On some Combinations oJTlatina. 217 



sical characters strictly resembled the siipersulphurei of 

 platiiia. From the experiments I have made on it, which 

 will hereaher be noticed, it appears to be a true sulphuret 

 of platina containinii 22 per cent, of sulphur. 



Experiment 2. — Ten grains of the same hydrosulphuret, 

 heated as in the above experiment, furnished simiiar results; 

 the quantity of s.as was precisely the same. The sulphuret 

 obtained weighed 8"25 grains. 



Experiment 3. — Twelve grains of hvdrosulphuret, which 

 in drying had been exposed to a higher temperature than 

 that used in the preceding experiments, aflbrded similar 

 proilucts ; but the sulphuretted hydrogen gas was less in 

 quantity, it did not amount to a half of a cubical inch. This 

 deficiency must be referred to the increased temperature, by 

 which the gas was expelled and found in the water, as has 

 been before noticed. The proportion of sulphureous acid 

 gas was small, but the odour of it was more perceptible; 

 there was also less water and more sulphur than in the ex- 

 periments detailed. The quantity of sulphuret of platina 

 obtained amounted to 9-83 grains, which, on being decom- 

 pounded at a red heat in a platina crucible, afforded results 

 varying but little from those previously procured. 



From these experiments we shall probably gain near ap- 

 proximations to the true composition of the hvdrosulphuret 

 of platina. They all closely agree as to the quantity of 

 sulphur and platina, but differ as to the proportion of gas 

 obtained ; which has been accounted for. Of the three ex- 

 periments above detailed, the first two appear to me to be 

 most worthv of confidence. As the hydrosulphuret had in 

 the first experiment been least exposed to the agency of 

 the atmosphere, and consequently would furnish more cor- 

 rect results, I shall venture to make its data the basis for 

 determining the proportions of its constituent parts. From 

 this experiment the following results are derived : 



f Sulphuretted hydrogen 1'25 grains") » f grains. 



c I cub. inch = 436 | So | — 4-56 



£ J Sulphuret of platina 8-30(» lo) —8300 



"^ ] Sulphur 0-400 ^ ~ "S — 4-00 



— j Water impregnated with sul- | " 



L phuretted hydrogen ... . 0844 J o"^ L— 8-44 

 I have estimated the weight of 100 cubical inches of sul- 

 phuretted hydrogen gas at 36'5 grains. It is derived from 

 Sir H. Davy's statements, who says that 100 cubical inches 

 weigh between 36, and 37 grains. 



The sulphuret of plalma contained 22 per cent, of sul- 

 phur ; consequenlly the above 83 grains consisted of 6J'74 



platina 



