1 66 Experiments to determine 



parts of this powder contain 67^ parts of nitre, lyy 3 ^ 

 parts of sulphur, and of charcoal 1 5-^ parts- 

 Mr. Kirwan has shewn, that in 100 parts of nitre 

 there are 7 parts of water of crystallization ; conse- 

 quently, in 100 parts of gunpowder, as it contains 67^ 

 parts of nitre, there must be 4 j'oVo parts of water. 



Now, as i cubic inch of gunpowder, when the powder 

 is well shaken together, weighs exactly as much as i 

 cubic inch of water at the temperature of 55 F., namely, 

 253.175 grains Troy, a cubic inch of gunpowder in its 

 driest state must contain at least 10 VoVo grains of 

 water; for it is 100 to 4.711, as 253.175 to 10.927. 

 But besides the water of crystallization which exists 

 in the nitre, there is always a considerable quantity of 

 water in gunpowder, in that state in which it makes 

 bodies damp or moist. Charcoal exposed to the air has 

 been found to absorb nearly \ of its weight of water ; 

 and by experiments I have made on gunpowder, by 

 ascertaining its loss of weight on being much dried, and 

 its acquiring this lost weight again on being exposed to 

 the air, I have reason to think that the power of the 

 charcoal, which enters into the composition of gun- 

 powder, to absorb water remains unimpaired, and that 

 it actually retains as much water in that state as it 

 would retain were it not mixed with the nitre and the 

 sulphur. 



As there are i5tV P arts f charcoal in 100 parts of 

 gunpowder, in i cubic inch of gunpowder (253.175 

 grains Troy), there must be 38.989 grains of charcoal ; 

 and if we suppose \ of the apparent weight of this 

 charcoal to be water, this will give 4.873 grains in 

 weight for the water which exists in the form of moisture 



o 



in i cubic inch of gunpowder. 



