[ *98 ] 
a Tingle faft ; for I had feveral inftances of the fame 
kind in the preceding year; but it feemed fo very 
extraordinary, that air fhould grow worfe bv t'ne 
continuance of the fame treatment by which it had 
grown better, that, whenever I obferved it, I con- 
cluded that 1 had not taken fufficient care to fatisfv 
niyfelf of its previous reftoration. 
That plants are capable of perfectly reftoring air 
injured by relpiration, may, I think, be inferred 
with certainty from the perfect reftoration, by this 
means, of air which had pafled through my lungs, 
fo 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 one inftance occurred in the year 1771, 
a lprigof mint having grown in a jar of this kind 
of air, from the 25th of July to the 1 yth of Au- 
guft following ; and another trial I made with the 
fame fuccefs the 7th of July 1 772, the plant having 
grown in it from the 29th of June preceding. I11 
this cafe alfo I found that the effedt 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 confiderable time, without making any 
fenfible alteration in 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 iscontinually 
done to the atmofphere by the refpiration of fuch 
a number of animals, and the putrefadlion of fuch 
mafles of both vegetable and animal matter, is, in 
part at leaft, repaired by the vegetable creation. 
