_The numbers refer to the pages._
α rays discovery of, 141 nature of, 141 magnetic deviation of, 142 _et seq._ electrostatic deviation of, 146 velocity of, 148 value of _e_/_m_ for, 148 charge carried by, 151 _et seq._ number of α particles expelled from one gram of radium, 155 mass and energy of, 156 origin of, in atomic disintegration, 157 scintillations produced by, 158 _et seq._ absorption of, by matter, 161 _et seq._ increase of absorption with thickness of matter traversed, 163 relative absorption of α rays from radio-elements, 164 absorption of, by gases, 165 _et seq._ connection between absorption and density, 169 relation between ionization and absorption, 170 theory of absorption of, 170 _et seq._ range of ionization of, 172 _et seq._ complexity of α rays from radium, 174 _et seq._ effect of thickness of layer of radiating matter on emission of, 195 relative ionization produced by α and β rays, 196 _et seq._ phosphorescence by α rays, 202 _et seq._ connection of, with radio-active changes, 235, 444 _et seq._, 455 from the emanations, 263 emission of energy from radio-elements in form of α rays, 419 _et seq._ connection of heat emission of radium with α rays, 421 _et seq._ number of ions produced by an α particle, 433 absence of, in rayless changes, 454 emission from active products, 454 _et seq._ loss of weight due to expulsion of, 473 α particles consist of helium, 479 _et seq._ magnetic deflection of, from radium C, 543 velocity and _e_/_m_ for, from radium C, 543 _et seq._ diminution of velocity of, in passing through matter, 545 diminution in velocity of, in passing through aluminium, 545 velocity of, when ionization ceases, 545 _et seq._ connection of phosphorescent, photographic, and ionization effects produced by, 546 _et seq._ energy required to produce an ion by α rays, 551
Abraham apparent mass of moving charged body, 71, 127
Absorption law of, in gases, 64 _et seq._ relative absorption of α, β and γ rays by matter, 111 connection between absorption and ionization, 134 _et seq._, 170 _et seq._ of β rays by solids, 134 _et seq._ connection between absorption and density for β rays, 137 of β rays in radio-active matter, 140 of α rays by solids, 161 _et seq._ of α rays in gases, 167, 170 _et seq._ connection between absorption and density for α rays, 169 theory of, 170 _et seq._ of γ rays by solids, 179 _et seq._ connection between absorption and density for γ rays, 181 of rays from the emanations, 263 of penetrating rays from the earth, 520, 540
Actinium methods of separation of, 20 _et seq._ properties of, 21 similarity to “emanating substance” of Giesel, 21 possible connection with radio-activity of thorium, 28 emanation from, 249 excited activity produced by, 311 effect of magnetic field on excited activity from, 324 separation of actinium X, 365 decay of actinium X, 365 source of actinium emanation, 365 analysis of active deposit of, 366 radiations from products of, 368 penetrating power of β and γ rays from, 368 products of, 369 table of products of, 449 possible origin of, 464
Actinium A separation and period of, 367 _et seq._
Actinium B period of, 368 properties of, 368
Actinium X separation and decay of, 364 _et seq._ production of emanation by, 365
Adams decay of activity of emanation from well water, 511 decay of excited activity from the emanation, 511
Age of radium, 457 of sun and earth, 492 _et seq._
Allan, S. J. increase with time of excited activity from atmosphere, 505 radio-activity of snow, 506 effect of conditions on decay of activity from air, 519, 523
Allan and Rutherford decay of excited activity from the atmosphere, 503 ionization of air in closed vessels, 534
Allen, H. S. and Lord Blythswood radium emanation in Bath springs, 513
Anderson and Hardy action of radium rays on the eye, 217
Armstrong and Lowry radio-activity and phosphorescence, 444
Arnold rays from phosphorescent substances, 4
Aschkinass and Caspari action of radium rays on microbes, 216
Atmosphere excited activity from, 501 _et seq._ radio-activity of, due to emanations, 504 diffusion of emanations into, from the earth, 507 effect of temperature, pressure, &c. on radio-activity of, 517 _et seq._ presence of very penetrating radiation in, 520 comparison of radio-activity of, with radio-elements, 521 _et seq._ amount of radium emanation in, 524 _et seq._ ionization of, due to radium emanation, 526
Atom number of per c.c., 54 disintegration of, 234 _et seq._ complex nature of, 235 changing atoms, 444 _et seq._ possible causes of disintegration of, 486 evolution of, 496
Atomic weight of radium by chemical methods, 17 from spectroscopic evidence, 18 emanations, 273 of radio-elements and connection with radio-activity, 445
β rays discovery of, 113 magnetic deflection of, 114 complexity of, 116 examination by the electrical method, 118 effect of, on a fluorescent screen, 119 charge carried by the, 120 _et seq._ electrostatic deviation of, 124 velocity of, and value of _e_/_m_ for, 126 variation of _e_/_m_ with velocity of, 127 _et seq._ distribution of velocity amongst β particles, 131 absorption of, 134 _et seq._ variation of absorption with density, 136 _et seq._ number of β particles stopped by matter, 137 _et seq._ variation of intensity of, with thickness of layer, 140 secondary β rays, 189 _et seq._ relative ionization produced by α and β rays, 196 relative energy emitted in form of α and β rays, 196 _et seq._ phosphorescent action of, 201 _et seq._ physical action produced by, 207 _et seq._ chemical action of, 213 physiological action of, 216 from Ur X, 347 from active deposit of radium, 377 _et seq._ significance of appearance of, only in last radio-active changes, 455 change of weight due to expulsion of, 473
Barium platinocyanide phosphorescence of, under radium rays, 203 change of colour due to radium rays, 205
Barkla polarization of X rays, 80
Barnes and Rutherford heating effect of radium emanation, 421, 429 connection of heating effect with radio-activity, 421 heating effect of active deposit, 425 heating effect of γ rays, 429 heating effect of emanation, 431 division of heating effect among active products, 433
Bary phosphorescence under radium rays, 202
Baskerville activity of thorium, 29 phosphorescence of kunzite under radium rays, 203
Baskerville and Kunz phosphorescence of substances under radium rays, 204
Beattie, Smolan and Kelvin discharging power of uranium rays, 7
Becquerel rays from calcium sulphide, 4 rays from uranium, 5 _et seq._ permanence of uranium rays, 6 discharging power of uranium rays, 6 magnetic deflection of radium rays by photographic method, 114 _et seq._ curvature of radium rays in a magnetic field, 115 _et seq._ complexity of radium rays, 116 _et seq._ electrostatic deflection of β rays of radium, 124 _et seq._ value of _e_/_m_ for β rays of radium, 126 _et seq._ magnetic deviation of α rays of radium and polonium, 145 trajectory of rays of radium in magnetic field, 148 scintillations due to cleavage of crystals, 160 γ rays from radium, 179 secondary rays produced by active substances, 187 phosphorescence produced by radium rays, 201 conductivity of paraffin under radium radiation, 210 effect of temperature on uranium rays, 210 chemical action of radium rays, 214 removal of activity from uranium by precipitation with barium, 219 theory of radio-activity, 438
Bemont et M. et Mme Curie discovery of radium, 13
Berndt spectrum of polonium, 23
Blanc thorium in sediments from hot springs, 514
Blythswood, Lord and Allen, H. S. radium emanation in Bath springs, 513
Bödlander and Runge evolution of gases from radium, 215
