38 Experiments upon Gunpowder. 



any given quantity of powder to be confined in a space 

 that is just capable of containing it, and that, in this 

 situation, it is by any means set on fire. Let us sup- 

 pose this space to be the chamber of a piece of ord- 

 nance of any kind, and that a bullet or any other solid 

 body is so firmly fixed in the, bore, immediately upon 

 the charge, that the whole effort of the powder shall 

 not be able to remove it. As the powder goes on to 

 be inflamed, and the elastic fluid is generated, the pres- 

 sure upon the inside of the chamber will be increased, 

 till at length, all the powder being burnt, the strain 

 upon the metal will be at its greatest height, and in this 

 situation things will remain, the cohesion or elasticity 

 of the particles of metal counterbalancing the pressure 

 of the fluid. 



Under these circumstances very little heat would be 

 generated ; for the continued effort of the elastic fluid 

 would approach to the nature of the pressure of a 

 weight ; and that concussion^ vibration, and friction among 

 the particles of the metal, which in the collision of elas- 

 tic bodies is the cause of the heat that is produced, 

 would scarcely take effect. 



But, instead of being firmly fixed in its place, let the 

 bullet now be moveable, but let it give way with great 

 difficulty, and by slow degrees. In this case the elastic 

 fluid will be generated as before, and will exert its whole 

 force upon the chamber of the piece ; but as the bullet 

 gives way to the pressure, and moves on in the bore, 

 the fluid will expand itself and grow weaker, and the 

 particles of the metal will gradually return to their 

 former situations ; but the velocity with which the 

 metal restores itself being but small, th'e vibration that 

 remains in the metal, after the elastic fluid has made its 



