251 
on tJie Air^ before the period of Maturity, 
changing the fruit, to the action of the sun for four days. This 
gaseous mixture consisted of, 
Before the experiment, 
Oxygen Gas, 
- 20.3.7 
Azote, - 
76.63 
Carbonic Acid, 
- 80.0 
1050.0 
Aft&r the exi^erimeiit, 
Oxygen Gfis, - 258 
Azote, - - 773 
Carbonic Acid, - - 21 
1052 
So that 59 parts of carbonic acid had disappeared during the 
experiment, and were replaced by 54.3 of oxygen gas. When 
a similar experiment was made without renewing the fruit, the 
oxygen gas was increased in 48 hours from 210 to 239 parts ; 
and the carbonic acid reduced, during the same period, from 50 
to less than 8 parts. 
Having obtained these results with peas, M. De Saussure next 
had recourse to a variety of plum (Heine Claude or green-gage), 
employed by M. Berard. This fruit was gathered when quite 
green, about five weeks before coming to maturity. When exposed 
to the solar rays in spring water, these plums produced oxygen 
gas, and diminished greatly the proportion of carbonic acid, but 
in a degree less than the pease, from the smaller extent of their 
surface. The leaves of this plum afforded similar results when 
placed in the same circumstances. In like manner, when con- 
fined in air through the night, this fruit destroyed its oxygen, 
and produced carbonic acid ; and, on the contrary, under expo- 
sure to the solar rays, it augmented the proportion of oxygen 
by decomposing the carbonic acid retained in its substance. 
Again, by alternate exposure in obscurity and sunshine, the to- 
tal changes in the air were inconsiderable ; and in an artificial 
atmosphere that contained ^^^th its bulk of carbonic acid, the 
whole of that acid, during four days exposure to the sun, en- 
tirely disappeared, and was in great part replaced by oxygen 
A month after the preceding experiments, others were made 
with the same variety of fruit, when within two or tliree days of 
its maturity. It had now nearly doubled its size, and being 
in this state eonfined, for twelve hours through the night, in a 
recipient of common air, it destroyed a portion of its oxygen, 
but less in quantity than at an earlier period of its growth. In 
sunshine also, during twelve hours exposure, it reduced, in a 
