150 Mr. Davy on a new fulminating platinum. 
difference in the composition of the oxide, as deduced from 
the experiments with the nitrous and muriatic acids, compared 
with those on the immediate decomposition of the oxide by 
heat. But as this difference is only about 1 per cent, of oxy- 
gene greater by the latter than the former methods, there 
can be no ground to suppose the state of oxidation different 
in either case. 
The quantity of platinum and of oxygene, or of oxide of 
platinum, in the fulminating compound, having been deter- 
mined, it remained to ascertain the proportion of ammonia in 
the powder. With this object in view, I made a number of 
experiments on the decomposition of the powder by the 
agency of heat in close vessels. I first used small green 
glass retorts containing the powder and filled with recently 
boiled mercury ; but I found in two trials the retorts would 
not stand the shock from a single grain, but snapped off at 
the neck at the instant of the explosion, owing perhaps to the 
principal explosive force being directed downwards. I then 
had recourse to straight tubes, varying in length from nine to 
eighteen inches, and in diameter of bore from one-third to 
half an inch. The quantity of the powder I used in these tubes 
was from half a grain to two grains. The experiments were 
made in this way : the powder being placed in the tube, it 
was held in an oblique direction, and filled with dry mercury, 
so that when inverted in a vessel of mercury, all the powder 
remained nearly at the top of the tube. The tube was then 
fastened to a brass stand, in an inclined position, and heat 
sufficient to explode the powder was communicated by means 
of red hot balls, or by a spirit lamp. In a number of trials 
made in this way there was no instance ip which the whole 
