None
of insulators, 172 of air in closed vessels, 351, 373 increase of, with time, in a closed vessel, 351 of air in caves and cellars, 357 variation of in closed vessels with pressure and nature of gas, 376 variation of with temperature for air in closed vessels, 377 Conservation of radio-activity examples of, 308 Cooke, H. L. penetrating rays from the earth, 366 number of ions per c.c. in closed vessels, 376 radio-activity from ordinary matter, 378 Corpuscle (see Electron) Crookes (Sir W.) spectrum of polonium, 20 separation of Ur X, 178 nature of a rays, 116 scintillations produced by radium, 127 spinthariscope, 127 number of scintillations independent of pressure and temperature, 128 theory of radio-activity, 319 cathode rays, 347 Crookes and Dewar absence of nitrogen spectrum in phos- phorescent light of radium at low pressures, 169 Curie, Mme permanence of uranium rays, 6 discovery of radio-activity of thorium, 10 radio-activity of uranium and thorium minerals, 11 relative activity of compounds of ura- nium, 12 coloration of radium crystals, 15 spectrum of radium, 15 nature of a rays, 116 Curie, Mme (cont.) absorption of a rays from polonium, 131 secondary radiation tested by electric method, 148 slowly decaying excited activity from radium, 264 bismuth made active by solution of barium, 289 recovery of activity of radium, 303 Curie, P. magnetic deviation of radium rays by electric method, 96 heat emission of radium at low tem- perature and variation of heat emis- sion with age of radium, 159, 160 conductivity of dielectrics under radium rays, 172 radio-activity of radium unaffected by temperature, 173 decay of activity of radium emana- tion, 206 et seq. discovery of excited radio-activity from radium, 250 nature of the emanation, 318 Curie, M. et Mme discovery of radium, 13 charge carried by radium rays, 102 luminosity of radium compounds, 168 production of ozona by radium rays, 174 coloration of glass by radium rays, 174 theory of radio-activity, 318 possible absorption by radio-elements of unknown radiations, 321 Curie, J. et P. quartz piezo-electrique, 87 et seq. Curie, P. et Danne diffusion of radio-active emanation, 231 decay of excited activity from radium, 262 occlusion of radium emanation in solids, 264 Curie, P. and Debierne active gases evolved from radium, 210 phosphorescence produced by radium emanation, 211 distribution of luminosity, 211 rate of production of emanation inde- pendent of pressure, 224 effect of pressure on amount of ex- cited activity, 282 Curie, P. and Laborde heat emission of radium, 158 origin of heat from radium, 319 Current through gases, 28 et seq. variation of with distance between the plates, 56 et seq. INDEX 387 Current (cont.) variation of with pressure of gas, 58 et seq. variation of, with nature of gas, 61 measurement of, by galvanometer, 69 measurement of, by electroscope, 70 et seq. measurement of, by electrometer, 84 measurement of, by quartz piezo- electrique, 87 magnitude of, for one gram of radium, 156 Danne and Curie, P. diffusion of radium emanation, 231 decay of excited activity from radium, 262 occlusion of radium emanation in solids, 264 Danysz action of radium rays on skin, 177 Darwin, G. H. age of sun, 343 Debierne actinium, 22 emanation from actinium, 208 effect of magnetic field on activity excited from actinium, 288 barium made active by actinium, 289 Debierne and Curie evolution of gas from radium, 175 active gas evolved from radium, 210 phosphorescence produced by radium emanation, 211 distribution of luminosity, 211 rate of production of emanation inde- pendent of pressure, 224 effect of pressure on excited activity, 282 Decay of heating effect of emanation, 162 of activity of Th X, 180 of activity of UrX, 182 significance of law of, 189 effect of conditions on the rate of, 190 of activity of thorium emanation, 200 of activity of radium emanation, 206 excited activity due to thorium for long exposure, 256 excited activity due to thorium for short exposure, 258 excited activity due to radium, 261 excited activity of slow decay due to radium, 264, 291 excited activity from atmosphere, 351 et seq. of activity of rain and snow, 356 of emanation from earth, 358 differences in, of excited activity from atmosphere, 368 Deflection of rays in a magnetic field, 92 - of /3 rays in a magnetic field, 95 et seq. of /3 rays in an electrostatic field, 106 of a rays in a magnetic field, 117 et seq. of a rays in an electrostatic field, 121 of "ions activants" in a magnetic field, 288 Demarcay spectrum of radium, 16 Des Coudres magnetic and electric deviation of a rays of radium, 122 determination of elm for a rays, 122 velocity of cathode rays diminished in passage through matter, 139> Dewar emission of heat from radium in liquid hydrogen, 160 Dewar and Crookes absence of nitrogen spectrum in phos- phorescent light of radium at low pressures, 169 Dielectrics conduction of, under radium rays, 172 Diffusion of ions, 49 of radium emanation into gases, 228 et seq. of thorium emanation into gases, 233 of radium emanation into liquids, 235 Discharge