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SECTION XXIIL 



In planting trees for rendering the air 

 wholefomer^ it feerns not to be quite 

 indifferent what kind of trees are 

 made ufe of 



AFTER what is already faid 

 on the fubjecl:, there will be no 

 doubt left, that vegetables have a 

 remarkable fhare in cleanfing and 

 purifying our atmofphere. But as 

 it feems to follow from my experi- 

 ments, that fome trees yield by the 

 day a purer dephlogifticated air than 

 others, and that fome feem to be 

 lefs difpofed to infect common air 

 by night, it can fcarce be confidered 

 as a matter entirely indifferent what 

 kind of trees ought to be planted^ 



if 