Boltwood origin of radium, 460 amount of radium in minerals, 460 proportionality of uranium and radium in minerals, 461 production of lead by uranium, 484 radium emanation in spring water, 514 method of standardization of amount of emanation in waters, 514
Boys rate of dissipation of charge, 531
Bragg and Kleeman theory of absorption of α rays, 172 _et seq._ relation between ionization and absorption, 174 _et seq._ range of α rays in air, 174 four sets of α rays from radium, 174 _et seq._
Bronson use of steady deflection method with an electrometer, 104 decay of thorium emanation, 242 decay of excited activity from actinium, 312
Brooks, Miss variation of excited activity from thorium for short exposures, 304 effect of dust on distribution of excited activity, 305 decay curves of excited activity of radium measured by α and β rays, 307 _et seq._ decay curves of excited activity from actinium, 312
Brooks and Rutherford absorption of α rays by matter, 161 comparison of absorption of α rays from radio-elements, 164 diffusion of radium emanation, 270 decay of excited activity from radium, 306
Bumstead presence of thorium emanation in atmosphere, 512
Bumstead and Wheeler diffusion of radium emanation, 273 emanation from surface water and the soil, 512, 522 identity of emanation from soil with radium emanation, 512, 522
Burton radium emanation in petroleum, 516
Burton and McLennan penetrating radiation from the earth, 520 radio-activity of ordinary materials, 537 emanation from ordinary matter, 538
Campbell radio-activity of ordinary materials, 540
Canal rays discovery of, 78 magnetic and electric deflection of, 78 value of _e_/_m_ for, 78 similarity of, to α rays, 110
Capacity of electroscopes, 87 of electrometers, 94, 102 standards of, 102
Carbonic acid radio-activity of natural, 516
Caspari and Aschkinass action of radium rays on microbes, 216
Cathode rays discovery of, 73 magnetic and electric deflection of, 74 value of _e_/_m_ for, 75 radiation of energy from, 79 comparison of, with β rays, 120 absorption of, by matter, 136, 137 _see also_ β rays
Caves radio-active matter present in air of, 514 _et seq._ radio-activity of air of, due to emanation from the soil, 515
Changes (_see_ Transformations)
Charge carried by the ions, 50 _et seq._ negative charge carried by β rays, 120 measurement of charge carried by β rays, 121 _et seq._ positive charge carried by α rays, 145 measurement of charge carried by α rays, 151 _et seq._
Chemical nature of emanation, 267 of active deposit, 312
Chemical actions of radium rays production of ozone, 213 coloration of glass and rock-salt, 213 on phosphorus, 214 on iodoform, 214 on globulin, 214 evolution of hydrogen and oxygen, 215
Child potential gradient between electrodes, 65 variation of current with voltage for surface ionization, 66
Clouds formation of, by condensation of water round ions, 46 _et seq._ difference between positive and negative ions in formation of, 49
Collie and Ramsay spectrum of emanation, 292
Collision ionization by, 39, 57 number of ions produced by β rays per cm. of path, 434 total number of ions produced by collisions of α particles, 434
Coloration of crystals of radiferous barium, 15 of bunsen flame by radium, 15 of glass by radium rays, 213 of rock-salt, fluor-spar and potassium sulphate by radium rays, 213
Concentration of excited activity on negative electrode, 297 activity of radium independent of, 466
Condensation of water round the ions, 46 _et seq._ of emanations, 277 experimental illustration of, 279 temperature of, 280 difference between point of, for emanations of thorium and radium, 283 from air sucked up from the earth, 510
Conductivity of gases exposed to radiations, 31 _et seq._ variation of, with pressure, 61 _et seq._ variation of, with nature of gas, 64 comparison of, for gases exposed to α, β, and γ rays, 64 comparison of, when exposed to γ rays and to hard X rays, 184 of insulators, 209 of air in caves and cellars, 507 _et seq._ of air in closed vessels, 531 _et seq._ variation of, in closed vessels with pressure and nature of gas, 534 variation of, with temperature for air in closed vessels, 536 increase of, with time, in a closed vessel, 537
Conservation of radio-activity examples of, 469 _et seq._
Cooke, H. L. penetrating rays from the earth, 520 number of ions per c.c. in closed vessels, 534 radio-activity from ordinary matter, 536
Cooke, W. T. and Ramsay radio-activity produced by radiations of radium, 472
Corpuscle (_see_ Electron)
Crookes, Sir W. spectrum of radium, 17 spectrum of polonium, 23 nature of cathode rays, 73 nature of α rays, 142 scintillations produced by radium, 158 spinthariscope, 158 number of scintillations independent of pressure and temperature, 159 phosphorescence of diamond, 204 separation of Ur X, 219 theory of radio-activity, 441
Crookes and Dewar absence of nitrogen spectrum in phosphorescent light of radium at low pressures, 206
Crystallization effect of, on activity of uranium, 349
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 uranium, 12 coloration of radium crystals, 15 spectrum of radium, 16 discovery of polonium, 22 nature of a rays, 142 absorption of α rays from polonium, 163 secondary radiation tested by electric method, 188 slowly decaying excited activity from radium, 311 recovery of activity of radium, 375 bismuth made active by solution of barium, 417
Curie, P. magnetic deviation of radium rays by electric method, 114 conductivity of dielectrics under radium rays, 209 radio-activity of radium unaffected by temperature, 210 decay of activity of radium emanation, 247 discovery of excited radio-activity from radium, 295 heat emission of radium at low temperature and variation of heat emission with age of radium, 419 nature of the emanation, 439
Curie, M. et Mme discovery of radium, 13 charge carried by β rays, 121 luminosity of radium compounds, 205 production of ozone by radium rays, 213 coloration of glass by radium rays, 213 theory of radio-activity, 439 possible absorption by radio-elements of unknown radiations, 442
Curie, J. et P. quartz piezo-électrique, 105 _et seq._
Curie, P. et Danne diffusion of radio-active emanation, 272 decay of excited activity from radium, 309 decay curves of radium and equation, 309 occlusion of radium emanation in solids, 310 changes in radium, 381 effect of temperature on active deposit, 390
Curie, P. and Debierne evolution of gas from radium, 215 active gases evolved from radium, 251 phosphorescence produced by radium emanation, 252 distribution of luminosity, 252 rate of production of emanation independent of pressure, 266 effect of pressure on amount of excited activity, 266, 317
Curie and Dewar production of helium by radium, 479
Curie, P. and Laborde heat emission of radium, 419 origin of heat from radium, 440 radium emanation in waters of hot springs, 514
Current through gases, 31 _et seq._ variation of, with distance between the plates, 59 _et seq._ variation of, with pressure of gas, 61 _et seq._ variation of, with nature of gas, 64 measurement of, by galvanometer, 84 measurement of, by electroscope, 85 _et seq._ measurement of, by electrometer, 90 _et seq._ measurement of, by quartz piezo-électrique, 105
Dadourian presence of thorium emanation in the earth, 512
Danne on deposit of radium not containing uranium, 465
Danne et Curie diffusion of radio-active emanation, 272 decay of excited activity from radium, 309 decay curves of radium and equation, 309 occlusion of radium emanation in solids, 310 changes in radium, 381 effect of temperature on active deposit, 390
Danysz action of radium rays on skin, 216
Darwin, G. H. age of sun, 492
Debierne actinium, 21 emanation from actinium, 249 decay of excited activity from actinium, 311 effect of magnetic field on activity excited from actinium, 324 barium made active by actinium, 417
