207 
100 parts of the air of the garden occasioned a 
diminution to 79 parts. 
If the results of this experiment be calculated 
upon it, 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 sup- 
plied in a natural manner with carbonic acid gas ; 
and the quantity 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 case, I proved by pouring lime-water 
into the water, when an immediate precipitation 
was occasioned. The increase of azote I am in- 
clined to attribute to common air disengaged from 
the water. 
The following experiment I consider as con- 
ducted under circumstances more analogous to 
those existing 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 on the surface of water im- 
pregnated with carbonic acid gas. A vessel of 
thin flint glass, of the capacity of 230 cubical 
inches, having a funnel furnished with a stop- 
cock inserted in the top, was made to cover the 
grass ; and the apparatus was exposed in an open 
place ; a small quantity of water was daily sup- 
plied to the grass by means of the stop-cock.* 
Every day likewise a certain quantity of water was 
* See Fig. 17- 
