SULPHUUETS. 197 



1 atom tin . . 7'25 



1 atom sulphur . 2 



9-25 



(2.) If protosulphuret of tin be reduced to a 

 fine powder, triturated with the third of its 

 weight of sulphur, and the mixture be distilled 

 in a heat raised very nearly to redness, till no 

 more sulphur passes off, the sulphuret increases 

 in weight about ten and a half per cent., or, 

 more exactly, 9*25 of protosulphuret became 

 10*25. It is obvious from this, that a sesquisul- 

 phuret of tin has been formed, composed of 



1 atom tin . . 7-25 



l,i atom sulphur . 3 



10-25 



This sulphuret has a yellowish colour, the metal- 

 lic lustre, and takes a fine polish when rubbed 

 upon a hard body. 



(3.) Persulphuret of tin may be obtained by 

 precipitating permuriate of tin by means of sul- 

 phuretted hydrogen. The well known substance 

 called Mosaic gold, which is in beautiful yellow 

 scales, and which is prepared in the dry way, by 

 a process pointed out by Mr. Woulfe, is a per- 

 sulphuret of tin. Its constituents are 



1 atom tin . . 7'25 



2 atoms sulphur 4 



11-25 



N 3 



