t 9 i 



It will, perhaps, appear probable, 

 that one of the great laboratories of 

 nature for cleanllng and purifying 

 the air of our atmofphere is placed 

 in the fubftance of the leaves, and 

 put in action by the influence of the 

 light; and that the air thus purified, 

 but in this irate grown ufeleis or 

 noxious to the plant, is thrown out 

 for the greateft part by the excre- 

 tory ducts, placed chiefly, at leaft in 

 far the moil part of plants, on the 

 under ride of the leaf. 



Is there not fome probability that 

 the under part of the leaves may 

 have been chiefly deitined for this 

 purpofe: becaufe in this way the 

 dephlogifdcated air, gufhing conti- 

 nually out of this fur (ace, is inclined 

 to fall rather downwards, as a bene- 

 ficial fhower tor he u:c of the ani- 

 mals who all breathe in a region of 



the 



