82 Experiments upon Gunpoivder. 



far would it be advantageous, were it possible, to dimin- 

 ish the specific gravity of gunpowder, and the fluid gen- 

 erated from it, without lessening its elastic force? It 

 would certainly act upon very light bullets with greater 

 force ; but when heavy ones came to be made use of, 

 there is reason to think that, except extraordinary pre- 

 caution was taken to prevent it, the greatest part of the 

 force would be lost by the vent and by windage. 



The velocity with which elastic fluids rush into a void 

 space is as the elasticity of the fluid directly, and in- 

 versely as its density ; if, therefore, the density of the 

 fluid generated from powder were four times less than it 

 is, its elasticity remaining the same, it would issue out 

 at the vent, and escape by the side of the bullet in the 

 bore, with nearly four times as great a velocity as it does 

 at present ; but we know from experiment that the loss 

 of force on those accounts is now very considerable. 



In the experiments Nos. 76 and 77, when the piece 

 was fired with 145 grains of powder, the velocity of the 

 bullets at a medium was 1040 feet in a second ; but in 

 the 88th and 8pth experiments, when the bullets were 

 even heavier, and the piece was fired with the same quan- 

 tity of powder, the mean velocity was 1232 feet in a sec- 

 ond. The difference, = 192 feet in a second, answers to 

 a difference of force, greater in the last experiments than 

 in the first in the proportion of 14 to 10. 



I know of no way to account for this difference but 

 by supposing that it was owing entirely to the escape of 

 the elastic fluid by the vent and by windage, in those 

 experiments where the vent was open, and the bullets 

 were put naked into the piece. 



An elastic bow, made of very light wood, will throw 

 an arrow, and especially a light one, with greater velocity 



