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SECTION XVH. 
Experiments towards inveftigating 
what plants or trees infect the 
Surrounding air the leaft by night. 
; ies 1 PLACED in four dif- 
as near as 1 could, of leaves upon 
their ftalks of the following trees, 
_fime-tree, oak, laurocerafus, walnut. 
I placed all thofe jars over-night 
in a room, each inverted upon a 
dith ; in each jar was as much wa- 
ter as would preferve the leaves 
alive by keeping the ftalks wet. 
Next morning I found the air of 
all the jars contaminated: that of 
the walnut-leaves was become unfit 
< 2s for bigs and extinguifhed : 
= wees $ 
