Mr. Davy on a new fulminating platinum. 149 
platinum. It is decomposed at a full red heat, and yields only 
oxygene and platinum. I presume this compound has not 
yet been described ; an account of it I hope to have the honour 
of shortly laying before the Society. 
Exp. 5. Ten grains of the powder, after being decomposed 
by the agency of nitrous acid, as in the preceding experiment, 
afforded 8.5 grains of dark grey oxide of platinum. But a 
little of it appeared to be damp ; it was put into a small dry 
retort and exposed to a dull red heat ; nitrous acid vapour 
appeared in the neck of the retort, but no gas was expelled. 
Whilst the retort was yet warm the bulb was taken off, and 
the oxide when carefully collected weighed 8.25 grains, 
p'rom the two last experiments it appears that 100 grains of 
the fulminating powder contain 82.5 grains of oxide of pla- 
tinum, for 10 : 8.25 : : loo : 82.5. 
In one experiment in which I decomposed the dark grey 
oxide of platinum at a full red heat, 10 grains afforded me 
8.82 grains of platinum. In another instance, 7 grains of the 
oxide yielded 6.187 g ra i ns of platinum. If the mean of these 
experiments be taken, 100 grains of the oxide will contain 
88.3 platinum 
11.7 oxygene 
100.0 
If the results obtained in the five preceding experiments 
be compared with the subsequent ones on the composition of 
the grey oxide of platinum, they lead to the conclusion, that 
the platinum in the fulminating powder is in the same state 
of oxidation as the oxide directly procured from the powder 
by the agency of the nitrous acid. There is indeed a slight 
