Analyfis of the Air. 3 1 1 
Experiments relating to the nature of digef- 
tion in a warmth equal to that of the ftomach, 
but have been hitherto prevented by pur- 
fuing other Experiments. 
Thus we fee that all thefe mixtures do 
in fermentation generate elaftick air, but 
thofe which emit thick fumes, charged with 
fulphur, reforb more than was generated 
in proportion to the fulphureoufncfs and 
thicknefs of thofe fumes. 
I have alfo {hewn 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- 
ftances, and efpecially from the fermenta- 
tion and diffolution 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 produ&ion, part of which 
does we fee refume its elaftick quality, when 
briskly thrown off from thofe bodies by fer- 
mentation, in the diffolution 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~ 
X 4 getables. 
