968 On some ComUnations of Platina. 



Mr. J. Sovverby junior put into rny hands a compound 

 he had obtained, in attempting to destroy some diamond 

 powder by the agency of nitre in a platina crucible. A 

 quantity of nitre was mixed with diamond powder, and ex- 

 posed to a low red heat for some time in a common fire; 

 on examining the results, it was found that the crucible 

 had lost several grains in weight. After the separation of 

 the residual diamond powder, the substance in question 

 remained. Ii was washed with distilled water, aud on ex- 

 amination exhibited the following properties. Its colour 

 was black. It was in small grains. It had a shining lustre 

 resembling blende. It was tasteless, and insoluble in water. 

 When a little of it was heated to redness on a slip of 

 platina, oxygen gas was disengaged, and the platina reduced 

 to the melailic state. It did not appear to be affected by 

 strong nitric or sulphuric acid at a boiling heat. There 

 was scarcely any action produced on it by boiling nitro- 

 muriatic acid. 



It was dissolved with some little difficulty in boiling 

 muriatic acid ; and when the excess of acid was expelled, 

 the insoluble compound of platina and chlorine remained, 

 and muriate of potash. Three grains of the black powder 

 were heated to redness in a small glass retort ; more than 

 half a cubical inch of oxygen gas was obtained, some water, 

 and 2-4 grains of a gray substance having the metallic 

 lustre. This substance readily rendered turmeric paper 

 brown. After the alkali had been separated from it by a 

 considerable portion of distilled water, the platina weighed 

 1"3 grain. 



From these experiments it seems that this substance is 

 compounded of oxide of platina, potash, and water. I shall 

 not attempt to give the proportions of its constituent parts, 

 the quantity in my possession was too minute to determine 

 this point with precision. This substance can only be 

 formed at comparatively low temperatures. A more inti- 

 mate acquaintance with it may probably lead to the know- 

 ledge of some interesting combinations of platina. 



From the preceding statements it would seem, that at 

 present we have no distinct knowk-dge of the oxides of 

 platina in a pure or separate state ; and that those sub- 

 stances which have been considered as oxides, are in fact 

 compounds of this metal with metallic bases, and oxygen 

 or chlorine. 



As hydrogen is known to reduce certain metallic oxides in 

 particular cireumstances, it occurred to me, that it might 

 probably be employed with advantage to determine the jiro- 



poriiou 



