C > 3 



the water ; and the absorption was not quite rls of its 

 volume. 10 parts .of the residual gas exposed to a 

 solution of green sulphate of iron, impregnated with 

 nitrous gas, a substance which rapidly absorbs oxygene 

 from air, occasioned a diminution to SO parts. 00 

 parts of the air of the garden occasioned a diminution 

 to 7$ parts. 



If the results of this experiment be calculated 

 upon, it will appear that the air had been slightly 

 deteriorated by the action of the grasses. But the 

 weather was unusually cloudy during the progress of 

 the experiment ; the plants had not been supplied in a 

 natural manner with carbonic acid gas ; and the quan- 

 tity formed during the night, and by the action of the 

 faded leaves, must have been partly dissolved by the 

 water ; and that this was actually the casr, I proved 

 by pouring lime-water into the water, when an imme- 

 diate precipitation was occasioned. The increase of 

 azote I am inclined to attribute to common air disen- 

 gaged from the water. 



The following experiment I consider as conduct- 

 ed under circumstances more analogous to those exis- 

 ting in nature. A turf four inches square, from an 

 irrigated meadow, clothed with common meadow 

 grass, meadow fox- tail grass, and vernal meadow grass, 

 was placed in a porcelain dish, which swam onthe sur- 

 face of water impregnated with carbonic acid gas. A 

 vessel of thin flint glass, of the capacity of 230 cubi- 

 cal inches, having a funnel furnished with stop-cock 

 inserted in the top, was made to cover the grass ; and 

 the apparatus was exposed in an open place j a small 