action of rays on spark and electrode- less, 171 Disintegration account of theory of, 126, 193, 323 et seq. list of products of, 326 helium a product of, 327 et seq. rate of, in radio-elements, 332 et seq. emission of energy in consequence of, 336 et seq. possible causes of, 338 et seq. of matter in general, 347 et seq. Dissipation of charge in closed vessels, 351, 373 in caves and cellars, 357 effect of pressure and nature of gas on, 376 et seq. effect of material of vessel on, 378 et seq. Dolezalek electrometer, construction of, 78 et seq. Dorn charge carried by radium rays, 104 electrostatic deflection of ft rays from radium, 106 discovery of radium emanation, 205 effect of moisture on emanating power of thorium, 214 electrolysis of radium solution, 276 25—2 388 INDEX Dorn (cont.) loss of weight of radium, 336 Durack ionization by collision of electrons of great velocity, 139 Dust effect of, in recombination of ions, 39 effect of, on distribution of excited activity, 260 Earth amount of radium in, 344 age of, 344 excited activity deposited on, 354 activity concentrated on peaks of, 354 emanation from, 363 very penetrating radiation from, 366 Ebert condensation of emanation from the earth, 359 Ebert and Ewers emanation from the earth, 358 Electric field deflection of j8 rays by, 106 deflection of a rays by, 121 movement in, of carriers of excited activity, 282 et seq. action on, of carriers of excited ac- tivity from "emanating substance," 287 Electrolysis separation of radio-tellurium by, 21 of solutions of emanation X, 276 of thorium solutions, 277 of radium solutions, 276 Electrometer description of, 74 et seq. use of, in measurements, 74 construction of, 76 et seq. Dolezalek, 78 adjustment and screening of, 79 special key for, 81 application of, to measurements of radio-activity, 81 et seq. measurement of current by, 84 capacity of, 85 use with quartz piezo-electrique, 87 Electron definition of, 53 identity of /3 rays with electrons, 102 et seq., 107 variation of apparent mass of electron with velocity, 108 et seq. evidence that mass of electron is electro-magnetic, 112 diameter of, 112 production of, under different condi- tions, 347 Electroscope description of, used by Curie, 70 Electroscope (cont.) construction of, for accurate measure- ments, 71 use of, in measurements of minute currents, 71 of C. T. E. Wilson, 73 use of, in measuring conductivity of air in closed vessels, 373 et seq. use of, for determining radio-activity of ordinary matter, 378, 380 Elster and Geitel radio-active lead, 25 effect of magnetic field on conductivity produced in air by radium rays, 95 scintillations produced by active sub- stances, 127 action of radium rays on spark, 171 photo-electric action of body, coloured by radium rays, 174 radio-active matter in earth, 345 discovery of excited activity in atmo- sphere, 351 emanations from the earth, 357 radio-activity of air in caves, 362 radio-activity of the earth, 362 radio-activity of natural carbonic acid, 364 variation of radio-activity in atmo- sphere with meteorological condi- tions, 364 et seq. effect of temperature and pressure on atmospheric radio-activity, 365 Emanation «* rate of heat emission by, 158 A variation of heat emission with time, 160 of thorium, discovery and properties, 197 methods of measurement of, 199 decay of activity of, 200 effect of thickness of layer, on amount of, 202 increase of, with time, to a maxi- mum, 204 of radium, 205 decay of activity of, 206 of actinium, properties of, 208 of radium, phosphorescence produced by, 209 et seq. rate of emission of, 213 effect of conditions, on rate of emis- sion of, 214 regeneration of emanating power, 215 continuous rate of production of, 216 et seq. source of thorium emanation, 220 source of radium emanation, 222 radiations from, 222 effect of pressure on production of, 224 chemical nature of, 225 INDEX 389 Emanation (cont.) experiments to illustrate gaseous na- ture of, 227 rate of diffusion of radium emanation, 228 et seq. rate of diffusion of thorium emana- tion, 233 diffusion of, into liquids, 235 condensation of, 236 et seq. temperature of condensation of, 238 et seq. volume of, from 1 gram of radium, and thorium, 246 heat emission of, 247 connection between emanations and excited activity, 253 et seq. effect of removal of, on activity of radium, 300 effect of rate of escape of, on activity of radium, 302 fraction of activity of radium, due to, 304 experimental separation, and volume of, 311 et seq. decrease of volume of, with time, 313 radio-activity of atmosphere, due to emanations, 354 sucked up from the earth, 357 rate of decay of activity of, from the earth, 358 condensation of, from atmosphere, 359 in caves, 357 in well-water, and springs, 360 in natural carbonic acid gas, 364 from " fango," 363 effect of meteorological conditions on amount of, in atmosphere, 364 from metals, 378 Emanation X (see Excited radio-activity) definition of, 256 chemical and physical properties of, 275 electrolysis of, 276 effect of temperature on, 277 emission of heat by, 278 transmission of, to negative