358 
CHEMICAL PRINCIPLES. 
Oxides of 
tina. 
pla- Vlt The oxides of Plalina. 
Platina has two oxides, of which however one only has beeti 
hither known to us. I took some platina obtained from the 
triple ammoniacal muriate, and, having dissolved it in the 
nitromuriatic acid, I evaporated the solution to dryness. I 
then dissolved this dried mass in water, and again evaporated 
to dryness, in order to get rid of any excess of acid. The 
dried muriate was then reduced to a powder, and in the next 
place exposed to a considerable heat in a sand bath, where I let 
it remain as long as it continued to give out oxymuriatic gas. 
It was thus reduced into a pulverized mass of greyish hue, 
which by candle light seemed rather inclining to a red. This 
powder was not soluble in water, which, indeed, had scarcely 
any effect on it. In some experiments the water assumed 
a yellowish tinge, owing to some of the muriate of the oxide 
remaining undecomposed. I also observed, that when the 
muriate of the oxide of platina was obtained by means of 
common water, containing a small quantity of muriate of 
natron, this and the oxide of platina remained undecomposed 
at a temperature which decomposes the murias platinicus. But 
in this case the double muriate is entirely, separated from the 
murias platinosus by means of water. 
The greyish-green powder (or murias platinosus) obtained 
by this process underwent no immediate change on being 
exposed to the air. But after the lapse of some months its 
surface became black. Heated to a red heat it is decomposed, 
and gives out oxymuriatic gas, leaving a residuum of metallic 
platina. It is scarcely soluble in the muriatic acid, to which it 
however imparts a red colour, and from which it may be preci- 
pitated by means of an alkali. When macerated for a length 
of time with the muriatic acid, the murias platinosus is gradu- 
ally converted into murias platinicus, -and is dissolved. At a 
temperature equal to that of boiling water, the same change is 
produced by the nitro-muriatic acid. But neither the sulphuric 
nor the nitric acid occasion in it the slightest change. 
fa.J Oxidum platinosum. If the murias platineus be di- 
gested with a solution of caustic alkali, the muriate become* 
black, 
