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The Two firft Propofitions contain the Proofs that 
a permanent elaftic Fluid is conftantly generated in 
the Explofion of Gunpowder ; this is evinced by well- 
known Experiments daily repeated, and acquiefced 
in by all who have frequented the ufual Courfes of 
Experimental Philofophy, of which thefe Experi- 
ments generally make a Part ; fo that the Author pre- 
lumes he may confider this Point as inconteftably 
eftablifhed, at lead he has never yet met with any 
who have queftioned it. 
The Third Proportion is, That the Elafticity of 
this Fluid produced by the Firing of Gunpowder, is, 
ceteris paribus , direftly as its Denfity ; and the Ex- 
periment by which this was confirmed, was letting 
fall feparately Two Quantities of Powder, the one 
double the other, on a red-hot Iron included' in an 
exhaufled Receiver j and it appeared by the Defcent 
of the Mercury, that the Elafticity of the Fluid pro- 
duced from the double Quantity of Powder, was 
nearly double the Elafticity of that produced from the 
Engle Quantity ; that is, the Elafticity was nearly as 
the Denfity of the Fluid. 
But it may perhaps be thought, that a ftngle Ex- 
periment is too {lender a Foundation on which to 
build fo material a Principle, fince all fubfequent 
Reafonino;s on the Force of Powder in fome meature 
depend on it. In Reply to this it may be faid, that 
the Author recited this {ingle Experiment on ac- 
count of the great Quantity of Powder made ufe of 
in it, which was Threc-fixteenths of an Ounce; but 
that he had really made many more equally con- 
clulive, which he thought it unneceflary to mention. 
However, thofe who doubt of this Propofition, may 
fa- 