elec- trode, 282 et seq. irregularities in decay of activity of ThX due to, 295 removal of, by successive precipita- tions, 296 theory of effect of production of, on activity of ThX, 295 et seq. Emanating power measurement of, 213 effect of conditions on, 214 regeneration of, 215 " Emanating substance " of Giesel separation and properties of, 23 et seq. similarity of, to actinium, 24 "Emanating substance" of Giesel (cont.) emanation from, 209 excited activity produced by, 287 action of an electric field on, 287 Energy of a particle, 125 of /9 particle, 151 comparison of, for a and /3 particles, 150 emitted from radio-elements, in form of a rays, 154 emitted from radium in form of heat, 158 et seq. emission of, from the emanation, 161 et seq., 247 emission of, from radio-active pro- ducts of radium, 278 total emission of, from 1 gram of radio-elements, 336 latent store of, in matter, 337 Eve conductivity of gases for very pene- trating Rontgen rays, 145 Evolution of matter evidence of, 348 Ewers and Ebert emanation from the earth, 358 Excited radio-activity heat emission due to, 161 et seq. discovery and properties of, 250 concentration of, on negative elec- trode, 252 connection of, with the emanations, 253 removal of, by acids, 255 decay of, due to thorium, 256 decay of, for short exposurgTo thorium, 259 effect of dust on distribution of, 260 decay of, from radium, 261 of radium, of very slow decay, 264 connection between decay curves of, and times of exposure, 265 theory of successive changes to give rise to, 268 changes in emanation X of thorium, 270 et seq. changes in emanation X of radium, 272 physical and chemical properties of emanation X, 275 electrolysis of active solutions, 276 effect of temperature on, 277 emission of heat, due to, 278 variation with electric field, of amount of, 280 effect of pressure on distribution of, 282 transmission of, 282 et seq. from actinium, and " emanating sub- stance," 287 390 INDEX Excited radio-activity (cont.) possible connection of polonium and radio-tellurium with, 290 et seq. from the atmosphere, 351 et seq. concentration of, on negative elec- trode, 351 decay of, 353 due to emanation in atmosphere, 354 distribution of, on surface of earth, 354 concentration of, on prominences of the earth, 354 of rain and snow, 356 decay of, on rain and snow, 356 due to emanation from earth, 357 produced by emanation from tap water, 360 effect of meteorological conditions on amount of, 364 amount of, at Niagara Falls, 366 rate of decay of, dependent on con- ditions, 368 Exner and Haschek spectrum of radium, 17 Eye action of radium rays on, 177 Fehrle distribution of excited activity on a plate, in electric field, 282 Fluorescence produced in substances by radium rays, 18 produced in substances by radium and polonium rays, 166 Fog large amount of excited activity, during, 365 Forch loss of weight of radium, 336 7 rays discovery of, 141 absorption of, by matter, 142 connection between absorption of, and density, 143 discussion of nature of rays, 143 et seq. conservation of radio-activity mea- sured by, 311 measurement of radio-activity by means of, 321, 339 Gases evolved by radium, 175 presence of helium in gases from radium, 176, 327 et seq. Gates, Miss F. effect of temperature on excited ac- tivity, 278 discharge of quinine sulphate, 372 Geitel natural conductivity of air in closed vessels, 351, 373 Geitel and Elster radio-active lead, 25 effect of magnetic field on conducti- vity produced by radium rays, 95 scintillations produced by active sub- stances, 127 action of radium rays on spark, 171 photo-electric action of bodies co- loured by radium rays, 174 radio-active matter in earth, 345 discovery of radio-active matter in atmosphere, 351 emanations from the earth, 357 radio-activity of air in caves, 362 radio-activity of the soil, 362 radio-activity of natural carbonic acid, 364 variation of radio-activity of air, with meteorological conditions, 364 et seq. effect of temperature and pressure on radio-activity in atmosphere, 365 Giesel coloration of bunsen flame by radium, 15 separation of radium by crystallization of bromide, 15 emanating substance, 23 radio-active lead, 26 magnetic deviation of ft rays, 95 temperature of radium bromide above air, 159 decrease with time of luminosity of radio-active screen, 168 coloration of bodies by radium rays, 174 evolution of gases from radium, 176 action of radium rays on eye, 177 emanation from the emanating sub- stance, 209 luminosity produced by radium ema- nation, 209 excited activity from emanating substance, 287 bismuth made active by radio-active solution, 289 activity of radium dependent on age, 300 Glass coloration produced in, by radium rays, 174 phosphorescence produced by emana- tion, 210 Globulin action of radium rays on, 175 Goldstein canal strahlen, 92 coloration of bodies by radium rays, 174 INDEX 391 Grier and Kutherford magnetic deviation of /3 rays of thorium, 96 relative current due to a and /3 rays, 150 nature of rays from Ur X, 294 Hardy coagulation of globulin by radium rays, 175 Hardy and Miss