126 Experiments to determine 



from the vibration or friction of its parts, occasioned 

 by the violent blow it received in the explosion of the 

 powder ; but I acknowledge fairly, that it does not 

 seem to be possible to account in a satisfactory manner 

 for the very considerable degree of heat which the bar- 

 rel acquired in these experiments, merely on that sup- 

 position. 



That this hard substance, found in the barrel after an 

 experiment in which the generated elastic vapour had 

 been completely confined, was actually in a fluid or 

 elastic state in the moment of the explosion, is evident 

 from hence, that in all those cases in which the weight 

 was raised, and the stopper blown out of the bore, 

 nothing was found remaining in the barrel. It was 

 very remarkable that this hard substance was not found 

 distributed about in all parts of the barrel indifferently, 

 but there was always found to be more of it near the 

 middle of the length of the bore, than at either of its 

 extremities ; and the upper part of the vent tube in 

 particular was always found quite filled with it. It 

 should seem from hence, that it attached itself to those 

 parts of the barrel which were soonest cooled; and hence 

 the reason, most probably, why none of it was ever 

 found in the lower part of the vent tube, where it was 

 kept hot by the red-hot ball by which the powder was 

 set on fire. 



I found by a particular experiment, that the gun- 

 powder made use of, when it was well shaken together, 

 occupied rather less space in any given measure than the 

 same weight of water; consequently, when gunpowder is 

 fired in a confined space which it fills, the density of the 

 generated elastic fluid must be at least equal to the 

 density of water. The real specific gravity of the solid 



