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Radio-Activity

Chapter 55: INDEX.
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About This Book

A systematic physical account examines the properties and behaviors of naturally radioactive substances, presenting the disintegration theory as a unifying explanation for spontaneous atomic change and decay chains. It reviews the ionization of gases and the electric, magnetic, and velocity properties of emitted radiation, describes alpha, beta, and gamma rays and emanations, and outlines experimental methods and quantitative measurement techniques. Additional chapters analyze successive transformations among radio-elements, summarize recent results on rays and emanations, and include appendices on alpha-ray studies and the occurrence and chemistry of radioactive minerals, with brief comments on physiological effects.

INDEX.

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
  • 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
  • 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
  • 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