216 On some Comhinati07is of Platint, 



Analysis. 



The method I employed to ascertain the component parts 

 of-this substance was of the simplest kind, but I know of 

 rfo mnde which oflcrs more correct results. It is founded 

 on a property, which, in the class of metallic hydrosui- 

 phurets, I believe, almost exclusively belongs to those of 

 platina and g"ld ; namely, that of being; decompounded by 

 the agency of heat and air, the meial alone remaining in a 

 state of puritv. T made many experiments on the hvdrosul- 

 phuret of platina before I obtained any satisfactory results. 

 Those which nearly agree, and which seem to afford evi- 

 dences of its constitution, T shall immediately relate. 



Experiment 1. Ten grains of hydrosulphuret of platina 

 were heated in a small retort over mercury, gas was soon 

 disengaged, and a little limpid fluid condensed in the neck 

 of the retort ; the heat was continued for several minutes, 

 and when the retort had acquired a dull red, the substance 

 became partiallv ignited*, a copious evolution of gas im- 

 niediatelv ensued, and a little yellow sublimate was depo- 

 sited. Whi n the gas ceased to come over, and no further 

 change could be produced bv the utmost heat of a spirit- 

 lamp, the retort was suffered to cool, and the results w.ere 

 carefully examined. The gas obtained, allowance being 

 iDade for the common air, and corrections for temperature 

 and pressure, amounted to rSA of a cubical inch, and was 

 almost entirely sulphuietted hydrogen gas, with a minute 

 quantity of sulphureous acid gas. On agi;ation it was ab- 

 sorbed by water, and instantly produced a dark-coloured 

 precipitate with a solution of the nitrates of lead and silver. 

 It had the precise odour of sulphuretted hydrogen gas, and 

 inflamed with a lighted taper in contact with the atmo- 

 sphere, depositing sulphur on the sides of the tube. The 

 limpid fluid was water impregnated with sulphuretted hy- 

 drogen, and produced similar effects on metallic solutions as 

 tliose above stated. The yellow sublimate was a slight 

 film of sulphur, and weighed about -j-Vhs of a grain. This 

 estimate of the su!|)hur must be considered merely as an 

 approximation, as it was in a moist state. The |)recise 

 quantity of water and sulphur thus ol.itained could not be 

 deternnncd with precision ; but they could scarcely together 

 have exceeded a grain in weight. The fixed substance at 

 the bottom of the retort weighed 8"3 grains, and in its phy- 



* This pliaenoir.er.on of the prcdiicrion of fire, accompanied by the se- 

 paration of one of the constituent pavt; of the hydrosiilplmret, appears to 

 be perfectly an;ilo{;oiis zo that obiervcd by Sii- H. Davy in the decompoii- 

 V«a of tuci'.lorine "as at an eJevaicd tcmpeiaturc. 



sical 



