None
Discarding the last figure, which considering the probable errors in the measurements has no meaning, the devia- tion from the whole number 2 is 1%, which would be quite satisfactory but for the fact that the volume com- parison having been made between dry ammonia and moist nitrogen, the volume of the latter is affected by an error of about 2%. No notice is taken of this in the discussion of the result. Moreover, the fact of the nitrogen being in this case evolved in the liquid, which unless allowed to stand for a considerable time and agitated is apt to become super- saturated, makes an appreciable error due to this cause more than probable; the effect would be to make the volume as measured too small, an error in the opposite direction to the first one. As pointed out by Cornish, since the solubility of the ammonia in the strongly alkaline hypobromite solution is but small, the reaction occurs mainly near the surface of the solution, which thereby is soon deprived of the active hypo- bromite (made evident by the loss of the yellow colour), after which, if left to itself, the velocity of the reaction becomes very small, and some mechanical help is necessary to mix the solution and bring more hypobromite into contact with the ammonia. This difficulty becomes more marked, the narrower the gas measuring tube used ; which lands us on the horns of the dilemma that whilst accuracy of measurement demands a narrow tube, the desirability of completing the experiment within reasonable time points to the use of a wide one. In the writer's experience this difficulty has proved so serious that the experimental procedure has been modified by using a 100 c.c. tube fitted with a cork and funnel just as in the previous experiment ; the tube is filled by downward dis- placement as described by Ramsay and by Cornish, and the P. c. 26 402 The Law of Combining Volumes cork with the funnel-tap closed is pushed in from below, after which the pressure in the tube is brought to that of the atmosphere by opening the tap for a second. Some hypo- bromite solution is then run in, the tube being at first kept cool by means of ether. The hypobromite should be added about 5c.c. INDEX Accuracy attainable in experiments, degree of 20, 35 Acetylene, action of bromine on 124 ; preparation of 124 Acids and bases, neutralisation equiva- lents of 290, 294, 299 Air, constituents of 118 ; corrections for buoyancy of 14, 17, 21, 31; density of 190; heating of metals in 146 ; liquid 17, 118, 135, 140 Alchemists 193 Allotropic modifications of elements 78 Aluminium, equivalent weight of 306, 344 Ammonia, volume composition of 396 Ammonium chloride, effect of heat on 65 ; molecular weight of 374, 375 ; Stas's analysis of 59, 231 Ammonium hydrogen sulphite 56 Ammonium sulphite, action on iodine of 56, 219 ; preparation of 56, 219 Anaximenes' conception of " element" 104 Animate matter and inanimate, dis- tinction between 49, 50 Antecedent data, definition of 12 ; discussion of, with reference to ex- periment on density of hydrogen chloride 18 Antimony sulphide, invariable com- position of 230 Argentiferous lead, fractional crystal- lisation of 127 ; production of silver from 121 Argon, discovery of 78, 126 ; physical properties of 136 ; separation of other inert gases from 133 Aristotle, four-element hypothesis sup- ported by 104 Assumptions made in experimental work, discussion of 12 Atmolysis 132 Atomic heat of elements, constancy of 107, 364 Atomic hypothesis 268, 321, 361 Atomic weight and combining weight, relation between 360, 375 Atomic weight, selection of 324, 326 ; of carbon 373, 377 ; of cobalt 61 ; of nickel 61 ; of tellurium 374 Atoms 104, 365 Avogadro's hypothesis 365, 381 Bacon, acceptance of law of Conserva- tion of Mass 193 ; opposition to Aristotelian and Paracelsian doc- trines 106 Baker and Bennett's determination of atomic weight