Page:Radio-activity.djvu/584

  comparison of absorption of α rays from radio-elements, 164
  diffusion of radium emanation, 270
  decay of excited activity from radium, 306

Bumstead
  presence of thorium emanation in atmosphere, 512

Bumstead and Wheeler
  diffusion of radium emanation, 273
  emanation from surface water and the soil, 512, 522
  identity of emanation from soil with radium emanation, 512, 522

Burton
  radium emanation in petroleum, 516

Burton and McLennan
  penetrating radiation from the earth, 520
  radio-activity of ordinary materials, 537
  emanation from ordinary matter, 538


Campbell
  radio-activity of ordinary materials, 540

Canal rays
  discovery of, 78
  magnetic and electric deflection of, 78
  value of e/m for, 78 similarity of, to α rays, 110 Capacity of electroscopes, 87 of electrometers, 94, 102 standards of, 102 Carbonic acid radio-activity of natural, 516 Caspari and Aschkinass action of radium rays on microbes, 216 Cathode rays discovery of, 73 magnetic and electric deflection of, 74 value of e/m for, 75 radiation of energy from, 79 comparison of, with β rays, 120 absorption of, by matter, 136, 137 see also β rays Caves radio-active matter present in air of, 514 et seq. radio-activity of air of, due to emanation from the soil, 515 Changes (see Transformations) Charge carried by the ions, 50 et seq. negative charge carried by β rays, 120 measurement of charge carried by β rays, 121 et seq. positive charge carried by α rays, 145 measurement of charge carried by α rays, 151 et seq.

Chemical nature
  of emanation, 267
  of active deposit, 312

Chemical actions of radium rays
  production of ozone, 213
  coloration of glass and rock-salt, 213
  on phosphorus, 214
  on iodoform, 214
  on globulin, 214
  evolution of hydrogen and oxygen, 215

Child
  potential gradient between electrodes, 65
  variation of current with voltage for surface ionization, 66

Clouds
  formation of, by condensation of water round ions, 46 et seq.
  difference between positive and negative ions in formation of, 49

Collie and Ramsay
  spectrum of emanation, 292

Collision
  ionization by, 39, 57
  number of ions produced by β rays per cm. of path, 434
  total number of ions produced by collisions of α particles, 434

Coloration
  of crystals of radiferous barium, 15
  of bunsen flame by radium, 15
  of glass by radium rays, 213
  of rock-salt, fluor-spar and potassium sulphate by radium rays, 213

Concentration
  of excited activity on negative electrode, 297
  activity of radium independent of, 466

Condensation
  of water round the ions, 46 et seq.
  of emanations, 277
  experimental illustration of, 279
  temperature of, 280
  difference between point of, for emanations of thorium and radium, 283
  from air sucked up from the earth, 510

Conductivity
  of gases exposed to radiations, 31 et seq.
  variation of, with pressure, 61 et seq.
  variation of, with nature of gas, 64
  comparison of, for gases exposed to α, β, and γ rays, 64