( 613 ) 
for K,Te,S, :sf>.77 0 ) ; 33.5V, Te, 33.4’/, S and 33.1V, K, which 
answers to a formula K 10 Te,S, s ; another time (for a product prepared 
from K,Te0 4 ): 44.7% Te, 31.47% S, and 23.7% K, which would 
correspond to K 12 S s0 Te 7 ; again another time at somewhat higher 
temperature: 37.5%Te, 34.3%S and 28.1%K, which leads to a 
formula K la Te 8 S 19 . 
The behaviour is practically analogous to that found in the poly- 
sulphides of the alkalies towards sulphur, where, according to 
Kuster’s researches 1 ), very complicated equilibria between different 
polysulphides and their dissociation products occur in the solution; 
and to that of selenium towards sulphides where, according to 
Messinger 2 ), a portion of the sulphur of the complex sulphohydrogen 
sulphides may be replaced by selenium, forming such compounds 
as Na s S Se, which, therefore, belong to the type of a fmulphide. 
The behaviour of amorphous tellurium towards sulphide solutions as 
described previously also agrees with the notion that we are dealing 
here with salts of complex tellurohydrogen sulphides which in such 
solutions are in dissociation-equilibria with each other and are 
moreover split hydrolytically. 
The type of the ^sulphides becomes then of particular importance 
next to that of the ^sulphides: K 10 S 12 Te, may be derived from 
K a S 8 by isomorphous substitution of % of the S by Te; K,Te a S 7 and 
(NH 4 ) 4 Te,S 7 similarly from K a S„ or (NH 4 ) a S,; on the other hand 
KjjTejS,, has again the character of the type K 2 S 4 etc. 
$ 10. Although these compounds do not as a rule occur in measur¬ 
able forms (the K-salt was obtained a few times as beautiful rhombic 
parallelopipeds with faint double refraction and without perceptible 
dichroism) I finally succeeded in obtaining very large, yellow crystals, 
with many planes, of a barium salt prepared by dissolving the black 
precipitate formed by the action of H,S on potassium tellurite in 
BaS-solution. The analysis indeed, did not always yield precisely the 
same results, but still the composition agreed closely with the formula 
Ba 8 S 7 Te s ; in one instance the normal composition; 45,8% Ba; 25*/, S 
and 29,1 °/ 0 Te was actually found. These crystals were accurately 
investigated and proved to be so well constructed that, in their habit, 
they did not remind us of mixed crystals but, on the contrary, 
made a vivid impression of belonging to a true chemical compound. 
The following data were found: 
Large yellow transparent crystals fairly stable in the air but, after 
some time, assuming a greyish colour. They are well constructed, 
l ) Kuster, Z. f. anorg. Cbero. 44. 431. 
3 ) Messinger, Berl. Ber. 30 805 (1897). 
41 * 
