the Force of Fired Gunpowder. 171 



mospherical air is doubled with an increase of heat in- 

 dicated by 437 degrees of Fahrenheit's scale; and I was 

 lately informed by that excellent chemist and natural 

 philosopher, M. Bertholet, that he has found by re- 

 peated experiments, that the expansions with heat of all 

 the gazes, or different kinds of permanently elastic fluids, 

 are precisely the same, whatever may be the difference 

 of their specific gravities, or of their chemical or other 

 properties. 



Supposing now that the permanently elastic fluids 

 generated in the combustion of gunpowder follow the 

 same law in their expansions with heat, we can easily 

 determine, by computation, how much the expansive 

 force of those fluids will be augmented by any given 

 augmentation of heat. 



If the temperature of air of the atmosphere be 60 F. 

 when the expansive force of the permanently elastic fluid 

 generated in the combustion of gunpowder being at 

 that temperature is equal to 250 atmospheres; if the 

 temperature of that fluid be raised 437 degrees, or if it 

 become ^97 of Fahrenheit's scale (6o-J-437= 497)> 

 there can be no doubt whatever but its elastic force will 

 be doubled ; or that it will become 500 times greater 

 than the mean pressure of the atmosphere. 



If its temperature be raised 437 degrees higher, or if 

 it be heated to 934 F., its elasticity will be again 

 doubled, and will become = 1000 atmospheres, which is 

 the initial force of the elastic fluid generated in the com- 

 bustion of fired gunpowder, according to Mr. Robins. 



But there are many strong reasons for supposing that 

 the heat generated in the combustion of gunpowder is 

 vastly higher than that indicated by 937 of Fahrenheit's 

 scale. 