Debierne and Curie evolution of gas from radium, 215 active gases evolved from radium, 251 phosphorescence produced by radium emanation, 252 distribution of luminosity, 252 rate of production of emanation independent of pressure, 266 effect of pressure on amount of excited activity, 266, 317
Decay of activity of Th X, 221 of activity of Ur X, 223 significance of law of, 229 effect of conditions on the rate of, 232 of activity of thorium emanation, 241 of activity of radium emanation, 247 of activity of actinium emanation, 249 of excited activity due to thorium for long exposure, 302 of excited activity due to thorium for short exposure, 304 of excited activity due to radium, 306 _et seq._ excited activity of slow decay due to radium, 311 of excited activity from actinium, 311 of radium A, B and C, 377 _et seq._ of radium D, E and F, 397 _et seq._ of heating effect of emanation, 423 of excited activity from atmosphere, 502 of activity of rain and snow, 506 of emanation from the earth, 508 differences in, of excited activity from atmosphere, 521 _et seq._
Demarçay spectrum of radium, 16
Deposit, active connection of, with excited activity, 301 physical and chemical properties of, 312 electrolysis of, 313 effect of temperature on, 315 effect of pressure on distribution of, 317 transmission of, by positive carriers, 318 _et seq._ nomenclature of, 328 theory of changes in, 331 _et seq._ theory of activity due to, 337 _et seq._ theory of rayless change in, 341 _et seq._ of thorium, 302 _et seq._, 351 _et seq._ analysis of, 351 rayless change in, 352 effect of temperature on, 354 period of products of, 355 of actinium, 311 _et seq._ decay curves of, 311 analysis of, 367 rayless change in, 367 period of products of, 368 radiations from, 368 of radium, 376 _et seq._ connection of excited activity with, 306 general analysis of, 376 _et seq._ analysis of, of rapid change, 377 _et seq._ analysis of α ray curves, 377 α ray curves of, 378 β ray curves of, 379 analysis of β ray curves, 381 equations of activity curves, 389 effect of temperature on, 390 volatility of, 391 of slow transformation, 311, 397 variation of α ray activity of, 398 variation of β ray activity of, 399 separation of constituents of, 401 _et seq._ successive products in, 402 variation of activity of, for long periods, 407 presence in old radium, 408 effect of, on variation of activity of radium with time, 409 presence in pitchblende, 410 connection with radio-tellurium, 411 connection with polonium, 411, 412 connection with radio-lead, 413 connection of, with radio-active induction, 415 _et seq._ heat emission of, 425 _et seq._ use of, to determine number of β particles from radium, 435 use of, as source of α rays, 543
Des Coudres magnetic and electric deviation of α rays, 148 determination of _e_/_m_ for α rays, 148
Dewar emission of heat from radium in liquid hydrogen, 420
Dewar and Crookes absence of nitrogen spectrum in phosphorescent light of radium at low pressures, 206
Dewar and Curie production of helium by radium, 479
Dielectrics condition of, under radium rays, 209
Diffusion of ions, 51 _et seq._ of radium emanation into gases, 270 of thorium emanation into gases, 275 of radium emanation into liquids, 276
Discharge action of rays on spark and electrodeless, 208
Disintegration account of theory of, 234, 325, 445 list of products of, 449 rate of, in radio-elements, 457 emission of energy in consequence of, 474 _et seq._ helium a product of, 476 _et seq._ possible causes of, 486 _et seq._ of matter in general, 496 _et seq._
Dissipation of charge in caves and cellars, 514 _et seq._ in closed vessels, 531 effect of pressure and nature of gas on, 534 _et seq._ effect of material of vessel on, 536 _et seq._
Dolezalek electrometer, construction of, 94 _et seq._
Dorn charge carried by β rays, 122 electrostatic deflection of β rays from radium, 124 discovery of radium emanation, 246 effect of moisture on emanating power of thorium, 255 electrolysis of radium solution, 313 loss of weight of radium, 474 radium emanation in springs, 513
Dreyer and Salomonsen coloration of quartz by radium rays, 213
Dunston analysis of thorianite, 486
Durack ionization by collision of electrons of great velocity, 171
Dust effect of, on recombination of ions, 42 effect of, on distribution of excited activity, 305
Earth amount of radium in, 493 _et seq._ age of, 496 excited activity deposited on, 504 activity concentrated on peaks of, 504 emanation from, 507 very penetrating radiation from, 520
Ebert condensation of emanation from the earth, 510 apparatus for determining number of ions per c.c. in air, 527 velocity of ions in air, 528
Ebert and Ewers emanation from the earth, 508
Electrolysis separation of radio-tellurium by, 25 of solutions of active deposit, 313 of radium solutions, 313 of thorium solutions, 314
Electrometer description of, 90 _et seq._ use of, in measurements, 90 construction of, 91 _et seq._ Dolezalek, 94 adjustment and screening of, 95 special key for, 97 application of, to measurements of radio-activity, 97 _et seq._ measurement of current by, 100 capacity of, 101 use with steady deflection, 103 use with quartz piezo-électrique, 105
Electron definition of, 56 production of, under different conditions, 76 _et seq._ identity of β rays with electrons, 120 _et seq._ variation of apparent mass of electron with velocity, 127 _et seq._ evidence that mass of electron is electromagnetic, 129 _et seq._ diameter of, 131
Electroscope description of, used by Curie, 85 construction of, for accurate measurements, 86 use of, in measurements of minute currents, 86 of C. T. R. Wilson, 89 use of, in measuring conductivity of air in closed vessels, 531 _et seq._ use of, for determining radio-activity of ordinary matter, 537
Elster and Geitel radio-active lead, 27 effect of magnetic field on conductivity produced in air by β rays, 113 scintillations produced by active substances, 158 action of radium rays on spark, 208 photo-electric action of body, coloured by radium rays, 214 radio-active matter in earth, 494 discovery of excited activity in atmosphere, 501 emanations from the earth, 507 radio-activity of air in caves, 507 radio-activity of the soil, 515 radio-activity of fango, 516 variation of radio-activity in atmosphere with meteorological conditions, 517 effect of temperature and pressure on atmospheric radio-activity, 518
Emanation of thorium, discovery and properties of, 238 methods of measurement of, 240 decay of activity of, 241 effect of thickness of layer on amount of, 243 increase of, with time to a maximum, 245 of radium, 246 decay of activity of, 247 of actinium, properties of, 249 of radium, phosphorescence produced by, 251 rate of emission of, 254 effect of conditions on rate of emission of, 255 regeneration of emanating power, 256 continuous rate of production of, 257 source of thorium emanation, 261 source of radium and actinium emanation, 263 radiations from, 263 effect of pressure on production of, 265 chemical nature of, 267 experiments to illustrate gaseous nature of, 268 rate of diffusion of radium emanation, 269 rate of diffusion of thorium emanation, 275 diffusion of, into liquids, 276 condensation of, 277 temperature of condensation of, 280 volume of, from one gram of radium and thorium, 288 measurement of volume of, from radium, 289 diminution of volume of, 290 spectrum of emanation, 292 connection between emanation and excited activity, 298 effect of removal of, on activity of radium, 371 _et seq._ fraction of activity of radium due to, 374 effect of rate of escape of, on activity of radium, 374 heat emission of, 420, 431 variation of heat emission with time, 421 _et seq._ enormous emission of energy from emanation, 431 radio-activity of atmosphere due to emanations, 504 sucked up from the earth, 507 in caves, 507 _et seq._ rate of decay of activity of, from the earth, 508 condensation of, from the atmosphere, 510 in well water and springs, 510 _et seq._ from “fango,” 516 effect of meteorological conditions on amount of, in atmosphere, 517 _et seq._ from metals, 538
