the Force of Fired Gunpowder. 125 



I have said that the solid substance into which the 

 elastic vapour generated in the combustion of gun- 

 powder was transformed was as hard as a stone. This I 

 am sensible is but a vague expression ; but the fact is, 

 that it was very hard, and so firmly attached to the in- 

 side of the barrel, and particularly to the inside of the 

 upper part of the vent tube, that it was always neces- 

 sary, in order to remove it, to make use of a drill, and 

 frequently to apply a considerable degree of force. This 

 substance, which was of a black colour, or rather of a 

 dirty grey, which changed to black upon being exposed 

 to the air, had a pungent, acrid, alkaline taste, and smelt 

 like liver of sulphur. It attracted moisture from the 

 air with great avidity. Being moistened with water, and 

 spirit of nitre being poured upon it, a strong efferves- 

 cence ensued, attended by a very offensive and penetrat- 

 ing smell. Nearly the whole quantity of matter of which 

 the powder was composed seemed to have been trans- 

 formed into this substance ; for the quantity of elastic 

 fluid which escaped upon removing the weight was- very 

 inconsiderable ; but this substance was no longer gun- 

 powder ; it was not even inflammable. What change 

 had it undergone? what could it have lost ? It is very 

 certain that the barrel was considerably heated in these 

 experiments. Was this occasioned by the caloric, disen- 

 gaged from the powder in its combustion, making its 

 escape through the iron ? And is this a proof of the 

 existence of caloric^ considered as a fluid sui generis ; and 

 that it actually enters into the composition of inflam- 

 mable bodies, or of pure air, and is necessary to their 

 combustion ? I dare not take upon me to decide upon 

 such important questions. I once thought that the heat 

 acquired by a piece of ordnance in being fired arose 



