[eve] primary and secondary gamma rays 



PJmergent secondary radiation using secondary y rays. 



Pb. 100 



Sn 68.5 



Zn 63.0 



Cu 63.5 



Fe ." 64.5 



A1 70.0 



C 75.0 



45 



Fig 5. 



The curve obtained, shown in figure 5, is typical of easily absorbed 

 Y rays. 



Gamma Rays from llRAmuM X. 



About one and a half kilograms of uranyl nitrate were placed 

 in a cylindrical glass vessel so as to form a layer about 6 cm. thick. 

 This was placed beneath the vertical cylindrical electroscope described 

 earlier in the paper, plates were fixed close to the electroscope and 

 the emergent secondary radiation was observed by the reversal 

 method. The y rays from Uranium X are feeble, and the measure- 

 ments were difficult and uncertain, but the results obtained were: — 



