on platinum, do not burn away. Name. Physical Characters. Chemical Characters. Calcium Oxalate, mulberry calculus, CaC 204 Tricalcium Phosphate, hone-ea 7 'th calculus, Ca 2 P 04 Magnesium Ammo- nium Phosphate, triple phosphate cal- culus, MgNH4P04 Mixed Phosphates of Ca, Mg, and NH4, fusible calculus Deep brown, hard and rough ; thick layers (common) Pale brown, with regu- lar lamince (uncom- mon) White, brittle, crys- talline, with an un- even and not usually laminated surface (uncommon) White, and rarely laminated Insoluble in acetic acid, but soluble without effervescence in HCl ; heated to redness, it is converted into CaCOg which dissolves with effervescence in acetic acid, and the solution gives a white precipitate with(NH4)2C204. Heated strongly before the blow-pipe, CaO remains, which, when moistened, is alkaline to test-paper. Infusible before the blow-pipe, and residue, when moistened, is not al- kaline. Soluble in HCl, and the solution gives a gelatinous precipi- tate with excess of NH4HO. Fusible with difficulty before the blow-pipe, evolving NH3, and re- sidue not alkaline. Soluble in HCl, and solution gives white crystalline precipitate with NH4HO. Readily fusible before the blow-pipe. Soluble in acetic acid, and solution gives a white precipitate with (NH4)2C204, and the filtrate from that precipitate gives a white pre- cipitate with excess of NH4HO. APPENDIX. WEIGHTS AND MEASURES OP THE METRICAL SYSTEM. From the British Pharmacopoeia 1867. 'Weights. I Milligramme = the thousandth part of one gramme, or o'ooi gramme. I Centigramme = the hundredth ,, o'oi „ I Decigramme = the tenth . ot ,, I Gramme . = weight of a cubic centimetre of water at 4°C. I'o ,, I Decagramme = ten grammes lo'o „ I Hectogramme = one hundred grammes loo'o „ I Kilogramme = one thousand grammes looo o (i kilo.). Measures of Capacity. I cubic centimetre, or the measure of i gramme of water. I Millilitre = I Centilitre = 10 I Decilitre = 100 I Litre . = 1000 10 100 1000 (i kilo.), Measures of Length. I Millimetre = the thousandth part of one metre or, o’ooi metre. I Centimetre = the hundredth „ - o-oi „ I Decimetre = the tenth „ o'l ,, I Metre . •= the tenth-millionth part of a quarter of the meridian of the earth. WEIGHTS AND MEASURES OF THE BRITISH 1867. Weights. PHARMACOPCEIA OF I Grain gr. I Ounce oz. I Pound lb. Minim Fluid Drachm Fluid Ounce Pint Gallon 437‘5 grams. 16 ounces — 7000 ,, Measures of Capacity, min. fl. drm. = 60 minims, fl. oz. = 8 fluid drachms. O. — 20 fluid ounces. C. =8 pints. I Line = I Inch = 12 36 yV inch. 1 391393 I foot. Measures of Length, seconds-pendulum. I yard. = 3 feet Length of pendulum vibrating seconds of mean time in the ) . . , , latitude of London, in a vacuum at the level of the sea. f incies. (i cubic inch of distilled water at 62° F. and 30 inch Barom. - 252*458 grains.) Relations of Measures to Weights. I Minim is the measure of 0*91 grain of water. „ 54'68 grains of water. „ I ounce, or 437*5 „ 1*25 pound, or 8750*0 ,, 10 pounds, or 70,000*0 ,, I Fluid Drachm I Fluid Ounce I Pint I Gallon 1 w cc W 03 <1 w CO M w p s Jzj P P=< P=< o JZi o 03 M P^ P O O O w h-i o lD w p^ 1:3 (n < W c/T VO M M 00 ■'d- T}- ^ . 0 VO . ON 0 0 CO CN CO I'' 0 On 0 p CO CN p 0 5 > b *0 Vo *CN ro *0 V^ W rH CO (ON CO 0 ri CO (ON CO hH CO On CO CO (ON CO - s O ^ *5 S "S o (L> UQ ON T}- 10 -V}- ON ON ON J>. ro ^ o CNI Vo 11 II rC! o .S tin . . 0 ) iP o ^ p £ _ ^ g 2 a g'§--S 4 i B.-S'^ lOQgQdt^S ii ^ IB g ^ ,f= w VO i_i fvj M OC lOvO Cs c^^voM w Ooo -^vn Mf^lOM M ooo o N t^VOM M ooo r^ m O (M O O O O O O OJ O M M O M CO r— vn Cnvo "O r^sO o o O O vO t^vo o^o >0 On VO "O CTnVO O On O O O p o o M N o M OJ OJ NO M CO ?>. CO Th M t^NO. o 3>- !>■ CO M I_l t^NO O CO o M 4>. CO O CO p p M i>. vp p p- b b b vH t^NO b i>- r^vo O M r^NO 1-4 !>. VO CO M t^vo 00 M ro CO hh NO uooO CO lO CO i-i NO 1-000 o o o ooo CO »0 CO t-i NO O ^ VO CO M b O CO VO CO CO VO CO CH to CNi VO M O M M O NO M O VO M VO M !>. O VO c-l O M O VO o vp M O CNJ O boo M b b vD CH o N NO M O NO c-l O M -a as I -o O "S a c ^ c: o.y CJ ■ ^ O ‘^•§3 O o ^ 'I 2 8 U M tn O .r P cl *o ! UQ o c (U ^ .y ^ V 4 -o V, O C3 O ^ U (U ^ a o o 03 cci ?