Production of Fluorescent Rontgen Radiation. 367 



radiation. Supposing now on the internal incidence face of 

 this ionization-chamber a single gold leaf is affixed; and the 

 tin rays again passed through the chamber. There is then 

 superimposed on the original effect due to the air, the 

 ionization produced by that fraction of the corpuscular rays 

 produced by the tin radiation which is able to escape from the 

 gold and produce ionization in the air. If now a second leaf 

 be added, and if it happens that corpuscles are able to 

 penetrate more than one thickness of leaf, there should be 

 an increase in the ionization due to that fraction of the cor- 

 puscular rays from the first leaf which is able to penetrate 

 the second leaf, and thus ionize the air in the chamber. In 

 this way leaf after leaf was added until further leaves produced 

 no increase in the intensity of ionization. At this point the 

 layer of gold on the internal incidence face could be con- 

 sidered infinitely thick from the point of view of corpuscular 

 rays. 



In the following table the values of the ionization corre- 

 sponding to the various numbers of radiating leaves are 

 given. 



Table II. 



Metal acting as corpuscular radiator — Gold. 



Exciting radiation — Tin. 



Thickness of gold = 9'9 to 10-1 x 10~ 6 cm. 



No. of gold leaves 



serving as corpuscular 



radiator. 



Intensity of Ionization 

 due to : — 

 (I.) Direct air effect. 

 (II.) Corpuscles expelled 

 from gold. 



Intensity of 



corpuscular 



radiation. 







2-0 

 6-0 

 79 

 86 

 9-0 

 89 





 4-0 

 5-9 

 66 

 70 

 69 



1 



2 



3 



6 



9 





From these results a curve (p. 368) is plotted showing 

 the relation between ionization due to corpuscular radiation, 

 and the number of leaves which served as corpuscular 

 radiator. 



2 C2 



