Page:Radio-activity.djvu/589

 from metals, 538

Emanating power measurement of, 254 effect of conditions on, 255 regeneration of, 256

Emanium or "emanating substance" of Giesel (see Actinium)  discovery of, 21   separation and properties of, 21   similarity of, to actinium, 21   emanation from, 249   excited activity produced by, 311   action of an electric field on, 323  Energy   of α particle, 156   of β particle, 196   comparison of, for α and β particles, 196   emitted from radium in form of heat, 419 et seq.   emission of, from the emanation, 431   emission of, from radio-active products of radium, 433   total emission of, from 1 gram of radio-elements, 474 et seq.   latent store of, in matter, 475  Eve   conductivity of gases exposed to X rays, 64   conductivity of gases exposed to X rays and γ rays, 183, 184   secondary rays produced by β and γ rays, 189 et seq.   magnetic deflection of secondary rays from γ rays, 193   variation of activity of radium with concentration, 467   amount of radium emanation in the atmosphere, 524 et seq.   ionization due to emanation in atmosphere, 526 et seq.

Evolution of matter evidence of, 497

Ewers and Ebert emanation from the earth, 508

Excited radio-activity discovery and properties of, 295 et seq.  concentration of, on negative electrode, 297   connection of, with the emanations, 298   removal of, by acids, 300   decay of, due to thorium, 302   decay of, for short exposure to thorium, 304   effect of dust on distribution of, 305   decay curves for different times of exposure, 306 et seq.   decay of, from radium, 306   decay curves of, measured by α rays, 308   decay curves of, measured by β rays, 309   decay curves of, from actinium, 311   of radium, of very slow decay, 311   effect of solution on, 312   electrolysis of active solutions, 313   effect of temperature on, 315   variation with electric field, of amount of, 316   effect of pressure on distribution of, 317   transmission of, 318   from actinium and emanium, 323   heat emission due to, 425 et seq.   from the atmosphere, 501 et seq.   decay of, 502   due to emanation in atmosphere, 504   distribution of, on surface of the earth, 504   concentration of, on prominences of the earth, 504   of rain and snow, 506   produced by emanation from tap water, 510   effect of meteorological conditions on amount of, 517 et seq.   amount of, at Niagara Falls, 520   rate of decay of, dependent on conditions, 522 et seq.

Exner and Haschek spectrum of radium, 17

Eye action of radium rays on, 217

Fehrle distribution of excited activity on a plate in electric field, 318

Fluorescence produced in substances by radium rays, 18 produced in substances by radium and polonium rays, 201 et seq.

Fog large amount of excited activity during, 518

Forch loss of weight of radium, 474

γ rays relative conductivity of gas exposed to γ and hard X rays, 64, 184 discovery of, 179 absorption of, by matter, 179 et seq. connection between absorption of, and density, 182 discussion of nature of rays, 182 et seq.