the Force of Fired Gunpowder. 139 



pressed in German apothecary's grains, and the relation 

 of these quantities to the quantity required to fill the 

 barrel and its vent tube completely. 



Thus, as the barrel and its vent tube were capable of 

 containing 25.641 apothecary's grains of powder, if we 

 suppose this quantity to be divided into 1000 equal 

 parts, this will give 39 of those parts for i grain; 78 

 parts for 2 grains ; 390 for 10 grains, &c. For it is 

 25.641 to 1000, as I to 39, very nearly. 



As this method of expressing the quantities of powder 

 shows at the same time the relative density of the gen- 

 erated elastic fluid, it is the more satisfactory on that 

 account : it will also considerably facilitate the computa- 

 tions necessary, in order to ascertain the ratio of the 

 elasticity of this fluid to its density. 



The elastic force of the fluid generated in the com- 

 bustion of the charge of powder is measured by the 

 weight by which it was confined, or rather by that which 

 It was just able to move, but which it could not raise 

 sufiiciently to blow the leathern stopper quite out of the 

 mouth of the bore of the barrel. 



This weight, in all the experiments, except those 

 which were made with very small charges of powder, 

 was a piece of ordnance of greater or less dimensions 

 or greater or less weight, according to the force of the 

 charge, placed vertically upon its cascabel, upon the steel 

 hemisphere which closed the end of the barrel ; and the 

 same piece of ordnance, by having its bore filled with a 

 greater or smaller number of bullets, as the occasion re- 

 quired, was made to serve for several experiments. 

 • The weight employed for confining the generated 

 elastic fluid is expressed in the following table in pounds 

 avoirdupois ; but in order that a clearer and more perfect 



