On some Qombinations of Platina. 26S 



general characters resembled precisely the sub-phosphoret 

 of platina t'ormerly described. 



Being desirous of ascertaining the effect of carburetted 

 hydrogen gas on solutions of platina, a Retort containing an 

 aqueous solution of platina was filled with carburetted hy- 

 drogen gas obtained from acetate of potash. After some 

 time, the fluid acquired a purple tint, a slight film of a 

 blueish-gray colour covered the surface, and there was an 

 absorption of the gHs. In an experiment of this kind, the 

 results were examined. The substance deposited, appeared 

 to be merely a mixture of carbonaceous matter and metallic 

 platina. 



The precipitates obtained by the agency of phosphoretted 

 and carburetted hydroeen gases on solutions of platina 

 were not deemed worthy of a more minute examination. 

 I must not forget to notice, that in these experiments I was 

 kindly assisted by my friend Mr. William Moore. 



3. Of the Comhinations of Platina iciih Oxygen. 



The methods which are employed with success to pro- 

 cure the oxides of the conmion metals, wholly fail in the 

 case of platina. The difficul^ty of obtaining pi;re oxides of 

 this metal arises from the property it has of forming triple 

 compounds with alkalies or earths, and chlorine or muriatic 

 acid. A want of due attention to this circumstance has 

 occasioned several erroneous statements in ihe writings of 

 some distinguished chemists. Thus Bergman, in his early 

 Treatise on Platina, states that a calx of this metal may be 

 obtained by the agency of mineral alkali on a solution of 

 platina*. He says also, that it may be procured by the use 

 of the volatile alkali in ])articu!ar circumstances. The 

 various trials that I have made with these bodies in different 

 states, lead me to conclude that they are not oxides, but 

 peculiar triple con)pounds. 



M. Proust t says, that a pure oxide of platina maybe 

 obtained by treating the potash muriate of platina with 

 potash, and neutralizing with sulphuric acid; but I have not 

 seen the details of the experiment. When dry potash mu- 

 riate of platina is boiled with a strong solution of caustic 

 potash, it is dissolved; and \\ hen neutralized bv sulphuric 

 »cid, it affords a substance of a dull yellow colour, which, 

 when washed and diied, yields chlorine gas by being heated 

 to redness, and is partially decomposed : another compound, 

 of a dull yellowish-brown colour, may also be procured by 



*t Physic:-.! and Cliemic.il Essays, vol. ii. p, 174. 

 j- AaitaUs deChiiide,\.oi\:c yiVu. p. 17y. 



boilinc 



