^^ on TIN. 



Facts and ob- If it be grafiiially heated, it affords water of new forma- 

 tfnand k'* "" - ^^^"' ^"^ §^^^^ °"^ sulphureous gas, a little free sulphur, and a 

 •pounds. residuum of very beautiful mosaic gold. 



These latter products distinctly shew, that the hydro-sul- 

 phuret cannot sustain a high temperature without a tendency to 

 become simplified ; that the tin, for example, communicates 

 oxigen to the two principles of sulphurated h^xlrogen, retaining 

 only such a proportion as the affmities render necessary for the 

 new combination in which it becomes mosaic gold ; and, lastly, 

 if the temperature be augmented, the mosaic gold, abandon- 

 ing this oxigen, passes into the state of metallic sulphuret, a com- 

 bination still more simple than mosaic gold. 



Minor Hydro-Snlphuret of Tin. 



If a saturated solution of tin at the minimum be treated ia 

 the way already described, a powder is obtained of the colour 

 of coffee, or a little darker, which is to be washed in boiling 

 water. This slight heat augmenting the attraction of the par-^ 

 tides, enables the hydro-sulphuret to resist the action of the air, 

 which otherwise is apt to change it from brown to yellow, even 

 whilst on the filtrc, that is to say, from minimum to maximum. 



This hydro-sulphurct is distinguished from the preceding by 

 the following qualities : 



It is black, or appears so; will not dissolve in potash with- 

 out changing its state; and yields no mosaic gold by heat. 



It possesses, in common with the foregoing, the property of 

 dissolving with effervescence, of restoring the gas which satu- 

 rated its base ; and, consequently, of giving muriate of tin at a 

 minimum, if muriatic acid be used. 



If this hydro-sulphuret, when fresh, be heated with potash, 

 it divides in two: one part of its base gives to the other all its 

 oxigen, and is thus reduced to the state of simple metallic sul- 

 phuret. In this state it is collected togetiier at the bottom of 

 the vessel. The other part, raised by this addition to the maxi- 

 mum, attracts also the sulphurated hydrogen of the former, and 

 thus becomes hydro-sulphuret major. T4ie metallic sulphuret 

 being thus separated, a yellow powder is precipitated by acids 

 from the liquor, possessing all the characters desciibed in the 

 h};dro-'Suiphuret of tin at a maximum. I have observed, '\\\ 

 speaking of antimony, that its hydro-sulphuret, or kermes, 

 treated with potabh, can also yield sulphuret of antimony. 



Black 



