the Force of fired Gunpowder. 281 
gunpowder is less rapid than it has hitherto been supposed to 
be, and the objection in question falls to the ground. 
Mr. Robins's theory supposes that all the powder of which 
a charge consists is not only set on fire, but that it is actually 
consumed and “ converted into an elastic fluid before the bullet 
“ is sensibly moved from its place” I have already in the for- 
mer part of this paper offered several reasons which appeared 
to me to prove that, though the' inflammation of gunpowder is 
very rapid, yet the progress of the combustion is by no means 
so instantaneous as has been imagined. I shall now give an 
account of some experiments which put that matter out of all 
doubt. 
It is a fact well known that on the discharge of fire-arms of 
all kinds, cannon and mortars as well as muskets, there is al- 
ways a considerable quantity of unconsumed grains of gun- 
powder blown out of them ; and, what is- very remarkable, and 
as. it. leads directly to a discovery of the cause of this effect is 
highly deserving of consideration, these unfconsumed grains 
are not merely blown out of the muzzles of fire-arms ; they 
come out also by their vents or touch-holes, where the fire en- 
ters to inflame the charge ; as many persons who have had the 
misfortune to stand with their faces near the touch-hole of a 
musket, when it has been discharged, have found to their cost. 
Now it appears to me to be extremely improbable, if not ab- 
solutely impossible, that a grain of gunpowder actually in the 
chamber of the piece, and completely surrounded by flame, 
should, by the action of that very flame, be blown out of it, 
without being at the same time set on fire. But if these grains 
of powder are actually on fire when they come out of the piece, 
and are afterwards found at a distance from it unconsumed, 