Emanating power measurement of, 254 effect of conditions on, 255 regeneration of, 256
Emanium or “emanating substance” of Giesel (_see_ Actinium) discovery of, 21 separation and properties of, 21 similarity of, to actinium, 21 emanation from, 249 excited activity produced by, 311 action of an electric field on, 323
Energy of α particle, 156 of β particle, 196 comparison of, for α and β particles, 196 emitted from radium in form of heat, 419 _et seq._ emission of, from the emanation, 431 emission of, from radio-active products of radium, 433 total emission of, from 1 gram of radio-elements, 474 _et seq._ latent store of, in matter, 475
Eve conductivity of gases exposed to X rays, 64 conductivity of gases exposed to X rays and γ rays, 183, 184 secondary rays produced by β and γ rays, 189 _et seq._ magnetic deflection of secondary rays from γ rays, 193 variation of activity of radium with concentration, 467 amount of radium emanation in the atmosphere, 524 _et seq._ ionization due to emanation in atmosphere, 526 _et seq._
Evolution of matter evidence of, 497
Ewers and Ebert emanation from the earth, 508
Excited radio-activity discovery and properties of, 295 _et seq._ concentration of, on negative electrode, 297 connection of, with the emanations, 298 removal of, by acids, 300 decay of, due to thorium, 302 decay of, for short exposure to thorium, 304 effect of dust on distribution of, 305 decay curves for different times of exposure, 306 _et seq._ decay of, from radium, 306 decay curves of, measured by α rays, 308 decay curves of, measured by β rays, 309 decay curves of, from actinium, 311 of radium, of very slow decay, 311 effect of solution on, 312 electrolysis of active solutions, 313 effect of temperature on, 315 variation with electric field, of amount of, 316 effect of pressure on distribution of, 317 transmission of, 318 from actinium and emanium, 323 heat emission due to, 425 _et seq._ from the atmosphere, 501 _et seq._ decay of, 502 due to emanation in atmosphere, 504 distribution of, on surface of the earth, 504 concentration of, on prominences of the earth, 504 of rain and snow, 506 produced by emanation from tap water, 510 effect of meteorological conditions on amount of, 517 _et seq._ amount of, at Niagara Falls, 520 rate of decay of, dependent on conditions, 522 _et seq._
Exner and Haschek spectrum of radium, 17
Eye action of radium rays on, 217
Fehrle distribution of excited activity on a plate in electric field, 318
Fluorescence produced in substances by radium rays, 18 produced in substances by radium and polonium rays, 201 _et seq._
Fog large amount of excited activity during, 518
Forch loss of weight of radium, 474
γ rays relative conductivity of gas exposed to γ and hard X rays, 64, 184 discovery of, 179 absorption of, by matter, 179 _et seq._ connection between absorption of, and density, 182 discussion of nature of rays, 182 _et seq._ secondary rays produced by γ rays, 189 measurement of radio-activity by means of, 442, 467 conservation of radio-activity measured by, 471
Gases evolved by radium, 215 presence of helium in gases from radium, 216
Gates, Miss F. effect of temperature on excited activity, 315 discharge of quinine sulphate, 530
Geitel natural conductivity of air in closed vessels, 501, 531
Geitel and Elster radio-active lead, 27 effect of magnetic field on conductivity produced by radium rays, 113 scintillations produced by active substances, 158 action of radium rays on spark, 208 photo-electric action of bodies coloured by radium rays, 214 radio-active matter in earth, 494 discovery of radio-active matter in atmosphere, 501 emanations from the earth, 507 radio-activity of air in caves, 507 radio-activity of the soil, 515 radio-activity of fango, 516 variation of radio-activity of air with meteorological conditions, 517 effect of temperature and pressure on radio-activity in atmosphere, 518
Giesel coloration of bunsen flame by radium, 15 separation of radium by crystallization of bromide, 15 emanating substance, 21 radio-active lead, 27 magnetic deviation of β rays, 113 decrease with time of luminosity of radio-active screen, 205 spectrum of phosphorescent light of emanium due to didymium, 206, 207 coloration of bodies by radium rays, 213 evolution of gases from radium, 215 action of radium rays on the eye, 217 emanation from the emanating substance, 250 luminosity produced by radium emanation, 251 decay of excited activity of emanium, 312 activity of radium dependent on age, 371 bismuth made active by radio-active solution, 417 temperature of radium bromide above air, 420
Gimingham and Rossignol decay of thorium emanation, 242
Glass coloration produced in, by radium rays, 213 phosphorescence produced in, by emanation, 252
Glew simple form of spinthariscope, and scintillations, 159
Globulin action of radium rays on, 214
Godlewski effect of crystallization on activity of uranium, 349 diffusion of uranium X, 350 separation of actinium X, 365 source of actinium emanation, 365 recovery and decay curves of actinium, 366 penetrating power of β and γ rays from actinium, 368 radiations from active products, 368
Goldstein canal rays, 78 coloration of bodies by radium rays, 213
Gonder, Hofmann, and Wölfl properties of radio-active lead, 27, 413
Grier and Rutherford magnetic deviation of β rays of thorium, 114 relative current due to α and β rays, 195 nature of rays from Ur X, 347
Hardy coagulation of globulin by radium rays, 214
Hardy and Miss Willcock coloration of iodoform solutions by radium rays, 214
Hardy and Anderson action of radium rays on the eye, 217
Harms number of ions per c.c. in closed vessel, 534
Hartmann spectrum of phosphorescent light of emanium, 206
Haschek and Exner spectrum of radium, 17
Heat rate of emission of, from radium, 419 _et seq._ emission of, from radium at low temperatures, 420 connection of heat emission with the radio-activity, 421 _et seq._ source of heat energy, 421 _et seq._ rate of emission of, after removal of the emanation, 422 _et seq._ rate of emission of, by emanation, 423, 431 variation with time of heat emission of radium, and of its emanation, 423 heating effect of the emanation, 423, 431 heating effect of active deposit, 425 proportion of heating effect due to radio-active products, 433 origin of, in radium, 442 _et seq._ total heat emission during life of radio-elements, 474 _et seq._ heating of earth by radio-active matter, 493
Heaviside apparent mass of moving charged body, 71, 127
Helium produced by radium and its emanation, 476 _et seq._ amount of, from radium, 480 origin of, 480
Helmholtz and Richarz action of ions on steam jet, 47
Hemptinne action of rays on spark and electrodeless discharge, 208
Henning resistance of radium solutions, 208 effect of voltage on amount of excited activity, 316
Henning and Kohlrausch conductivity of solutions of radium bromide, 208
Hertz electric deviation of cathode rays, 73
Heydweiler loss of weight of radium, 474
Himstedt action of radium rays on selenium, 208 radium emanation in springs of Baden, 513
Himstedt and Meyer production of helium by radium, 479
Himstedt and Nagel action of radium rays on the eye, 217
Hofmann, Gonder, and Wölfl properties of radio-active lead, 27, 413
Hofmann and Strauss radio-active lead, 27
