arisen from the attraction of carbonic acid by the al- 
kaline fluid, and this carbonic acid must have been 
in part formed out of the oxygen gas of the atmos- 
phere ; for had it been formed by the plant, inde- 
pendently of the surrounding atmosphere, no dimi- 
nution of volume would have taken place. 
238. Several cuttings of willow were, likewise, 
placed in a large-mouthed bottle filled with water, 
and confined in about 85 cubic inches of atmosphe- 
ric air, from the 20th to the 24th of August. The 
. mouth of the inverted jar was surrounded by mer- 
cury, and it was set aside in day light, but not expo- 
sed to the direct rays of the sun. One hundred parts 
of this air lost five by agitation with lime water, and 
thirteen parts more, by the slow combustion of phos- 
phorus ; so that the three remaining parts, required 
to make up the ^^ f oxygen gas, which the air ori- 
ginally contained, must have been converted into car- 
bonic acid, which was in part attracted by the film 
of water that covered the mercury, and partly by the 
water though which it was passed when submitted to 
examination. 
239. The whole of the experiments which have 
been now detailed appear to us to establish, in a sa- 
tisfactory manner, the conclusions which, in our for- 
mer publication (32. 3. 4.), we ventured to draw ; 
for they prove that the oxygen gas of the atmosphere 
is converted into carbonic acid gas by the process of 
vegetation, and that the bulk of the latter gas nearly 
or exactly corresponds with that of the former; and, 
consequently, they demonstrate that the air is deterio- 
rated by the growth of plants, in the same manner 