Willcock coloration of iodoform solutions by radium rays, 175 Hardy and Anderson action of radium rays on the eye, 177 Harms number of ions per c.c., in closed vessel, 376 Haschek and Exner spectrum of radium, 17 Heat rate of emission of, from radium, 158 emission of, from radium at low temperatures, 159 rate of emission of, after removal of the emanation, 162 rate of emission of, by the emanation, 162 variation with time of heat emission of radium, and of its emanation, 162 • connection of heat emission with the radio-activity, 161 source of heat energy, 163 heating effect of the emanation, 247 heating effect of emanation X, 278 et seq. proportion of heating effect, due to radio-active products, 280 total heat emission during life of radio -elements, 336 heating of earth by radio-active matter, 344 Heaviside apparent mass of moving charged body, 109 Helium produced by radium and its emana- tion, 327 amount of, from radium, 331 origin of, 331 Helmholtz and Kicharz action of ions on steam jet, 44 Hemptinne action of rays on spark, and electrode- less discharge, 171 Henning resistance of radium solutions, 171 effect of voltage on amount of ex- cited activity, 281 Heydweiler loss of weight of radium, 336 Himstedt action of radium rays on selenium, 171 Himstedt and Nagel action of radium rays on eye, 177 Hofmann and Strauss radio-active lead, 26 Hofmann and Zerban active substance from pitchblende, 25 Huggius, Sir W. and Lady spectrum of phosphorescent light of radium bromide, 169 Hydrogen production of, by radium rays, 176 Induced radio-activity (see Excited radio-activity) Induction radio-active, 21 meaning, and examples of, 289 Insulators conduction of, under radium rays, 172 Iodoform coloration produced in, by radium rays, 175 lonization theory of, to explain conductivity of gases, 28 et seq. by collision, 36, 54 variation of, with pressure of gas, 58 et seq. variation of, with nature of gas, 62 comparison of, produced by rays, 93, 149 total, produced by 1 gram radium, 154 production of, in insulators, 172 natural ionization of gases, 373 et seq. Ions in explanation of conductivity of gases, 28 et seq. rate of recombination of, 37 et seq. mobility of, 39 et seq. difference between mobility of positive and negative, 42, 43 condensation of water around, 43 et seq. difference between positive and nega- tive, 46 charges carried by, 47 diffusion of, 48 et seq. charge on ion same as on hydrogen atom, 51 number of, produced per c.c., 52 size and nature of, 52 et seq. definition of, 52 et seq. production of, by collision, 36, 54 velocity acquired by, between colli- sions, 55 energy required to produce, 55 comparative number of, produced in gases, 62 392 INDEX Ions (cont.) disturbance of potential gradient by movement of, 63 number of, produced by a particle, 155 production of, in insulators, 172 number produced per c.c., in closed vessels, 375 Joly absorption of radium rays by at- mosphere, 343 (see foot-note) Kauffmann variation of ejm with velocity of electron, 108 et seq. Kelvin theory of radio-activity, 320 age of sun and earth, 343, 344 Kelvin, Smolan and Beattie discharging power of uranium rays, 7 Kunz phosphorescence of willemite, and kunzite, 168 Kunzite phosphorescence of, under radium rays, 168 Laborde and Curie heat emission of radium, 19, 158 origin of heat from radium, 319 Langevin coefficient of recombination of ions, 38 velocity of ions, 39 et seq. energy required to produce an ion, 55 secondary radiation produced by X- rays, 146 Larmor electrons and matter, 108 structure of the atom, 126 radiation from accelerated electrons, 340 Lead, radio-active preparation of, 26 radiations from, 26 Le Bon rays from bodies exposed to sunlight, 5 discharging power of quinine sulphate, 9, 372 Lenard ionization of gases by ultra-violet light, 9 action of ions on a steam jet, 44 negative charge carried by Lenard rays, 102 absorption of cathode rays propor- tional to the density, 113 Lerch, von chemical properties of emanation X, 275 Lerch, von (cont.) electrolysis of solution of emanation X, 276 effect of temperature on excited act- ivity, 278 Lockyer inorganic evolution, 349 Lodge connection of heat emission with a rays, 164 instability of atoms, 340 Lorentz structure of atoms, 126 Lowry and Armstrong radio-activity and phosphorescence, 323 Luminosity of radium compounds, 168 change of, in radium compounds with time, 168 spectrum of phosphorescent light from radium bromide, 169 of radium compounds unaffected by temperature, 173 Magnetic field effect of on rays, 92 deflection of /3 rays by, 95 et seq. ,, ,, a rays by, 117 et seq. ,, ,, "ionsactivants"by, 288 Marckwald preparation of radio-tellurium, 21 apparent mass of electron, 107 et seq. variation of mass of electron with speed, 108 et seq. of a particle, 122, 125 Materials radio-activity of ordinary, 370, 378 Matteucci rate of dissipation of charge in closed vessels, 373 McClung coefficient of recombination of ions, 38 McClung and Eutherford energy required to produce an ion, 55 variation of current with thickness of layer of uranium, 149 estimate