338 on blende; 



and the metal I hate heated redhot a hundred parts of the same blende 

 vdiiTulphur. w * th as inucft sulphur; and, when the operation was ended, 

 it had not increased a single grain, or even changed colour. 

 Hence we may conclude, first, that the metal in blende is 

 saturated with sulphur; and secondly, that it is free from 

 oxigen, otherwise the sulphur is a combustible, which 

 would have taken its oxigen from it. The following ex- 

 periment does not allow me to doubt this. 

 Artificial sul- I heated together a mixture of sulphur and pure oxide of 

 phuretofzmc, zinc> a hundred and twenty-five grains of each: the pro- 

 duce was a hundred and thirty-six grains. Apprehensive 

 however, that it might not be saturated, I heated it with 

 fresh sulphur, by which it was increased to a hundred and 

 thirty-eight grains. On heating it with sulphur a third 

 time, it did not go beyond a hundred and thirty-eight. I 

 repeated the experiment twice more, and the product 



58 parts su!- stopped at a hundred and thirty-eight grains. Hence we 

 phurtolOOof il . . .. _. *. * ■* ,. _ a , e 



£ mc may infer, if there were no mistake, that 38 parts of 



sulphur took the place of 25 of oxigen, that were con- 

 densed in the oxide. It would be superfluous to say, that 

 this process evolved torrents of sulphurous gas. 



Morveau is I believe the first, who reproduced sulphuret 

 of zinc by heating its oxide with sulphur. The artificial 

 blende remains pulverulent: but it appears to me by Mor- 

 vcau's account, that it is capable of being melted by a 

 Transparency strong heat. Blende is transparent; hence, they say, its 

 no^roof that me t^l must be oxided. But the sulphurets of mercury and 

 the metal is of arsenic are transparent likewise ; yet they are free 

 Sulphuret of ^ rom 0X1 S eia ' The sulphuret of arsenic, I know not whe- 

 arsenic iher I have mentioned the fact, supports any temperature 



to which you choose to expose it, without affording any 

 indication of sulphurous gas, or losing its transparency. 

 Arsenic acid or oxide gives out sulphurous gas in abundance, 

 when heated with sulphur, and affords a transparent sul- 

 phuret, similar to that produced by the metal itself. These 

 compounds therefore contain no oxigen ; and consequently 

 transparency is no argument for the oxidation of a suiphu. 

 ret. But why should zinc refuse to unite directly with 

 sulphur? I confess I see no reason for it. I had intended 



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