Jan. s, 1924 
Physiological Studies on Apples in Storage 
25 
method of estimating co 2 output and o 2 intake 
Most of the work in which both 0 2 absorption and C 0 2 output have 
been studied has been carried out by placing fruit in closed chambers, 
and analyzing the included atmosphere for 0 2 and C 0 2 at the end of a 
certain interval. This results in the fruit being exposed to an atmosphere 
higher in C0 2 pressure and lower in 0 2 pressure than the air. The 
work of Kidd and West ( 14 ), as well as investigations reported here, 
has demonstrated the importance of C 0 2 and 0 2 concentrations in the 
ripening of apples. 
In order to determine both C 0 2 given off and 0 2 absorbed without 
exposing the fruit to varying concentrations of these two gases, the 
apparatus shown in Figure 14 was used. A large bottle containing a 
water reserve (A) is connected by a double siphon feed of glass tubing 
to a second bottle (B). The siphon feed maintains a constant water 
Fig. 14.-—Apparatus for determining the amount of CO2 given off and the amount of O2 absorbed by the 
fruit. 
level in bottle B. Bottle B has a tubulature at the bottom, by which it 
is connected, through rubber and glass tubing, to a third bottle, C. 
Bottle C is full of pure 0 2 , being filled by displacement of water. A 
second tube from bottle C is connected into the closed desiccator D 
which contains the fruit. In the bottom of the desiccator D is placed a 
wide beaker containing KOH, a solution approximately twice normal 
being used. 
As the fruit respires 0 2 is absorbed by it and C 0 2 is given off. The 
C 0 2 given off in the desiccator D is absorbed in the KOH solution in 
the bottom of the desiccator; a negative pressure consequently develops 
in the desiccator, due to loss of 0 2 . As a result pure 0 2 passes over 
from C, and the loss in 0 2 in bottle C is replaced by water which flows 
from bottle B. It is important that the height of the water level in B 
be so adjusted that it will be just level with the end of the connection 
