[ 68 J 
The influence of plants ‘on the 
air Of a room in which they are 
kept is different in ‘the night from 
what it is in the day. In the day 
plants are apt to contribute fome- 
what to purify.the air_of the room, 
if they are placed fo as to receive 
all the light of the fun poffible: 
if they,are: placed fo. as. not,to re- 
ceive the ~direét influence of the 
fun, but to be free from any fhade, 
they feem to have no influence at 
all, either in improving the air of 
the room or in fouling “it. ~But 
when they-are-placed-in a~part of 
the room the moft remote from the 
windows, fo as to be much fhaded, 
they are “apt to render the air of 
the. room more or iefs’ impure, im 
proportion to their fize, and to the 
more or lefs degree of light of the 
place where me ftand. Atnight 
Ss sr 