Hofmann and Zerban connection of activity of thorium with uranium, 29
Huggins, Sir W. and Lady spectrum of phosphorescent light of radium bromide, 205
Hydrogen production of, by radium rays, 215
Induced radio-activity (_see_ Excited radio-activity)
Induction radio-active, 24 meaning and examples of, 415 _et seq._
Insulators conduction of, under radium rays, 209
Iodoform coloration produced in, by radium rays, 214
Ionization theory of, to explain conductivity of gases, 31 _et seq._ by collision, 39, 57 variation of, with pressure of gas, 61 _et seq._ variation of, with nature of gas, 64 comparison of, produced by rays, 111, 194 production of, in insulators, 209 total, produced by 1 gram of radium, 433 _et seq._ natural ionization of gases, 531 _et seq._ connection of, with phosphorescent and photographic actions, 549
Ions in explanation of conductivity of gases, 31 _et seq._ production of, by collision, 39, 57 rate of recombination of, 40 _et seq._ mobility of, 42 _et seq._ difference between mobility of positive and negative, 43 _et seq._ condensation of water around, 46 _et seq._ difference between positive and negative, 49 charge carried by, 50 diffusion of, 51 _et seq._ charge on an ion same as on hydrogen atom, 54 number of, produced per c.c., 54 size and nature of, 55 _et seq._ definition of, 56 _et seq._ velocity acquired by, between collisions, 58 energy required to produce, 58, 551 comparative number of, produced in gases, 65 disturbance of potential gradient by movement of, 65 production of, in insulators, 209 number of, produced by α particle, 433 number produced per c.c. in closed vessels, 533 _et seq._
Joly motion of radium in an electric field, 211 absorption of radium rays by atmosphere, 492 (see foot-note)
Kaufmann velocity of cathode rays, 75 variation of _e_/_m_ with velocity of electron, 127 _et seq._
Kelvin theory of radio-activity, 441 age of sun and earth, 492, 493
Kelvin, Smolan and Beattie discharging power of uranium rays, 7
Kleeman and Bragg theory of absorption of α rays, 172 _et seq._ relation between ionization and absorption, 174 _et seq._ range of α rays in air, 174 four sets of α rays from radium, 174 _et seq._
Kohlrausch conductivity of water altered by radium rays, 208
Kohlrausch and Henning conductivity of solutions of radium bromide, 208
Kunz phosphorescence of willemite and kunzite, 203
Kunz and Baskerville phosphorescence of substance under radium rays, 204
Kunzite phosphorescence of, under radium rays, 203
Laborde and Curie heat emission of radium, 419 origin of heat from radium, 440 radium emanation in waters of hot springs, 514
Langevin coefficient of recombination of ions, 41 velocity of ions, 45 _et seq._ energy required to produce an ion, 58 secondary radiation produced by X rays, 187 slow moving ions in air, 528
Larmor radiation theory, 77 radiation of energy from moving electron, 79 structure of the atom, 157
Lead, radio-active preparation of, 26 radiations from, 26
Le Bon rays from bodies exposed to sunlight, 5 discharging power of quinine sulphate, 9, 530
Lenard ionization of gases by ultra-violet light, 9 action of ions on a steam jet, 47 penetrating power of cathode rays, 73 negative charge carried by Lenard rays, 120 absorption of cathode rays proportional to density, 136, 137
Lerch, von chemical properties of active deposit of thorium, 313 electrolysis of solution of active deposit, 313 effect of temperature on excited activity, 315 temporary activity of active deposit from thorium, 415
Lockyer inorganic evolution, 499
Lodge, Sir Oliver electronic theory, 69 instability of atoms, 487
Lorentz structure of atoms, 157
Lowry and Armstrong radio-activity and phosphorescence, 444
Luminosity of radium compounds, 205 change of, in radium compounds with time, 205 spectrum of phosphorescent light from radium bromide, 206 of radium compounds unaffected by temperature, 210
Mache radium emanation in hot springs, 513
Mache and von Schweidler velocity of ions in air, 528
Makower diffusion of radium emanation, 274 diffusion of thorium emanation, 276
Marckwald preparation of radio-tellurium, 25 rate of decay of radio-tellurium, 411
Mass apparent mass of electron, 71, 127 variation of mass of electron with speed, 127 _et seq._ of α particle, 147 _et seq._
Materials radio-activity of ordinary, 528, 536 _et seq._
Matteucci rate of dissipation of charge in closed vessels, 531
McClelland absorption of γ rays, 181 secondary rays from β and γ rays from radium, 192
McClung coefficient of recombination of ions, 41 conductivity of gases exposed to X rays, 64 ionization by α rays from radium C, 550
McClung and Rutherford energy required to produce an ion, 58 variation of current with thickness of layer of uranium, 195 estimate of energy radiated from radio-elements, 418 radiation of energy from radium, 438
McLennan absorption of cathode rays, 65 radio-activity of snow, 506 excited radio-activity at Niagara Falls, 519
McLennan and Burton penetrating radiation from the earth, 520 radio-activity of ordinary materials, 537 emanation from ordinary matter, 538
Metabolon definition of, 446 table of metabolons, 449 radio-elements as metabolons, 457
Meteorological conditions effect of, on radio-activity of atmosphere, 517
Methods of measurement in radio-activity, 82 _et seq._ comparison of photographic and electrical, 83 _et seq._ description of electrical, 84 _et seq._
Meyer and Himstedt production of helium by radium, 479
Meyer and Schweidler magnetic deviation of β rays by electrical method, 113 absorption of β rays of radium by matter, 136 activity proportional to amount of uranium, 195 emanation from uranium, 348 effect of crystallization on activity of uranium, 349 rate of decay of radio-tellurium, 411
Minerals, radio-active constant ratio of radium to uranium, 459 _et seq._ list of minerals, 461 age of, 485 composition of, 554 _et seq._
Mobility of ions, 43 _et seq._
Moisture effect of, on velocity of ions, 43, 45 effect of, on emanating power, 255
Molecule number of, in 1 c.c. of hydrogen, 54
Molecular weight of radium emanation, 273 of thorium emanation, 275
Nagel and Himstedt action of radium rays on the eye, 217
Niewenglowski rays from sulphide of calcium, 4
Nomenclature of successive products, 328 _et seq._
Number of molecules per c.c. of hydrogen, 54 of ions produced in gas by active substances, 55 of β particles expelled from 1 gram of radium, 124 of α particles emitted per gram of radium, 155 of ions produced per c.c. in closed vessels, 534
Occlusion of emanation in thorium and radium, 258 of radium emanation by solids, 310
Owens saturation current affected by dust, 42 penetrating power of rays independent of compound, 164 absorption of α rays varies directly as the pressure of gas, 169 effect of air currents on conductivity produced by thorium, 238
Oxygen change into ozone, by radium rays, 213 production of, from radium solutions, 215
Ozone production of, by radium rays, 213
Paraffin objection to, as an insulator, 96 conductivity of, under radium rays, 210
Paschen distribution of velocity amongst β particles, 131 _et seq._ absence of magnetic deflection of γ rays, 183 γ rays and electrons, 185 heating effect of γ rays, 186, 429
Patterson number of ions per c.c. in closed vessel, 534 natural conductivity of air due to an easily absorbed radiation, 536 effect of temperature on natural conductivity of air, 536
Peck and Willows action of radium rays on spark, 208
Pegram electrolysis of thorium solutions, 314 temporary activity of substances separated from thorium, 415
Penetrating power comparison of, for α, β and γ rays, 111 variation in, of β rays, 134 _et seq._ variation of, with density for β rays, 137 comparison of, for α rays from radio-elements, 164 variation of, with density for α rays, 169 variation of, with density for γ rays, 182
