374 
McLean. — Field Studies of the Carbon 
Table II. 
The amounts of carbon dioxide withdrawn from the air by the barium 
hydroxide and the amounts of carbon dioxide absorbed by the sugar- 
cane half-leaf, each two hours during May 14, 1918. (Computed from 
data given in 
Table I.) 
CO 2 absorbed 
Computed C 0 2 
content of air at 
27 0 c. 
parts per 10,000. 
Diff. in concentra- 
tion of Ba(OH ) 2 
CO:, absorbed by 
Period. 
, from air per 
from test and blank 
leaf per sq. metre. 
hour. 
Pettenkofer in c.c. 
of acid. 
grms. 
5 - 30 - 7 - 3 ° a.m. 
0*0262 
3.90 
0*05 
0*029 
7.30- 9.30 „ 
0*0216 
3.21 
1.70 
0-992 
9.30-11.30 „ 
0.0205 
3.04 
1.65 
0*963 
11.30 a.m.-i.30 p.m. 
0*0210 
3 -i 3 
1*40 
0.8 17 
I ' 3 ° - 3 * 3 ° P-m. 
0*0199 
2.96 
1.50 
0.875 
3 - 30 - 5-30 „ 
0*0203 
3*02 
1.70 
0 * 93 ° 
5*30-6.30 „ 
0*0214 
3*!8 
*0*05 
0*027 
Total 13 hrs. 
4*633 
The march of the carbon dioxide absorption as shown by the apparatus, 
for a period of 13 hours of daylight, is presented graphically in Diagram 1, in 
Diagram i. Amounts of carbon dioxide absorbed per sq. m. during two-hour periods 
by a detached sugar-cane leaf on May 14, 1918. 
