INDEX.

Weichert velocity of cathode rays, 76
Weight loss of by radio-elements, 473 attempts to measure loss of in radium, 474
Wheeler and Bumstead diffusion of radium emanation, 273 emanation from surface water and the soil, 512, 522 identity of emanation from soil with radium emanation, 512, 522
Whetham effect of valency of ion on colloidal solutions, 215 production of radium from uranium, 463
Wiedemann thermo-luminescence, 207
Wiedemann and Schmidt thermo-luminescence, 207
Wien value of e/m for canal rays, 78 positive charge of canal rays, 78 amount of charge carried by β rays, 124
Willcock, Miss and Hardy coloration of iodoform solution by radium rays, 214
Willemite phosphorescence of, under radium rays, 203 use of, to show condensation of emanation, 279
Willows and Peck action of radium rays on spark, 208
Wilson, C. T. R. ions as nuclei of condensation, 47 et seq. difference between positive and negative ions as condensation nuclei, 49 equality of charges carried by positive and negative ions, 50 construction of electroscope, 86, 88 natural ionization of air in vessels, 501 radio-activity of rain and snow, 505, 506 loss of charge in closed vessels, 531 et seq., 534 presence of ions in dust-free air shown by condensation, 533 number of ions produced per c.c., 533 effect of pressure and nature of gas on ionization in sealed vessels, 534
Wilson, H. A. charge on ion, 51
Wilson, W. E. radium in sun, 491
Wölfl, Hofmann and Gonder properties of radio-active lead, 27, 413
Wood, A. radio-activity of ordinary materials, 540
Zara, Levi Da and Vincenti radium emanation in spring waters, 516
Zeeman action of magnetic field on light, 77
Zeleny velocity of ions, 42 et seq. difference of velocity of ions, 45 potential gradient between electrodes, 65
Zerban and Hofmann connection of activity of thorium with uranium, 29
Zinc Sulphide scintillations produced in by α rays, 158 cause of luminosity of, 160, 549

562