INDEX.

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

551