[ 40 J 
all diminifhable by nitrous air. Tob- 
ferved fome: difference in “various 
kinds of plants in this refpeét, and 
-found that water plants feem to 
pofieis this quality in a greater de- 
gree than others. The willow tree 
and the perficaria urens were found 
eminent in producing this effect: 
and may it not be providentially or- 
-dained it fhould be fo, as thofe plants 
grow better i in marfhy, low grounds, 
and even in ftagnated waters, whofe 
ttoms are generally muddy, and 
yield a great deal of inflammableair, 
which may be collected at the fur- 
face of the water by {tirring up the 
ground, and may be kindled = 
throwing a ‘burning papér upon t 
water, which is an amufing experi- 
ment by night? Plants, however, 
want longer time to correct this kind 
of air, at leaft that which is ex- 
