310 Analjfts of the Air. 
in proportion to the fulphureoufnefs and 
thicknefs of thofe fumes. 
I have alfo fhewn in many of the fore- 
going Experiments, that plenty of true per- 
manent elaftick air is generated from the 
fermenting mixtures of acid and alkaline fub- 
ftanccs, and efpecially from the fermenta- 
tion and diflblution of animal and vegeta- 
ble bodies : Into whofe fubftances we fee it 
is in a great proportion intimately and firmly 
incorporated , and confequently, great quan- 
tities of elaftick air muft be continually ex- 
pended in their produdion, part of which 
does we fee refume its elaftick quality, when 
briskly thrown off from thofe bodies by fer- 
mentation, in the diftblution of their texture. 
But part may probably never regain its elaf- 
ticity, or at leaft not in many centuries, that 
efpecially which is incorporated into the 
more durable parts of animals and ve- 
getables. However we may with pleafure 
fee what immenfe treafures of this noble 
and important element, endued with a 
moft a£livc principle, the all- wife Providence 
of the great Author of nature has provided ; 
the conftant waftc of it being abundantly 
fupplyed by heat and fermentation from in- 
numerable 
