[ 2 9° ] 



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- 

 itructed the leaves in yielding a 

 tolerable quantity of bubbles, was 

 {q 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, I am 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 

 3 corruption 