Penetrating radiation from the earth and atmosphere, 520
Perrin charge carried by cathode rays, 73 theory of radio-activity, 437
Phosphorescence production of, by radium, 19 production of, by radium and polonium rays, 201 _et seq._ comparison of, produced by α and β rays, 202 of zinc sulphide, 202 of barium platinocyanide, 203 of willemite and kunzite, 203 produced by radium emanation in substances, 203, 252 diminution of, with time, 205 of radium compounds, 205 spectrum of phosphorescent light of radium bromide, 205 spectrum of phosphorescent light of “emanium,” 206 production of by heat (thermo-luminescence), 207 use of, to illustrate condensation of emanations, 279 connection of with ionization, 547 _et seq._
Phosphorus action of radium rays on, 214 ionization produced by, 529
Photo-electric action produced by radium rays in certain substances, 214
Photographic method, advantages and disadvantages of, 83 relative photographic action of rays, 83 connection of photographic action with ionization, 546
Physical action of radium rays on sparks, 208 on electrodeless discharge, 208 on selenium, 208 on conductivity of insulators, 209
Physiological action of radium rays production of burns, 216 effect on bacteria, 216 effect on eye, 217
Piezo-électrique of quartz description of, 105
Pitchblendes comparison of radio-activity of, 11 radio-elements separated from, 13 _et seq._ radium continually produced from, 459 constitution of, 557
Polarization of uranium rays absence of, 7
Polonium methods of separation of, 22 rays from, 23 decay of activity of, 23 discussion of nature of, 24 similarity to radio-tellurium, 26 magnetic deviation of α rays from, 146, 150 slow moving electrons, 153 increase of absorption with thickness of matter traversed, 163 connection of, with radium F, 411
Potential required to produce saturation, 32 _et seq._ fall of potential needed to produce ions at each collision, 58 gradient due to movement of ions, 65
Precht and Runge spectrum of radium, 17 atomic weight of radium, 18 heating effect of radium, 420
Pressure effect of, on velocity of ions, 46 effect of, on current through gases, 61 _et seq._ production of emanation independent of, 265 effect of, on distribution of excited activity, 317 effect of, on natural conductivity of air in closed vessels, 534
Products, radio-active list of, from radio-elements, 449 properties of, 449 amount of in radium, 452 _et seq._ radiations from, 455
Quartz piezo-électrique use of, in measurement of current, 105
Quinine sulphate discharging power of, 530 phosphorescence of, 530
Radiations emitted by uranium, 8 emitted by thorium, 10 emitted by radium, 18 emitted by actinium, 21 emitted by polonium, 23 method of measurement of, 82 _et seq._ methods of comparison of, 108 three kinds of, 109 analogy to rays from a Crookes tube, 110 relative ionizing and penetrating power of, 111 difficulties of comparative measurement of, 112 β rays, 113 α rays, 141 γ rays, 179 secondary rays, 187 comparison of ionization of α and β rays, 194 phosphorescent effect of, 201 _et seq._ physical actions of, 207 _et seq._ chemical actions of, 213 _et seq._ physiological actions of, 216 from the emanation, 263 from Ur X, 347 connection of, with heat emission, 421 _et seq._ from different active products, 455 conservation of energy of each specific type of, 469 _et seq._
Radio-lead connection of, with polonium, 411 _et seq._ connection of, with radium D, 413
Radio-tellurium rate of decay of, 411 connection of with radium F, 411
Radium discovery of, 13 separation of, 13 spectrum of, 16 atomic weight of, 17 radiations from, 18 compounds of, 19 nature of radiations from, 109 β rays from, 113 α rays from, 141 γ rays from, 179 secondary rays from, 187 production of phosphorescence by, 201 _et seq._ spectrum of phosphorescent light of, 206 physical actions of, 207 _et seq._ chemical actions of, 213 _et seq._ physiological actions of, 216 emanation from, 246 properties of emanation from, 247 _et seq._ chemical nature of emanation from, 267 diffusion of emanation from, 269 condensation of emanation from, 277 amount of emanation from, 288 volume of emanation from, 289 spectrum of emanation from, 292 excited radio-activity from, 295 _et seq._ decay of excited activity from, 306 _et seq._ difference in properties of radium and the emanation, 327 nomenclature of products, 328 theory of successive changes in, 330 alteration of activity of, by removal of emanation, 371 _et seq._ recovery of activity of, after removal of emanation, 372 effect of escape of emanation on recovery of activity of, 374 non-separable activity of, 375 period and properties of radium A, B and C, 376 _et seq._ analysis of active deposit of rapid changes of radium, 377 analysis of β ray curves, 381 _et seq._ analysis of α ray curves, 386 _et seq._ equations of activity curves, 389 effect of temperature on active deposit of, 390 relative activity due to products of, 395 active deposit of slow transformation, 397 physical and chemical properties of radium D, E and F, 398 _et seq._ effect of temperature on active deposit of slow change, 401 separation of radium F by bismuth, 402 products of, 402 _et seq._ rate of transformation of radium D, 404 _et seq._ variation of the activity of the active deposit over long periods of time, 407 amounts of radium D, E and F in old radium, 408 variation of activity of, with time, 409 products of in pitchblende, 410 origin of radio-tellurium, 411 origin of polonium, 411, 412 origin of radio-lead, 413 temporary activity of inactive matter separated from pitchblende, 415 _et seq._ heat emission of, 419 _et seq._ heat emission of emanation from, 420, 431 heating effects due to products of, 433 theories of radio-activity of, 437 _et seq._ discussion of theories of radio-activity of, 441 _et seq._ energy of radiations, not derived from external source, 442 _et seq._ theory of radio-active change, 444 _et seq._ list of active products of, 449 amount of products of, 452 rate of change of, 457 life of radium, 457 origin of, 459 _et seq._ production of, by uranium, 459 _et seq._ amount of in 1 gram of uranium, 461 amount of, in minerals, 461 radio-activity of, independent of concentration, 466 _et seq._ disappearance of, 467 life of, independent of concentration, 468 conservation of radio-activity of, 469 _et seq._ loss of weight of, 473 experiments to determine loss of weight of, 474 total emission of energy from 1 gram of, 474 _et seq._ production of helium from, 476 helium, disintegration product of, 479 _et seq._ amount of helium from, 480 possible causes of disintegration of, 486 _et seq._ amount of, to account for heat of sun, 491 possible connection of with heat of sun, 491 possible connection of with heat of earth, 493 probable amount of, in earth, 495 amount of, in atmosphere, 495, 524 presence of, in atmosphere, 521 _et seq._
Radium A decay curve of, 378 radiation from, 381 effect of, on activity curves, 386 _et seq._ connection with later changes, 392 activity supplied by, 393
Radium B absence of rays in, 381 effect of, on activity curves, 381 _et seq._ effect of temperature on, 390 volatility of, 390 absence of heating effect of, 433 nature of rayless change in, 454, 552
Radium C radiations from, 381 analysis of β ray curves of, 381 _et seq._ analysis of α ray curves of, 386 _et seq._ effect of temperature on, 390 activity supplied by, 394 _et seq._ heating effect of, 425 use of, as a source of β rays, 435 explosive nature of change in, 456 magnetic deflection of rays from, 543 velocity and value of _e_/_m_ for rays from, 544
