[ xxxii ] 
produced no fuch. effect, and that; 
what he thought more extraordi- 
nary, the phials, in which the above 
mentioned plants had grown, the 
infide of which were covered with 
a green kindof 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 not, as he had imagined, 
contributed any thing to the pro- 
duction of this pure air. See Dr: 
osrelh s laft work, p: 337 and 338. 
~ Thus far this matter was carried 
on when I took it up in June laft. 
‘Imutt acknowledge, that, from what 
‘is above related from Dr. Prie/ley’s 
“works, I had little doubt but there 
-was fome quality in plants proper 
for correcting bad air, and improv- 
_ ing ordinary air. My curiofity led 
-\me to inveftigate in what manner 
mi this - 