of tellurium 138 Balance, errors attending use of 26 Barium oxide, use of in Brin process for preparing oxygen 119 Barometer reading, experimental error in 27 Bases and acids, neutralisation equiva- lents of 290, 294, 299 Becher and phlogiston theory 147, 360 Benzoic acid, sublimation of 65 Bergman, quantitative work of 228 Berthelot, La Revolution Chimique 141 Berthollet, denial of Law of Fixed Katios 228 Berzelius, accurate quantitative work of 228, 231, 269, 271; analysis of chlorides of copper 270, 280, oxides of copper 270, 292, oxides of iron 270, 292, 295, oxides of lead 270, 271, 292, 295, sulphides of iron 196, 270, 292, 295, sulphides of lead 292, 293, 295, sulphuric anhydride 270, sulphurous anhydride 270 ; syn- thesis of litharge 270 ; apprecia- tion of Eichter's work 292, 294; contributions to establishment of Eichter's Law 292 ; conversion of lead sulphide to sulphate 293, 297 ; publication of table of atomic weights 364 ; ratio potass chlorate to chloride 94 ; standard for atomic weights 316 ; system of symbolic notation 322 ; system of selection of atomic weight 324, 326, 372 Binary compounds 297, 309, 363 Biot 4 ; discovery of optical rotatory power 62 Black, use of quantitative methods 82 Blondlot's rays 51 Boyle, Eobert, acceptance of law of Conservation of Mass 193 ; definition of "element" 106; experiments on combustion 143, 156 ; opposition to Aristotelian and Paracelsian doc- trines 106 ; use of qualitative methods 404 Index 82 ; views on increase of weight during combustion 146 Boyle's Law 12, 384 Brin process for preparation of oxygen 119 Bromine, action on unsaturated organic compounds 124 ; action on mercury 226 Buchholz 228 Buoyancy of air, corrections for 14, 17, 21, 31 Calcination of tin and lead, Lavoisier's work on 149, 194 ; increase of weight noticed by Key 143 Calcium, combining weight of 346, 356 Calcium carbide 124 Calcium carbonate, composition of 249 Calcium nitrate, effect of heat on 70, 72 Calxes, metallic, reduction of 143 Camphor, sublimation of 65 Cannizzaro molecular and atomic weight determinations by Avogadro's hypothesis 368, 372 Carbon, atomic weight of 373, 377 ; combining weight of 345 Carbon bisulphide as solvent 56, 123 Carbon dioxide, composition of 267, 268, 271 ; production and properties of 210 ; synthesis of 256 Carbon monoxide 257 ; composition of 267, 268, 271 Carbonates of potassium 261, 272 Carburetted hydrogen, heavy (ethylene) 268 ; light (methane) 268 Cavendish, determination of equivalent weights 289; neutralisation equiva- lents of acids and bases 290, 294 ; production of hydrogen 143 ; syn- thesis of water 10 Cerium, separation from didymium and lanthanum 128, 132 Charcoal, cocoanut, use of in absorbing gases 118, 201 Charcoal used for production of high vacua 17 Charles' Law 12, 384 Chemical change unaccompanied by change in weight 28, 34, 205 ; nature of 53 ; Landolt's work on 34, 205 Chemistry, definition of 58 ; school- teaching of 7, 254, 378 Chlorides, volumetric estimation of 65, 69 Chlorine, combining weight of 342, 351 , 355 ; composition of 77 ; density of 46 ; elementary nature of 78 Cinnamic acid, action of bromine on 124 Classification of the sciences 48 Classification of substances into com- plex and simple (elements) 103 Classification of complex substances into mixtures and compounds 111 Cobalt, atomic weight of 61 Coefficient of solubility 119 Combining volumes, Gay-Lussac's law of 380 Combining weights, accurate determi- nation of 296 ; discussion of experi- mental determination of 324, 328; standard for 315 ; and atomic weight, relation between 360 ; of aluminium 344, calcium 346, 356, carbon 345, chlorine 342, 351, 355, hydrogen 340, iodine 348, magnesium 344, nitrogen 317, 328, 333, 335, 339, 358, potassium 342, radium 330, 335, silver 342, sodium 352, tellurium 329, 331, 332, 335, tin 344, zinc 344 Combustion 77, 142, 177 