Page:Radio-activity.djvu/601

 source of energy of radiation, 442 et seq.  theory of radio-active change, 444 et seq.   table of active products, 449   rate of change of, 458   life of, 458   radium probable product of, 459 et seq.   amount of radium in, 460 et seq.   amount of, in radio-active minerals,  461   growth of radium in, 463   conservation of radio-activity of, 469   total emission of energy from 1 gram of, 475   possible causes of disintegration of, 486 et seq.

Uranium X separation of, by Crookes, 219 separation of, by Becquerel, 219 decay of activity of, 223 recovery of activity of, 223 theory to explain production of, 224 et seq.  material nature of, 226   explanation of decay of activity of, 229   changes in, 346 et seq.   radiations from, 347 et seq.   method of measurement of radiations from, 347   effect of crystallization on activity of, 349   diffusion of, 350   Velocity   of ions in electric field, 42 et seq.   difference between, of positive and negative ions, 43 et seq.   of β particle or electron, 126 et seq.   variation of mass of electron with, 127   of α particle, 148   of transmission of carriers of excited activity, 320 et seq.   of ions in atmosphere, 528  Villard   discovery of γ rays from radium, 179   alteration of X ray screen with time, 205   activity produced by cathode rays, 530  Vincenti and Levi Da Zara   radium emanation in spring waters, 516  Voller   variation of activity of radium with concentration, 467  Volume   of radium emanation, calculation of, 289   decrease of, of radium emanation, 290   Walker, G. W.   theory of electrometer, 90  Walkhoff   action of radium rays on skin, 216  Wallstabe   diffusion of radium emanation into liquids, 276  Water   emanation from, 510 et seq.   decay of activity of emanation from, 511 et seq.

Water-falls amount of excited activity produced at Niagara, 520 electrification produced near, 520

Watts, Marshall atomic weight of radium, 18

Weichert velocity of cathode rays, 76

Weight loss of by radio-elements, 473 attempts to measure loss of in radium, 474

Wheeler and Bumstead diffusion of radium emanation, 273 emanation from surface water and the soil, 512, 522 identity of emanation from soil with radium emanation, 512, 522

Whetham effect of valency of ion on colloidal solutions, 215 production of radium from uranium, 463

Wiedemann thermo-luminescence, 207

Wiedemann and Schmidt thermo-luminescence, 207

Wien value of e/m for canal rays, 78 positive charge of canal rays, 78 amount of charge carried by β rays, 124

Willcock, Miss and Hardy coloration of iodoform solution by radium rays, 214

Willemite phosphorescence of, under radium rays, 203 use of, to show condensation of emanation, 279

Willows and Peck action of radium rays on spark, 208