384 
Allan (cont.) 
radio-activity of snow, 356 
effect of conditions on decay of ac- 
tivity from air, 369 
Allan and Rutherford 
decay of excited activity from atmo- 
sphere, 353 
ionization of air in closed vessels, 376 
Anderson and Hardy 
action of radium rays on eye, 177 
Armstrong and Lowry 
radio-activity and phosphorescence, 
323 
Arnold 
rays from phosphorescent substances, 
4 
Aschkinass and Caspari 
action of radium rays on eye, 177 
Atmosphere 
excited radio-activity from, 351 et seq. 
radio-activity of, due to emanations, 
354 
diffusion of emanations into, from 
earth, 357 
effect of temperature, pressure, &c. on 
radio-activity of, 364 
presence of very penetrating radiation 
in, 366 
comparison of radio-activity of, with 
radio-elements, 368 
Atom 
number of, per c.c., 51 
complex nature of, 126 
disintegration of, 126 
number of, transformed per second, 
332 
changing atoms, 322 et seq. 
possible causes of disintegration of, 
338 et seq. 
evolution of, 347 et seq. 
Atomic weight 
of radium by chemical methods, 17 
from spectroscopic evidence, 18 
of emanations, 232 
of radio-elements and connection with 
radio-activity, 323 et seq. 
B rays 
discovery of, 95 
magnetic deflection of, 95 et seq. 
complexity of, 98 et seq. 
examination by the electrical method, 
100 
effect of, on a fluorescent screen, 101 
charge carried by the, 102 et seq. 
electrostatic deviation of, 106 
velocity of, and value of e/m for, 106 
et seq. 
variation of e/m with velocity of, 108 
et seq. 
INDEX 

B vays (cont.) 
absorption of, 112 
variation of absorption with density, 
113 et seq. 
variation of intensity of, with thick- 
ness of layer, 115 
relative lonization produced by a and 
B rays, 149 
relative energy emitted in form of 
a and 6 rays, 150 et seq. 
phosphorescent action of, 166 
physical action produced by, 171 et seq. 
chemical action of, 174 
physiological action of, 176 
from UrX, 293 
from emanation X-of radium, 302 
appearance of, only in last of radio- 
active changes, 304 
change of weight due to expulsion of, 
336 
Barium platinocyanide 
phosphorescence of, under radium 
rays, 167 
change of colour due to radium rays, 
168 
Barnes and Rutherford 
heating effect of radium emanation, 
161 
connection of heating effect with radio- 
activity, 160 et seq. 
heating effect of emanation, 247 
heating effect of excited activity, 279 
division of heating effect among active 
products, 279 
Baskerville 
activity of thorium, 25 
phosphorescence of kunzite under ra- 
dium rays, 168 
phosphorescence produced by radium 
rays, 168 
Beattie, Smolan and Kelvin 
discharging power of uranium rays, 7 
Becquerel 
rays from calcium sulphide, 4 
rays from uranium, 5 et seq. 
permanence of uranium rays, 6 
discharging power of uranium rays, 6 
magnetic deflection of radium rays by 
photographic method, 96 
curvature of radium rays in a mag- 
netic field, 96 et seq. 
complexity of radium rays, 98 et seq. 
electrostatic deflection of B rays of 
radium, 106 
value of e/m for B rays of radium, 
107 
magnetic deviation of a rays of radium 
and polonium, 120 
trajectory of rays of radium in mag- 
netic field, 123 et seq. 