Radium D origin of name of, 376 connection of, with active deposit, 403 period of transformation of, 406 effect of, on variation of activity, 407 presence in old radium, 408 effect of, on activity of old radium, 409 presence in pitchblende, 410 connection with radio-lead, 413 amount of, in 1 ton of uranium, 454
Radium E effect of temperature on, 401 connection of, with β ray activity active deposit, 403, 400 connection with radio-lead, 413
Radium F variation of activity due to, 398 effect of temperature on, 401 separation of, on bismuth plate, 402 connection with active deposit, 403 variation of activity of, over long periods of time, 407 presence in old radium, 409 effect of, on activity of old radium, 409 presence in pitchblende, 410 connection with radio-tellurium, 411 connection with polonium, 411, 412 connection with radio-lead, 413
Rain radio-activity of, 505 decay of activity of, 506
Ramsay, Sir W. amount of helium in thorianite, 486
Ramsay and Collie spectrum of emanation, 292
Ramsay and Cooke radio-activity produced by radiation from radium, 472
Ramsay and Soddy evolution of gas from radium, 215 production of hydrogen and oxygen from radium, 215 chemical nature of the emanation, 268 gaseous nature of the emanation, 268 volume of emanation, and change with time, 289 helium from radium emanation, 291 amount of helium produced by radium, 480
Ramsay and Travers amount of helium in fergusonite, 486
Rayless changes discussion of, 454, 552
Re, F. theory of radio-activity, 441
Recombination of ions, 40 _et seq._ constant of, 42
Recovery of activity of thorium after removal of Th X, 221 of activity of uranium after removal of Ur X, 223 significance of law of, 224 effect of conditions on rate of, 232 of activity of radium after removal of emanation, 372 of heating effect of radium, 423
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, 256
Richarz and von Helmholtz action of ions on steam jet, 47
Richarz and Schenck theory of radio-activity, 441
Rossignol and Gimingham decay of thorium emanation, 242
Runge spectrum of radium, 17
Runge and Bödlander evolution of gas from radium, 215
Runge and Precht spectrum of radium, 17 atomic weight of radium, 18 heating effect of radium, 420
Russel photographic action of substances, 83
Saake amount of emanation in air at high altitudes, 519
Salomonsen and Dreyer coloration of quartz by radium rays, 213
Saturation current meaning of, 33 _et seq._ application of, to measurements of radio-activity, 84 measurement of, 100 _et seq._
Schenck radium emanation in springs, 513
Schenck and Richarz theory of radio-activity, 441
Schmidt discovery of radio-activity of thorium, 10
Schmidt and Wiedemann thermo-luminescence, 207
Schuster number of ions per c.c. in air of Manchester, 528 radio-activity of matter, 529
Schweidler and Mache velocity of ions in air, 528
Schweidler and Meyer magnetic deviation of β rays by electrical method, 113 absorption of β rays of radium by matter, 136 activity proportional to amount of uranium, 195 emanation from uranium, 348 effect of crystallization on activity of uranium, 349 rate of decay of radio-tellurium, 411
Scintillations discovery of, in zinc sulphide screen, 158 connection of, with α rays, 158 illustration of, by spinthariscope, 158 cause of, 160 production of, by action of electric field, 160
Searle apparent mass of moving charged body, 71, 127
Secondary rays examination of, by photographic method, 187 examination of, by electrical method, 188 production of, by β and γ rays, 189 _et seq._ from different materials, 191 amount of, depends upon atomic weight, 192 magnetic deflection of, 193
Seitz absorption of electrons by matter, 137 _et seq._
Selenium action of radium rays on, 208
Simon value of _e_/_m_ for cathode rays, 75, 129
Simpson amount of excited activity in north of Norway, 519
Slater, Miss effect of temperature on active deposit of thorium, 354
Smolan, Beattie and Kelvin discharging power of uranium rays, 7
Snow radio-activity of, 506 decay of activity of, 507
Soddy comparison of photographic and electrical action of uranium rays, 83 nature of rays from Ur X, 347 production of radium from uranium, 463
Soddy and Ramsay evolution of gas from radium, 215 production of hydrogen and oxygen from radium, 215 chemical nature of the emanation, 268 gaseous nature of the emanation, 268 volume of the emanation, and change with time, 289 helium from radium emanation, 291 amount of helium produced by radium, 480
Soddy and Rutherford separation of Th X, 220 decay of activity of Th X, 221 recovery of activity of thorium freed from Th X, 221 decay of activity of Ur X, 223 recovery of activity of uranium freed from Ur X, 223 explanation of decay and recovery curves, 224 rate of production of Th X, 227 theory of decay of activity, 229 influence of conditions on rate of decay and recovery of activity, 233 disintegration hypothesis, 234 decay of activity of radium emanation, 247 measurements of emanating power, 254 effect of temperature, moisture, and solution, on emanating power, 255 regeneration of emanating power, 256 constant rate of production of emanation of radium and thorium, 257 source of thorium emanation, 261 radiations from the emanation, 264 chemical nature of emanation, 267 condensation of emanations of radium and thorium, 277 temperature of condensation of emanation, 278 effect of successive precipitations on activity of thorium, 358 recovery of activity of radium, 372 theory of radio-activity, 439 theory of radio-active change, 445 conservation of radio-activity, 469
Soil radio-activity of, 507 _et seq._ difference in activity of, 508 _et seq._
Solution coloration of, by radium, 15 of active deposit in acids, 312 electrolysis of active, 313
Source of thorium emanation, 261 of radium and actinium emanations, 263
Spark action of radium rays on, 208
Spectrum spark spectrum of radium, 15, 16 flame spectrum of radium, 17 effect of a magnetic field on spectrum of radium, 17 of polonium, 23 of phosphorescent light of radium bromide, 206 of emanation, 292 of helium in radium gases and emanation, 477
Spinthariscope description of, 158
Springs emanation from water of, 513
Stark energy to produce an ion, 58
Stoney, Johnstone use of term electron, 76
Strauss and Hofmann radio-active lead, 27
Strutt conductivity of gases for radiation, 63, 64 conductivity of gases produced by γ rays, 64, 183 negative charge carried by β rays, 122 _et seq._ absorption of β rays proportional to density, 136 nature of α rays, 142 attempt to measure charge of α rays, 153 constant ratio of uranium to radium in minerals, 462 connection of thorium with helium, 483 absorption of radium rays from sun by atmosphere, 492 presence of radium in Bath waters, 513 radio-activity of ordinary matter, 536
Sun effect of radium in, 491 age of, 492
Temperature effect of, on intensity of radiations from uranium and radium, 210 effect of, on luminosity, 210 rate of decay of radium emanation unaffected by, 249 of condensation of emanations, 283 rate of decay of thorium emanation unaffected by, 287 effect of, on excited activity, 315 effect of, on active deposit of thorium, 354 effect of, on active deposit of actinium, 368 effect of, on active deposit of rapid change of radium, 390 effect of, on active deposit of slow change, 401 of radium above surrounding space, 419 effect of, on amount of excited activity in atmosphere, 518 effect of, on natural ionization of air, 536
Theories of radio-activity, review of, 437 _et seq._ discussion of, 441 _et seq._ disintegration theory, 445 _et seq._
Thermo-luminescence, 207
