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-from the accension of those highly inflammable matters, called bitu- 
pistol is required to be charged, the inflammable air should be kept in a corked bottle, to the mouth 
of which the aperture A of the pistol must be applied very closely, in the same moment that the cork 
is removed, keeping the pistol inverted over it. In this case it is plain, that the common air, which 
is in the pistol, will mix with the inflammable air, because the former being heavier than the latter, 
will descend into the bottle, &c. When the pistol has been thus kept over the bottle for about ten or 
fifteen seconds, it must be removed, and both the pistol and the bottle must be instantly corked. If 
now this charged pistol be held by applying the thumb and fingers to the lower part of it, so as to 
touch the tinfoil B, and an electric spark be given to the knob H, by approaching it to the prime con¬ 
ductor of an electrical machine, or to the knob of a small charged electric phial, the inflammable air 
in the pistol will be fired by the spark, which will necessarily pass between G and the tinfoil C, and 
will drive the cork I to a considerable distance. The above-mentioned bottle filled with inflammable 
air is sufficient to charge the pistol several times successively, without being again filled with inflam¬ 
mable air, especially if it is pretty large; only it should be minded, that when the pistol has been filled 
out of the same bottle-several times, the inflammable air in that bottle becomes mixed with a good deal 
of common air, for which reason the pistol should then be kept some time longer upon the bottle, in 
order to charge it. Sometimes the pistol will not explode, which is owing to its having been kept too 
long over the bottle, so as to become filled entirely with inflammable air; the common air contained in 
it being descended into the bottle in consequence of its greater specific gravity. 
Fig. IQth, represents a brass pistol for inflammable air, which is more commonly sold at the philo¬ 
sophical instrument shops. It is here represented as transparent, in order to shew its internal con¬ 
struction. It consists of a brass chamber ABC, to the mouth of which A a cork is fitted. To the 
bottom of it a perforated brass piece is screwed, into which a glass tube DE is cemented, and into this 
tube is cemented a wire GF, furnished with a knob F at one end, and bent at the other extremity, so 
as to come within about one or two tenths of an inch of the brass piece. Fig. the 20th, shews this 
brass piece separate, and also the brass cap I, which, when the pistol is not used, is screwed at H, in 
the manner shewn by the dotted line, and serves to defend the tube E. This pistol is charged and dis¬ 
charged in the same manner as the glass one described above, but, being much larger, it requires a 
greater quantity of inflammable air, and consequently makes a greater explosion. 
It is easily comprehended, that in the pistols described above, there cannot be introduced a mixture 
of inflammable and common air in any required proportion, much less can there be introduced a mix¬ 
ture of inflammable and oxygen air. In order to avoid this great inconvenience. Dr. Ingenhousz 
contrived another pistol, into which any required mixture of elastic fluids may be introduced. This 
pistol, and its separate parts, are exhibited in fig. the 21st, plate II. A a is the barrel of the pistol. 
B is the box or chamber for the elastic fluids, b the place where the barrel is screwed to the box. C 
the handle of the pistol. D is the wire or handle of the piston LK, the lower part of which, hh, is 
made square, in order to prevent its turning round. E is a hole on the side of the box, which is occa¬ 
sionally shut, by screwing the small nut e in it. F is a piece of brass with a female screw, which is 
fixed to the wooden handle by means of three strong screws, and to which the lower part f of the box 
is screwed. G is a piece of ivory fixed to the piston with a conical ivory termination L, which fits the 
conical end of the box. M. is the perforation in the wooden handle, through which the brass wire D 
passes. N is a small brass ball at the extremity of a wire, which passes through the canal R in the 
ivory cone. O is another piece of wire which passes through another hole, and touches the brass under 
the ivory piece. The wires are both fixed into the holes by means of the cement mentioned above. P 
is the small interval between the extremities of the two wires, through which the electric spark passes, 
when given by means of a charged electrical bottle to the ball N. 
When the parts of this pistol are put together, as shewn by ABCD, the piston is pulled back, so 
as its part K may be at F, and the box is filled with inflammable and respirable air; the electric spark 
given to the small brass ball, as mentioned above, will inflame the gas, and its force will push a bullet, 
which is previously fixed into the barrel just where this is screwed to the box. But in order to 
charge the pistol with a mixture of inflammable and common air, or inflammable and oxygen air, in 
2 N 
