Absorption of X-Rays. 479 



from the experiment, exhibited in the following table, that 

 X. a. k. for aluminium is independent of the thickness of the 

 absorbing screen. 



Table II. 



Thickness of 



aluminium screen 



in cm. (a). 



Thickness of 

 water sheet in 

 cm. (d 2 - d^). 



X. a. k. 

 (d 2 — d x ) 55 - 5 

 a.m. 



0-06 

 0-09 

 0-1 1 

 0-25 



0-38 

 0-60 

 071 

 1-51 



3-5 

 3-7 

 3-6 

 33 



Mean 3"5 



In the following table there is exhibited as a proof a 

 series of observations, respecting absorption in aqueous 

 solutions of KC1 of various concentrations. 



Table III. 



Spec, weight. 



dumber of 

 gram-molecules 

 KOI pr l.(m.). 



Thickness of water sheet 

 in cm. (d 2 —d 1 ). 



X. m. k. 



obs. 



corr. 



1-1515 

 1-1260 

 1-1088 

 1-0897 

 1-0740 

 1-0540 

 1-0396 

 1-0189 



359 

 2-84 

 2-46 

 2-02 

 1-68 

 1-22 

 0-88 

 0-43 



106 

 0-98 

 0-87 

 0-67 

 0-56 

 0-49 

 0-27 

 016 



1-18 

 1-07 

 0-94 

 073 

 0-61 

 0-52 

 0-29 

 018 



18-2 

 20-9 

 21-3 

 200 

 20-1 

 23-6 

 18-3 

 23-2 



Mean 20"7±0-5 



