394 
Phosphorus 
action of radium rays on, 175 
ionization produced by, 371 
Photo-electric action 
produced by radium rays in certain 
substances, 174 
Photographic 
method, advantages and disadvan- 
tages of, 67 
relative photographic action of rays, 
68 
Physical action of radium rays 
on sparks, 171 
on electrodeless discharge, 171 
on selenium, 171 
on conductivity of insulators, 172 
Physical properties 
of emanation X, 275 
Physiological action of radium rays 
production of burns, 176 
effect on bacteria, 177 
effect on cancer, 177 
effect on eye, 177 
Piezo-électrique of quartz 
description of, 87 
Pitchblendes 
comparison of radio-activity of, 11 
radio-elements separated from, 13 et 
seq. ~ 
radium continually produced from, 
334 
Polarization of uranium rays 
absence of, 7 
Polonium 
methods of separation of, 19 
rays from, 20 
decay of activity of, 20 
discussion of nature of, 21 
similarity to radio-tellurium, 22 
magnetic deviation of a rays from, 
121 
increase of absorption with thickness 
of matter traversed, 131 
phosphorescent action of rays from, 
166 
possible origin of polonium and con- 
nection with radium, 290 et seq. 
penetrating rays from, 305 
Potential 
required to produce saturation, 30 
et seq. 
fall of potential, to produce ions each 
collision, 55 
gradient, due to movement of ions, 
63 
Precht and Runge 
atomic weight of radium, 17 
heating effect of radium, 164 
Pressure 
effect of, on velocity of ions, 43 
INDEX 
Pressure (cont.) 
effect of, on current through gases, 
58 et seq. 
production of emanation, independent 
of, 224 
effect of, on distribution of excited 
activity, 282 
effect of, on natural conductivity of 
air in closed vessels, 376 
Products, radio-active 
radiations from, 304 
division of activity amongst, 306 
list of from radio-elements, 326 
Quartz piezo-électrique 
use of, in measurement of current, 37 
Quinine sulphate 
discharging power of, 9, 372 
phosphorescence of, 372 
Radiations 
emitted by uranium, 8 
emitted by thorium, 10 
emitted by radium, 18 
emitted by polonium, 20 
emitted by actinium, 23 
methods of measurement of, 67 et seq. 
methods of comparison of, 90 
three kinds of, 91 
analogy to rays from a Crookes tube, 
92 
relative ionizing and penetrating 
power of, 93 
difficulties of comparative measure- 
ment of, 93 et seq. 
B rays, 95 et seq. 
a rays, 115 et seq. 
y rays, 141 et seq. 
secondary rays, 146 
comparison of ionization of a and B 
rays, 149 et seq. 
connection of, with heat emission, 
160 
phosphorescent effect of, 166 
physical actions of, 171 et seq. 
chemical actions of, 174 et seq. 
physiological actions of, 176 
from the emanation, 222 
from Ur X, 293 
non-separable activity of radio-ele- 
ments consists of a rays, 304 
from different active products, 304 
conservation of energy of each specific 
type of, 308 
Radium 
discovery of, 13 
separation of, 13 
spectrum of, 15 
atomic weight of, 17 
radiations from, 18 

