[ i9S 3 
fufpended my judgment concerning the efficacy of 
plants to reftore this kind of noxious air, till I 
fhould have an opportunity of repeating my experi- 
ments, and giving more attention to them. Ac- 
cordingly I refumed the experiments in the fum- 
mer of the year 1772, when I prefently had the 
mofi indifputable proof of the reftoration of putrid 
air by vegetation ; and as the fa ft is of fome im- 
portance, and the fiibfequent variation in the fiate 
of this kind of air is a little remarkable ; I think 
it neceflary to relate fome of the fafts pretty cit- 
cumfiantially. 
The air, on which I made the firft experiments, 
was rendered exceedingly noxious by mice dying in 
it on the 20th of June. Into a jar nearly filled 
with one part of this air, I put a fprig of mint, 
while I kept another part of it in a phial, in the 
fame expofure ; and on the 27th of the fame month, 
and not before, I made a trial of it, by introducing 
a moufe into a glafs vefiel, containing 24. ounce mea- 
fures filled with each kind of air ; and I noted the 
following fafts. 
When the vefiel was filled with the air in which 
the mint had grown, a very large moufe lived five 
minutes in it, before it began to fhew any fign of 
uneafinefs. I then took it out, and found it to be as 
firong and vigorous as when it was firft put in ; 
whereas in that air which had been kept in the 
phial only, without a plant growing in it, a younger 
moufe continued not longer than two or three fe- 
conds, and was taken out quite dead. It never 
breathed after, and was immediately motionlefs. 
After half an hour, in which time the larger moufe 
Cc2 (which 