-i C o v(U 0) iq Q K a) 5_ o r. G3 O) o Vx ^cu X) O o •’&: >N Ph CO VO CO CO 'Cj- vo NO NO oo CO o f—t H > fl4 O cn W py cn < W o c '-' b/) r o i2 4 > CO sr CD o >P O •s o bJD w c O o M o 00 N M O o o M ON CO N o o o o o On 00 o o o o o O ON 00 o o o o o o o On o o o o o o o O p p p p p p p p c b b b b b b b o N o t^co M N o o N ON NO 00 1— 1 o o O M ON NO CO o o o o 1— 1 O'. NO 00 o o o o o 1— 1 ON NO o o o o o o 1— 1 ON p p o p p p p l-X b b b b b b b b N o VO NO N M CO NO N N O NO N M N O N N o NO N hX o O N N o NO N o o O N N o 'ch NO o o O O N N o p p p o P N N P b b b b b b N N M M voM CO CON cX VOO r^NNO OCONMVOOt^N o o CON MVoOt^ OOOcONhhVOO OOOOconmvo O O O O CO N M CO'.N CO N coo C\CO O O ■Cf CO N CO rtco 00 O VO -ct- co B S • a a ^ I § cj ^ bX) cj ^5 ^.2 u U o vP o N ^cjqSq o oo b VO cj Vx bO NO ON 'Cf CO O i 56 , 178. „ anhydrous, 156. „ aromat, 155. „ dil., 155. „ free, 196. Sulphurous, 57, 98. „ estimation, lo. Tannic, 81. Tartaric, 77, 109, 155, 156, 180. Thiocyanic, 65. Thiosulphuric, 57. Uric, 198. Valerianic, 75. Acids, biliary, 198. Free, estimation, 155. Mineral, 144. Acidulous radicals, 49-81, 130-13 7. Gravimetric estimation, 176-180. Acidum aceticum, 106. ,, dil., 10. „ glacial e., 10. Arseniosum, 105. Carbolicum, 10. Citricum, no. Hydrochloricum, 10, 82. „ dil., 10. , Hydrocyanicum, 10. „ dilutum, 103. Nitricurn, 10, loi. „ , dil., 10. Nitro-hydrochloricum, dilutum 10, lOT. Oxalicum, 108. Phosphoricum, dilutum, 104. Sulphuricum, 10, 99. „ aromat., 10. „ dil., 10 Sulphurosum, 10, 98. Tartaricum, 109. Aconitia (aconitine), 142, 148. Adulterations, quinine, 139. yEther, purus, 10. ^theris nitrosi spiritus, 10. Spiritus, 10. Albumen (urine), 197. Albuminoid ammonia, 189. Albuminuria, 196. Alcohol amylicum, 10. Percentage, Fownes, 195. Rectified, 7. Thermometers, 4. Alcoholio strength, 194. Alkaline carbonates, estimation, 154. Hydrates, estimation, i^-?. Nitrates, 178. Phosphates, 179. 'Alkaloid table, Brunner, 147, 148. Alkaloids, mixed, 191, 143. Alkaloids, official, detection, 138, 142. Poisonous, 147. Alum, 18. Alumen, 100. Aluminic oxide, 172. Aluminium, 39. Dry reaction, 39. Estimation, 172. Separation, 39. Wet reactions, 39. Ammonia, albuminoid, 189. Conversion, 178. Free, 189. Ammonise carbonas, 94, 154. Liquor, 10, 88, 154. „ fort, 154. Phosphas, 104. Spiritus aromaticus, 10. Ammoniatum hydrargyrum, 84. Ammonii bromidum, 88. Chloridum, 82. Ammonium, 48. Dry reactions, 48. Estimation, 176. Separation, 48. Solubility, 137. Wet reactions, 48. Ammonium Bromide, 88. Carbonate, 94, Chloride, 82. Ferric citrate, in. Hydrate, 88. Oxalate, 108. Platino- chloride, 176. Sulphydrate, 145. Ammonium-aluminium sulphate, 100. Ammonium, quinine, and ferrous ferric citrates, 112. Amorphous phosphorus, 67. Analysis, cinchona barks, 191. Qualitative, 82-137. Quantitative, gravimetric, 163- 180. ,, volumetric, 150- 162. Special processes, 186-200. Spectrum, 19. Toxicological, 114-149. INDEX. 203 Analysis, ultimate organic, 181-185. Urinary calculi, 199, 200. Urine, 196-199. Volumetric, Sutton, 161. Analyzer, 22. Aneroid barometer, 14. Aniline, 138. Antimonic acid, 73. Antimonii chloridi liquor, 10. Chloridum, 85. Oxidum, 93, Antimonious antimonic oxide, 169. Antimonious chloride, 85. Oxide, 93. Sulphide, 98. Antimonium sulphuratum, 98. Tartaratum, no. Antimony, 34, 144. Dry reaction, 34. Estimation, 169. . Separation, 34. Solubility, 136. Stain, 145. , Wet reactions, 34. Apparatus, volumetric, 150. Argenti oxidum, 90. Argentic chloride, 165. Nitrate, loi. „ standard solution, 152. Sulphate, 135. Arseniate, separation from phosphate, . 72 - Arseniate, ferrous, 106. Of soda, estimation, 157. Arseniates, 71, 72, 105, 134, 179. Arsenic, 33, 144, 145. Dry reaction, 33. Estimation, 170. Separation, 34. ' Stain, 145. Wet reactions, 33. Arsenic acid, 69, 71, 179. Arsenicalis liquor, 10. Arsenic! liquor hydrochloricus, 10. Arsenious acid, 71, 105. Estimation, 157. Sulphide, 170. Arsenites, 71, 105. Atmospheric pressure, 13. Atropia (atropine), 141, 142, 143, 148. Aurantii syrupus, 10. Auric chloride, 180. Available chlorine, estimation, 158. Axes (crystalline), 18. B. Balance, the, 8. Barium, 43. Dry reaction, 44. Estimation, 173. Separation, 44. Solubility, 137. Wet reactions, 43. Barium sulphate, 173, 178. Bark, yellow, 191. Barks, cinchona analysis, 191. Barometer, 13, 14. Aneroid, 14. Barometrical pressure, 7. Bath, steam, 7. Battery, the, 22. Beads, specific gravity, ii. Beberia (beberine), 142. Beberiae sulphas, 112. Benzoates, 79, 80, 131, 135. Benzoic acid, 79, 135. Bicarbonate sodium, 95. Bichromate potassium, 94. Bile (urine), 198. Biliary acids, 198. Bismuth, 30. Dry reaction, 31. Estimation, 168. Separation, 31. Solubility, 136. Wet reactions, 30. Bismuth and ammonium citrate, in. Oxide, 168. Sulphide, 168. Bismuth! et ammoniae citratis liquor, 10, III. Oxidum, 93. Subcarbonas, 97. Subnitras, 102. Bismuthic oxynitrate, 102. Bismuthyl carbonate, 97. Nitrate, 102. Blood (urine), 199. Blowpipe, 23, 24. Supports, 24. Bodeker’s test (urine), 197. Bodies, amorphous, 17. Crystalline, 1 7. Isomorphous, 18. Polymorphous, 17. Boiling point, 7. Mercury, 4. Water, 4. Boracic acid, 59. Borax, 18, 106, 155. 