of energy radiated from radio- elements, 154 radiation of energy from radium, 317 McLennan absorption of cathode rays, 62 radio-activity of snow, 356 excited radio-activity at Niagara Falls, 366 McLennan and Burton penetrating radiation from the earth, 366 INDEX 393 McLennan and Burton (cont.) radio-activitv of ordinary materials, 378 emanation from ordinary matter, 379 Mercury emanation from, 381 Metabolon definition of, 324 table of metabolons, 326 radio-elements as metabolons, 332 Meteorological conditions effect of, on radio-activity of atmo- sphere, 364 Methods of measurement in radio-activity, 67 et seq. comparison of photographic and elec- trical, 67 et seq. description of electrical, 68 et seq. Meyer and Schweidler magnetic deviation of £ rays by elec- trical method, 95 absorption of ft rays of radium by matter, 113 Mobility of ions, 39 et seq. Moisture effect of, on velocity of ions, 40, 42 effect of, on emanating power, 214 Molecule number of, in 1 c.c. of hydrogen, 51 molecular weight of radium emana- tion, 232 molecular weight of thorium emana- tion, 234 Molecular weight of radium emanation, 232 of thorium emanation, 234 Nagel and Himstedt action of radium rays on eye, 177 Niewenglowski rays from sulphide of calcium, 4 Number of molecules per c.c. of hydrogen, 51 of ions produced in gas by active substances, 52 of a particles emitted per gram of radium, 155 of ions, produced per c.c. in closed vessels, 375 Occlusion of emanation in thorium and radium, 217 of radium emanation by solids, 264 Owens saturation current affected by dust, 39 effect of air currents on conductivity produced by thorium, 197 Owens (cont.) penetrating power of rays independent of compound, 132 absorption of a rays varies directly as pressure of gas, 137 Oxygen change into ozone, by radium rays, 174 production of from radium solutions, 176 Ozone production of, by radium rays, 174 Paraffin objection to as an insulator, 80 conductivity of, under radium rays, 173 Patterson number of ions per c.c. in closed vessel, 376 natural conductivity of air due to an easily absorbed radiation, 377 effect of temperature on natural con- ductivity of air, 377 Pegram electrolysis of thorium solutions, 277 Penetrating power comparison of for a, ft and, y rays, 93 variation in, of ft rays, 98 et seq. comparison of, for a rays from radio- elements, 136 variation of, with density for ft rays, 112 et seq. variation of, with density for a rays, 137 variation of, with density for y rays, 143 Penetrating radiation from the earth and atmosphere, 366 Perrin negative charge of cathode rays, 102 theory of radio-activity, 316 Phosphorescence production of, by radium, 18 production of, by radium and polon- ium rays, 166 comparison of, produced by a and ft rays, 168 of zinc sulphide, 167 of barium platino-cyanide, 168 of willemite and kunzite, 168 diminution of, with time, 168 of radium compounds, 168 spectrum of phosphorescent light of radium bromide, 169 production of by heat (thermo-lumin- escence), 170 produced by radium emanation in substances, 210, 227 use of, to illustrate condensation of emanations, 237 394 INDEX Phosphorus action of radium rays on, 175 ionization produced by, 371 Photo-electric action produced by radium rays in certain substances, 174 Photographic method, advantages and disadvan- tages of, 67 relative photographic action of rays, 68 Physical action of radium rays on sparks, 171 on electrodeless discharge, 171 on selenium, 171 on conductivity of insulators, 172 Physical properties of emanation X, 275 Physiological action of radium rays production of burns, 176 effect on bacteria, 177 effect on cancer, 177 effect on eye, 177 Piezo-electrique of quartz description of, 87 Pitchblendes comparison of radio-activity of, 11 radio-elements separated from, 13 et seq. radium continually produced from, 334 Polarization of uranium rays absence of, 7 Polonium methods of separation of, 19 rays from, 20 decay of activity of, 20 discussion of nature of, 21 similarity to radio-tellurium, 22 magnetic deviation of a rays from, 121 increase of absorption with thickness of matter traversed, 131 phosphorescent action of rays from, 166 possible origin of polonium and con- nection with radium, 290 et seq. penetrating rays from, 305 Potential required to produce saturation, 30 et seq. fall of potential, to produce ions each collision, 55 gradient, due to movement of ions, 63 Precht and Eunge atomic weight of radium, 17 heating effect of radium, 164 Pressure effect of, on velocity of ions, 43 Pressure (cont.) effect of, on current through gases, 58 et seq. production of emanation, independent of, 224 effect of, on distribution of excited activity, 282 effect of, on natural conductivity of air in closed vessels, 376 Products, radio-active ' radiations from, 304 division of activity amongst, 306 list of from radio-elements, 326 Quartz piezo-electrique use of, in measurement of current, 37 Quinine sulphate discharging power of, 9, 372 phosphorescence of, 372 Kadiations emitted by uranium, 8 emitted by thorium, 10 emitted by radium, 18 emitted by