L xv ] 
beftowed fome labour upon. this 
fubject, both as a philofopher and 
as a phyfician, | 
When I firft found in the works 
of that excellent philofopher and 
inventive genius, the reverend Dr, 
_ Prieftley, his important difcovery, 
that plants wonderfully thrive in 
putrid air; and that the vegetation 
of a plant could corre&t air fouled 
by the burning of a candle, and re- 
ftore it again to its former purity 
and fitnefs for fupporting flame, 
and for the ref{piration of animals; + 
I was ftruck with admiration: and I 
could not read afterwards, but with 
a kind of extafy, the application 
which Sir John Pringle made of 
this difcovery in his elaborate dif- 
courfe, delivered at the Royal So- 
ciety in November 1773, when he 
conferred, as prefident of that 
learned 