204 INDEX. Borates, 59, 60, 106, 134. Boric acid, 59. B.P. volumetric solution, oxalic acid, 162. Bromates, 52, 130. Bromic acid, 52. Bromide ammonium, 88. Potassium, 18, 87. Bromides, 51, 87, 88, 130, T33, 176. Estimation, 156. Insoluble, 51. Separation of from nitrates, 63. , With iodides, detection of, 53. Bromidum ammonii, 88. Potassii, 87. Bromine, 10, 51. Estimation, 177. Vapour, 145. Brown lead, 93. Brucia (brucine), 141, 143, 148. Brunner’s alkaloid table, 147, 148. Bunsen burner, 20, 25. Burette, 15 1. C. Cadmii iodidum, 86. Cadmium, 32. Dry reaction, 32. Estimation, 167. Separation, 132. Solubility, 136. Wet. reactions, 32. Cadmium iodide, 86. Oxide, 167. Sulphide, 167. Calcic carbonate, 180. Oxide, 180. Calcii chloridum, 83. Phosphas, 105. Calcis carbonas precipitata, 96. Chloratae liquor, 10. Hydras, 89. Hypophosphis, 104. Liquor, 89, 154. „ sacchar., 154. Sulphas, 99. Calcium, 45. Dry reaction, 45. Estimation, 173. Separation, 45. Solubility, 137. Wet reactions, 45. Calcium carbonate, 173, 174. „ precipitated, 96. Chloride, 83. Calcium hypophosphite, 104. Oxide, I, 90, i 73 >'a 74 - Phosphate, 105. Sulphate, 99. Calculation (volumetric), 152. Calculi, urinary, analysis, 199, 200. Calorescence, 20. Calorimeter, 5. Calx, 90. Chlorata, 85. „ solution, 145. Cane sugar, 18. Carbolates, 79, 131, 135. Carbolic acid, 79. Detection of, 80. Carbon, 59. Estimation, 181, 182, Carbonate ammonium, 94. Bismuthyl, 97. Calcium, 173, 174, 180. „ precipitated, 96. Ferrous, 96. Lithium, 94. Potassium, 95. Sodium, 18, 95. Strontium, 174. Carbonates, 59, 94-97, 130. Alkaline, estimation, 154. Carbonic acid, 59. . Anhydride, 59. Cell, voltaic, 22. Galvanic, 22. Celsius thermometer, 3. Centigrade thermometer, 3. Centigramme, 8. Centilitre, 8. Centimetre, 8. Centi-normal solution, 150. Cerii oxalas, 108. Cerium, 38. Dry reactions, 38. Separation, 39. Solubility, 137. Wet reactions, 38. Cerium oxalate, 108. Chemical processes, 1-25. Chlorate potassium, 85. Chlorates, 50, 85, 131. Chlori liquor, 10. Chloric acid, 50. Chloride ammonium, 82. Antimonious, 85. Argentic, 165. Auric, 180. Calcium, 83. INDEX. 205 Chloride, ferric, 84. Mercur-ammonium, 84. M erotic, 83. Mercurous, 83, 166. Palladious, 52. Platinic, 84. Sodium, 18, 83, 176. Stannous, 84. Zinc, 83. Chlorides, 49, 82-85, 13 1, 133. Estimation, 156. Separation of, 50, 53. Insoluble, 50. Chlorides (urine), 199. With bromides, detection of, 51. With iodides, detection of, 53. Chloridum antimonii, 85. Calcii, 83. Hydrargyri, 83. Sodii, 83, Zinci, 83. Chlorinated lime, 85. Soda, 85. Chlorine, 49. Estimation, 177, 184. Available, estimation, 158. Chlorine as chlorides (water), 188. Chlorites, 50. Separation of, 50. Chloroform, 7, 10. Chloroform! spiritus, 10. Chlorous acid, 50. Chromate, acid potassium, 18. Chromates, 73, 134. « Chromic acid, 73. Chromium, 39. Detection of, 71. Dry reactions, 40. Estimation, 172. Separation, 40. Solubility, 137. Wet reactions, 39. Chromium oxide, 172, 173. Cinchona alkaloids, complete analysis, 191. Cinchona pallida, 191. „ rubra, 191. Cinchonae flavae extractum liq., 10. Cinchonidine, 139, 192. Cinchoninia (cinchonine), 139, 143, 192. Cinchonine in quinine, detection, 139. Cinnabar, 91. Cinnamates, 80. Cinnamic acid, 80. Circular polarization, 21. Citrate ammonium, ferric, in. Bismuth and ammonium, in. Lithium, no. Potassium, no. ^ Citrates, 78, no, 131, 134. Separation of,- 78. Citric acid, 78, no. Clarke’s table (water hardness), 187. Cobalt, 43. Dry reactions, 43. Estimation, 170. Separation, 43. Solubility, 137. Wet reactions, 43. Codeia (codeine), 140. Coil, induction, 23. Colchicina (colchicine), 142, 143,148. Colloids, 17. Combustion furnace, 181. Condenser, 6. Confirmatory reagents, 26. Conia (conine), 138, 148. Conversion of thermometric scales, 4. Copper, 31, 167. Dry reactions, 32. Estimation, 167. Separation, 32. Wet reactions, 31. Copper (ic), solubility, 136. ' ' „ (ous)^ solubility, 136. Correction, volume of gases for temperature, 15. Pressure, 15. Creasote, 10. Crucible, 6. Crystals, 17. Crystalline bodies, 17. Crystallization, 17. Water of, 18. Cubic system, 18. Cupellation, 6, 168. Cupri sulphas, 100. Cupric oxide, 167. Salts, 66. Sulphate, 18, 100. Current, galvanic, 22. Cyanates, 65. Cyanic acid, 65. Cyanides, 63, 64, 103, 130, 133, 176. Detection of, 67. Insoluble, 65. Separation from chlorides, 65. Cyanogen, 63, 156. Cyanuric acid, 65. 2o6 INDEX, D. Case 3. Substance insoluble Decagramme, 8. in water and acids, 132. Decalitre, 8. VI. Detection and separation of Decametre, 8. acidulous radicals, 132-135. Decantation, 2. Separations, 133. Decigramme, 8. VII. Solubility. Table, 136. Decilitre, 8. Dextro-gyration, 21. Decimetre, 8. Diabetic urine, 196. Deci-normal solution, 150. Dialysis, 19. Delphinia, 142, 148. Diammonium hydrogen phosphate, Density of gases' 13. 