494 Mr Beatty, On a Dissymmetry in the Emission, etc. 



interchanged was also negligible. The radiation from Al was 

 excited by very penetrating rays from the bulb, and was passed 

 through Al sheets to cut out the softer portions. 



On repeating the experiments with a Cu leaf replacing that 

 of Ag, similar results were obtained (Table II). 



Table II. Comparison of ratios for Ag and Cu. 



In the case of the Cu leaf the cathode energy excited by the 

 Fe and Cu radiations was too small to measure. 



It will be seen that : 



1°. A dissymmetry exists in the amount of energy due to 

 cathode particles emerging from opposite sides of a metal sheet. 

 This dissymmetry increases as the radiation becomes more pene- 

 trating. 



2°. For a given radiation the dissymmetry is the same for 

 Ag and Cu leaves. 



Bragg and Glasson* have shown that a similar dissymmetry 

 exists in the case of secondary Rontgen radiations. They state, 

 however, that when the secondary radiator is Fe or Cu, both of 

 which give out a quantity of homogeneous soft secondary radiation, 

 the dissymmetry is greatly reduced. 



In the present research Cu and Ag leaves were used because in 

 the former case the homogeneous radiation is much more easily 

 excited. The dissymmetry in the cathode distribution appears to 

 be independent of the presence or absence of excited homogeneous 

 radiation. 



I beg to thank Professor Sir J. J. Thomson for his interest in 

 this investigation. 



* " On a Want of Symmetry shown by Secondary X-Eays," Philosophical 

 Magazine, June, 1909, p. 855. 



