the Force of Filled Gtmpowder. 165 



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 

 722° of Fahrenheit's scale (which is only 122 degrees 

 higher than that of boiling quicksilver, or boiling lin- 

 seed oil) falls short of the heat of iron which is visibly 

 red-hot in daylight by i^c^c^ degrees ; but the flame of 

 gunpowder has been found to melt brass, when this 

 metal, in very small particles, has been mixed with the 

 powder; and it is well known that to melt brass a heat 

 is required equal to that of 3 807 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 131,072 at- 

 mospheres. 



That the elasticity of steam would actually be in- 

 creased by heat in the ratio here assumed can hardly be 

 doubted. It has absolutely 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. 



A doubt might possibly arise with respect to the ex- 

 istence of a sufficient quantity of water in gunpowder 

 to fill the space in which the powder is fired with steam, 

 at the moment of the explosion ; but this doubt may 

 easily be removed. 



The best gunpowder, such as was used in my experi- 

 ments, is composed of 70 parts (in weight) of nitre, 18 

 parts of sulphur, and 16 parts of charcoal; hence 100 



