CRYSTALLOGRAPHICAL RELATIONSHIP 255 



Crystal system : Rhombic bipyramidal. 

 Axial constants : a : b : c=-9770 : 1 : 1-4386. 



Forms present: jOllj, jlOlj. J100J occurs seldom and very 



poorly developed. 



J120J not found, though observed by Pratt. 

 S. G. =3-513 at 20. 



No analyses were made in the case of this salt, as there was 

 no question as to its identity, and sufficiently full analyses had 

 already been made by Pratt to establish its formula. 



Rb 2 TlCl 5 H 2 

 Fie. 6 



Cs 2 TlCl 5 H 2 

 PIG. 7 



Cs 2 TlCl 5 H 2 



The solution contained CsTl and T1C1 3 in the proportion 

 2:1. There crystallised on evaporation large hexagonal 

 plates of CsgTlgClg, and these gradually gave place to prisms of 

 Cs 2 TlCl 5 H 2 0. This salt is sparingly soluble in water, and 

 crystals 5 6 mms. long were frequently obtained. The larger 

 crystals were usually opaque. They are elongated along the 

 b axis, with well-developed faces of jlOlj (Fig. 7). The end 



