HIDROSULPHURET OF ZINC. 33& 



to treat zinc with cinnabar, and other sulphurets; but dif- 

 ferent objects have prevented me. 



The sulphuret of zinc is frequently concealed by foreign Different co- 

 oxides and sulphurets: hence red, black, ash-coloured, ,ours . donofc 



r ' constitute spe- 



green, and other blendes, of which so many species have cies in blendes, 



been made. Now this is precisely the same, as if, in the 



natural history of wool, different species were to be made 



of those that are dyed red, black, gray, or green. 



There are blendes coloured by red oxide of iron, which Blackblendes 

 appear black; but their powder is red. These may be ^^of iron, 

 analysed by muriatic acid, which will cause the iron to 

 descend to its minimum of oxidation, on account of the 

 sulphuretted hydrogen formed during their solution. We 

 should be aware of this, that we may not suppose the 

 oxide to be at a minimum,- where nature has placed only 

 oxide at a maximum. 



There are some that contain lead in the state of oxide, Blendes with 

 or of sulphuret, If these be exposed to the action of 

 muriatic acid, the whole of the lead is found in the solu- 

 tion : but if oxigenized muriatic acid be used, we must 

 look for the lead in the residuum only. The reason of this 

 is obvious; the sulphur of the blende, being acidified, pre- 

 cipitates the lead iu the state of sulphate. 



llidrosulphuret of Zinc. 

 Sulphuretted hidrogen precipitates zinc from its solutions Hidrosnlplmret 

 in a yellowish white powder, which is a llidrosulphuret. zinc ' 

 .This precipitation however is limited. When the acid is 

 freed from a considerable portion of the oxide, so as to be 

 in excess, it disputes the remainder with the hidrogen, and 

 the precipitation stops. It is necessary therefore, to add a 

 little potash, to neutralize this excess. The alkaline hidro. 

 sulphurets produce the same precipitate. The nitric acid 

 acts with vehemence on this llidrosulphuret, burning its 

 hidrogen, and part of its sulphur. Muriatic acid applied 

 cold expels the sulphuretted hidrogen in abundance. This 

 bidrosulphiiret at a red heat gives out water and sulphurous 

 acid, and is converted into a simple sulphuret, or blende. 

 The sulphuret of xinc, whether native or artificial, yields 

 sulphuretted hidrogen ; which however is not an educt, but 

 a product. 



Ambergris, 



