470 WycJtoff — Crystal Structure of Ammonium Chloride. 



made by H. E. Merwin, to whom the writer wishes to 

 express his sincere gratitude not only for this determin- 

 ation but also for discussions of the crystallographic 



Fig. 1. 







■ ..-:■'■ ~ m .;--- ■•■--:- ■ 

 p. - :-' :: X- : .1-,':-. . .-,• ■•' ^ 



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t 1 



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f 



v \ 



V- - 



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Pigtre 1. A Lane photograph of ammonium chloride produced by passing 

 the X-rays in a direction roughly normal to a cube face. 



aspects of this problem. He says: "The refractive 

 index of ammonium chloride crystals grown from solu- 

 tion with urea was the same as that of the pure salt used 

 for the solution, 1.639±0.001. This is lower than 

 Grailich's rough value usually quoted. Contamination 



