the Force of Fired Gtmpowder. 169 



SUPPLEMENTARY OBSERVATIONS. 



Although there is no reason to doubt of the 

 accuracy of M. Betancour's experiments, yet there 

 is one important point which still remains to be ascer- 

 tained, before the hypothesis I have here endeavoured 

 to establish on the results of those experiments, respect- 

 ing the force exerted by steam in combustion of gun- 

 powder, can be admitted. 



The steam, the elastic force of which was measured 

 in M. Betancour's experiments, remained constantly in con- 

 tact with water ^ in a liquid state. How far did the 

 presence of this water, and the progressive change of a 

 part of it to steam, as the heat was gradually increased, 

 and the addition to the density of the steam which re- 

 sulted therefrom, contribute to the iiicrease of the elas- 

 ticity of the steam which was observed ? 



This is a very important question, and the solution 

 of it must necessarily decide the fate of our hypothesis : 

 and after mature consideration, I am myself inclined to 

 think that I have been precipitate in ascribing too much 

 to the agency of steam in the force exerted by fired 

 gunpowder. I was led into this error, if it be one, on 

 finding the explanation of the cause of the force of gun- 

 powder given by Mr. Robins to be quite inadequate to 

 its effects, as shewn in my experiments. But I did not 

 at first advert to the degree in which one of the sup- 

 positions made by Mr. Robins (namely, that respecting 

 the heat of the generated elastic fluid) is gratuitous ; nor 

 did I then perceive how very probable it is that he has 

 greatly underrated it. 



The supposition of Mr. Robins respecting the heat 



