Sulphur and Phosphorus with Platina. 99 



limed, and the super-sulphuret of platina remained at the 

 bottom of the retort. 



Physical and Chemical Properties. 

 Super-sulphuret of platina is of a dark iron-grav colour 

 approachins to black. It is procured in fine powder, or iri 

 small lump's the particles of which are loosely aggregated 

 toa;eiher. In the former state, it has a dull earlhy appear- 

 ance ; in the latter, it exhibits a feeble metallic lustre. It is 

 soft to the touch, and when rubbed on the fingers, or on 

 paper, it leaves a shining black mark, similar to that of 

 black lead. It has no smell nor taste. It is not easy to 

 ascertain its specific gravity with precision. From a trial 

 I made, it appeared to be about 3-5, distilled water being 

 1 ; but this is probably too low. It is a nonconductor of 

 electricity. It does not appear to be affected by the atmo- 

 sphere, or bv water ; at least, no visible change was per- 

 ceived in it 'after being exposed to these agents for some 

 days. I have not been able to fuse it. 



The mineral acids scarcely produce any effect on super- 

 sulphuret of platina. A single grain of it was boiled suc- 

 cessively in pure concentrated nitric, nitro-muriatic, and 

 sulphuric acids, but it apparently underwent no change ; 

 the residuum, after bein§ washed and dried, lost no sensible 

 weight. In the case of the nitro-muriatic acid, however, 

 there was a minute quantity ot sulphur acidified, which 

 was indicated by a slight precipitate on the addition of 

 nitrate of barvtes. 



A strong solution of pure potash when boiled with super- 

 sulphuret of phuina occasioned no visible change in it; 

 but when the alkali was dry and fused with it, a partial 

 decomposition took place. When it is mixed with oxy- 

 muriate of potash and heated, it is decomposed with bril- 

 liant combustion. Sulphureous acid gas and oxygene gas 

 are expelled, and the odour of chlorine is exhaled. The 

 same mixture detonates loudly when it is smartly struck 

 with a hammer. • ■ c 



When super-sulphuret of platina is mixed with fine 

 zinc filings and exposed to an elevated temperature lu a 

 retort over mercury, it is decomposed with vivid ignition, 

 and sulphuret of zinc is formed. When heated in a simdar 

 way with iron filings, it is partially decomposed. When it 

 is heated in chlorine gas, sulphurane appears to be formed; 

 but the decomposition stems to be only partial : the resulli 

 1 have not examined with precision. 



SuDcr-suluiuiret uf platina is not decomposed at a red 

 •^ ^ heat 



