C 143 ] 



mer purity as foon as the leaves are 

 produced. And this is what Abbe 

 Fontana found to be a conftant 

 fact. 



If I had more leifure, I fhould be 

 inclined to expatiate in a wide and 

 open field of reflections, which pre- 

 fent themfelves to my mind, and to 

 draw all the confequences which 

 feem to flow, as from a fountain- 

 head, from the already mentioned 

 obfervations. 



Is it not probable, that thofe who 

 labour under confumptive and afth- 

 matic complaints, and who find the 

 greateft relief, and fometimes a per- 

 fect cure, by retiring to mild cli- 

 mates, where vegetation is lively, 

 and begins fooner in the fpring, 

 mould go to fuch places where the 

 conftitution of the air is found by 

 experience to be during the whole 



year 



