554 PHILOSOPHICAL TRAKSACTIONS. [aNNO 1779- 



flame of a candle, by withdrawing the thumb when the orifice was close to the 

 flame: the air instantly took fire, and exploded with such a strong report, that, 

 if the phial had not been very stout, it would most probably have been shattered 

 into pieces, notwithstanding its wide orifice. We repeated the same experiment 

 with the same success. I was the more astonished at the uncommon loud report, 

 considering the wide orifice of the phial, because, having often tried aether air in 

 the same way with common air, I never found it explode with any considerable 

 degree of force; and therefore I found it necessary, in order to procure a loud 

 report, to kindle it by an electrical spark directed through the pistol, when its 

 orifice was shut up by a cork, the resistance of which was the chief cause of the 

 report. 



This wonderful effect in an open vessel could not fail of giving me a good ex- 

 pectation of a very powerful effect, if this compound air was shut up in an air 

 pistol by a cork squeezed into its orifice. As it had been now kindled twice by 

 the flame of a candle, I wanted to kindle it by the same means in an air pistol; 

 for this purpose we drilled a small hole in the side of the pistol, which was made 

 of tin, and contained about Q cubic inches of space. We filled it with dephlo- 

 gisticated air in the same manner as we had filled the phial by means of water; 

 and after having poured into it one drop of aether by means of a glass tube, in 

 the manner above described, we shut the orifice by thrusting a cork into it, and 

 kept a finger applied to the touch-hole drilled in the side of the pistol. To avoid 

 accidents if the pistol should burst, we thought it prudent to squeeze the cork 

 very gently into the orifice, so that the resistance should be very moderate. 

 Abbe Fontana wrapped a towel round the pistol for security's sake, leaving only 

 the touch-hole uncovered; which being brought near the flame of a wax taper, 

 the air instantly took fire, and exploded with such a strong report, that his hear- 

 ing, as well as mine, was much hurt by it. The cork, which was a very sound 

 one, flew to pieces against the wall ; and the Abbe felt such a considerable shock 

 in his hands, that he did not think it safe to repeat the experiment, unless a 

 stronger pistol could be procured. 



Encouraged by such uncommon and unexpected effects, I went immediately 

 to Mr. Nairne to inquire, whether he still had in his possession a strong brass air 

 pistol, which he had made last summer according to my direction? I was lucky 

 enough to find it: nothing was to be done to it but to drill a touch-hole in the 

 left side of it, in order to kindle it by a flame if required. This touch-hole was 

 to be snut up by a brass male screw fitted exactly to it, when the pistol was in- 

 tended to be fired by an electrical spark. The air box of this pistol was a cylinder 

 4 inches long and 1 inches in diameter. The fore part of the air box, to which 

 the pistol barrel, fitted to receive a leaden ball or a cork, was fixed, had a broad 