104. Vapours, 13. Diamond, 18. Detection of alkaloids, 138-142. Digitalin, 148. Mixed, 143. Disodium hydro-arseniate, 105. Of metals, 26. Distillate, 6. Detection of unknown salts, 1 13-137. Distillation, fractional, 6. I. General preliminary examina- Double refraction, 21. tion, 1 1 3. Drying precipitates, 164. Case I. Substance a fluid, 113- Dumas (nitrogen estimation), 184. “ 5 - Dupre, Dr. (morphia), 140. Case 2. Substance a solid, 115, Dynamic electricity, 22. 1 16. II. Preparation of solution for E. analysis of metals, if sub- stance be not already dis- Ebullition, 7. Elaterin, estimation, 193. solved, 1 17. Elaterium, 193. III. Detection of metal, 117. Electric light, 23. Table. Detection of metal in Electricity, 22. solution, with one base, Dynamic, 22. 118. - Statical, 22. Table. Separation of metals Electrode, negative, 23. into groups, 120. Positive, 23. Table A. Metals. Group I., 121. „ B. „ Group II., Electrolysis, 22. ' Element, galvanic, 22. Division (^), 122. Emetine, estimation, 193. Erdmann’s float, 15 1. „ C. „ ^ Group II., Division (^), 123. Ether, pure, 7. ,, D. „ Group III., Ethiops mineral, 98. Division {a), 124. Ethylsulphates, 75. ,, E. „ Ditto, cum phos- Evaporation, 7. phoric acid, 125. Extractum cinchonae flavae liq., 10. „ F. „ Group III., Sarzae liq., 10. Division {b), 126. Extraordinary ray, 21. „ G. „ Group IV., 127. ,, H. „ Group V., 128. F. IV. Preliminary examination of Fahrenheit thermometer, 3. acidulous radicals, 130. Fehling’s solution, 159, 160. V. Preparation of solution before Test (grape sugar), 198. analysis of acidulous radi- Ferri arsenias, 106. Carbonas saccharata, 96. cals, 132'. Case I. Substance soluble in lodidi syrupus, 10. water, or in solution, 132. Case 2. Substance insoluble lodidum, 87. Oxidum magneticum, 92. in water; soluble in acids. Perchloridi liquor, 10, 84. 132. „ tinctura, 10. INDEX, 207 Ferri pernitratis liquor, 10, 102. Peroxidum humidum, 89. „ hydratum, 89. Persulphatis liquor, 10, loi. Phosphas, 105. Sulphas, 17, 100. „ granulata, 17. Ferri etammonise citras, in. „ et quiniae citras, 1 1 2. Ferric chloride, 84. Hydrate, 89. Oxide, 1 7 1. Oxy-hydrate, 89. Ferricyanic acid, 66. Ferricyanide potassium, 103. Ferricyanides, 66, 103, 131, 132. Ferro from ferri cyanides, separation, 66 . Ferrocyanic acid, 65. Ferrocyanide potassium, 18, 103. Ferrocyanides, 65, 66, 103, 13 1, 132. Ferroso-ferric oxide, 92. Ferrous arseniate, 106. Carbonate, 96. Iodide, 87. Phosphate, 105. Salts, estimation, 158, 159. Sulphate, 18, 100. Ferrum tartaratum, in. Filters, preparation of, 163. Swedish, 163. Filtration, 3. Flame, constitution of, 23. Oxidizing, 24. Reducing, 24. Flask, measuring, 151. Fleitmann’s test, 145. Float, Erdmann, 15 1. Fluorescence, 20. Fluoric acid, 49. Fluoride, silicon, 6i. Fluorides, 49. Foil, platinum, 25. Formates, 74. Detection of, 74. Formic acid, 74. Fractional distillation, 6. Solution, I. Frauenhofer’s lines, 20. Free acids, estimation, 155. Ammonia, 189. Sulphuric acid, 196. Freezing mixtures, 5. Point, mercury, 4. „ water, 4. Fresenius, 24. Fulminic acid, 65. Furnace, combustion, 181. Fusion, 6. G. Galileo, 13. Gallates, 135. Gallic acid, 81. Gallic, tannic, and pyrogallic acid, 81. Galvanic cell, 22. Current, 22. Element, 22. Gas, permanent, sp. gr., 15. Gases, density of, 13. Girdwood & Rogers (strychnia), 146. Glucose, estimation, 159. Glycerin, 10. Gmelin’s test (bile pigments) 198. Gold, 35. Dry reaction, 36. Estimation, 168. Separation, 36. Solubility, 137. Wet reactions, 35. Gramme, 8, 9. Grape sugar (urine), 197. Gravimetric estimation, 165, Acidulous radicals, 176-180. Metals, 165-176. Gravimetric quantitative analysis, 163-180. Group metals, 120-128. Reagents, 26. Grove’s battery, 22. H. Hardness, permanent (water), 188. Total (water), 187. Heat, latent, 5. Measurement of, 3. Hectogramme, 8. Hectolitre, 8. Hectometre, 8. Hemidesmi syrupus, 10. Herapathite, 192. Herschellian rays, 20. Hexagonal system, 18. ' Hydrargyri chloridum, 83. lodidum rubrum, 18, 87. „ viride, 86. Lotio nigra, 91. Nitratis liquor acidus, 10, 102. Oxidum flavum, 91. „ rubrum, 91. 2o8 INDEX. Hydrargyri subchloridum, 83. Sulphas, 100. Hydrargyrum ammoniatum, 84. Hydras calcis, 89. Hydrate, ammonium, 88. Hydrates, 54, 88. Alkaline, estimation, 153. Ferric, 89. Insoluble, 55. Soluble, 54. Hydrato-carbonate magnesium, 96. Zinc, 96. Hydriodic acid, 52, 176. Hydrobromic acid, 51, 176. Hydrochloric acid, 49, 82, 176. Hydrocyanic acid, 63, 103, 145, 146, ' 156, 176. Scheele’s iron test, 64. Schdnbein’s test, 64. Silver test, 63. Sulphur test, 64. Hydrofluoric acid, 49. Hydrofluosilicic acid, 61. Hydrogen, estimation, 181, 182. Hydrometer, 9, 10. Sykes, ii. ' Twaddell, ii. Hydrosulphuric acid, 55. Hypobromides, 51. Hypobromous acid, 51. Hypochlorites, 50, 85, 13 1. Hypochlorous acid, 50. Hypophosphite calcium, 104. Sodium, 103. Hypophosphites, 67, 103, 104. Hypophosphorous acid, 67. Hyposulphite sodium, 98. Hyposulphites, 