polonium, 20 emitted by actinium, 23 methods of measurement of, 67 et seq. methods of comparison of, 90 three kinds of, 91 analogy to rays from a Crookes tube, 92 * relative ionizing and penetrating power of, 93 difficulties of comparative measure- ment of, 93 et seq. /3 rays, 95 et seq. a rays, 115 et seq. 7 rays, 141 et seq. secondary rays, 146 comparison of ionization of a and /5 rays, 149 et seq. connection of, with heat emission, 160 phosphorescent effect of, 166 physical actions of, 171 et seq. chemical actions of, 174 et seq. physiological actions of, 176 from the emanation, 222 from Ur X, 293 non-separable activity of radio-ele- ments consists of a rays, 304 from different active products, 304 conservation of energy of each specific type of, 308 Kadium discovery of, 13 separation of, 13 spectrum of, 15 atomic weight of, 17 radiations from, 18 INDEX 395 Radium (cont.) compounds of, 19 nature of radiations from, 90 et seq. /3 rays from, 95 et seq. a rays from, 115 et seq. y rays from, 141 et seq. secondary rays from, 147 heat emission of, 158 et seq. production of phosphorescence by, 166 et seq. spectrum of phosphorescent light of, 169 physical actions of, 171 et seq. chemical actions of, 174 physiological actions of, 176 emanation from, 205 et seq. properties of emanation from, 205 et seq. chemical nature of emanation from, 225 et seq. diffusion of emanation from, 228 et seq. condensation of emanation from, 236 et seq. amount of emanation from, 246, 312 heat emission of emanation from, 247, 278 excited radio-activity from, 251 et seq. decay of excited activity from, 261 et seq. successive changes in emanation X of, 272 properties of emanation X of, 275 heating effect due to products of, 278 radio-active induction due to, 289 connection of, with polonium, 291 alteration of activity of, by removal of emanation, 300 recovery of activity of, after removal of emanation, 301 effect of escape of emanation on . recovery of activity of, 302 non-separable acthity of. 302, 304 radiations from active products of, 304 division of activity amongst active products of, 306 conservation of radio-activity of, 308 determination of volume of emanation of and diminution with time, 313 et seq. theories of radio-activity of, 316 discussions of theories of radio-activity of, 320 energy of radiations, not derived from external source, 321 theory of radio-active change, 322 list of active products of, 326 polonium possible product of, 326 production of helium from, 327 helium disintegration product of, 327 amount of helium from, 331 Radium (cont.) rate of change of, 332 life of, 333 origin of, 333 possible production of, by uranium, 334 loss of weight of, 335 experiments to determine loss of weight of, 336 total emission of energy from 1 gram of, 336 possible causes of disintegration of, 338 amount of, to account for heat of sun, 342 possible connection of with heat of sun, 342 probable amount of, in earth, 345 possible connection with heat of earth, 344 Rain radio-activity of, 355 decay of activity of, 356 Ramsay and Soddy evolution of gas from radium, 176 chemical nature of the emanation, 227 gaseous nature of the emanation, 227 volume of emanation, and change witfi time, 313 helium from radium emanation, 328 Re, Filippo theory of radio-activity, 320 Recombination of ions, 37 et seq. constant of, 39 Recovery of heating effect of radium, 162 of activity of thorium after removal of Th X, 181 of activity of uranium after removal of Ur X, 182 significance of law of, 185 effect of conditions on rate of, 191 of activity of radium, after removal of emanation, 301 Reflection no evidence of direct reflection for uranium rays, 7 diffuse reflection of rays, 7 Refraction no evidence of, for uranium rays, 7 Regeneration of emanating power, 215 Richarz and von Helmholtz action of ions on steam jet, 44 Runge spectrum of radium, 17 Runge and Precht atomic weight of radium, 17 heating effect of radium, 164 396 INDEX Eunge and Bodlander evolution of gas from radium, 176 Kussell photographic action of substances, 68 Saturation current meaning of, 30 et seq. application of, to measurements of radio-activity, 69 measurement of, 82 et seq. Schmidt discovery of radio-activity of thorium, 10 Schmidt and Wiedemann thermo-luminescence, 170 Schuster radio-activity of matter, 371 Schweidler and Meyer magnetic deviation of /3 rays by electric method, 95 absorption of /3 rays of radium, 113 Scintillations discovery of in zinc sulphide screen, 127 connection of, with a rays, 127 illustration of by spinthariscope, 127 cause of, 128 production of, by action of electric field, 128 Searle apparent mass of moving charged body, 109 Secondary rays examination of, by photographic method, 146 examination of, by electrical method, 148 Selenium action of radium rays on, 171 Simon value of e/m for cathode rays, 111 Smolan, Beattie and Kelvin discharging power of uranium rays, 7 Snow radio-activity of, 356 decay of activity of, 356 Soddy comparison of photographic and elec- trical action of uranium rays, 68 nature of rays from Ur X, 294 Soddy and Kamsay