[ xxxii ] 



produced no fitch effect, and that] 

 what he thought more extraordi- 

 nary, the phials, in which the above 

 mentioned plants had grown, the 

 iniide of which were covered with 

 a green kind of matter, continued 

 to yield air as well when the plants 

 were out of them as they had done 

 before ; he was convinced, that the 

 plants had riot, as he had imagined, 

 contributed any thing to the pro- 

 duction of this pure air. See Dr« 

 Prieftley's laft work, p. 337 and 338^ 

 Thus far this matter was carried 

 on when I took it up in June laffc 

 I muft acknowledge, that, from what 

 is above related from Dr. Prieftlefs- 

 works, I had little doubt but there 

 was fdme quality in plants proper 

 for correcting bad air, and improv- 

 ing ordinary air. My curiofity led 

 me to inveltigate in what manner 



this 