57, 98, 130. I. Ice, 18. Igniting precipitates, 164. Induction coil, 23. Insoluble bromides, 51. Chlorides, 50. Cyanides, 65. Hydrates, 55. Silicates, 180. Sulphides, 56. lodate with iodide, detection of, 54. lodates, 53, 130. Iodic acid, 53. Iodide, estimation, 177. Cadmium, 86. Ferrous, 87. Iodide, mercuric, 87. Mercurous, 86. Falladious, 52. Plumbic, 87. Potassium, 18, 86. Iodides, 52, 86, 87, 130, 133,176. Estimation, 156. lodidum cadmii, 86. Ferri, 87. Plumbi, 87. Potassii, 86. Iodine, 52, 86. Estimation, 177. Standard solution, 152. lodum, 86. Ipecacuanha (emetine), 193. Iron, 37. ,Dry reactions, 38. , Estimation, 171. „ indirect, 172. Separation, 38. Wet reactions, 37. Iron (ferrous), solubility, 137. „ (ferric), solubility, 137. Iron test (HCN), 146. Isomorphism, 18. Isomorphous bodies, 18. K. Kilogramme, 8, 9. Kilolitre, 8. Kilometre, 8. Kingston water sample, 190. L. Lactates, 76. Lactic acid, 76. Lactose, estimation, 159. Lsevo-gyration, 21. Latent heat, 5. Lead, 28. Dry reactions, 29. Estimation, 165. Separation, 29. Solubility, 136. Wet reactions, 28. Lead, brown, 93. Plumbate, 93. Red, 91, 93. Liebig’s quinine test, 139. Light, 19. Electric, 23. Polarized, 21. Lime, chlorinated, 85. Limonis syrupus, 10. INDEX. 209 Lines, Frauenhofer, 20. Liquid, supernatant, 2. Liquor ammoniae, 88, 154. „ fortior, 10, 154. Antimonii chlqridi, 10. Arseniealis, 10. Arsenici hydrochloricus, 10. Bismuthi et ammoniae citratis, 10, III. Calcis, 89, 154. „ chloratae, 10. „ saccharatus, 10, 154, Chlori, 10. Ferri perchloridi, 10, 84. „ pernitratis, 10, 102. „ persulphatis, 10, loi. Hydrargyria acidus, 10, 102. ,, nitratis, 10. Plumbi subacetatis, 10, 108, 155. Potassae, 10, 89, 154. „ effervesc. 155. Sodae, 10, 88, 154. „ effervesc. 155. „ chloratae, 10. Lithi^ carbonas, 94. , Citras, no. Lithium, 46. Dry reaction, 46. » Separation, 46. Solubility, 137. Wet reactions, 46. Lithium carbonate, 94. Litre, 8, 9. Lixiviation, 2. Lotio hydrargyri nigra, 91. M. Magnesia, 90. Mixture, 170, 179, 198. Magnesiae carbonas, 96. Sulphas, 99. Magnesium, 45. Dry reaction, 46. Estimation, 174. Separation, 46. Wet reactions, 45. Magnesium ammonium arseniate, 170. Hydrato-carbonate, 96. Oxide, 90. Phosphate, separation, 71. Pyrophosphate, 174. Sulphate, 18, 99. Malates, 77. Malic acid, 77. Manganates, 72. Manganese, 40. Dry reactions, 41. Estimation, 171. Separation, 41. Solubility, 137. Wet reactions, 40. Manganese peroxide, valuation, 16*2. Phosphate, separation, 71. Manganic acid, 72. Manganoso-manganesic oxide, 17 1. Manures, 161. Estimation, 183. Marsh’s test, 144. Maximum thermometers, 5. Measurement of heat, 3. Measuring, 7. Flask, 1 5 1. Meconates, 79, 132. Meconia (meconine), 140. Meconic acid, 79. Menstruum, the, i. Mercur-ammonium chloride, 84. Mercuric chloride, 83. Iodide, .87. Nitrate, basic, 91. Oxide, 91. ■ Sulphate, 100. Sulphide, 98, 166. Mercuricum, 30. Dry reactions, 30. Separation, 30. Wet reactions, 30. Mercurosum, 28. Dry reactions, 28. Separation, 28. Wet reactions, 28. Mercurous chloride, 83, 166. Iodide, 86. Oxide, 91. Mercury, 7. - Boiling point, 4. Estimation, 166. Freezing point, 4. Mercuiy (ic), solubility, 136. „ (ous), solubility, 136. Metallic antimony, 169. Copper, 167. Gold, 168. Nickel, 1 7 1. Platinum, 168. Salts, poisonous, 144. Tin, 169. Metals, detection of, 26. Gravimetric estimation, 165-176. • Group, 26, 120-128. 210 INDEX. Metals, Group I. 27-29. „ II. 29-36. „ in. 36-43. „ IV. 43-45. „ _ V. 45-48. Separation of, 26, 70. Metaphosphoric acid, 68. Methylated spirit, 195. Metre, 8, 9. Metrical weights, 8. Miller (methylated spirit), 195. Milligramme, 8. Millilitre, 8. Millimetre, 8. Millon’s mercurial test (urine), 197. Mineral acids, 144. Minimum thermometers, 5. Mixed alkaloids, 191. Detection, 143. Mixture, magnesia, 170, 179, 198. Mixtures, freezing, 5. Monoclinic system, 18. Moore’s test (grape sugar), 197. Mori syrupus, 10. Morphia (morphine), 139, 143, 147, 148. Mother liquor, 17. Mucilage, starch, 52. Murexid test, 197. N. Nadler (morphia), 148. Narceia (narceine), 140. Narcotia (narcotine), 140, 148. Negative electrode, 23. Nessler’s solution, 189, 190. Nickel, 42. Dry reactions, 42. Estimation, 171. Solubility, 137. Wet reactions, 42. Nicol’s prism, 21. Nicotia (nicotine), 138, 148. Nitrate argentic, 10 1. Bismuthyl, 102. Palladious, 52. Plumbic, 53, 103. Potassium, 18. Sodium, 18. Nitrate with iodide, detection, of, 63. Nitrates, 61, 62, loi, 102, 131, 135. Alkaline, 178. Nitric acid, 62, loi, 178. Nitric acid with nitrate, detection of, 63 - Nitrite with nitrate, detection of,' 62. Nitrites, 61, 131. Nitrogen as nitrates and nitrites, 188. Estimation, 183. Nitrosyl, 184. Nitrous acid, 61. Nitryl, 184. Normal oxides, 55. Solution, 150. Sulphides, 55. O. Official alkaloid, detection, 142. 