INDEX 
Becquerel (cont.) 
scintillations due to cleavage of crys- 
tals, 128 
y rays from radium, 141 
secondary rays produced by active 
substances, 146 
phosphorescence produced by radium 
rays, 166 
conductivity of paraffin under radium 
radiation, 173 
effect of temperature on uranium rays, 
173 
chemical action of radium rays, 175 
removal of activity from uranium by 
precipitation with barium, 179 
recovery of activity of uranium after 
precipitation with barium, 179 
penetrating rays from polonium, 305 
theory of radio-activity, 317 
Bemont et M. et Mme Curie 
discovery of radium, 13 
Benoist 
variation of absorption of Réntgen 
rays in matter, 144 
Berndt 
spectrum of polonium, 20 
Bédlander and Runge 
eyolution of gases from radium, 176 
Boys 
rate of dissipation of charge, 373 
Brooks, Miss 
variation of excited activity from 
thorium for short exposures, 260 
effect of dust on distribution of ex- 
cited activity, 260 
Brooks and Rutherford 
absorption of a rays by matter, 129 
comparison of absorption of a rays 
from radio-elements, 132 et seq. 
diffusion of radium emanation, 228 
decay of excited activity from radium, 
261 
Bumstead and Wheeler 
emanation from surface water and the 
soil, 361, 368 
identity of emanation from soil with 
radium emanation, 361 
absence of emanation in mercury, 381 
Burton and McLennan 
penetrating radiation from the earth, 
366 
radio-activity of ordinary materials, 
378 
emanation from ordinary matter, 379 
Canal rays 
similarity of to a rays, 92 
Capacity 
of electroscopes, 72 
of electrometers, 79, 85 
R, B.-A. 
385 
Capacity (cont.) 
standards of, 86 
Carbonic acid 
radio-activity of natural, 364 
Caspari and Aschkinass 
action of radium rays on eye, 177 
Cathode rays 
comparison of, with 8 rays, 102 et seq. 
absorption of, by matter, 113 
see also B rays, 95 et seq. 
Caves 
radio-active matter present in air of, 
357 
radio-activity of air of, due to emana- 
tion from the soil, 357 
Charge 
carried by the ions, 47 et seq. 
negative charge carried by 8 rays, 102 
et seq. 
measurement of charge carried by 6 
rays, 104 et seq. 
positive charge carried by a rays, 120 
Chemical nature 
of emanation, 225 
of emanation X, 275 
Chemical actions of radium rays 
production of ozone, 174 
coloration of glass and rock salt, 174 
on phosphorus, 175 
on iodoform, 175 
on globulin, 175 
evolution of hydrogen and oxygen, 
176 
Child 
potential gradient between electrodes, 
63 
variation of current with voltage for 
surface ionization, 64 
Clouds 
formation by condensation of water 
round ions, 43 et seq. 
difference between positive and nega- 
tive ions in formation of, 46 
Collision 
ionization by, 54 
number of ions produced by B rays 
per cm. of path, 139 
total number of ions produced by 
collisions of a particles, 156 
Coloration 
of crystals of radiferous barium, 15 
of bunsen flame by radium, 17 
of glass by radium rays, 174 
of rock salt, fluor spar and potassium 
sulphate by radium rays, 174 
Concentration 
of excited activity on negative elec- 
trode, 252 ; 
activity of radium independent of, 
339 
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