Complex substances, types of 111, 225 Compounds, binary and ternary 297, 309, 363; definition of 111, 122, 253 Conservation of Mass 192; work of Landolt and of Manley on 205 Copper, effect of heating in air 86 Copper calcium acetate, change pro- duced on heating 53 Copper, chlorides of 270, 280 Copper, oxides of 270 Cornish, Vaughan, Practical Proofs of Chemical Laws 217, 399 Courtois, discovery of iodine 109 Cuprous chloride 144, 281 Cuprous oxide, action of heat on 54 Curie, P. 6, 108 Curie, Mme. 108 ; fractional crystal- lisation of radium chloride 127 Dal ton, John, accuracy of experimental wqrk 292 ; analysis of hydrides of carbon 268 ; arbitrary rules for selec- tion of atomic weight 323, 363, 372 ; atomic theory of 268, 321, 361; defi- nition of element 106; rejection of Gay-Lussac's law of volumes 381 Davy, Sir Humphry, analysis of nitrous and nitric oxides 268 ; de- composition of water 10 ; definition of element 106; isolation of alkali metals 108 ; proof of elementary nature of chlorine 78, 110 ; qualita- tive work of 82 De Eerum Natura 104 Degree of accuracy obtainable in ex- periments 35 ; of measuring instru- ments 20 Index 405 Demarcay, work on resolution of didy- mium 133 Democritus, Atomic Theory of 104, 193, 321 Density, of air and nitrogen 169 ; of chlorine, class results for deter- mination of 46, 47 ; of hydrogen chloride, students' experiment 10; Gray and Burt's determination of 16 ; of oxygen, 266 ; of soluble gas, deter- mination of 41 Density, gaseous 184 Dephlogisticated air (oxygen) 145 Descartes' rejection of Aristotelian " elements " and Paracelsian "prin- ciples" 106 Deslandres 6 Didymium 128, 132 Diffusion, fractional 126 Distillation, fractional 22, 129, 139 Dulong and Petit 's Law 364 Dumas, determination of vapour density 188 ; method for determining composition of water 10, 198 Efficiency of balance, Landolt's ex- periments on 27 Element, conception of 103 ; four- element hypothesis 104 Elements, allotropic modifications of 78 Empedocles 104 Epicurus' Atomic Theory 104, 193, 321 Equivalent weight, see combining weights Equivalents, neutralisation of acids and bases 290, 294, 299 Error, experimental, see experimental errors Error, probable 24 ; in volumetric estimations 36 ; in accurate work 376 Errors of measurement 24 Ethylene, action of bromine on 124 ; Dalton's analysis of 268 Experimental errors, discussion of 24, 27, 31, 34, 38, 70, 161, 205, 296, 298, 341, 392, 398, 401 Ferrous hydrate, absorption of oxygen by 119, 144 Ferrous oxalate, preparation of pyro- phoric iron from 55 Ferrous salts 76 Fire air (oxygen) 145 Fixed Eatios, Law of 225 Fluorine, isolation of by Moissan 108 Formulae, selection of 325 Fractional crystallisation 127, 128, 131 Fractional distillation 22, 129, 139 Fractional precipitation 128 Fractionation 126 Gaseous density 184 Gassendi 106, 193 Gay-Lussac, investigation of properties of iodine 109; Law of Combining Volumes 380 Gay-Lussac and Humboldt, volume composition of water 380 Geber, three "principles" 105; work on calcination 143, 156 Glass vessels, condensation on walls of 15 Gray's work on nitric oxide 140, 201, 272 Gray and Burt's determination of den- sity of hydrogen chloride 16, 18, 139 ; Composition of hydrogen chloride 389 Guye and Bogdan, analysis of nitrous oxide 272 Guye and Fluss, analysis of nitrosyl chloride 202 Heavy carburetted hydrogen (ethylene) 268 Helium, physical constants of 136; production from radium 6 Hemihedrism 4, 62 Heraclitus 104 Heterogeneous substances 111, 225 Hofmann, lecture demonstrations of Gay-Lussac's Law 384, 395 ; vapour density determination 189 Homogeneous substances 111, 225 Hooke 146 Horn silver 96 Hydrogen, combining weight 340 ; dis- covery of 143 ; solubility of in palladium 139 Hydrogen chloride, composition of 77, 389 ; density of 10, 16 Hydrogen, heavy carburetted (ethy- lene) 268 Hydrogen, light