Profefor Wit.t1AMs on Earthquakes. 297 
of water, air, or heat, the more readily they ferment.—And 
when they do ferment, they will produce a vapour more or lefs 
ftrong, according to' the quantities of the fermenting matter, 
and the degree of the fermentation. But in no method isa 
more powerful vapour produced, than by fre. What an amaz- 
ing effect will a fall {park of this have on nitre and fulphur, 
when niade up into fuch a compofition as that of gun-powder ! 
How {mall a quantity of this powder, when on fire, will ge- 
nerate a vapour of fufficient force to burft the firmeft rocks 1 
Air, by the application of fire, becomes fo elaftic, as to break 
through all oppofition.—And there are many effects produced 
by the vapour of water, when intenfely heated, which make 
it probable, that the force of gun-powder is not near equal to 
it. And, in general, all combuftible bodies are capable of be- 
ing turned into vapour, by the action of fire.—And fire feems 
to be a fluid, which is fpread through almoft all bodies what- 
foever. Itcertainly exifts, in very large quantities, in the bowels 
of the earth.—Some parts, as the volcanoes are a&ually burn- 
ing, and have been throwing out fire, flame, ‘fmoke, cinder, 
rocks and lava, for many ages.—And where there are no fuch 
appearances of it, it exifts, and is diffufed in great quantities. 
"That this is the cafe is evident from hot {prings,-—the warmth 
that is always found in deep mines and pits,—and thofe burn- 
ing mountains that have been thrown up from the bottom of 
the fca.—And when colle&ed into large quantities, its effects 
on water, irs. the fumes of fermenting minerals, and. all kinds 
of. combuftible bodies, would be to generate a vapour more or | 
lefs gne "dos to the qUAR GO of the minerals of which 
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