TO 
days of fine weather in the month of July. Ther 
plant, at this period, looked well and healthy ; the 
mercury had risen considerably into the jar ; and on 
examining the gas, there was a deficiency of 2.3 
of a inch. After removing all the carbonic 
acid by an alkaline solution, the remaining gas 
measured two cubic inches, and proved to be oxy- 
gen. This experiment he repeated t\vo or three 
times on different plants \\ ith similar results. 
30 f. That the oxygen, obtained in these experi- 
ments., did not proceed directly from thevegetable, Mr 
t)avy ascertained, by having, at the same time, kept 
another plant, in all circumstances exactly similar, in 
a jar of nitrogen gas. The diminution ef bulk in 
this gas did not exceed -?V of an inch ; and A more 
w^rn abstracted by the hydro-sulphuret of potassa, 
which he considered to be oxygen fof med from the 
decomposition of the water of the plant *. 
302. Mr Davy having thus ascertained the fact of 
the decomposition of carbonic acid, next made expe- 
riments to prove that plants, by their own powers, 
independently of the agency of light, were unable to 
effect this decomposition. He placed a small plant 
of clnroima cent annum in a jar of pure carbonic 
acid inverted in mercury, and then set it aside in a 
dark closet. At the end of four days, the air had 
diminished a little, and the plant looked sickly. The 
air was now examined ; and after the carbonic acid 
was removed, there remained only a small portion of 
an incombustible gas. 
* Beddoes' Contributions to Science, p. 16$. 
