﻿410 Prof. W. H. Bra^o - on the Relation between certain 



for the 7 line of Pd and Ag are not so reliable as the 

 others. 





Table I. 





A°- 



Pd. 



Eh. 





0-562 

 0557 

 0-495 

 0-488 



0-589 

 0583 

 0516 

 0-503 



0619 

 0-614 



0545 

 0-534 



a. 



(3 







These measurements were undertaken in the attempt to 

 throw some further light on the relation between wave- 

 length and absorption in certain cases. Barkla has shown 

 that in general the X rays characteristic of any substance 

 are strongly absorbed by substances of lesser atomic weight 

 as compared with substances of greater atomic weight. The 

 phenomenon may be more definitely expressed in terms of 

 wave-length. An instance is given in the table on p. 627 

 of the December (1914) number of the Philosophical 

 Magazine. The ft ray of silver (0'495 A.U., see the table 

 above) is very strongly absorbed by Pd as compared with 

 Sn or even Ag itself. Some figures given in the table 

 quoted are reproduced here (Table II.) in slightly altered 

 form, and will make the point clear. 



Table II. 



X ray. 



Log. of 



wave-length 



in A.r. 



Log. of atomic absorption 

 coefficient X 10 22 . 



Pd. 



Ag- 



A* 6 



1-6946 

 1-7126 

 1-7364 

 1-7459 

 T-7657 

 1-7882 



2 064 

 1-301 

 1-350 

 1377 

 1-452 

 1-498 



1-260 

 1-342 

 1-394 

 1-403 

 1-477 

 1-545 



Pd/3 



Rh/3 



As. a 



Pd a 



Eha 





These are plotted in fig. 2. All the points representing 

 the way in which the absorption of the different rays by 



