Page:Radio-activity.djvu/594

Oxygen (cont.) 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 platino-cyanide, 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

Polarization of uranium rays
  absence of, 7

Polonium
  methods of separation of, 22
  rays from, 23
  decay of activity of, 23
  discussion of nature of, 24
  similarity to radio-tellurium, 26
  magnetic deviation of α rays from, 146, 150
  slow moving electrons, 153
  increase of absorption with thickness of matter traversed, 163
  connection of, with radium F, 411

Potential
  required to produce saturation, 32 et seq.
  fall of potential needed to produce ions at each collision, 58