256 



INDIUM AND THALLIUM IN 



faces are comparatively small, but give good reflections, 

 whereas the faces of jlOlj are badly striated. jlOOj occurs, 

 but the faces are narrow and very poorly developed. J120J 

 was not found on any crystal examined. 



Crystal system : Rhombic bipyramidal. 



Axial constants : a : b :c='9690 : 1 : 1-4321. 



S. G.= 3-879 at 20. 



Forms present : |011j, JlOlj, jlOOj. 



Here, too, Pratt observed the form J120J on some of the 

 crystals he examined, although the form did not occur on the 

 crystals from any of the crops examined by me. 



As in the case of the preceding salt, a quantitative analysis 

 was deemed unnecessary here. 



(NH 4 ) 2 InCl 5 H 2 



This salt was obtained by Meyer ( 1 6) on evaporating a solution 

 containing (NH 4 )C1 and InCl 3 , in his attempt to isolate a 

 compound similar to K 3 InCl 6 1 JH 2 0. He mentioned that the 

 crystals seemed different in form from those of the potassium 

 salt, but evidently no detailed examination was made. 



The habit of the crystals seems to vary with the composi- 

 tion of the original solution. From a solution where the 

 proportion of the NH 4 ions to the In ions was that represented 

 by the formula (NH 4 ) 3 InCl 6 2H 2 0, crystals of (NH 4 ) 2 InCl 5 

 H 2 O were precipitated which were elongated along the b axis, 

 had well-developed faces of |101|, fairly good faces of J120J, 



