Mr. Davy on a new fulminating platinum. 151 
of the powder exploded at once;' it went off at intervals, as 
its particles reached the proper temperature, without pro- 
ducing much noise, though the gas generated was driven 
down the tubes with sufficient violence to force, in most 
cases, some of the powder out of the tubes. This mode of 
operating seemed to promise more accurate results than any 
other that occurred to me. The products, in cases when the 
tubes did not break, were the same, viz. a quantity of gas, 
aqueous moisture, and platinum in alloy with mercury. But 
the quantity of gas varied in most instances, owing to the 
difficulty of exploding the whole of the powder. In two 
cases, however, I obtained corresponding results. In one of 
these experiments a grain of the powder, after being dried at 
about 212 0 , and decomposed in contact with dry mercury 
afforded 0.18 of a cubic inch of gas ; in the other, half a 
grain of the powder furnished, under similar circumstances, 
0.09 of a cubic inch of gas. But in both of these experi- 
ments, it is proper to rehnark, a minute portion of the powder 
had been thrown out of the tubes by the explosions. This 
was evident on inspecting the surface of the mercury, and 
from the slight explosions which took place when a heated 
iron was brought near. 
Though the preceding experiments could furnish no data 
for determining , the exact proportion, they might at least 
afford approximations to the true quantity of ammonia in the 
fulminating powder ; and this consideration induced me to 
examine the gas I procured with some attention. I shall 
briefly state the particulars of one examination of this kind, 
the barometer being at 30°, and the thermometer at 6 o°. The 
permanent gas obtained from one grain of the fulminating 
