upon Gun-powder , &c. 26 r 
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 effedt 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 cook 
Of the manner In which pieces acquire heat in firing a 
1 was much furprifed upon taking hold of the barrel imme- 
diately after the experiment N° 17. 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, ^ not withft an din g 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 aflion, 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<ft, for 
it had been my conftant praddice to take hold of the piece to 
wipe it out as foon as an experiment was finiihed, 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 
