bECOttPOSlTION OF SULPHUR. 371 



I made several experiments, among which the following 

 appeared to me the most conclusive. 



Exp. 3. The solution of azotized sulphuret of potash 3d experiment, 

 strongly acidulated with sulphuric acid saturated with ni- 

 trous gas yields a copious precipitate of sulphur, while all 

 the other acids scarcely throw down any. 



Several chemists, to explain this truly remarkable pro- Explained 

 perty of nitrous gas, have supposed, that this gas was de- 

 composed; and that its oxigen, by combining with the 

 hidrogen that holds the sulphur in solution, favours the pre* 

 cipitation of the sulphur. 



Yet if it. were true, that oxigen had the property of pre- erroneously, 

 cipitating sulphur from its solution, why does not the oxi- 

 muriatic acid act in the same manner as the nitrous gas: 

 Can oxigen possess two such opposite properties, particu* 

 larly when it acts in similar circumstances ? This explana- 

 tion then presents an anomaly far from favourable to the 

 different hypotheses opposed to the consequences I have 

 drawn from my experiments. It is proper therefore to 

 examine the question ii\ another point of view. 



In the first place nitrous gas docs not act in the solution accounted for. 

 of azotized sulphuret of potash by oxigenizing the hidro- 

 gen of the sulphuret: for this solution, far from contain- 

 ing a surplus of hidrogen beyond the composition of the 

 sulphur, is on the contrary deprived of a part of that which 

 constitutes the sulphur. Accordingly it is by hidrogenizing 

 the dishidrogenized carbon of the sulphur, that the latter 

 is precipitated from its solution, which is very different from 

 the explanation that has been given of this phenomenon. 

 Thus the nitrous gas acts on the solution of -azotized sul- 

 phuret of potash only in consequence of the affinity this 

 gas has for oxigen, and of that which the dishidrogenized 

 carbon of the sulphur has for hidrogen; an action that 

 concurs at the same time to decompose the water, and with 

 which is combined that exerted by the sulphur on' the 

 oxigen. 



* B 2 VIL On 



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