314 Mr. Chenevix’s 'Enquiries concerning the Nature 
When mixed solutions of three or more metals are exposed 
to the action of recent muriate of tin, or of green sulphate of 
iron, their action upon each other appears in a much more 
striking, as also in a much more complicated point of view. 
EXPERIMENTS UPON PLATINA. 
I shall now state some experiments which I have had occasion 
to make upon platina, during the foregoing researches. Very 
little is known concerning this metal, its oxides, or its salts ; and, 
although I have not had occasion to extend the enquiries very 
far, yet my experiments may serve to establish a few points. 
I dissolved a quantity of purified platina* in nitro-muriatic 
acid, and precipitated by lime. A great portion of platina re- 
mained in the liquor, although I had used an excess of the above 
earth. I redissolved the precipitate in nitric acid, and evaporated 
to dryness. The result was, a subnitrate of platina. I then ex- 
posed the mass, in a crucible, to a heat capable of expelling the 
acid altogether; and the oxide remained alone. When this was 
reddened, at a heat which certainly was not capable of melting 
silver, the oxide was reduced, and appeared with a metallic 
lustre. The weight of the various products, in the above ex- 
periments, was such as to give the following proportions in the 
oxide, and the subnitrate of platina. 
Yellow oxide of platina is composed of, 
Platina - - - 87 
Oxygen - - - -13 
100. 
* By purified platina, I have always understood, in this Paper, platina reduced, at a 
gentle heat, from the salt obtained by pouring a concentrate solution of muriate of 
ammonia into a .concentrate solution of platina. 
