1822.] Scientific Intelligence. 155 
gas, part of which they absorb ; this absorption is generally less in the 
n air than under a receiver. 
In the dark they absorb more oxygen, when green, than when they 
are becoming ripe. During their exposure to the sun, they extricate, 
either wholly or partially, the oxygen of the carbonic acid they absorb 
during the night, and leave no trace of this acid in their atmosphere. 
Several fruits, detached from the plant, thus add oxygen gas to air 
which contained no carbonic acid. When their vegetation is very 
feeble or languid, they corrupt the air under all circumstances, but 
less in the sun than in darkness. 
Green fruits detached from the plant, and exposed to the succes- 
sive action of night and the sun, alter the air but little either in purity 
or volume; the slight variations observable in this respect depend 
either upon their greater or less power of forming carbonic acid, or 
upon their composition, which is modified by the degree of their matu- 
rity ; thus green grapes appear to assimilate a small quantity of the oxy- 
gen of the carbonic acid which they form in the air that they vegetate 
in night and day ; while grapes which are nearly ripe, exhibit in their 
atmosphere entirely during the day, the oxygen of the acid which they 
produced in darkness. If there be no mistake in this result, which was 
‘not strongly marked, but constant in all my experiments, it denotes the 
passage from the acid to the sweet state, indicating that the acidity of 
green fruits tends to fix the oxygen gas of the atmosphere, and that 
this acidity disappears when the fruit imbibes only carbon from the air 
or carbonic acid. 
Green fruits decompose, either totally or in part, not enly the car- 
bonic acid which they have produced during the night, but also that 
which is artificially added to their atmosphere. When the latter expe- 
riment is made with watery fruits, and which, such as apples and 
grapes, evolve the acid gas slowly; they are observed to absorb* in 
the sun, a much greater portion of gas than an equal quantity of water 
would do in a similar mixture. They afterwards disengage the oxy- 
gen of the absorbed acid, and thus appear to form it in their interior. 
Their power of decomposing carbonic acid becomes weaker as they 
ripen. 
apesind vegetation, they absorb the oxygen and hydrogen of water, 
depriving it of its fluid form. These results are frequently unobserv- 
able, excepting when the volume of air exceeds that of the fruit 30 or 
40 times, and the heating action of the sun is much weakened: if these 
precautions be neglected, several fruits corrupt the air, even in the 
sun, by forming carbonic acid with the surrounding oxygen; but still, 
in the latter case, the mere comparison of their effect in the dark, with 
that which they produce under the successive influence of night and of 
the sun, shows that they decompose carbonic acid. 
The differences of M. Berard’s results and mine are principally 
derived from the circumstance of his having enclosed the fruits in a 
space not exceeding six or eight times their volume, which was too 
small, to prevent their suffering from the proximity or contact of the 
sides of the receiver heated by the sun. Some succulent plants resist 
this trial, and my results with the cactus, may have induced this che- 
* In the sun, the absorption in a mixture of | part of carbonic acid and 20 parts of 
air is equal to about two-thirds of the yolume of hese fruits. 
