50 M. De Saiissiirc (m the Influence of Green Fruits 
night, the air sufferecl a sliglit diminution of volume, lost about 
Jth of its oxygen, and acquired a considerable portion of car- 
bonic acid. 
The experiment was next varied by placing the same quan- 
tity of peas in nearly an equal volume of atmospheric air, and 
inverting the vessel over water. The vase was then exposed to 
the direct action of the solar rays, moderated by being passed 
dirough a window. As a single day was not sufficient to afford 
a decisive result, the vegetables were withdrawn in the evening 
through the water, and replaced, on the following morning, by 
others recently gathered. These operations were repeated for 
four days on the same air, to guard against any change occur- 
ring in the fruit, and also against leaving it in the air when the 
sun had withdrawn. On the evening of the fourth day, after 
forty-eight hours exposure of the vessel to the sun, the bulk of 
-air was somewhat increased by an addition chiefly of oxygen 
gas and a little azote, without any trace of carbonic acid. 
Before the expei-iment, the air was com- 
posed of Oxygen, - 207.9 
Azote, - 782.1 
Ccirbonic Acid, - 0.0 
After the experiment, 
Oxygen, - - - 223.97 
Azote, - _ - 789,53 
Carbenic Acid, - - 0.0 
The 'addition of oxygen is to be ascribed to the carbonic acid 
existing in t!ie iVuits, and with them transported and decom- 
posed in the vessel. 
Thus then the green fruit of peas converts the oxygen of the' 
air into carbonic acid during the night; and, when exposed to 
the solar rays during, the day, it reconverts this acid into oxygen 
.gas. , ^ 
M. De Saussure also found, that if these lx)dies were placed 
alternately in sunshine and in obscurity for two entire days and 
nights, the air in the recipient then underwent successive chan- 
ges, which nearly counterbalance each other ; so that, at the 
close of ihe experiment, it had suffered no other degree of 
change than might Ibe attributed to errors of observation. 
Still farther to evince the decomposition of carbonic acid by 
green fruits, he next placed a similar quantity of peas in an 
^artificial gaseous mixture, composed of atmospheric air and car- 
fbonic acid, and expr)sed them, with the same precautions, of 