01eates,_75, 76. Oleic acid, 75. Opium, 146. Valuation, 192. Ordinary ray, 21. Sulphur, 55. Organic analysis, ultimate, 181-185. Orthophosphates, 68. Orthophosphoric acid, 68. Oxalate ammonium, 108. Cerium, 108. Oxalates, 76, 108, 130, 134. Oxalic acid, 76, 108, 145, 180. B.P. solution,, 162. Standard solution, 15 1. Oxide, aluminic, 172. Antimonious, 93. ,, antimonic, 169. Bismuth, 93, 168. Cadmium, 167. Calcium, i, 90, 173, 174, 180. Chromium, 172, 173. Cupric, 167. Ferroso-ferric, 92, 171. Magnesium, 90. Manganoso-manganesic, 171. Mercuric, 91. Mercurous, 91. Plumbic, 92, 165. Silver, 90. Stannic, 169. Zinc, 1 7 1. Oxides, 55, 90-94. Normal, 55. Oxidizing flame, 24. Oxidum antimonii, 93. Argenti, 90. Bismuthi, 93. Ferri magneticum, 92. Hydrargyri flavum, 91. „ rubrum, 91. Plumbi, 92. INDEX. 211 Oxidum zinci, 91. Oxy-hydrate, ferric, 89. Oxynitrate, bismuthic, 102. P. Palladious chloride, 52. Iodide, 52. Nitrate, 52. Palladium (test), 177. Papaverine, 14 1. Papaveris syrupus, 10. Penny, Professor, 159. Perchlorates, 50. Periodates, 54. Periodic acid, 54. Permanent gas, sp. gr., 15. Hardness (water), 188. Permanganate potassium, 92. Permanganates, 72. Permanganic acid, 72. Peroxide, plumbic, 93. Peroxides, 55/ Pettenkofer’s test (biliary acids), 198. Phenates, 79. Phenic acid, 79. Phosphate, detection of, 69,’ 70. Calcium, 105. Ferrous, 105. Sodium, 18. ,, solution, standard, 161. Phosphates, 68, 69, 103, 104, 134, 178. Alkaline, 179. Urine, 198. Phosphides, 67. Phosphites, 68. Phosphoric acid, 104, 178. Estimation, 161. Separation, 170. c. Iron and aluminium, 179. c. Lime and magnesia, 179. Phosphorous acid, 68. Phosphorus, 67. . Estimation, 185. Phosphorus, amorphous, 67. Red, 67. Picrotoxin, 148. Platinic chloride, 84. Platinum, 36. Dry reaction, 36. Estimation, 168. Separation, 36. Solubility, 137. Wet reactions, 36. Platinum foil, 25. Wire, 25. Plumbate lead, 93. Plumbi acetas, 107, 155. Carbonas, 97. lodidum, 87. Nitras, 103. Oxidum, 92. Subacetatis liquor, 10, 108, 155. Plumbic acetate, 53, 107. Hydrato-carbonate, 97. Iodide, 87. Nitrate, 53, 103. Oxide, 92, 165. Oxyacetate solution, 108. Peroxide, 93. Sulphate, 166. Poisonous alkaloids, 147. Metallic salts, 144. Polarization, circular, 21. Polarized light, 21. Polarizer, 22. Polymorphous bodies, 17. Polysulphides, 56, 130. Positive electrode, 23. Potable water, 146-190. Potassa caustica, 89, 154. Sulphurata, 97. Potassse acetas, 107. Bicarbonas, 95, 154. Bichromas, 94. Carbonas, 95, 154. Chloras, 85. Citras, no. Liquor, 10, 89, 154. Permanganas, 92. Prussias, flava, 103. „ rubra, 103. 'Sulphas, 99. Tartras, 109, 155. acida, 109, 155. Potassii bromidum, 87. lodidum, 86. Potassium, 47. Dry reaction, 47. Estimation, 175. Solubility, 137. Wet reactions, 47. Potassium acetate, 107. Acid chromate, 18. Antimonyl tartrate, no. Bichromate, 94. Bromide, 18, 87. Carbonate. 95. Chlorate, 85. Citrate, no. Cobaltous nitrite, 170. 212 INDEX. Potassium dichromate, standard solu- tion, 152. Ferric tartrate, in. Ferricyanide, 103. Ferrocyanide, 18, 103, 161. Hydro-tartrate, 109. Iodide, 18, 86. Nitrate, 18. Organic salts, estimation, 154. Permanganate, 92. Platino-chloride, 175. Poly sulphide, 97. Sodium tartrate, 109. Sulphate, 99, 175. Tartrate, 109. Precipitate, 2. Precipitated calcium carbonate, 96. Sulphur, 55. Precipitates, drying, 164. Igniting, 164. Washing, 163. Weighing, 164. Precipitation, 2. Preparations, scale, in, 112. Pressure, atmospheric, 13. Prism, 19. Nicol’s, 21. Process Dumas, 184. Sonnenschein, 149. Stas, 147, 149. Varrentrapp & Will, 184. Processes, chemical, 1-25. Special analytical, 186-200. Proof spirit, 7. Prussian blue, 64, 146. Pyrogallates, 135. Pyrogallic acid, 81. Pyrology, 23. Pyrometer, 4, 5. Pyrophosphate magnesium, 174. Pyrophosphoric acid, 68. Q. Qualitative analysis, 82-137. Unknown salts, 1 13-137. Quantitative analysis, gravimetric, I 163-180. Volumetric, 150-162. Quartz, 18. Quinia (quinine), 138, 143. Adulterations, 139. Estimation, 191. Test, Liebig, 139. „ Stoddart, 139. Quinicine, 192. Quinidine, 139, 192. Quinine and ferrous ferric, 112. R. Radicals, acidulous, 49-81, 130-137. Gravimetric estimation, 176-180. Ray, extraordinary, 21. Ordinary, 21. Rays, Herschellian, 20.. Of light, 19. Reagents, confirmatory, 26. Group, 26. Separatory, 26. Reaumur thermometer, 3. Receiver, the, 6. Rectified spirit, 7. Red lead, 91, 93. Phosphorus, 67. Reducing flame, 24, Reflection, 19. Refraction, 19. Double, 21. Regular system, 18. Residue, the, 6, 7. Total (water), 189. Rhamni syrupus, 10. Rhoeados syrupus, 10. Rhombic system, 18. Rogers & Girdwood (strychnia), 146. Rosae Gallicae syrupus, 10. S. Salicin, 142. Salicylates, 135. Salicylic acid, 80. Salts, ferrous, estimation, 158, 159. Metallic, poisonous, 144. Solubility of, 136. Unknown, qualitative analysis of, 113-137-. Sapo mollis (solution), 187. Sarzse extractum liq., 10. Scale preparations, in, 112. Scales, thermometric, 4. Scammonium, 193. Scammony resin, estimation, 193. Semi-normal solution, 150. Sennse syrupus, i o. Separation — Group Metals, 120-128. Of metals, 26. Separatory reagents, 26. Sherry, estimation, 194. Shock, electric, 22. Silica, 61. INDEX. 