876 On some Combinations of Platina. 



quainted with : and it does not appear that any pure oxide 

 ot platina has yel been dissolved in nitric acid, so as to 

 furnish this sah. 



The insoluble sulphate of platina, according to Mr. 

 Chenevix, wa:j procured by expelling the muriatic acid from 

 the dry muriate of platina, by means of sulphuric acid, and 

 evaporating to dryness. The results I have obtained from 

 a careful repetition of his experiments, are very different. 

 It will be proper to relate some of them. 



Experiment 1. — 15 grains of a compound of chlorine 

 and platina (obtained by evaporating an acid solution of 

 platina to dryness, and exposing the dry mass to an elevated 

 temperature,) were boiled with some concentrated test sul- 

 phuric acid in a platina crucible. The process was con- 

 tinued until all the sulphuric acid appeared to be expelled. 

 A substance analogous to the compound of platina and 

 chlorine remained. A fresh quantity of sulphuric acid 

 being added, heat was applied till no more sulphuric funses 

 could be perceived. The residual substance was then de- 

 compounded at a red heat, and during the process the 

 smell of chlorine was distinctly perceived. 



Experiment 2. — Several grains of a similar compound to 

 that employed in the preceding experiment, were treated 

 precisely in the same way with sulphuric acid. Acid was 

 added three successive times with a little water. After the 

 expulsion of the acid by heat, the remaining substance 

 had the precise characters of the original compound. It 

 was now boiled to dryness with a concentrated solution of 

 pure soda. It became black. It was digested in distilled 

 water. The clear solution gave not the slightest precipitate 

 with muriate of barytes, but a very copious one with nitrate 

 of silver. Hence, it contained no sulphuric acid. 



These experiments seem clearly to prove that sulphuric 

 acid does not decompose the compound of platina and 

 chlorine, or the substance which has been considered as an 

 insoluble muriate. The following experiment appears to 

 prove, that stron|j sulphuric acid does not expel the muriatic 

 acid from a solution of platina, so as to destroy the com- 

 bination of chlorine and this metal. 



Experiment 3. — Some platina was dissolved in concen- 

 trated nitvo-muriatic acid ; the solution was treated with 

 strong sulphuric acid; a yellow substance precipitated*, 

 and muriatic acid was expelled. After the whole had been 

 boiled for some time, fresh sulphuric acid was added, and 



•I am inclined to believe that this yellow substance is pUtinane. I cou'd 

 •vc abtaia it in this instance so as tu examine it- 



the 



