﻿990 



Prof. C. G. Barkla and Mr. V. Collier on the 



Table I. 



Mass absorption coefficients I — j. 



Radiator. 



Absorber. 



C. 



Al. 



H- 



Pt, 



Au. 



Zn- 



4 26 

 2-49 

 204 



1-9 

 1-32 

 1-16 

 •81 

 •46 

 •35 

 •31 

 ■29 

 •26 

 •248 



39-4 



22-5 



18-9 



16-4 



10-9 



9-4 

 47 



[5-3] 

 2-5 



1-57 



1-21 



•92 



•8 



•6 



175 

 105-3 



87-5 



77-1 



52-3 



45-2 



26-5 



133 



16-5 



56-1 



46 



354 



162-5 

 105-7 



92-1 



176 



168 



165 



103 

 56-5 

 471 



1782 



106-1 



102 



135-5 



147 



159-6 



111 

 61-4 

 51-7 



As 



Sc 



Br 



Rb 



Sr 



Mo 



Ag 



Sn 



Sb 



I 



Ba 



Ce 



i 



General absorption curve showing relation between absorption in 

 element R and in standard substance (Aluminium). The connexion 

 with the fluorescent X-ray spectrum is shown by the position of the 

 spectral lines of It in the lower portion of figure. 



hitherto experimented upon. Thus fig. 2 shows in the lower 

 portion the fluorescent line spectrum of any element, 

 horizontal distances from left to right representing instead 

 of wave-lengths, absorbability in aluminium. Tw t o definite 

 absorbabilities have been found in the fluorescent X-radiation 

 from a number of elements, the line of series L being 

 rouohlv 300 times as absorbable as that of series K. As the 