213 Silicates, 60. Insoluble, 180. Soluble, 180. Silicic acid, 60, 180. Anhydride, separation of, 61. Silicon fluoride, 61. Silver, 27. Dry reaction, 27. Estimation, 165. Separation, 27. Solubility, 136. Wet reactions, 27. Silver oxide, 90. Test (HCN), 146. Siphon, 2. Soda, arseniate of, estimation, 157. Caustica, 88, 153, 154. Chlorata, 85. Chlorinated, 85. Lime, 183. Tartarata, 109, 155. Sodae acetas, 107. Arsenias, 105. Bicarbonas, 95, 154. Carbonas, 95, 154. Chloratae liquor, 10. Hypophosphis, 103. Liquor, 10, 88, 154. Phosphas, 104. Sulphas, 99. Valerianas, 108. Sodii chloridum, 83. Sodium, 47. Estimation, 176. Separation, 47. Solubility, 137. Wet reactions, 47. Sodium acetate, 107. „ solution, 16 1. Bicarbonate, 95. Carbonate, 18, 95. Chloride, 18, 83, 176. Hydrate, standard solution, 15 1. Hypophosphite, 103. Hyposulphite, 98. Nitrate, 18. Organic salts, estimation, 154. Phosphate, 18. Sulphate, 99, 176. Thiosulphate (hyposulphite), standard solution, 152. Valerianate, 108. Soleil, M., 22. Solubility (salts), 136. ^ Soluble hydrates, 54. Soluble silicates, 180. Sulphides, 56. Solution, I. Calx chlorata, 145. Centi-normal, 150. Deci-normal, 150. Fehling, 159, 160. Fractional, i. Nessler, 189, 190. Normal, 150. Plumbic oxyacetate, 108. S'emi-normal, 150. Sodium acetate, r6i. Solutions, standard, 150, 15 1. Solvent, the, i. Sonnenschein’s process, 149. Special analytical processes, 186-200. Specific gravity, 9-17. Beads, ii. Commercial application, 13. Fluids, 9, 10. Mass, insoluble, ii, 12. „ soluble, 12. Powders, ii. Solid bodies, ii, 12. Vapour, 16. Spectra, absorption, 21. Spectrum analysis, 19. Spirit, methylated, 195. Proof, 7. Rectified, 7, 10. Sweet nitre, 196. Spirits, alcoholic, strength, 194. Spiritus aetheris, 10. ,, nitrosi, 10. , Ammoniae aromaticus, 10. Chloroformi, 10. Square prismatic system, 18. Stain, antimony, 145. Arsenic, 145, Standard solutions, 150, 151. Argentic nitrate, 152. Iodine, 152. Oxalic acid, 15 1. Phosphate, 161. Potassium dichromate, 152. Sodium hydrate, 15 1. Thiosulphate (hyposul- phite), 152. Uranic nitrate, 161. Stannates, 73. Stannic acid, 73. Oxide, 169. Stannites, 73. Stannous chloride, 84. 214 INDEX. Starch mucilage, 52. Stas’s process, 147, 149. Statical electricity, 22. Steam bath, 7. Stearates, 75. Stearic acid, 75. Stoddart’s quinine test, 139. Strontium, 44. Dry reaction, 44. Estimation, 174. Separation, 44. Solubility, 137. Wet reactions, 44. Strontium carbonate, 174. Strychnia (strychnine), 14 1, 142, 146, 148. Sub-carbonas bismuthi, 97. Sub-chloridum hydrargyri, 83. Sublimation, 6. Fractional, 6. Succinates, 7 6, 77, 135. Succinic acid, 76, 135. Sugar, grape (urine), 197. Ultimate analysis, 182. Sulphate, argentic, 135. Barium, 173, 178. Beberine, 112. Calcium, 99. Cupric, 100. Ferrous, 18, 100. Magnesium, 18, 99. Mercuric, 100. Plumbic, 166. Potassium, 99, 175. Sodium, 99, 176. Zinc, 18, 99. Sulphates, 58, 99, 100, 132, 178. (Urine), 199. Sulphide, antimonious, 98. Arsenious, 170. Bismuth, 168. Cadmium, 167. Mercuric, 98, 166. Sulphide in presence of sulphite and sulphate, detection of, 56. Sulphides, 55, 57, 97, 98, 130, 177. Insoluble, 56. Normal, 55. Soluble, 56. Sulphides, sulphites, and sulphates, separation of, 59. Sulphites, 57, 5 S, 98, 130- Sulphocarbolates, 79, 131, 135. Sulphocyanates, 65. Sulphocyanides, 13 1, 132. Sulphovinates, 75, 13 1. Sulphur, 55. ^ Estimation, 185. Precipitated, 55. Precipitatum, 97. Sublimatum, 97. Test (HCN), 146. Sulphuric acid, 7, 58, 99, 178. Sulphurous acid, 57, 98. Estimation, 157. Supernatant liquid, 2. Sutton’s “Volumetric Analysis,” 161. Swedish filters, 163. Sweet spirit of nitre, 196. Syrupus aurantii, 10. Ferri iodidi, 10. Hemidesmi, 10. Limonis, 10. Mori, TO. ' Papaveris, 10. Rhamni, 10. Rhoeados, 10. ' Rosae Gallicae, 10. Simplex, 10. Sennae, 10. Tolutanus, 10. System, cubic, 18. Hexagonal, 1.8. Monoclinic, 18. Regular, 18. Rhombic, 18. Square prismatic, 18. Triclinic, 18. Sykes’ hydrometer, 1 1. T. Table, Clarke (water hardness), 187. F own es, (alcohol percentage), 195. Group metals, 120-128. Tannates, 135. Tannic acid, 81. Tartaric acid, 77, 109, 180. Tartrate potassium, 109. „ antimonyl, no. „ ferric, in. „ sodium, 109. Tartrates, 77, 109, 131, 134. Tension (vapour), 7. Test, Fleitmann, 145. Iron (HCN), 146. Marsh, 144. Measure, 150. Mixer, 15 1. Murexid, 197. Silver (HCN), 146. INDEX. 