INDEX 389 
Emanation (cont.) 
experiments to illustrate gaseous na- 
ture of, 227 
rate of diffusion of radium emanation, 
228 et seq. 
rate of diffusion of thorium emana- 
tion, 233 
diffusion of, into liquids, 235 
condensation of, 236 et seq. 
temperature of condensation of, 238 
et seq. 
volume of, from 1 gram of radium, 
and thorium, 246 
heat emission of, 247 
connection between emanations and 
excited activity, 253 et seq. 
effect of removal of, on activity of 
radium, 300 
effect of rate of escape of, on activity 
of radium, 302 
fraction of activity of radium, due to, 
304 
experimental separation, and volume 
of, 311 et seq. 
decrease of volume of, with time, 313 
radio-activity of atmosphere, due to 
emanations, 354 
sucked up from the earth, 357 
rate of decay of activity of, from the 
earth, 358 
condensation of, from atmosphere, 359 
in caves, 357 
in well-water, and springs, 360 
in natural carbonic acid gas, 364 
from ‘‘ fango,” 363 
effect of meteorological conditions on 
amount of, in atmosphere, 364 
from metals, 378 
Emanation X (see Excited radio-activity) 
definition of, 256 
chemical and physical properties of, 
275 
electrolysis of, 276 
effect of temperature on, 277 
emission of heat by, 278 
transmission of, to negative elec- 
trode, 282 et seq. 
irregularities in decay of activity of 
Th X due to, 295 
removal of, by successive precipita- 
tions, 296 
theory of effect of production of, on 
activity of Th X, 295 et seq. 
Emanating power 
measurement of, 213 
effect of conditions on, 214 
regeneration of, 215 
““Emanating substance” of Giesel 
separation and properties of, 23 et seq. 
similarity of, to actinium, 24 
‘“‘Hmanating substance ” of Giesel (cont.) 
emanation from, 209 
excited activity produced by, 287 
action of an electric field on, 287 
Energy 
of a particle, 125 
of 8 particle, 151 
comparison of, for a and f particles, 
emitted from radio-elements, in form 
of a rays, 154 
emitted from radium in form of heat, 
158 et seq. 
emission of, from the emanation, 161 
et seq., 247 
emission of, from radio-active pro- 
ducts of radium, 278 
total emission of, from 1 gram of 
radio-elements, 336 
latent store of, in matter, 337 
Eve 
conductivity of gases for very pene- 
trating Roéntgen rays, 145 
Evolution of matter 
evidence of, 348 
Ewers and Ebert 
emanation from the earth, 358 
Excited radio-activity 
heat emission due to, 161 et seq. 
discovery and properties of, 250 
concentration of, on negative elec- 
trode, 252 
connection of, with the emanations, 
253 
removal of, by acids, 255 
decay of, due to thorium, 256 
decay of, for short exposure to thorium, 
259 
effect of dust on distribution of, 260 
decay of, from radium, 261 
of radium, of very slow decay, 264 
connection between decay curves of, 
and times of exposure, 265 
theory of successive changes to give 
rise to, 268 
changes in emanation X of thorium, 
270 et seq. 
changes in emanation X of radium, 
272 
physical and chemical properties of 
emanation X, 275 
electrolysis of active solutions, 276 
effect of temperature on, 277 
emission of heat, due to, 278 
variation with electric field, of amount 
of, 280 
effect of pressure on distribution of, 282 
transmission of, 282 et seq. 
from actinium, and ‘‘ emanating sub- 
stance,” 287 
