35 6 -Abbe Fontana’s Experiments and 
but never longer. It is true, however, that I breatheddt 
with fume oppreffion, even from the beginning, which 
does not happen when the inflammable air contained in 
a bladder is breathed, the lungs being in a natural ftate. 
And now it feems no longer difficult to give an anfwer 
to the queftion propofed above, and to account for the 
fmall difference obferved in the breathing of the two dif- 
ferent kinds of air in the bladders. The inflammable 
air, when joined to a great quantity of common air, may 
be breathed fafely, becaufe there is a quantity of com- 
mon air fufficient for various infpirations, and that the 
mixture of the two airs may be breathed till this com- 
mon air is thoroughly infedled. But the inflammable air 
itfelf is not altered nor decompofed by the refpiration. 
Wherefore we muff conclude, that the inflammable air is 
not fuch a kind of air as can by itfelf alone be diredtly 
ufeful for refpiration. It muff rather be confidered as if 
there was nothing of that air in the cafe of the bladder; 
and indeed It is found by experience, that the pulmonary 
air itfelf may be breathed eight or nine times in an 
empty bladder. The not being able to breathe it eleven 
times fucceflively, as was done when there was inflam- 
mable air in the bladder, and the feeling an oppreffion 
in the firfl: cafe and not in the fecond, muff; be intirely 
attributed to the want of thirty-five cubic inches of air 
expirated, 