evolution of gas from radium, 176 chemical nature of the emanation, 227 gaseous nature of the emanation, 227 volume of the emanation, and change with time, 313 helium from radium emanation, 320 Soddy and Rutherford separation of ThX, 179 Soddy and Rutherford (cont.) decay of activity of Th X, 181 recovery of activity of thorium, freed from Th X, 181 decay of activity of UrX, 182 recovery of activity of uranium, freed from Ur X, 182 explanation of decay and recovery curves, 183 rate of production of ThX, 186 theory of decay of activity, 188 influence of conditions on rate of decay and recovery of activity, 190 et seq. disintegration hypothesis, 194, 324 decay of activity of radium emanation, 206 measurements of emanating power, 213 effect of temperature, moisture, and solution, on emanating power, 214 regeneration of emanating power, 215 constant rate of production of emana- tion of radium and thorium, 216 et seq. source of thorium emanation, 220 radiations from the emanation, 222 chemical nature of emanation, 226 condensation of emanations of radium and thorium, 236 et seq. temperature of condensation of emana- tion, 238 et seq. effect of successive precipitations on activity of thorium, 2J6 recovery of activity of radium, 300 conservation of radio-activity, 309 theory of radio-activity, 318 theory of radio-active change, 324 Soil radio-activity of, 362 difference in activity of, 362 Solution coloration of, by radium, 15 of emanation X in acids, 275 electrolysis of active, 276 Source of the thorium emanation, 220 of radium emanation, 222 Spark action of radium rays on, 171 Spectrum spark spectrum of radium, 15, 16 flame spectrum of radium, 17 effect of a magnetic field on spectrum of radium, 17 of polonium, 20 of phosphorescent light of radium bromide, 169 of helium in radium gases and emana- tion, 329 INDEX 397 Spectrum (cont.) of emanation, 329 Spinthariscope description of, 127 Springs emanation from water of, 360 Stark energy to produce an ion, 55 Strauss and Hofmann radio-active lead, 25 Strutt conductivity of gases for radiation, 61, 62 negative charge carried by radium rays, 104 absorption of /3 rays proportional to density, 113 nature of a rays, 116 conductivity of gases produced by 7 rays, 62, 144 absorption of radium rays from sun by atmosphere, 343 radio-activity of ordinary matter, 378 emanation from mercury, 381 Sun effect of radium in, 342 age of, 343 Temperature of radium above surrounding space, 158 effect of, on intensity of radiations from uranium and radium, 173 effect of, on luminosity, 173 rate of decay of radium emanation unaffected by, 208 of condensation of emanations, 238 et seq. rate of decay of thorium emanation unaffected by, 246 effect of, on excited activity, 277 effect of, on amount of excited activity in atmosphere, 364 et seq. effect of, on natural ionizationofair,377 Theories of radio-activity, review of, 316 discussion of, 320 disintegration theory, 324 Thermo-luminescence, 170 Thomson, J. J. relation between current and voltage for ionized gases, 31 difference between ions as condensa- tion nuclei, 46 charge on ion, 47 theory of electrometers, 85 path of charged particle in uniform magnetic field, 96 apparent mass of moving charged body, 108 Thomson, J. J. (cont.) structure of atom, 126, 347 theory of radio-activity, 319 cause of heat emission from radium, 321 possible causes of disintegration of radium, 342 nature of electrons, 347 emanation from tap-water and deep wells, 360 Thomson, J. J., and Kutherford ionization theory of gases, 28 et seq. Thorium discovery of radio-activity of, 10 emanation from, 11 preparation of non-radio-active tho- rium, 25 nature of radiations from, 90 et seq. )3 rays from, 95 et seq. a rays from, 115 et seq. 7 rays from, 141 et seq. rate of emission of energy by, 154 separation of Th X from, 179 recovery of activity of, 181 disintegration of thorium, 193 emanation from, 197 properties of emanation from, 198 et seq.f diffusion of emanation from, 233 condensation of emanation from, 236 et seq. excited radio-activity from, 250 et seq. successive changes in emanation X of, 272 explanation of initial portion of decay curve, 295 et seq. explanation of initial portion of re- covery curve, 295 et seq. effect of successive precipitations on, 296 recovery curve after large number of precipitations, 297 theory of decay curve of Th X, 298 non- separable activity of, 296, 304 radiations from active products of, 304 et seq. division of activity amongst active products of, 306 et seq. conservation of radio-activity of, 308 et seq. resume of results, 311 et seq. theories of radio-activity of, 316 et seq. discussion of theories of radio-activity, 320 et seq. source of energy of radiations, 320 et seq. theory of radio-active change, 322 et seq. table of radio-active products of, 326 rate of change of, 332 et seq. % 398 INDEX Thorium (cont.) life of, 333 total emission of energy from 1 gram of, 337 possible causes of disintegration of, 338 et seq. Thorium X methods of separation of, 179 law of decay of activity of, 182 law of recovery of activity of, 