upon Gun-powder , &c. 315 
der which was de fig tied for great guns and mortars was weaker 
than thole which were intended to be nfed in fmaller pieces : 
for if there is any foundation for thefe conjectures, it is cer- 
tain, that the weakeft powder, or the heavieft in proportion to 
its elaffic force, ought to be u fed to impel the heavieft bullets, 
and particularly in guns that are imperfectly formed, where the 
vent is large, and the windage very great. 
I am perfectly aware, that an objection may here be made, 
viz. that the elafiic fluid,, which is- generated from gun-powder, 
muff be fuppofed to have the fame properties very nearly,- 
whatever may be the proportion of the feveral ingredients, and 
that therefore the only difference there 'can be in powder is, 
that one' kind may generate more of this fluid, and another lefs 5 
and that' when it is generated, it aCls in the fame manner, and 
will alike efcape, and with the fame velocity, by any pafiage it 
can find. But to this I anfiwer, though the fluid may be the 
fame, as undoubtedly it is, and though its denfity and elaffi- 
city may be the fame in all cafes at the infant of its generation, 
yet in the explofion, the elaffic and un-elaftic parts are fo mixed 
and blended, that I imagine the fluid cannot expand without 
taking the grofs matter along with it, and the velocity with 
which the flame iffues out at the vent is to be computed from 
the elafficity of the fluid, and the denfity or weight of the fluid 
and the grofs matter taken together, and not Amply from.! 
the elafficity and denfity of the fluid. If antimony in an im- 
palpab e powder, or any other' heavy body, wasp intimately 
mixed with water in a veffel of any kind, and kept in fufpenfion 
by ihaking or ffirring them about ; and if a hole was opened 
in the fide or bottom of the veffel, the water would not rim 
out without taking the particles of the folid body along with 
it. And in the fame manner I conceive the folid particles that 
remain 
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