Cases of Ionization by X-Rays, 



37.5 



hydrogen, and chlorine have no characteristic radiations 

 within the range of penetrating power used. 



Fiff. 2. 



flBSORBAB/LirY OP X-/?/1DI/tTIOH |~A AV At. 



The results may be stated thus : — 



Every element has its own characteristic secondary 

 X-radiations, which it emits when exposed to X-radiations 

 of more penetrating type, in agreement with Stokes's Law 

 of Fluorescence. This characteristic line spectrum in X-rays 

 determines the variation in intensity of secondary X-radiation 

 from the element, .the variation in absorption of X-rays in 

 the element, the variation in ionization in the element, the 

 variation in intensity of corpuscular radiation from the 

 element, as the penetrating power of the X-radiaticn is 

 varied. 



Thus if we pass a beam of X-rays of gradually increasing 

 penetrating power through two substances A and B in the 

 gaseous state, then when the X-radiation has not a penetrating- 

 power close, on the more penetrating side, to that of the 

 radiations characteristic of any element in A or B, the 



