the Force of fired Gunpowder. 287 
have found by experiments made with a view merely to ascer- 
tain that fact. 
I will finish this paper by a computation, which will show 
that the force of the elastic fluid generated in the combustion 
of gunpowder, enormous as it is, may be satisfactorily ac- 
counted for upon the supposition that its force depends solely 
on the elasticity of watery vapour, or steam. 
It has been shown by a variety of experiments made in Eng- 
land, and in other countries, and lately by a well conducted 
set of experiments made in France by M. de Betancour, and 
published in Paris under the auspices of the Royal Academy 
of Sciences, in the year 1790, that the elasticity of steam is 
doubled by every addition of temperature equal to 30 degrees 
of Fahrenheit's thermometer. 
Supposing now a cavity of any dimensions (equal in capa- 
city to 1 cubic inch, for instance) to be filled with gunpow- 
der, and that on the combustion of the powder, and in conse- 
quence of it, this space is filled with steam (and I shall pre- 
sently show that the water, existing in the powder as water, is 
abundantly sufficient for generating this steam) ; if we know 
the heat communicated to this steam in the combustion of pow- 
der, we can compute the elasticity it acquires by being so heated. 
Now it is certain that the heat generated in the combustion 
of gunpowder cannot possibly be less than that of red-hot iron. 
It is probably much greater, but we will suppose it to be only 
equal to 1000 degrees of Fahrenheit’s scale, or something less 
than iron visibly red-hot in daylight. This is about as much 
hotter than boiling linseed oil, as boiling linseed oil is hotter 
than boiling water. 
As the elastic force of steam is just equal to the mean pres- 
