ON TIN, -v 45 



Black liydro-sulphuret, heated in a retort, gave iibun dance Facts ami oIj, 

 of water and a little free sulphur, but no sulphureous gas, and tf^rndT^^com.. 

 was reduced to a pure and simple metallic sulphuret ; thatpoimds. 

 is to say, although the quantity of tin in this hydro-sulph.urct 

 be as 22. to 100, it docs not stop a.t this inferior degree of 

 oxidation, which would turn it into mosaic gold. It should 

 l»eem, that the hydrogen, being presented to the oxigen of the 

 oxide in a more powerful degree than in hydro-sulphuret at a 

 maximum, saturates and converts it entirely into water, lea^- 

 jng none with the metal, which, as we have seen, can never 

 form mosaic gold without a certain portion of oxigeji. 



We shall now proceed to the changes effected in. mosSSi^ 

 gold -by potash. 



Mosaic Gold and Potasli. 



Liquid potash, assisted by heat, quietly dissolves mosa'i<? 

 gold, and assumes a greenish shade. From this solution 

 acids sepaiate a yellow powder, which is no longer mosaic 

 gold but hydro-sulphuret at the maximum : there is, therefore, 

 a decomposition of water ; the base of the mosaic gold, deprives 

 it of oxigen, to raise itself to the maxin^tim of oxidation, whilst 

 the hydrogen, on the other hand, combining with thesul^>hur, 

 constitutes sulphurated hydrogen, and the mosaic gold thus 

 becomes transformed into hydro-sulphurated oxide major; or, 

 in other words, into hydro-sulphuret of tin major ; in fact, 

 this precipitate possesses none of the properties of mosaic 

 gold ; muriatic acid dissolves it, disengages the sulphurated 

 hydrogen, and reduces it to a simple solution of muriate, 

 whose basis is at a maximum. 



This reminds us of that decomposition of water, which 

 accompanies the transformation of sulphur of antimony into 

 kermes. The antimony is oxided at the expencc of the water, 

 which it decomposes ; whilst its sulphur is hydrogened, and 

 furnishes the antimonial oxide with the requisite saturating 

 acid. There is, however, between antimony and tin this tlif- 

 ference : that thcwgh the latter is raised suddenly to its max- 

 imum in potash, antimony never passes its minimum hi 

 changing into kermes. Indeed, it is still more surprising to 

 observe that sulphuret of tin, whose affinity to ox^cn appars 



far 



