194 SULPHURETS. 



tallic lustre, and a crystalline appearance. Its 

 avidity for oxygen is so great that when put into 

 nitric acid it decomposes both the acid and the 

 liquid. When protacetate of manganese is pre- 

 cipitated by an alkaline hydrosulphuret, or by a 

 current of sulphuretted hydrogen gas, a yellowish 

 precipitate falls, which becomes red when col- 

 lected on the filter, and at last white ; when 

 heated, it gives out water and becomes green. 

 It is uncertain, at present, whether this precipi- 

 tate be a hydrosulphuret of manganese, or a 

 hydrated sulphuret ; but what remains after the 

 powder is exposed to heat is a sulphuret of man- 

 ganese. 



Sulphuret of manganese is found native at 

 Nagyag, in Transylvania, and has been described 

 by the German mineralogists under the name of 

 Manganblende. It was considered, from the 

 analyses of Klaproth and Vauquelin, as a com- 

 pound of protoxide of manganese and sulphur ; 

 but modern chemists have ascertained that it 

 is in reality a sulphuret of manganese. It 

 has a steel grey colour, and occurs crystal- 

 lized in oblique four-sided prisms ; the frac- 

 ture is foliated, and the specific gravity 3*950. 

 The constituents of sulphuret of manganese 

 are 



1 atom manganese * 3*5 



1 atom sulphur . . 2 



