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beflowed fome labour upon this 

 fubjedt, both as a philofopher and 

 as a phyfician. 



When I firfb found in the works 

 of that excellent philofopher and 

 inventive genius, the reverend Dr. 

 Prieftley, his important difcovery, 

 that plants wonderfully thrive in 

 putrid air; and that the vegetation 

 of a plant could correct air fouled 

 by the burning of a candle, and re- 

 itore it again to its former purity 

 and fitnefs for fupporting flame, 

 and for the refpiration of animals j 

 I was ftruck with admiration : and I 

 could not read afterwards, but with 

 a kind of extafy, the application 

 which Sir John Pringle made of 

 this difcovery in his elaborate dif- 

 courfe, delivered at the Royal So- 

 ciety in November 1773, when he 

 conferred, as prefldent of that 



learned 



