246 INDIUM AND THALLIUM IN 



DETAILED CRYSTALLOGRAPHY OF THE VARIOUS SALTS 



K 3 T1C1 6 2H 2 



I : The series R 3 MX 6 2H 2 



This salt crystallises equally well in two distinct habits, 

 one of which has already been described by Fock (7). In the 

 one case the crystals are elongated along the c axis (Fig. 1), 

 and the prism faces jllOj are well developed. The other 



2H a O (6) 

 FIG. 2 



KjTlCl, 2H 2 (a) 

 FIG. 1 



habit, which was not observed by Fock, is illustrated in Fig. 2. 

 The crystals are here tabular on JOOlj, and the faces of jllOj 

 are reduced to very narrow bands. jlOlj is in all cases small, 

 but was represented in all the crystals examined, jlllj is 

 well developed, and gives particularly good reflections. 



The following are the crystallographical data : 



System : ditetragonal bipyramidal. 



Axial constants : a : c=l : '7941. 



Forms present : J100} J110} JOOlj jlOlj Jill}. 

 S. G.= 2-859 at 20. Cleavage indistinct,// jlOOj. 



