( H” ) 
duced from the fir’d Grain weight of Gunpowder, was 
equal but to the bulk of n Grains of the fame; that 
Number being nearly the 20th part of 222, the Number 
of Grains contain’d in a Cubical Inch, as aforefaid. Which 
fhews that the whole fpace at firft deferred by the Water 
upon firing the Gunpowder , was not fupply’d with real 
Air. The Temperature of the Air I all along confi- 
dered, and found it contributed nothing to this odd Phe- 
nomenon , which how to account for I know not •, I only 
fuggeft, that the Springs, or Conftituent parts of the 
Ambient Air, as well as thofe contain’d in the Body of 
the Gunpowder, may, upon firing, be capable of being bro- 
ken, or at lead: fo Diftended, as to polfefs fo large a 
fpace, and require fo long a time to recover their Na- 
tural State again. And this, I prefume, could never 
have been dilcoyfer’d but by the confinement of the 
fame Air in which the Explofion was made. 
And as this Difcovery is altogether new, fo the Ap- 
plication of it may be as ufeful. But I fhall wholly 
leave that to this Honourable Society, who be if know 
how, molt aptly to apply it. 
Notwithstanding the Account of this Experiment 
feems to Run-counter with the Accounts formerly gi- 
ven of the firing of Gunpowder in V tcuo ; yet confider- 
ing the different Mediums in which the Experiments 
were made, they may be the eafier reconcilable : For 
when the Gunpowder was fired in fo thin a Medium as 
the near approach to a Vacuum , that then the remaining 
Air in the Receiver could fuffer by the Explofion, but 
in proportion to the Quantity, which muft be fo incon- 
fiderable, as not to be taken notice of. Befides, when I 
come to repeat thofe Experiments, I doubt riot but I 
lhall difcover fome Occurrences that were the n paft by 
; unheeded, that may render them more agreeable to this 
| lafr, than they now; feetn to appear. 
■f 
|| 
Is 
14 X 2 
III. An 
