192 SULPHURETS. 



by the magnet. This sulphuret may be obtained 

 also artificially, by mixing intimately together 2 

 parts of protosulphuret of iron and 1 part of sul- 

 phur, and heating it in a temperature which 

 must never be elevated to redness. When per- 

 sulphuret of iron is heated to redness in close 

 vessels, one half of the sulphur is sublimed and 

 protosulphuret of iron remains. It is a com- 

 pound of 



1 atom iron . . . 3-5 



2 atoms sulphur . . 4 



7-5 



Berthier has shown, that protosulphuret of iron 

 is formed when protosulphate of iron is heated 

 in a charcoal crucible. 



When magnetic pyrites is dissolved in an acid 

 some sulphur precipitates : hence, it obviously 

 contains either a slight excess of sulphur, or a 

 slight mixture of cubic pyrites ; for protosul- 

 phuret of iron dissolves in acids without any de- 

 posite of sulphur. 



Nickel, 10. Sulphuret of nickel. It may be formed 

 by fusing a mixture of oxide of nickel and sul- 

 phur in close vessels, and continuing the heat 

 till the excess of sulphur is driven off. This 

 sulphuret occurs in the mineral kingdom, and 

 was formerly distinguished by the name of 

 Plaarkies (hair pyrites). When a current of 