182 theory to explain production of, 183 material nature of, 185 continuous production of, 186 explanation of decay of activity of, 188 et seq. effect of conditions on the rate of change of, 190 et seq. disintegration hypothesis to explain production of, 193 et seq. minute amount of, produced, 195 effect of successive separations of, on activity of thorium, 296 theory of decay curve of, 296 et seq. Tommasina scintillations produced by electrifica- tion, 128 Townsend ions by collision, 36, 54 coefficient of recombination, 38 diffusion of ions, 49 et seq. comparison of charge on ion with that on hydrogen atom in electrolysis, 51 number of molecules per c.c. of gas, 51 ionization by collision for different speeds, 139 Transmission of excited radio-activity of radium and thorium, 282 et seq. of excited radio-activity of actinium, 287 Troost rays from hexagonal blende, 4 Uranium discovery of radio-activity of, 5 persistence of radiations of, 6 discharging power of rays, 7 absence of reflection, refraction and polarization, 7 examination of uranium minerals, 11 et seq. relative activity of compounds of uranium, 12 nature of radiation from, 90 et seq. /3 rays from, 95 et seq. a rays from, 115 et seq. y rays from, 142 et seq. emission of energy by, 154 separation of Ur X from, 179 recovery of activity of, 182 Uranium (cont.) non-separable activity of, 294, 304 radiations from Ur X, 293 method of measurement of activity of Ur X, 294 changes in, 294 conservation of radio-activity of, 308 et seq. resume of results, 311 et seq. theories of radio-activity, 316 et seq. discussion of theories of radio- activity, 320 et seq. source of energy of radiation, 320 et seq. theory of radio-active change, 322 et seq. table of active products, 326 rate of change of, 332 et seq. life of, 333 radium possible product of, 334 total emission of energy from 1 gram of, 337 possible causes of disintegration of, 338 et seq. Uranium X separation of, by Crookes, 178 separation of, by Becquerel, 179 decay of activity of, 182 recovery of activity of, 182 theory to explain production of, 183 material nature of, 185 explanation of decay of activity of, 188 et seq. radiations from, 293 method of measurement of radiations from, 294 changes in, 294 Velocity of ions in electric field, 39 et seq. difference between, of positive and negative ions, 42 et seq. of [3 particle or electron, 107 et seq., 110 et seq. variation of mass of electron with, 108 et seq. of a particle, 122 et seq. of transmission of carriers of excited activity, 284 Villard discovery of 7 rays from radium, 141 alteration of X ray screen with time, 168 activity produced by cathode rays, 372 Volume of radium emanation, calculation of, 246 of emanation, determination of, 313 decrease of, of radium emanation, 313 INDEX 399 Walker, G. W. theory of electrometer, 75 Walkhoff action of radium rays on skin, 176 Wallstabe diffusion of radium emanation into liquids, 235 Water emanation from, 360 decay of activity of emanation from, 361 Water-falls amount of excited activity produced at Niagara, 366 electrification produced near, 366 Watts, Marshall atomic weight of radium, 17 Weight loss of by radio-elements, 335 attempts to measure loss of, in radium, 336 Wheeler and Bumstead emanation from surface water and the soil, 361, 368 identity of emanation from soil with radium emanation, 361 absence of emanation in mercury, 381 Whetham effect of valency of ion on colloidal solutions, 175 possible cause of disintegration of atom, 342 Wiedemann and Schmidt thermo-luminescence, 170 Wiedemann thermo-luminescence produced by radium rays, 170 Wien amount of charge carried by radium rays, 105 positive charge of canal rays, 125 Willcock, Miss, and Hardy coloration of iodoform solution by radium rays, 175 Willemite phosphorescence of under radium rays, 168 use to show condensation of emana- tion, 237 Wilson, W. E. radium in sun, 342 Wilson, H. A. charge on ion, 48 Wilson, C. T. E. ions as nuclei of condensation, 44 et seq. difference between positive and nega- tive ions as condensation nuclei, 46 equality of charges carried by positive and negative ions, 47 construction of electroscope, 73 natural ionization of air in vessels, 351 radio-activity of rain and snow,355,356 loss of charge in closed vessels, 373 presence of ions in free air shown by condensation, 375 number of ions produced per c.c., 375 effect of pressure and nature of gas on. ionization in sealed vessels, 376 Zeleny velocity of ions, 39 et seq. difference of velocity of ions, 40, 42 potential gradient between electrodes, 63 Zerban and Hofmann active substances from pitchblende, 25 Zinc Sulphide scintillations produced in by a rays, 127 cause of luminosity of, 127 et seq. scintillations due to cleavage of crystals, 128 CAMBRIDGE: PRINTED BY j. AND c. F. CLAY, AT THE UNIVERSITY PRESS. 14 DAY USE RETURN TO DESK FROM WHICH This book is due on the last date stamped below, or on the date to which renewed. Kenewed books are subject to immediate recall LD21-35m-8 '72 (Q4189slO)476 — A-32 General Library University of California Berkeley. 