24 6 Count Rumford’s Experiments to determine 
which attends the breaking of a small glass tube than any 
thing else to which I can compare it. In many of the experi- 
ments in which the elastic vapour was confined, this feeble 
report attending the explosion of the powder was immediately 
followed by another noise, totally different from it, which ap- 
peared to be occasioned by the falling back of the weight 
upon the end of the barrel, after it had been a little raised, but 
not sufficiently to permit the leather stopper to be driven quite 
out of the bore. In some of these experiments, a very small 
part only of the generated elastic fluid made its escape : in 
these cases the report was of a peculiar kind, and though per- 
fectly audible at some considerable distance, yet not at all 
resembling the report of a musket. It was rather a very strong, 
sudden hissing, than a clear, distinct, and sharp report. 
Though it could be determined with the utmost certainty 
by the report of the explosion, whether any part of the gene- 
rated elastic fluid had made its escape, yet for still greater 
precaution, a light collar of very clean cotton wool was placed 
round the edge of the steel hemisphere, where it reposed upon 
the end of the barrel, which could not fail to indicate by the 
black colour it acquired, the escape of the elastic fluid, when- 
ever it was strong enough to raise the weight by which it was 
confined sufficiently to force its way out of the barrel. 
Though the end of the barrel at the mouth of the bore was 
covered with a circular plate of gold, in order the better to de- 
fend the mouth of the bore against the effects of the corrosive 
vapour, yet this plate being damaged in the course of the ex- 
periments (a piece of it being blown away), the remainder of 
it was removed ; and it was never after thought necessary to 
replace it by another. When this plate of gold was taken 
