upon Gun-powder , &c. 261 
Concluding from the refult of the four experiments men- 
tioned above, as well as from the reafons juft cited, that the 
temperature of the piece has a confiderable effedl upon the force 
of the powder, I afterwards took care to bring the barrel to a 
proper degree of heat, by firing it once or oftener with powder 
each time I recommenced the experiments after the piece had 
been left to cool. 
Of the manner in which pieces , acquire heat in firing . 
I was much furprifed upon taking hold of the barrel imme- 
diately after the experiment N° 1 7. when it was fired with 330 
grains of powder without any bullet, to find it fo very' hot that 
I could fcarcely bear it in my hand, evidently much hotter than 
I had ever obferved it before, notwithstanding the fame charge 
of powder had been made ufe of in the two preceding experi- 
ments, and in both thefe experiments the piece was loaded 
with a bullet, which one would naturally imagine, by confining 
the flame, and prolonging the time of its adtion, would heat 
the barrel much more than when it was fired with powder 
alone. 
I was convinced that I could not be miftaken in the fa£t, for 
it had been my conftant pradtice to take hold of the piece to 
wipe it out as foon as an experiment was finifhed, and I never 
before had found any inconvenience from the heat in holding it. 
But in order to put the matter beyond all doubt, after letting 
the barrel cool down to the proper temperature, I repeated the 
experiment twice with the fame charge of powder and a bullet ; 
and in both thefe trials (experiments N° 18. and N° 19.) the 
heat of the piece was evidently much lefs than what it was in 
the experiment above mentioned (N° 17.). 
Vol. LXXL 2 N 
I now 
