106 Berzelius on a new Mineral Body, SfC. [Aug. 



absorbed. The seleniuret of iron does not melt, but it softens 

 and becomes agglutinated into a coherent mass, which often 

 prevents the vapour of selenium from passing through it. Sele- 

 niuret of iron has a metallic aspect, and a dark grey colour 

 bordering on yellow. It is hard, brittle, and has a granular 

 texture. When roasted at the flame of a candle, this seleniuret 

 gives out a portion of its selenium with the smell of horseradish, 

 and is gradually converted into a black fused mass, which, when 

 cold, breaks under a blow of the hammer, and exhibits a vitreous 

 texture. It seems to be a protoseieniuret of iron. 



Seleniuret of iron dissolves in muriatic acid with the evolution 

 of seleniuretted hydrogen gas; and this is the best method of pro- 

 curing this gas. The first effect of the acid is to render the liquid 

 cinnabar-red and muddy. The acid appears to separate from 

 the seleniuret of iron a portion of selenium in red flocks. This, 

 however, can only take place by a decomposition of the first 

 portion of seleniuretted hydrogen gas, which dissolves in the 

 liquid, and whose hydrogen combines with the oxygen of the 

 atmospherical air which it contains. The same phenomenon 

 takes place, if, during the development of this gas, the tempera- 

 ture diminishes, so as to allow atmospherical air to enter into the 

 apparatus. The clear greenish liquid becomes speedily muddy 

 by a cinnabar-red powder, with which it appears to be entirely filled. 



When seleniuret of iron is dissolved in muriatic acid there is 

 disengaged likewise another combustible gas, which neither 

 dissolves in water nor in caustic alkalies, and which of conse- 

 quence remains after the solution of seleniuretted hydrogen gas. 

 This gas has a peculiar and very disagreeable odour, which the 

 glasses retain for a long time even after being washed. This gas 

 produces a black precipitate in a solution of protonitrate of 

 mercury. 



Seleniuret of iron in powder combines easily with an excess of 

 selenium. This combination is a brownish powder, which does 

 not dissolve in muriatic acid, and which, when exposed to a red- 

 dish-white heat, loses its excess of selenium. 



4. Seleniuret of Cobalt. — Cobalt absorbs selenium readily, 

 and with the production of heat. When the compound is 

 heated to redness, it gives out its excess of selenium, melts, and 

 gives a metallic mass of a grey colour with a foliated fracture. 



5. Seleniuret of Tin. — Tin and selenium combine with the 

 evolution of heat. The tin swells, but does not become liquid. 

 The mass is grey, and possesses the metallic brilliancy in a very 

 high degree in those parts which were in contact with the glass, 

 or which have been rubbed by a polished piece of hematites. 

 Seleniuret of tin allows its selenium to escape, when heated, more 

 easily than any other seleniuret. The compound does not melt, 

 the selenium is volatilized, and the tin remains in the state of an 

 oxide. 



(To be continued.) 



