416 ZINC, CADMIUM, LEAD, &c. 



metals. I prepared some very pure copper on 

 purpose, and found that 8 grains of it, when con- 

 verted into sulphuret in a green glass tube, be- 

 came exactly 10 grains. Hence, it follows that 

 this sulphuret i a compound of 



Copper 8 

 Sulphur 2 



10 



2 is an atom of sulphur and 8 is two atoms 

 copper. So that this compound is a disulphuret 

 of copper. 



Besides these two sulphurets of copper, a 



of copper. . A f A J 



third seems to exist in combination with proto- 

 sulphuret of iron ; for M. Henry Rose found 

 copper pyrites to be a compound of 



Copper 34-4 

 Iron 30-47 



Sulphur 35-8? 



Silica 



101-01* 



The excess of 1 per cent, was probably in the 

 sulphur. But let us suppose the result to be 

 exact, the above numbers are equivalent to 



* Ann. de Chim. et de Phys. XXV. 197. 



