, [ 290 J 
-equal degree its former faculty,, by 
the coldnefs of the night. Water, 
‘in which I found ice in the morn- 
ing, and which the day before ob- 
firuéted the leaves in yielding a 
tolerable quantity of bubbles, was 
fo much recovered, when it was 
heated by the fun, that frefh leaves 
put in it yielded air-bubbles very 
brifkly, when the _ thermometer 
plunged in it was at 37. 
‘From what has been faid in the 
nineteenth Section, as well as from — 
other experiments, Iam more and 
more induced to believe that our 
atmofpheric air is a fubftance of a 
very changeable nature, and that 
it is, in common with a great.-many 
~ other fubftances, equally liable to 
-. become worfe, or of undergoing 
a kind of Corruption by the increafe 
of heat ; and that this tendency to 
<e 3 5 corruption 
