SULPHURETS. 203 



1 atom platinum . 12 



2 atoms sulphur . 4 



16 



When the bisulphuret of platinum is exposed to 

 a higher temperature, one-half of the sulphur is 

 driven off, and a sulphuret of platinum remains, 

 composed of 



1 atom platinum . 12 



1 atom sulphur . 2 



14 



The external appearance of the two sulphurets 

 of platinum is nearly the same. 



24. Sulphuret of rhodium. When the triple Rhodium, 

 salt of rhodium is mixed with a solution of hy- 

 drosulphuret of potash, no precipitate appears 

 at first j but, if the liquid be heated, a dark 

 brown powder falls, which becomes black when 

 dried. From the experiments of Berzelius it 

 would appear, that this sulphuret is composed of 



1 atom rhodium . 5-5 



1 atom sulphur . 2 



7-5 



Dr. Wollaston found that rhodium and sulphur 

 unite together when heated. The sulphuret 

 thus formed is bluish grey, and has the metallic 

 lustre ; and may be deprived of its sulphur by 



