the Force ofjired Gunpowder . 283 
ferent ways, but the most interesting experiments were made 
with one single large grain of powder, propelled by smaller and 
larger charges of very fine-grained powder. 
These large grains never failed to reach the screen; and 
though they sometimes appeared to have been broken into se- 
veral pieces, by the force of the explosion, yet they frequently 
reached the first screen entire; and sometimes passed through 
all the screens (five in number), without being broken. 
When they were propelled by large charges, and conse- 
quently with great velocity, they were seldom on fire when 
they arrived at the first screen, which was evident not only 
from their not setting fire to the paper (which they sometimes 
did), but also from their being found sticking in a soft board, 
against which they struck, after having passed through all the 
five screens ; or leaving visible marks of their having impinged 
against it, and being broken to pieces and dispersed by the 
blow These pieces were often found lying on the ground ; 
and from their forms and dimensions, as well as from other 
appearances, it was often quite evident that the little globe of 
powder had been on fire, and that its diameter had been dimi- 
nished by the combustion, before the fire was put out on the 
globe being projected into the cold atmosphere. The holes 
made in the screen by the little globe in its passage through 
them, seemed also to indicate that its diameter had been dimi- 
nished. 
That these globes or large grains of powder were always set 
on fire by the combustion of the charge can hardly be doubted. 
This certainly happened in many of the experiments, for they 
arrived at the screens on fire, and set fire to the paper ; and 
in the experiments in which they were projected with small 
mdccxcvii. P p 
