Facts and ob- far greater than that of mosaic gold, cannot decompose water 



scrvations on ,., . o , i ^ 



tiijanditscom- ' 



pounds. But mosaic gold is not singular in undergoing this inver- 



sion. For example, if oxide of tin at the minimum be heated 

 with potash and sulphur, the oxide will be suddenly raised 

 to the maximum, and changed into hydro-sulphuret major. 



If muriate of tin minor be poured into potash, exempt 

 from sulphurated hydrogen, it produces a yellowish precipi- 

 tate, inclining to fown, which is nothing else than hydro-' 

 sulphuret major. Oxide of tin at the minimum has, therefore, 

 a peculiar disposition to decompose water, and to be suroxi- 

 dated at its expence. Thus mosaic gold cannot be had by 

 the humid way. Pelletier, who went no ferther tlum the pre- 

 cipitation of the muriate in sulpliate of potash, thought he had 

 obtained mosaic gold, because his precipitate, when lieatedin 

 a retort, was converted into that substance ; but it did not 

 occur to him then, that what he was heating was not, as it 

 should have been, a composition capable of resisting acids -^ 

 ki a word, it was not mosaic gold. 



If all liquid sulphurets were hydrogened, as Berthollet 

 imagines, the precipitates which they give with muriate at g, 

 minimum, would be very much mixed with black hydro- 

 sulphuret; and, consequently, of a very deep colour; but 

 nothing is less general. 



When the precipitate is very yellow, capable of complete 

 solution in pot-ash, and the solution does not turn brown 

 ■when mixed with hydro-sulphurated water; the conclusion 

 must be that there are simple sulphurets of potash, as well as 

 compound ones. 



But we must not forget that no liquid sulphuret is strictly 

 without a little hydrogen, as I have demonstrated; it is this 

 which clouds the yellow colour of the hydro-sulphuret major, 

 and gives it a drab coloured hue; but these small portions 

 of hydrogen cannot be considered as necessary component 

 parts of the sulphurets ; nor as mediums without which the 

 sulphur could not be suspended in the alca."! ? I cannot ad- 

 mit this. Put diluted sulphuret of potash into three glasses, 

 aiiid add to two of them a little hydro-sulphuret of potash,' 

 in unequal proportions; then let a few drops of muriate ^f 



tin 