carburetted (methane) 268 Hydrogen, liquid 135 Hydrogen, peroxide 287 Hydrolysis of chlorides 349 Hypothesis, value of 361 Iceland Spar, composition of 249 Identity, meaning of term 59 Illustrative experiments 2, 8, 9 Inanimate and animate matter, dis- tinction between 49 Indestructibility of matter, a scientific principle 194 406 Index Indicators, limitations in use of 277 Inflammable air (hydrogen) 144, 147 Iodine, action of carbon bisulphide on 56 ; combining weight of 348 ; dis- covery of 109 ; position in Periodic System of 137 ; sublimation of 65 Iron, Berzelius's analysis of oxides of 270, 295; increase in weight when heated in air 2, 54, 86 ; properties of 75, 112, 123; pyrophoric 55; reduced 55; synthesis of calx by Lavoisier 194 Iron pyrites 270 Iron sulphide 295 Isomerism 4 Klaproth, quantitative work of 228 Kopp 319 Krypton, discovery of 78, 133 ; physi- cal properties of 136 Kunkel, quantitative work of 228 Laevo-tartaric acid discovered by Pasteur 3, 62 Landolt, test of efficiency of balance 27 ; work on Conservation of Mass, 32, 205 Lanthanum, separation from cerium and didymium 128, 132 Laurent 323 Lavoisier, analysis of two oxides of carbon 268 ; calcination of lead and tin, 149, 159, of iron 157, 194 ; criti- cism of phlogiston theory 148 ; de- monstration of Conservation of Mass 157 ; proof of composition of air 360 ; synthesis and analysis of mercury calx 3, 119, 150, 159, 175, 194, 360 ; use of quantitative methods 82 Lead, argentiferous, fractionation of 121 Lead, calcination of 149, 194 ; effect of heating in air 176 Lead nitrate, action of heat on 53, 58, 64 Lead oxalate 286 Lead, oxides of 176, 177, 270, 271 Lead-potassium iodide, action of heat on 53, 54, 58 Lead, red 176, 177 Lead sulphate 286, 289, 293, 296 Lead sulphide 286, 293, 295, 296 Leucippus 104, 321 Light carburetted hydrogen (methane) 268 Limited miscibility 79 Litharge (lead monoxide) 176, 177, 270, 286, 293, 295 Liquid air 17, 118, 135, 140; hydro- gen 135 Lithium 126 Liver of sulphur 144, 149 Lothar Meyer, Periodic System of 137 Lucretius, De Rerum Natura, 104, 193, 321 Magnesium, effect of heating in air of 2, 54, 86, 152 ; determination of combining weight of 37, 306, 307, 309, 344 Magnesium carbonate, effect of heat on 53 Magnesium nitride 55, 87, 152 Magnesium silicide 55, 87, 152 Manley's experiments on conservation of mass 205 Marble, action of hydrochloric acid on 210 Marggraf , quantitative work of 228 Marignac 94 Marsh gas (methane) 124 Mass, Law of Conservation of 192, 205 Mayow, work on combustion 143, 146, 157 Measuring instruments, accuracy of 20, 38 Mendeleeffs Periodic System 137, 371 Mercurius precipitatus per se 145, 150, 159, 175 Mercury (principle of ductility etc.) 105 Mercury bromides, synthesis of 226 Mercury calx, Lavoisier's synthesis and analysis of 3, 119, 150, 159, 175, 194, 360 Mercury iodides, synthesis of 254 Metal wools, use of 55 Meyer, Lothar, Periodic System of 137 Meyer, Victor, method for determina- tion of vapour densities 189 Miscibility, limited 79 Mistakes, distinction between experi- mental errors and 24 Mixtures 111, 122, 253 Moissan, isolation of fluorine 108 Molecular weights 366 ; of ammonium chloride 374, 375 Molecules 365 Morley, density of hydrogen 303 ; gravimetric composition of water 10, 198, 199 Multiple ratios, Law of 253, 318 Muriatic acid gas (hydrogen chloride) 77 N-rays 51 Neon 78, 133, 136 Neutralisation, equivalents of acids and bases 290, 294, 299 Nickel, atomic weight of 61 Nicol's prism 250 Index 407 Nitric acid 144 Nitric oxide, analysis of 139, 144, 201, 268, 272 Nitrogen 118, 136 ; combining weight of 317, 328, 333, 335, 339, 358 Nitrogen, "atmospheric" 61 ; "chemi- cal " 61 ; diffusion of 127 ; solubility of 119 Nitrosyl chloride, analysis of 202 Nitrous oxide, analysis of 118, 120, 123, 139, 268, 272 Noyes, synthesis of water 198, 200; synthesis of hydrogen chloride 