[ 39 ] 



few hours, nay even fometimes in an 

 hour and an half, they purify fo 

 much a body of air quite unfit for 

 reibiration, as to be 'equal in good- 

 nefs to atmofpheric air. They will 

 even do it when they are inclofed in 

 a glafs veflel, without any water. 

 One leaf of a vine, fhut up in an 

 ounce phial, full of air fouled by 

 breathing fo that a candle could not 

 burn in it, reftored this air to the 

 goodnefs of common air in the 

 fpace of an hour and a half. But 

 plants enjoy this privilege only in 

 the day-time, and when they grow 

 in unfhaded places. 



This power of plants extends itfelf 

 even to the worft of ail airs, in 

 which an animal finds his deitruc^ 

 tion in a moment ; fuch as is pure 

 inflammable and highly phlogifti- 

 cated air, which is little or fcarcely at 

 D 4 all 



