Experiments upon Gunpowder. 89 



Having now shewn by experiment the relation of the 

 velocities of bullets to their weights when care is taken 

 to prevent entirely the loss of force by the escape of the 

 elastic fluid through the vent, and by the windage, I 

 shall leave it to mathematicians to determine from these 

 data the properties of that fluid, or the relation of its 

 elasticity to its density. 



But before I take my leave of this subject, I would 

 just observe that Mr. Robins is not only mistaken in 

 the principle he assumes, respecting the relation of the 

 elasticity of the fluid generated from gunpowder to its 

 density, or rather the law of its action upon the bullet 

 as it expands in the bore, but his determination of the 

 force of gunpowder is also erroneous, even upon his 

 own principles ; for he determines its force to be 1000 

 times greater than the mean pressure of the atmosphere ; 

 whereas it appears, from the result of the pid experi- 

 ment, that its force is at least 1308 times greater than the 

 mean pressure of the atmosphere, as will be evident to 

 those who will take the trouble to make the computation. 



Of an Attempt to determine the explosive Force of Aurum 

 Fulminans, or a Comparison between its Force and that 

 of Gunpowder. 



Having provided myself with a small quantity of 

 this wonderful powder, upon the goodness of which I 

 could depend, I endeavored to ascertain its explosive 

 force, by making use of it, instead of gunpowder, for 

 discharging a bullet, and measuring, by means of the 

 pendulum, the velocity which the bullet acquired , and 

 concluding, from the tremendous report with which this 

 substance explodes, that its elastic force was vastly great- 

 er than that of gunpowder, I took care to have a barrel 



