556 PHILOSOPHICAL TRANSACTIONS. [aNNO 1779. 



hole and meet the flame. The contrary must be done when aether air is employed, 

 it being heavier than common air, and thus disposed to descend and fall on the 

 flame kept under it. 



To fill this pistol with any air, I commonly first fill an elastic gum bottle with 

 it, the orifice of which is just large enough to receive that part of the gun barrel 

 which is fixed to the air box: thus, by squeezing between my feet the elastic 

 gum bottle, I draw in at the same time the air by drawing up the piston. A 

 bladder is also very fit for this purpose, and has the advantage above an elastic 

 gum bottle in not requiring to be squeezed to draw the air out of it. Inflam- 

 mable air from metals will rise in the pistol of itself, when its orifice is kept on 

 the bottle containing it. 



If the pistol is destined to be always kindled by the flame of a candle or a 

 match, as I have described, it would be better to have no piston to it, as it may 

 then be filled by the means of water, and the explosive force will be so much the 

 greater, as some of the flame makes easily its way over the leather of the piston, 

 and rushes out backward, which I find is often the case, if the bullet is rammed 

 in the barrel somewhat too tightly. 



It would perhaps not be an easy undertaking to give a satisfactory reason, why 

 a drop of aether communicates to dephlogisticated air a much stronger explosive 

 force than common inflammable air from metals. May it not be said, tliat com- 

 mon inflammable air from metals, having only about a 5th of the specific gravity 

 of the dephlogisticated air, the 1 fluids do not penetrate each other so readily 

 and so intimately as the compound of dephlogisticated and aether air, which are 

 both nearly of the same specific gravity, each being somewhat heavier than com- 

 mon air? for it seems not improbable, that the swiftness with which the flame is 

 propagated through the mass of this compound air, depends partly on the inti- 

 mate mixture of the phlogiston with the dephlogisticated air. Might not this 

 phenomenon be ascribed to the greater bulk of inflammable air from metals, 

 compared with the small compass which one single drop of aether occupies, which 

 last ingredient, when pure, seems to be an essence of the inflammable principle 

 of the spirit of wine, a pure phlogiston concentrated in the form of a liquid? 

 indeed the inflammable air from metals seems to be rather a compound of phlo- 

 giston and some kind of elastic permanent fluid, than a pure inflammable fluid; 

 for this air, after having lost all its inflammability, by being kept a long while on 

 water, occupies still a considerable space, and is then become phlogisticated air; 

 that is to say, such an air as is not to be diminished by nitrous air, or to be 

 inflamed. 



Though I have no reason to alter my former assertion, that the force of gun- 

 powder is proportionable to the sudden extrication of a great quantity of the elastic 

 fluid generated in the moment of conflagration, and the expansion of this fluid 



