the Force of Fired Gunpowder. 109 



mean pressure of the atmosphere ; and this, according 

 to his theory, is the real measure of the force of gun- 

 powder fired in a cavity which it exactly fills. 



But what will become of this theory, and of all the sup- 

 positions 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 enormous force, but by supposing it to arise princi- 

 pally from the elasticity of the aqueous vapour generated 

 from the powder in its combustion. The brilliant dis- 

 coveries 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 com- 

 bined to make gunpowder ; and there is much reason to 

 believe that aqueous vapour, or steam, is actually formed 

 in its combustion. M. Lavoisier, I know, imagined 

 that the force of fired gunpowder depends in a great meas- 

 ure upon the expansive force of uncombined caloric sup- 

 posed to be let loose in great abundance during the com- 

 bustion 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 exist- 

 ence can hardly be doubted, being quite sufficient to ac- 

 count for all the phaenomena. 



It is well known that the elasticity of aqueous vapour 

 is considerably more augmented by any given augmen- 

 tation of temperature, than that of any permanently 

 elastic fluid whatever ; and those who are acquainted 



