I 96 1 



It is an amufing light to obferve 

 in a jar full of pump-water the ex- 

 tremity of a branch of a vine, which 

 contains leaves of different agesj 

 from the maturef! to thofe which 

 only begin to unfold themfelves. 

 The air-bubbles make firff their 

 appearance upon the old leaves^ 

 then upon thofe that follow, and 

 laft of all on the new-bbrn ones; 

 The fame proportion takes place alfo 

 in the lize of the bubbles ; the 

 larger! or older! leaves having al- 

 ways the larger! bubbles^ and there- 

 fore yielding far the greater! quan- 

 tity of dephlogifticated air. 



As it feems to be almofl a con- 

 flant rule, that the leaves which 

 yield the greater! quantity of air$ 

 yield alfo the purer! ; the fame 

 rule alfo takes place in the old and 

 new leaves. The young leaves 



feeni 



