248 



INDIUM AND THALLIUM IN 



System : Ditetragonal bipyramidal. 

 Axial constants : a : c=l : '8097. 



Forms present: J100J, jllOj, jlOlj, jlll(, jOOlj, J113J, with 

 indications of J103J. 



Cleavage very poor, // J100S. 



S. G.= 2-389 at 20. 



It will be observed that the crystallographical details 

 differ somewhat widely from the value given by Rammelsberg. 

 Rammelsberg gave no details with regard to his measure- 

 ments, which were made some thirty years ago, and would 

 consequently require in any case to be revised to-day. 



The estimations of the water of crystallisation gave the 

 following results : 



Average of Analyses 

 H 2 7-15% 



(NH 4 ) 3 TlCle2H 2 

 7-11 % 



(NH 4 ) 3 T1C1 

 5-43 % 



Considerable caution had to be exercised in heating this 

 salt. At temperatures above 150 dissociation took place, 

 the salt losing continuously in weight. Heating was con- 

 tinued at a temperature slightly under 150 until a practically 

 constant weight was reached, and presumably the whole of the 

 water of crystallisation had been liberated. The ammonium 

 salt, like the potassium salt, crystallises with two molecules 

 of water. 



K 3 InCl 6 2H 2 



This salt had been obtained by Meyer (6), and examined 



