233 
the Force of fired. Gunpowder. 
times greater than the mean pressure of the atmosphere ; and 
this, according to his theory, is the real measure of the force 
of gunpowder, fired in a cavity which it exactly fills. 
But what will become of this theory, and of all the suppo- 
sitions upon which it is founded, if I shall be able to prove, as 
I hope to do in the most satisfactory manner, that the force of 
fired gunpowder, instead of being 1000 times, is at least 50,000 
greater than the mean pressure of the atmosphere ? 
For my part, I know of no way of accounting for this enor- 
mous force, but by supposing it to arise principally from the 
elasticity of the aqueous vapour generated from the powder in 
its combustion. The brilliant discoveries of modern chemists 
have taught us, that both the constituent parts of which water 
is composed, and even water itself, exist in the materials which 
are combined to make gunpowder ; and there is much reason 
to believe that water is actually formed, as well as disengaged, 
in its combustion. M. Lavoisier, I know, imagined that the 
force of fired gunpowder, depends in a great measure upon the 
expansive force of uncombined caloric , supposed to be let loose 
in great abundance during the combustion or deflagration of 
the powder : but it is not only dangerous to admit the action 
of an agent whose existence is not yet clearly demonstrated, 
but it appears to me that this supposition is quite unnecessary; 
the elastic force of the heated aqueous vapour, whose existence 
can hardly be doubted, being quite sufficient to account for all 
the phaenomena. It is well known that the elasticity of aque- 
ous vapour is incomparably more augmented by any given 
augmentation of temperature, than that of any permanently 
elastic fluid whatever ; and those who are acquainted with the 
amazing force of steam, when heated only to a few degrees 
