458 Ifr Grotvther, On the Transmission of ^-rays. 



The absorption of a parallel pencil of homogeneous ;S-rays by 

 aluminium and platinum has been determined. The absorption 

 curve for aluminium is complicated, being neither "exponential" 

 nor "linear." It approximates, however, to a form very recently 

 suggested by Prof Sir J. J. Thomson. The absorption curve for 

 platinum after a steeper initial portion is exponential. This 

 result is assigned to secondary radiation. 



I take this opportunity of again expressing my best thanks to 

 Prof Sir J. J. Thomson for much kindly interest and many 

 helpful suggestions. 



