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a fingle fact ; for I had feveral inftances of the fame 

 kind in the preceding year; but it feemed fo very 

 extraordinary, that air mould grow worfe by the 

 continuance of the fame treatment by which it had 

 grown better, that, whenever I obferved it, I con- 

 cluded that I had not taken fufficient care to fatisfy 

 myfelf of its previous reftoration. 



That plants are capable of perfectly reftoringair 

 injured by refpiration, may, I think, be inferred 

 with certainty from the perfect reftoration, by this 

 means, of air which had paffed through my lungs, 

 £0 that a candle would burn in it again, though it 

 had extinguifhed flame before, and a part of the 

 fame original quantity of air ftill continued to do 

 lb. Of this oneinftance occurred in the year 1771, 

 a fprig of mint having grown in a jar of this kind 

 of air, from the 2 <,th of July to the 1 7th of Au- 

 guft following ; and another trial I made with the 

 fame fuccefs the 7th of July 1772, the plant having 

 grown in it from the 29th of June preceding. In 

 this cafe alfo I found that the effect was not owing 

 to any virtue in the leaves of mint ; for I kept them 

 conftantly changed in a quantity of this kind of 

 air, for a considerable time, without making any 

 fenfible alteration irk it. 



Thefe proofs of a partial reftoration of air by 

 plants in a ftate of vegetation, though in a con- 

 fined and unnatural fituation, cannot but render it 

 highly probable, that the injury which is continually 

 done to the atmofphere by the refpiration of fuch 

 a number of animals, and the putrefaction of fuch 

 mafles of both vegetable and animal matter, is, in 

 part at leaft, repaired by the vegetable creation. 



And, 