201 Olein 124 Optical activity 4, 62 Ostwald 6 Oxalates of potassium, composition of, 277 Oxygen 114, 118; density of 266; physical constants of 136 ; solubility of 119 Oxymuriatic acid gas (chlorine) 77 Palladium hydride 139, 199 Paracelsus' three principles 105 Pasteur, discovery of laevo-tartaric acid 3, 62 Pelouze 94 Penny 94 Periodic function 107 Periodic system 137, 371 Periodic table 128, 134, 137 Permanent ratios, Law of 284, 288 Phlogisticated air (nitrogen) 144 Phlogiston theory 147 Phosphorus, allotropic forms of 78; burning of 29, 34, 151, 154, 160, 206 Physics, definition of 58 Pipettes, errors in measurement by 25 Plane of polarisation, rotation of 3 Platinised asbestos 53, 114 Platinum, effect of heat on 53 Plato 104, 193 ' ' Plumbum vitriolatum ' ' (lead sul- phate) 289 Potassium, carbonates of 261, 276; combining weight of 342 ; discovery of 108 ; oxalates of 277; sulphates of 263 Potassium chlorate, 90, 93, 282, 283 ; formula for 337; properties of 263; solubility curve for 90 Potassium chloride, analysis of 238; formula for 337 ; solubility curve for 90 Potassium perchlorate, 90, 93, 282, 283 ; formula for 337 ; preparation of 263 ; solubility curve for 90 Priestley 144 ; discovery of oxygen 145, 150 Probable error 24, 376 Properties; qualitative 60, 64 ; quanti- tative 60, 64 Proust, proofs of fixity of composition 229, 249, 253 Purity of substances, determination of degree of 22 Pyrolusite 145 Pyrophoric iron 55 Pythagoras 104 Qualitative methods, Boyle, Davy 82 Qualitative properties 60, 67, 83 Quantitative methods, Lavoisier, Black 82 Quantitative properties 60, 61, 67, 83 Eacemic acid 3 Eadio activity 6, 127 Eadium, atomic weight of 325 ; com- bining weight of 99, 335; discovery of 108 ; production of helium from 6 Eadium bromide 6 Eadium chloride 335 Eamsay, Sir William 6, 399 ; discovery of argon 126, discovery of helium etc. 134 Eayleigh, Lord, discovery of argon 61, 126 ; on gaseous densities 21, 61, 303 Eegnault on gaseous densities 16, 17, 21, 188 Eesearch work and method 8, 9 Eey 143, 157 Eichards, T. W., determination of com- bining weights, 334, 339, 349 Eichter, quantitative work of 228 ; establishment of Law of Permanent Eatios 288, 289, 292, 294 Eotation of plane of polarisation 3 Eutherford, discovery of nitrogen 144 Sal ammoniac 65 Salt, one of the three Paracelsian principles 105 Scheele, discovery of oxygen 145, 175 ; research on air and fire 77, 144, 148, 163 School teaching of chemistry 7, 378 Sea serpent 51 Selenium, place in periodic table 137 Silver, combining weight of 338, 342; gravimetric estimation of 97 ; horn 96 ; preparation of pure 348 ; pro- duction of 97, 121 Silver chlorate, analysis of 338 Silver chloride, composition of 228, 231, 235, 338; preparation of 96; synthesis 59, 121 408 Index Silver iodate 297 Silver iodide 217, 297, 348 Silver nitrate 129 Silver oxide 287 Silver sulphide 217, 287 Smithells 133 Soddy 6 Sodium, combining weight of 347, 352 ; discovery of 108 Sodium ammonium racemate 4 Sodium ammonium tartrate 4 Sodium bicarbonate 61 Sodium peroxide 115 Solubility coefficient 119 Solutions 78, 112 Stahl 143; phlogiston theory of 147, 360 Stabler and Meyer 94 Standard of combining weights 315 Stas 94, 295, 296, analysis of am- monium chloride 59, 231, of silver chlorate 338 ; production of pure silver 348 ; synthesis of silver halides 59, 199, 217, 231, 334, 337, 338 Stearine 124 Sublimation 65, 66 Sulphates of potassium 263 Sulphur 105, 112, 123, 137, 285; principle of combustibility of 146 Sulphuric acid, specific gravity of solutions of 80 Sulphurous anhydride 117, 270, 285 Symbolic notation 318 * Tartaric acid 3 ; dextro 61 ; laevo 61 Tellurium 137 ; atomic weight of 374 ; combining weight of 331, 332 ; com- pounds 138 Ternary compounds 363 Thales 104 Thenard 110 "Thermite" 53 Thomsen, J. 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