C 199 3 



And, notwithilanding the prodigious mafs of air 

 that is corrupted daily by the abovementioned caufes ; 

 yet, if we coniider the immenfe profufion of ve- 

 getables upon the face of the earth, growing in 

 places fuited'to their nature, and confequently at 

 full liberty to exert all their powers, both inhaling 

 and exhaling, it can hardly be thought, but that 

 it may be a fufficient counterbalance to it, and 

 that the remedy is adequate to the evil. 



Dr. Franklin, who, as I have already obierved, 

 faw fome of my plants in a very flourithing flate, 

 in highly noxious air, was pleafed to exprefs very 

 great fatisfaction w T ith the refult of the ex peri* 

 ments. In his anfwer to the letter in which I in- 

 formed him of it, he fays, 



" That the vegetable creation fhould reftore the 

 " air which is fpoiled by the animal part of it, 

 t4 looks like a rational fyftem, and feems tobe of 

 " a piece with the reft. Thus fire purifies water 

 " all the world over. It purifies it by diftillation, 

 " when it raifes it in vapours, and lets it fall in 

 " rain; and farther frill by filtration, when* keep- 

 «* ing it fluids it furTers that rain to percolate the 

 " earth. We knew before, that putrid animal fub- 

 " fiances were converted into* fweet vegetables*. 

 " when mixed with the earth, and applied as 

 " manure; and now, it feems, that the fame pu- 

 ** trid fubflances, mixed with the air, have a fimi-' 

 " lar effect. The ftrong thriving ftate of your 

 " mint in putrid air feems to (hew that the air is- 

 " mended by taking fomething from it, and no£ 

 " by adding to it." He adds, " I hope this will' 

 " give fome. check to the rage of deftroying trees 

 2. ^ that 



