154 Experiments to determine 



quite fills the space in which it is confined, as 9431 at- 

 mospheres, the measure of its elastic fierce in the experi- 

 ments in question, to 20,108 atmospheres; which, ac- 

 cording to Mr. Robins's theory respecting the ratio of 

 the elasticities to the densities, would be the measure of 

 its initial force. 



But all my experiments tend uniformly to prove, that 

 the elasticities increase faster than in the simple ratio of 

 the corresponding densities ; consequently, the initial 

 force of the generated elastic fluid must necessarily be 

 greater than the pressure of 20,108 atmospheres. 



In one of my experiments, which I have often had oc- 

 casion to mention, the force actually exerted by the fl;uid 

 must have been at least equal to the pressure of 54,752 

 atmospheres. The other experiments ought, no doubt, 

 to shew, at least, that it is possible that such an enormous 

 force may have been exerted by the charge made use of; 

 and this, I think, they actually indicate. 



In the first set of experiments, which were made when 

 the weather was cold, though the results of them uni- 

 formly shewed the force of the powder to be much less 

 than it appeared to be in all the subsequent experiments, 

 made with greater charges and in warm weather, yet they 

 all shew that the ratio of the elasticity of the generated 

 fluid to its density is very different from that which Mr. 

 Robins's theory supposes; and that this ratio increases 

 as the density of the fluid is increased. 



Supposing (what on many accounts seems to be ex- 

 tremely probable) that this ratio increases uniformly, or 

 with an equable celerity, while the density is uniformly 

 augmented ; and supposing farther, that the velocity 

 and limit of its increase have been rightlv determined 

 from the result of the set of experiments, Table I., which 



