VOL. LXIX.] PHILOSOPHICAL. TRANSACTIONS. 555 



shoulder, which was fastened to the body of the air box by 6 strong brass screws, 

 which never had been loosened by former explosions. A leaden bullet, wrapped 

 up in leather, was forcibly rammed into the pistol- barrel as far as the screw, which 

 joins the barrel with the air box. The pistol was filled with pure dephlogisticated 

 air, which was drawn in by the piston from an elastic gum bottle, and 1 drop of 

 aether being poured into it, the air within was kindled by an electrical spark 

 directed through it. The air took fire: the explosion was as loud as that of a 

 common musket, and the force so great, that the whole fore part of the air box 

 with the pistol barrel flew oft', all the 6 screws were broken, and the strong and 

 tough metal of which they were made was rent. Three strong brass screws, by 

 which the bottom of the air box was fixed to the wooden handle, were loosened, 

 and the whole frame of the pistol was out of order. The substance of the air 

 barrel, where it was torn, was of the thickness of about a half-crown piece. 



Being now convinced, that though inflammable air from metals with dephlo- 

 gisticated or common air, is far inferior to the force of gunpowder, the explosive 

 force of the compound of dephlogisticated and aether air approaches it much 

 nearer, I thought it worth while to fit the pistol up in such a manner as to be 

 out of all danger of bursting. For this purpose I desired Mr. Nairne to adapt, 

 and solder to the fore part of the air box, a hollow cone of brass, the extremity 

 of which should terminate in the gun barrel. As the piston could not reach to 

 the extremity of this conical hollow, which consequently must be always filled 

 with common air, I desired him to fix to the piston an ivory cone, through which 

 the 1 wires would pass to meet each other at the surface of the cone, leaving an 

 interstice between them of about 1 line, through which the electrical spark should 

 leap and set fire to the air. This ivory cone shutting up exactly the whole cavity 

 of the air box, no air could come into it but what was drawn in by the piston. 

 The pistol thus fitted up answered tolerably well. The cone, instead of ivory, 

 may be made of solid glass, which is a better non-conductor than ivory. The 

 canals in the ivory, through which the 2 wires pass, may be made wide enough 

 to contain a glass tube, through which the wires pass; or to be filled with a non- 

 conducting cement, as sealing-wax, for the same purpose. The cone may even 

 be made of brass, provided 2 glass tubes are lodged in it, to give a passage to 

 the 2 wires. 



I kindle this pistol sometimes by putting in the touch-hole a little bit ot a 

 cotton thread soaked in moist gunpowder and dried afterwards; or a bit of those 

 paper matches which the Chinese put into those little squibs, which go by the 

 name of India crackers. I sometimes kindle it by holding the flame of a candle 

 or a burning paper to the touch-hole. In this case it is to be observed, that the 

 touch-hole must be kept upwards, if the pistol is loaded with inflammable air 

 from metals, because this air being lighter than common air, will rise out of the 



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