[ i 6 9 ] 
growing in it. The firffc of thefe experiments was 
made in the month of May; and they were frequently 
repeated in that and the two following months, with- 
out a fingle failure. 
For this purpofe I ufed the flames of different fuh~ 
fiances, though I generally ufed wax or tallow 
candles. On the 24th of June the experiment fuc- 
ceeded perfectly well with air in which fpirit of wine 
had burned out, and on the 27th of the fame month 
.it fucceeded equally well with air in which brim- 
flone matches had burned out, an effed of which X 
had defpaired the preceding year. 
This refloration of air I found depended upon the 
vegetating flate of the plant ; for though I kept a 
great number of the frefh leaves of mint in a fmall 
quantity of air in which candles had burned out, 
and changed them frequently, for a long lpace of 
time, I could perceive no melioration in the flate of 
the air. 
This remarkable effed does not depend upon any 
thing peculiar to mint, which was the plant that I 
always made ufe of till July 1772 ; for on the 16th 
of that month, I found a quantity of this kind of 
air to be perfedly reflared by fprigs of balm, which 
had grown in it from the 7th of the fame month. 
That this refloration of air was not owing to any 
aromatic effluvia of thefe two plants, not only ap- 
peared by the effential oil of mint having no fenfible 
elfed of this kind; but from the equally complete 
refloration of this vitiated air by the plant called 
groundfel, which is ufually ranked among the weeds, 
and has an offenfive fmell. This was the refult of 
an experiment made the 16th of July, when the 
Vol. LXIIo Z plant 
