CHAPTER VI. 
PROPERTIES OF THE RADIATIONS. — 
108. BeEsIDEs their power of acting on a photographic plate, 
and of ionizing gases, the radiations from active bodies are able 
to produce marked chemical and physical actions in various sub- 
stances. Most of these effects are due either to the a or 8 rays. 
The y rays produce little effect in comparison. Since the @ rays 
are similar in all respects to high velocity cathode rays, it is to be 
expected that they will produce effects similar in character to 
those produced by the cathode rays in a vacuum tube. 
Phosphorescent action. 
Becquerel! has studied the action of radium rays in producing 
phosphorescence in various bodies. The substance to be tested 
was placed above the radium in the form of powder on a very thin 
mica plate. Examination was made of the sulphides of calcium 
and strontium, ruby, diamond, varieties of spar, phosphorus and 
hexagonal blende. Substances like the ruby and spar, which phos- 
phoresce under luminous rays, did not phosphoresce under the 
radium rays. On the other hand, those which were made luminous 
by ultra-violet light were also luminous under the action of radium 
rays. The radium rays show distinct differences from X rays. For 
example, a diamond which was very luminous with radium rays 
was unaffected by X rays. It has been mentioned previously that 
the a rays from Marckwald’s preparation of polonium produce 
marked phosphorescence in the diamond. The double sulphate of 
AG. BR: 1295p: 912; 1899: 