Thomson, J. J. relation between current and voltage for ionized gases, 34 difference between ions as condensation nuclei, 49 charge on ion, 50 magnetic field produced by an ion in motion, 69 apparent mass of electron, 71 action of magnetic field on moving ion, 72 determination of _e_/_m_ for cathode stream, 73 origin of X rays, 80 slow velocity electrons from radio-tellurium, 153 charge carried by α rays, 154 theory of radio-activity, 440 cause of heat emission from radium, 442 structure of atom, 487 possible causes of disintegration of radium, 487 nature of electrons, 496 emanation from tap-water and deep wells, 510 radio-activity of ordinary materials, 539
Thomson, J. J. and Rutherford ionization theory of gases, 31 _et seq._
Thorium discovery of radio-activity of, 10 emanation from, 11 preparation of non-radio-active thorium, 29 nature of radiations from, 109 β rays from, 114 α rays from, 141 γ rays from, 180 separation of Th X from, 220 recovery of activity of, 221 disintegration of, 234 emanation from, 238 properties of emanation from, 239 diffusion of emanation from, 275 condensation of emanation from, 277 excited radio-activity from, 295 _et seq._ analysis of active deposit of, 351 _et seq._ rayless change in, 352 explanation of initial portion of decay curve, 358 explanation of initial portion of recovery curve, 358 effect of successive precipitations on, 358 recovery curve after large number of precipitations, 359 products of, 363 non-separable activity of, 363 radiations from active products of, 363 division of activity amongst active products of, 363 rate of emission of energy by, 432 theories of radio-activity of, 438 discussion of theories of radio-activity, 441 _et seq._ source of energy of radiations, 442 _et seq._ theory of radio-active change, 444 _et seq._ table of radio-active products of, 449 rate of change of, 458 life of, 458 conservation of radio-activity of, 469 total emission of energy from 1 gram of, 475 possible causes of disintegration of, 486 _et seq._
Thorium A period and properties of, 352 _et seq._ absence of rays in, 352 effect of temperature on, 354
Thorium B period and properties of, 352 _et seq._ effect of temperature on, 354 radiations from, 363
Thorium X methods of separation of, 220 law of decay of activity of, 221 law of recovery of activity of, 221 theory to explain production of, 224 material nature of, 226 continuous production of, 227 explanation of decay of activity of, 229 effect of conditions on the rate of change of, 233 disintegration hypothesis to explain production of, 234 minute amount of, produced, 237 effect of successive separations of, on activity of thorium, 358 _et seq._ analysis of decay and recovery curves of, 358 radiations from, 363
Tommasina scintillations produced by electrification, 160
Townsend ions by collision, 39, 57 coefficient of recombination, 41 diffusion of ions, 51 _et seq._ comparison of charge on ion with that on hydrogen atom in electrolysis, 53 number of molecules per c.c. of gas, 54 ionization by collision for different speeds, 171
Transformations, successive theory of, 325 _et seq._ nomenclature of, 328 activity due to, 337 detection of a rayless change in, 341 in uranium, 346 _et seq._ in thorium, 351 _et seq._ in actinium, 364 _et seq._ in radium, 371 _et seq._ list of, 449 origin of radium in, 459 helium, a result of, 476 _et seq._ possible cause of, 486 _et seq._ application of, to evolution of matter, 497 _et seq._
Transmission of excited radio-activity of radium and thorium, 318 _et seq._ of excited radio-activity of actinium, 323
Travers and Ramsay amount of helium in fergusonite, 486
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 radiations from, 109 β rays from, 114 α rays from, 141 γ rays from, 180 separation of Ur X from, 219 recovery of activity of, 219 changes in, 346 _et seq._ non-separable activity of, 347 radiations from Ur X, 347 _et seq._ method of measurement of activity of Ur X, 347 emission of energy by, 418 theories of radio-activity of, 437 _et seq._ discussion of theories of radio-activity, 441 _et seq._ source of energy of radiation, 442 _et seq._ theory of radio-active change, 444 _et seq._ table of active products, 449 rate of change of, 458 life of, 458 radium probable product of, 459 _et seq._ amount of radium in, 460 _et seq._ amount of, in radio-active minerals, 461 growth of radium in, 463 conservation of radio-activity of, 469 total emission of energy from 1 gram of, 475 possible causes of disintegration of, 486 _et seq._
Uranium X separation of, by Crookes, 219 separation of, by Becquerel, 219 decay of activity of, 223 recovery of activity of, 223 theory to explain production of, 224 _et seq._ material nature of, 226 explanation of decay of activity of, 229 changes in, 346 _et seq._ radiations from, 347 _et seq._ method of measurement of radiations from, 347 effect of crystallization on activity of, 349 diffusion of, 350
Velocity of ions in electric field, 42 _et seq._ difference between, of positive and negative ions, 43 _et seq._ of β particle or electron, 126 _et seq._ variation of mass of electron with, 127 of α particle, 148 of transmission of carriers of excited activity, 320 _et seq._ of ions in atmosphere, 528
Villard discovery of γ rays from radium, 179 alteration of X ray screen with time, 205 activity produced by cathode rays, 530
Vincenti and Levi Da Zara radium emanation in spring waters, 516
Voller variation of activity of radium with concentration, 467
Volume of radium emanation, calculation of, 289 decrease of, of radium emanation, 290
Walker, G. W. theory of electrometer, 90
Walkhoff action of radium rays on skin, 216
Wallstabe diffusion of radium emanation into liquids, 276
Water emanation from, 510 _et seq._ decay of activity of emanation from, 511 _et seq._
Water-falls amount of excited activity produced at Niagara, 520 electrification produced near, 520
Watts, Marshall atomic weight of radium, 18
Weichert velocity of cathode rays, 76
Weight loss of by radio-elements, 473 attempts to measure loss of in radium, 474
Wheeler and Bumstead diffusion of radium emanation, 273 emanation from surface water and the soil, 512, 522 identity of emanation from soil with radium emanation, 512, 522
Whetham effect of valency of ion on colloidal solutions, 215 production of radium from uranium, 463
Wiedemann thermo-luminescence, 207
Wiedemann and Schmidt thermo-luminescence, 207
Wien value of _e_/_m_ for canal rays, 78 positive charge of canal rays, 78 amount of charge carried by β rays, 124
Willcock, Miss and Hardy coloration of iodoform solution by radium rays, 214
Willemite phosphorescence of, under radium rays, 203 use of, to show condensation of emanation, 279
Willows and Peck action of radium rays on spark, 208
Wilson, C. T. R. ions as nuclei of condensation, 47 _et seq._ difference between positive and negative ions as condensation nuclei, 49 equality of charges carried by positive and negative ions, 50 construction of electroscope, 86, 88 natural ionization of air in vessels, 501 radio-activity of rain and snow, 505, 506 loss of charge in closed vessels, 531 _et seq._, 534 presence of ions in dust-free air shown by condensation, 533 number of ions produced per c.c., 533 effect of pressure and nature of gas on ionization in sealed vessels, 534
Wilson, H. A. charge on ion, 51
Wilson, W. E. radium in sun, 491
Wölfl, Hofmann and Gonder properties of radio-active lead, 27, 413
Wood, A. radio-activity of ordinary materials, 540
Zara, Levi Da and Vincenti radium emanation in spring waters, 516
Zeeman action of magnetic field on light, 77
Zeleny velocity of ions, 42 _et seq._ difference of velocity of ions, 45 potential gradient between electrodes, 65
Zerban and Hofmann connection of activity of thorium with uranium, 29
Zinc Sulphide scintillations produced in by α rays, 158 cause of luminosity of, 160, 549
