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removed by a siphon, and water saturated with car- 
bonic acid gas supplied in its place ; so that it may 
be presumed that a small quantity of carbonic acid 
gas was constantly present in the receiver. On 
the 7th of July, 1807, the first day of the experi- 
ment, the weather was cloudy in the morning, but 
fine in the afternoon ; the thermometer at 67 , the 
barometer 30.2 : towards the evening of this day 
a slight increase of the gas was perceived : the 
next three days were bright ; but in the morning 
of the 1 1th the sky was clouded; a considerable 
increase of the volume of the gas was now ob- 
served : the 12th was cloudy, with gleams of sun- 
shine ; there was still an increase, but less than in 
the bright days : the 1 3th was bright. About 
nine o’clock A. M. on the 14th the receiver was 
quite full ; and considering the original quantity 
in the jar, it must have been increased by at least 
30 cubical inches of elastic fluid : at times during 
this day globules of gas escaped. At ten on the 
morning of the 15th, I examined a portion of the 
gas ; it contained less than of carbonic acid gas : 
100 parts of it exposed to the impregnated solu- 
tion left only 7 5 parts ; so that the air was four per 
cent, purer than the air of the atmosphere. 
I shall detail another similar experiment made 
with equally decisive results. A shoot from a vine, 
having three healthy leaves belonging to it, at- 
tached to its parent tree, was bent so as to be 
placed under the receiver which had been used in 
the last experiment ; the water confining the com- 
mon air was kept in the same manner impregnated 
with carbonic acid gas : the experiment was car- 
