Mr. Davy on a new fulminating platinum. 155 
this quantity would also absorb something more than a grain 
of the alkali. 
Hence, to the quantity of ammonia already obtained from 
calculations derived from an actual experiment, viz. 5.97 
grains per cent., which in round numbers may be called 6 
grains per cent., we must add 2 grains per cent, for the alkali 
absorbed by the water present ; and making a slight allow- 
ance for deficiencies arising from the minute portion of the 
powder that escaped decomposition in the experiment on 
which these calculations are founded, I do not think the 
ammonia in the powder can be estimated at less than 9 grains, 
and the water at 8£ grains per cent. 
On these estimates, 100 grains of fulminating platinum 
will consist of oxide of platinum 82.5 
Ammonia - 9.0 
Water - - 8.5 
100.0 
V. Theory of the formation and decomposition of Fulminating 
Platinum. 
From the statements made in the preceding pages, fulmi- 
nating platinum appears to be composed of oxide of platinum, 
ammonia, and water. It is formed, as has already been stated, 
in cases when the ammonia-sulphate of platinum is boiled in 
a solution of fixed alkali. The theory of its formation is 
apparently simple, and is founded on the superior affinity of 
the fixed alkalies, over ammonia and oxide of platinum, for 
sulphuric acid. An examination of the circumstances con- 
Xs 
