ss Col. Gibbs on Gunpowder. 
from near the fire to the corner of the room, produces a con: 
siderable change in its weight. I presume, therefore, that 
the lime, which in its caustic state has also a great affinity to 
water, attracts a portion of it from the powder, and leaves it 
in a state of dryness best fitted for inflammation. But if the 
lime should remain too long mixed with the powder, it would 
probably attack the water of crystallization of the saltpetre, 
and, according to Count Rumford’s idea, destroy a great part 
- of the power. If also left exposed, attraction of moisture would 
take place from the atmosphere, the gunpowder would remain 
surcharged with humidity as before, and the lime would be 
only an inert mass. 
The examination of this subject led me to consider the in- 
crease of the power of gunpowder in various situations, and of 
its use im the field. It is well known that after a few dis- 
charges a cannon becomes heated, and the range is much 
greater, as well as the recoil. The charge of powder is there- 
fore reduced about one quarter, to produce the original effect. 
As [have not heard or seen any explanation of this fact, I shall 
take this opportunity of mentioning, that it appears to arise 
from the same cause as the first explained, viz., the desicca- 
tion of the powder. No person will dispute the heat acquired 
by a cannon, or even a musket, after repeated discharges 5 40° 
this heat rhust volatize or destroy a great portion of the mois 
ture combined with the powder, assist its speedy inflammation, 
and perhaps add to its power, by causing a more perfect com: 
bustion of tle inflammable parts of the gunpowder. This 
would cause a much greater volume of gas to be produced, 
and the high temperature would also greatly augment its elas 
ticity ; and it is well known that the effects of gunpowder 
depend upon the rapid production and high degree of elasticity 
_ of agreat quantity of seriform fluids or gases. 
= 
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nai eerhlnanssivenapuan — os ee 
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