Dec. x8,19x6 
Assimilation of Iron by Rice 
5ii 
To two lots of solutions carbon black was added at the rate of 0.0432 gm. 
per liter. This is about double the weight of the precipitate in the 
ordinary neutral solution with 0.008 gm. of iron per liter from ferrous 
sulphate. Two other solutions were made up using distilled water that 
had previously been treated with 0.086 gm. of carbon black per liter and 
then filtered. The neutral nutrient solution was used in all sets, and 
ferrous sulphate was the source of the iron. Two plants were grown in 
each flask, six flasks were taken as a unit, and the units duplicated for 
each treatment. The results of the test are given in Table V. 
Table V .—Comparative weights of rice plants grown in neutral nutrient solution with 
iron from ferrous sulphate and also with distilled water treated with carbon block 
Kind of distilled 'water used in 
nutrient solution. 
Ordinary distilled wdter. .. 
Do. 
Ordinary distilled water + 
carbon black. 
Do. 
Do. 
Do.: 
& 
|. 
« Ih' 
O 4 > 
*3 
Gm, 
+0. 002 
+ • 008 
+ . 002 
-f“ . 008 
4 - • 002 
-j- • 008 
£ 
’ll 
ft 
Green weight of 
stalks and leaves. 
Oven-dry weight of 
stalks and leaves. 
0 
f . 
f- 
J 
Average oven- 
dry weight of— 
Stalks and 
leaves. 
0 
4 
w 
Gm, 
Gm. 
Gm. 
Gm. 
Gm. 
f 1—6 
62. 19 
8. 27 
1. 86 
{ 7-“ 
65.07 
t 
8.48 
1. 92 
8. 38 
10. 27 
/ 13-18 
128.62 
16.31 
3- 73 
\ 19-24 
137- 5 ° 
16- 73 
4. 01 
16. 52 
20.39 
{23-3° 
58. 56 
7- 65 
1. 69 
131-36 
57- 01 
7-55 
1. 71 
7. 60 
9-30 
{37-42 
139. 40 
17- 54 
3- 54 
143-48 
127. 70 
I 5 - 9 I 
3- 47 
16.73' 
20. 24 
{49-54 
88. 20 
II. 10 
2, 56 
Iss— 60 
88. 10 
10. 97 
2.49 
11. 04 
13- 57 
{61-66 
148.53 
18. 49 
4*42 
167-72 
147- 87 
18. 62 
4- 65 
18. 56 
23. IO 
During growth lots with 0.002 gm. of iron per liter were of a slightly 
poorer color than lots with 0.008 gm., but no differences in color were 
apparent between the lots with different distilled waters or with carbon 
black. 
It is evident that the addition of carbon black to the nutrient solutions 
with 0.002 gm. of iron slightly depressed rather than increased the yield 
while carbon in the solution with 0.008 gm. of iron had no effect on the 
yield. Treating the distilled water with carbon and then filtering in¬ 
creased the yield in the solution with 0.002 gm. of iron by 32 per cent and 
in the solution with 0.008 gm. by 12 per cent. 
Previously treating the distilled water with carbon increased the growth 
less in the solution with 0.008 gm. of iron than in the solution with 0.002 
gm., possibly because the formation of the larger flocculent precipitate 
of iron in the former solution acted similarly to carbon in removing injuri¬ 
ous substances from the distilled water. Probably the adsorption of the 
other salts prevented the carbon when added directly to the nutrient 
