Page:Radio-activity.djvu/599

 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