I04 Experiments to determine 



gunpowder have been founded upon the supposition 

 that the elasticity of the generated fluid is, in all cases, 

 as its density ; but if this supposition should prove 

 false, all those computations, with all the practical rules 

 founded on them, must necessarily be erroneous ; and 

 the influence of these errors must be as extensive as the 

 uses to which gunpowder is applied. 

 . Having found by experience how difficult it is to con- 

 fine the elastic vapour generated in the combustion of 

 gunpowder, when the smallest opening is left by which 

 any part of it can escape, it occurred to me that I might 

 perhaps succeed better by closing up the powder en- 

 tirely, in such a manner as to leave no opening whatever, 

 by which it could communicate with the external air ; 

 and by setting the powder on fire, by causing the heat 

 employed for that purpose to pass through the solid 

 substance of the iron barrel used for confining it. 



In order to make this experiment, I caused a new 

 barrel to be constructed for that purpose ; its length was 

 3.45 inches, and the diameter of its bore -^-^ of an inch ; 

 its ends were closed up by two screws, each i inch in 

 length, which were firmly and immoveably fixed in their 

 places by solder ; a vacuity being left between them in 

 the barrel i.45 inch in length, which constituted the 

 chamber of the piece, and whose capacity was nearly 

 3-^Q- of a cubic inch. An hole 0.37 of an inch in di- 

 ameter being bored through both sides of the barrel, 

 through the center of the chamber, and at right angles to 

 its axis, two tubes of iron, 0.37 of an inch in diameter, 

 the diameter of whose bore was -^-^ of an inch, were 

 firmly fixed in this hole with solder, in such a manner 

 that while their internal openings were exactly opposite 

 to each other, and on opposite sides of the chamber, the 

 axes of their bores were in the same right line. 



