new inflammable Air or Gafs , &c. 40 r 
quantity of refpirable and inflammable air was drawn in. 
I had rammed into the barrel, adapted to it, a leaden bullet 
wrapped up in a piece of leather fo ftrongly that I did 
not expedl the refinance could be overcome by the ex- 
plofion. I fired it by an electrical fpark ; the inflamma- 
tion took place, the piftol grew hot, the ball was not 
propelled, and the pifton was driven more than half 
way down the cylinder by the preffure of the atmo- 
fphere adting upon it when the explofive air was con- 
fumed by the inflammation. 
The cafe is quite different in the firing of gunpowder, 
as there remains after its inflammation a mafs of air 
which occupies about 250 times the former bulk, ac- 
cording to Mr. ROBINS. 
As, in the foregoing experiment, the compound of 
inflammable and common air was reduced above the 
half of its former bulk, it feems more than probable, 
that the quantity of dephlogifticated and inflammable air 
extricated in the firing of gunpowder muft alfo un- 
dergo a fimilar diminution by its inflammation ; fo, that 
when there remains a mafs of air, 250 times the bulk of 
the gunpowder, the quantity of air extricated from the 
powder muft have been in reality not lefs than 500 
times the bulk of the powder, which agrees nearly with 
v 
the calculation of Mr. john bernquilli. Let us now 
' - fee 
