44 Experiments on Vegetation. 
clover and grass (the area of which was 20 in.) was confined 
under a receiver (whose capacity was 150 in.) over mercury for’ 
three days, and occasionally watered through the cock at the 
top of the receiver. When the air was examined, 2 in. of it and 
oue of nitrous equalled 2°3 in, But 2 in. of atmospherical and 
1 in. of nitrous =1-9 in. I have repeated these experiments at 
various periods, and have always obtained similar results. 
Exp.V. Sept. 6, 1816. A dish containing a portion of stone- 
crop in a yery healthy state, was placed under a receiver over 
mercury; and at the expiration of ten days I found 2 in. of the 
air and 1 in. of nitrous gas = 1°47 in., while the same propor- 
tions of common air and nitrous gas = 1°44 in. 
Exp.V1i. July 25, 1816. Several sprigs of bergamot mint 
growing in a pot were bent under a receiver as usual ; and in six 
days I found 2 in. of the air and | in. of nitrous gas =1°42 in. 
full; and 2 in. of common air and 1 in. of nitrous gas = 1°42 
bare. 
Perhaps it may be remarked, that the two last experiments 
produced but little effects on the atmosphere: but let it be re- 
collected that the object of these experiments was to ascertain 
whether vegetation inyproved the air of the atmosphere, by im- 
parting to it oxygen: and we see that in no instance what- 
ever was the air of the atmosphere improved hy vegetation 5 
but on the contrary it was always somewhat injured, and in some 
instances the whole of the oxygen disappeared. Is it not fair 
then to conclude that, so far from vegetation improving the at- 
mosphere, by decomposing the carbonic acid gas generated by 
animal respiration and combustion and liberating its oxygen, 
it like them combines with oxygen and generates the same kind 
of gas? 
Having so far identified the physiological operations of the 
animal and vegetable kingdoms on the air of the atmosphere, 
I next tried the effects of factitious airs on plants, to see how far 
they might correspond with the effects of the same gases on the’ 
animal ceconomy. 
For this purpose I selected that plant which I could act upon 
in the most natural manner. Experiments VII. VIII. and EX. 
Three turfs of clover and grass were placed under receivers (as in 
the former experiments). The first was inclosed in nitrogen gas; 
the second in carbonic acid gas; and the third in atmospherical 
air (as a standard by which to compare the other two). 
They were all placed in the open air, and exposed to the vi- 
cissitudes of day aud night, sunshine and cloudy. 
The effegt of the nitrogen on the first turf was evident in 
one hour, by the leaves.of the clover beginning to collapse and: 
the leafstalks ta bend; the leaves became yellow, and in ol 
ays 
