[ 40 ] 

 all diminifnable by nitrous air. I ob- 

 fen ed fome difference in various 

 ki ids of plants in this rcfpect, and 

 found that water plants feem to 

 poneis 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 mould be fa, as thofe plants 

 grow better in rnarmy, low grounds, 

 and even in itagnated waters, whofe 

 bottoms are generally muddy, and 

 yield a great deal of inflammable air, 

 which may be collected at the fur- 

 face of the water by flirring up the 

 ground, and may be kindled by 

 throwing a burning paper upon the 

 water, w T h-ich is an amufing experi- 

 ment by night ? Plants, however, 

 want longer time to correct this kind 

 of air, at leair, that which is ex- 

 tracted 



