100 



THE NEW KNOWLEDGE. 



Fig. 29 



taining a tiny amount of radium chloride, the leaves at 

 once collapse through the discharge of their electrification, 

 Fig. 29 (6). The approach of radium and the discharge 



of the leaves are simul- 

 taneous. Investigation 

 showed that the effect 

 was due to the fact that 

 the rays emitted by the 

 radium spontaneously 

 rendered the air a con- 

 ductor of electricity, and 

 naturally the electrifica- 

 tion of the leaves flew 

 away with as much ease 

 as if they had been touched by a copper wire. As a mat- 

 ter of fact, an electrified body is a more sensitive detector 

 of radio-activity than a photographic plate. In this prop- 

 erty of discharging electrified bodies the Becquerel rays are 

 identical with positive ions, corpuscles and X-rays. 



CHEMICAL EFFECT. 



Becquerel rays cause chemical action. Emitted from 

 radium they will discolour paper, cause glass to take a violet 

 tint, turn oxygen into ozone, yellow phosphorus into red 

 phosphorus, mercury perchloride into calomel and will 

 decompose iodoform. In the power of causing chemical 

 action, they resemble both the corpuscles in cathode rays 

 and X-rays. 



THE SECRET OF THE BECQUEREL RAYS. 



We have learned how Becquerel discovered his rays, we 

 have studied some of their properties, and we are now face 

 to face with the problem, most important of all. What are 

 they? 



