202 SULPHURETS. 



1 atom silver . 13-75 



1 atom sulphur 2 



15-75 



Gold,. 22. Sulphuret of gold. Oberkampf made us 



first acquainted with the sulphuret of gold. He 

 obtained it by precipitating nitro-muriate of gold 

 with sulphuretted hydrogen gas. From his ex- 

 periments it appears to be a trisulphuret, com- 

 posed of 



1 atom gold . . 25 

 3 atoms sulphur . 6 



31 



But the experiments of Oberkampf were repeat- 

 ed unsuccessfully by Javal and Berzelius. Ber- 

 zelius found that the sulphur was acidified at 

 the expense of the oxygen in the oxide of gold 

 existing in the solution. 



Platinum, 23. Sulphuret of platinum. There are two 

 sulphurets of platinum. When ammonio-mu- 

 riate of platinum is mixed intimately with sul- 

 phur, and the mixture heated in close vessels 

 till the sal-ammoniac flies off and the excess of 

 sulphur, a bisulphuret of platinum is formed. It 

 is grey coloured, and assumes the metallic lustre 

 when rubbed against a hard body. Its consti- 

 tuents are 



