of Atmospherical Air, Se. 127 
those which have the strongest smell, phlogisticate 
air. But it is well known on the other hand, that 
aromatic plants, in particular, afford very pure oxy- 
genous gas in great quantity. When vegetables vi- 
tiate air, it is probably owing to a beginning of pu- 
trefaction. This was the case in an experiment 
which Dr. Priestley relates in his third vol. of Ex- 
periments on Air, p. 278. A sprig of mint was in- 
troduced into a jar of dephlogisticated air, sometime 
in April. It was examined the 12th May. “ The 
dephlogisticated air,” says he, *¢ was injured, which 
I attributed to the rotting of some of the leaves of 
the plant.” I recollect only one experiment which 
has been made to ascertain the effect of flowers on 
atmospherical air. It is described in Dr. Priestley’s 
2d vol. of Experiments, p. 247. The air was consi- 
derably injured by a rose confined init. It would 
have thrown light on the subject, if notice had been 
taken, whether or not the volume of the air in that 
experiment was diminished. At all events it is cer- 
tain, that the effect was not produced by the smell 
or aroma of the flower, since cloves and musk, 
which I kept confined for a fortnight in atmosphe- 
rical air over mercury, neither diminished nor viti- 
ated it in the least. 
It is flattering to the antiphlogistians, that their , 
Opponents, in the very act of opposition, are oblig- 
ed to have recourse to their theory in explanation 
of certain phenomena, Dr, Priestley observing 
