nezv inflammable Air or Gafs , Sec. 399 
bably even lefs than — (as will be feen by and by), are 
extricated all at once, when confined (as in fire arms) in 
a fpace ~~ or rather ~ times lets than they can occupy 
when reduced to the temperature of the common atmo- 
fphere, and of confequence 2000 lefs than they can oc- 
cupy when heated in the moment of inflammation ; fo 
that the difference of the explofive force in the inflam- 
mation of the two compounds can be no lefs than as 4 is 
to 2000. 
It muff be here remembered, that air being a very com- 
preffible body, a moderate refiftance aeffing againft its rare- 
fadlion ealily overcomes the force of its expanfion, when 
this expanfion or rarefaction does not amount to more than 
four times its bulk (thatfuch a power ought not to be very 
great, we know by the force employed in ordinary wind 
guns and condenfing machines) whereas no condenfing 
machine has yet been contrived by which air could be 
condenfed to any thing approaching the ftate of conden- 
fation of this fluid as it exifts in the fubftance of nitre. 
It might be here objedled, that air compreffed to one 
tenth in a wind gun pofleffes a power not much fliort of 
gunpowder, though only — or^of it is let loofe at a time ; 
and that thus, inflammable air, though expanded only 
four times in the moment of inflammation, may exert 
a force approaching that of the wind gun, the whole 
G g g 2 mafs 
