On the Comhinatmt of Metals mth SuJphtv, j 1 7 



pure metallic oxides, but which are really lilts, containing a portion of add too ftrongly 

 adherent to be feparated but by means of an alkali. 



We may therefore confider the combinations formed by thefe metals, and probably by 

 many others likewlfe with acids as neutral falts, diflblved in a fuperabundance of acid, 

 which is taken from them by water, when the falts are precipitated in a truly neutral and 

 infoluble ftate. 



From the manner In which the muriatic acid afts upon the metallic fulphurets, it follows, 

 that the more oxigen is abforbed by the metals, in order to unite with this acid, the lefs of 

 fulphur will remain after the folutlon, and the contrary ; but if thefe metals abforb but 

 little oxigen, if they contain much fulphur, and if alfo rheir affinity for oxigen be not con- 

 Cderable, the whole of the metal will not be feparated from the fulphur by the muriatic 

 acid, becaufe in proportion as this combuftible body became more abundant, it oppofes 

 the folutlon of the metal by virtue of Its mafs ; this is the reafon why certain metallic ful- 

 phurets, which are not attacked by the muriatic acid, are decompofed by it, when a por- 

 tion of their fulphur has been feparated in diftillatlon. 



The mode of aftion of the nitric acid upon the metallic fulphurets is very different from: 

 this, for though the fulphur is not in this cafe attracted by any body, it Is neverthelefs 

 completely feparated from the metal', and thrown down In all its purity, if the experiment 

 be properly conduced : but if the combination of the nitric acid with the metal be not 

 aided by hidrogen, that takes place with the muriatic acid, it gives out to the metal a por^ 

 tion of oxigen much more readily than water; and it is In confequence of this affinity of 

 the oxigen for the metal, and of the oxide which is formed for the undecompofed acid^ 

 which is effedted by the folutlon. Thus every time that metallic fulphures are decompofed 

 by the nitric acid, there is a conftant formation of nitrous gas,, and never of fulphurated 

 hidrogen. 



It appears that in general fulphur has a greater affinity for the metals than for their 

 oxides, and that this affinity dlmlnifties in proportion to the quantity of oxigen they ab- 

 forb : they are fome which do not even combine with fulphur, except in the complete 

 metallic ftate ; thus for inftance, on triturating fome oxide of lead with fulphur, a portion 

 of the latter deflagrates, and the other combines with the lead, which is brought to the. 

 metallic ftate. 



Hence it appears that zinc does not combine with fulphur when it is completely metallic, 

 at leaft nature has not hitherto affiarded us fufficlent examples, and art has not fucceeded in 

 effisdting the combination of thefe two fubftances. What is known in mineralogy under, 

 the name of blende, or fulphurated zinc, has been improperly confidered by fome 

 mineraloglfts as a combinaion of metallic zinc with fulphur. It is, on the contrary, oxide 

 of fulphurated zinc, which very frequently contains hidrogen -, for, the blendes almoft 

 always diflblve in the acids, and produce fulphurated hidrogen gas. Thus a tranfparent 

 blend which a£ts in this manner with the acids, ought to be confidered as a real oxide 

 of hidro-fulphurated zinC) or rather fulphureo-hidrogen. There may be oxides of zinc 



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