the Force of fired Gunpowder. 
the elasticity will be equal to 
the pressure of 
16,384 atmospheres; 
— 32,768 
— 65 , 53 6 
and at 692° -f 30°= 722°, the elasticity will be equal to the 
pressure of 131,072 atmospheres, which is 130 times greater 
than the elastic force assigned by Mr. Robins to the fluid ge- 
nerated in the combustion of gunpowder; and about one sixth 
part greater than my experiments indicated it to be. 
But even here the heat is still much below that which is most 
undoubtedly generated in the combustion of gunpowder. The 
temperature which is indicated by 7 22 0 of Fahrenheit's scale, 
(which is only 122 degrees higher than that of boiling quick- 
silver, or boiling linseed oil,) falls short of the heat of iron 
which is visibly red-hot in daylight by 355 degrees : but the 
flame of gunpowder has been found to melt brass, when this 
metal, in very small particles, has been mixed with the pow- 
der ; and it is well known that to melt brass a heat is required 
equal, to that of 3807 degrees of Fahrenheit’s scale; 2730 
degrees above the heat of red-hot iron, or 3085 degrees higher 
than the temperature which gives to steam an elasticity equal 
to the pressure of 131072 atmospheres. 
That the elasticity of steam would actually be increased by 
heat in the ratio here assumed, can hardly be doubted. It has ab- 
solutely been found to increase in this ratio in all the changes 
of temperature between the point of boiling water (I may 
even say of freezing water) and that of 280° of Fahrenheit’s 
scale; and there does not appear to be any reason why the 
same law should not hold in higher temperatures. 
at the temperature 
of 
602° -j- 30° = 632° 
at 632° -f- 30° = 66 2 0 
at 662° 30° = 63 2 0 
