Page:Radio-activity.djvu/582

 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, 449 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