C 6 5 ] 



as the air, in which it grows, con* 

 tains more of this principle. 



When a plant grows in the open 

 air, it contaminates by night the 

 f unrounding air ; but this air, being 

 diluted with other air, does not ap-* 

 pear in reality to be altered by any 

 method yet found out : befides, it 

 is probable, that this air is rifen up 

 as foon as it was become phlogifti- 

 cated by the plant, being fpecifically 

 lighter than common air. It feems 

 therefore not improbable, that fome 

 plants, as for instance the hyofcyamus % 

 may contaminate in reality more air 

 at night than they improve in the day; 

 fo that, if all the air fpoiled by fuch. 

 a plant was fhut up with the plant 

 a whole night and a day, the air 

 would ftill be found contaminated s 

 but tho' this might be the cafe when 

 the plant is fhut up with the air, 

 F yet 



