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, 448
  • 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, 448
  • 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 footnote)
• 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, 448
  • 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, 448
  • properties of, 448
  • 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, 448
  • 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, 448
  • 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, 448
  • 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, 448
  • 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