On the Structure of Silver Crystals. 83 



oo r ii+a+K 



Let X ----- = S K , 

 n=0 n + a + K 



then S K =:S-=2--2- 



«^a + /c /i « = l ?l n-l u 



a + K— 1 „,» 



= ._ log (!_,)_ 2 



»— 1 ' t 



and 



A-a-l\l 





But 



Therefore 



B-g-)C:}) [ ( - i ry (1 - ff) a-ry- 



University of Pennsylvania, 

 Philadelphia, U.S.A. 



IX. Z7/£ Structure of Silver Crystals. 

 By L. Vegard, Dr.pldL* University of Christiania*. 



AS a contribution to the study of the inner structure of 

 crystals by the Rontgen ray analysis, I am going to 

 give an account of the determination of the crystalline 

 structure of silver. 



Silver crystals belong to the cubic system, and are found 

 in nature in very fine specimens of considerable size and 

 with well-developed regular crystal-faces. 



For the analysis I used the reflexion method of W. H. Bragg 

 and W. L. Bragg f , which is based on the determination of 

 the reflexion angle of a homogeneous beam of X-rays. 



The Rontgen-ray tube was of the sort recommended by 

 Bragg, with a rhodium anticathode. The Rontgen-ray 

 spectrometer was in principle the same as that constructed 



* Communicated by the Author. 



t W. H. Bragg and W. L. Bragg, Proc. Roy. Soc. A. vol. lxxxviii. 

 p. 428. 



