On some Combinations of Platina. 215 



ble in water. It appears to be a muriat of platina with a 

 lutle undecompounded hydrosulphuret. 



All these experiments were perlormcd on minute por- 

 tions ot the hydrusulphurel : it would be very desirable to 

 repeat them on larger quanlilies. 



From the foregoing statements, it is evident that the 

 substance obtained by the agency of sulphuretted hydro- 

 gen gas on a solution of platina is not a true sulphuret of 

 this metal. On a comparison of their chemical properties. 

 It will appear that they are decidedly different. Nor can 

 It be, it would seem, a compound of sulphuretted hydro- 

 gen gas with oxide of platina, for in this case no sul- 

 phuretted hydrogen gas would be furnished by its decom- 

 position in close vessels; water and sulphureous acid gas 

 would be the only results. Now in the actual products 

 water and sulphureous acid gas are found, but in such 

 small quantities, especially the latter, that oxygen and wa- 

 ter can only be considered as accidental, and not at all 

 essential to the constitution of ihe hydrosulphuret. They 

 may fairly be presumed to originate from other sources. 

 The hydrosulphuret was dried at a temperature scarcely 

 exceeding that of boiling water, and there can be no diffi- 

 culty in admitting that it still contained water. As it ab- 

 sorbed oxygen by exposure to air, and as in the course of 

 the experiments it must necessarily have been exposed for a 

 short time to this agency, the production of a small quan- 

 tity of sulphureous acid gas is easily accounted for. 



The actual results seem to prove that this substance is 

 composed of sulphuret of platina and sulphuretted hydro- 

 gen, or of platina, sulphur, and hydrogen; and the'facts 

 seem to admit of an easy Solution on this idea. The sul- 

 phuretted hydrogen may be presumed to be in a loose state 

 of combination with the sulphuret. Hence, by exposure 

 to the atmosphere, oxygen is absorbed, sulphuric acid and 

 walei are formed, and a sulphuret of platina remains which 

 is not affected by the air. The sulphuric acid formed by ex- 

 posing the hydrosulphuret to the heat of a sand-bath for 

 several days is quite colourless with water; the eflect seems 

 to be wholly unconnected with the solution of any of the 

 platina. I have not yet ascertained the precise limits of 

 the decomposition of ihe hydrosulphuret by the agency of 

 the air ; but it seems highly probable that it will be found 

 to be only in proportion tv> the quantity of sulphuretted 

 hydrogen it contains. The sul|)hurets of platina undergo 

 no apparent changes by being exposed to the atmosphere, 

 at least, for several da\s. 



O i Analysis. 