215 Test, sulphur (HCN), 146. Thebaia (thebaine), 141. Theory, undulatory, 19. Thermal units, 5. Thermometer, 3. Celsius, 3. Centigrade, 3. Fahrenheit, 3. Reaumur, 3. Thermometers, alcohol, 4. Maximum, 5. Minimum, 5. Thermometric scales, 4. Thiocyanates, 65. Thiocyanic acid, 65. Thiosulphates, 57. Separation of from sulphides, 57. Thiosulphuric acid, 57. Tin, 35. Dry reaction, 35. Estimation, 169. Separation, 35. Wet reactions, 35. Tin (stannic), solubility, 137. „ (stannous), solubility, 136. Tinctura ferri perchloridi, 10. Tinctures, alcoholic strength, 194. Tolutanus syrupus, 10. Torricelli, 13. Torricellian vacuum, 14. Total hardness (water), 187. Residue (water), 189. Toxicological analysis, 144. ■ Triclinic system, 18. Trommer’s test (grape sugar), 197. TwaddeU’s hydrometer, ii. U. Ultimate organic analysis, 181-185. Undulatory theory, 19. Units, thermal, 5. Uranic nitrate, standard solution, 161. Urea, 198. Estimation, 160. Uric acid, 198. Urinary calculi, analysis, 199, 200. Urine, albumen, 197. „ Bodeker’s method, 197. „ Millon’s mercurial colour test, 197. Analysis, 196-199. Bile, 198. „ Gm din’s test, 198. „ Pettenkofer’s test, 198. Urine, blood, 199. Chemical tests, 197. Chlorides, 199. Diabetic, 196. Grape sugar, 197. ,, Fehling’s test, 198. „ Moore’s test, 197. „ Trommer’s test, 197. Phosphates, 198. Specific gravity, 196. Sulphates, 199. V. Vacuum, Torricellian, 14. Valerianate, sodium, 108. Zinc, 108. Valerianates, 75, 108, 13 1. Valerianic acid, 75. Valuation, manganese peroxide, 162. Vaporization, 7. Vapour, bromine, 145. Specific gravity, 16. Tension, 7. Vapours, density of, 13. Varrentrapp & Will, 183. Veratria (veratrine), 141, 142, 148. Vermilion, 98. Vinegar, 10. Sulphuric acid, 196. Vinum Xericum, 194. Voltaic cell, 22. Voltameter, 23. Volumetric Quantitative Analysis, 150-162. I. General Principles, 150. II. Apparatus, 150. III. Standard Solutions, 15 1, 152. IV. Calculation of Results, 152, 153- y. Estimation Alkaline Hy- drates, 153, 154. VI. Estimation Alkaline Car- bonates, 154. VII. Estimation Organic Salts, Potassium and Sodium, 154. . VIII. Estimation Lead Salts, ^ 55 - IX. Estimation Free Acids, ^. 55 * . X. Estimation Hydrocyanic Acid, 156. XL Estimation Chlorides, Bromides, Iodides, 156. 216 INDEX. Volumetric Quantitative Analysis {continued) XII. Estimation Commercial Arseniate of Soda, 157. XIII. Estimation Arsenious Acid, 157- . XIV. Estimation Sulphurous Acid, 157. XV. Estimation Available, Chlorine, 158. XVI. Estimation Ferrous Salts, 158, 159- XVII. Estimation Glucose and Lactose, 159, 160. XVIII. Estimation Urea, 160. XIX. Estimation Phosphoric Acid, 16 1. XX. Valuation Manganese Per- oxide, 162. W. Wanklyn & Chapman, 186. Washing precipitates, 163. Water, 54. _ ^ Albuminoid ammonia, 189. Free ammonia, 189. Barometric pressure, 7. Boiling point, 4. Chlorine as chlorides, 188. Clarke’s table, 187. Of crystallization, 18. Freezing point, 4. Water, good sample, 190. Kingston, bad, 190. Nessler’s solution, 190. Nitrogen as nitrates and ni- trites, 188. Permanent hardness, 188. Potable, 186-190. Source of disease, 186. Total hardness, 187. „ residue, 189. Weighing, 7. , Precipitates, 164. Weights, metrical, 8. Will & Varrentrapp, 183. Wines, alcoholic strength, 194. Y. Yellow bark, 191. Z. Zinc, 41. Dry reactions, 42. Estimation, 171. Separation, 42. Solubility, 137. ‘ Wet reactions, 41. Zinc, acetate, 107. Chloride, 83. Hydrato-carbonate, 96. Oxide, 91, 1 7 1. Sulphate, 18, 99. Valerianate, 108. Butler Tanner, The Selwood Printing Works, Frome, and London. TO BE ISSUED IMMEDIATELY. A KEY TO #rpiik Materia BY DR. JOHN MUTER, M.A., F.C.S. FOURTH EDITION. 500 PAGES, CROWN 8vo. This standard work., so justly popular with students, which has passed through Hu’ee Editions in the incredibly short space {for a scientific book) of four years, contains — I. A complete description of the various articles of Materia Medica de- rived from the vegetable and animal kingdoms, and the preparations made therefrom. II. The best modes of isolating and detecting the active principles of the drugs. III. An original microscopic classification and description of the chief Starches found in the common articles of Materia Medica and food. IV. Comprehensive tables showing the 'botanical names, habitats, prepa- rations, etc., of all the official and non-official drugs in common use. V. Tabulated courses for the detection of resinous drugs, etc. The whole written in the most concise manner possible. London ; Published by William Baxter, at the Offices of the South London School of Pharmacy, Kennington Cross, S.E. ; and sold by Messrs. Simpkin & Marshall, Stationers’ Hall Court, E.C., and Messrs. Bailliere, Tindal & Cox, King William Street. Strand, W.C. l^Inlaielphta : PUBLISHED BY PRESLEY BLAKISTON, 1012, WALNUT STREET.