INDEX.

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

560