IOO 
Journal of Agricultural Research 
Vol. 26, No. 3 
Table X.—P b on suspensions and extracts of soil + oxalic acid; also titrations and cal- 
cium content of the extracts 
H2C201 
added. 
Oswego silt loam. 
Bates very fine sandy loam. 
Bates loam. 
0.04N per 10 
gm. soil. 
0 
> 
"3 
cr 
0) 
6 
i 
w 
1 
3 
to 
0 
2 
-M 
w 
si 
0 
nJ 
& 
O 
6 
s| 
3 £ 
<s 
0 
c 
0 
1 
cn 
3 
to 
ts 
2 
$ 
W 
0 
CC 
£ 
>0 
0 
d 
! « 
oS 
O 
j 
8 
a 
3 
to 
0 
2 
+4 
X 
w 
W 
O 
cs 
£ 
% 
0 
d 
it 
OJ 
0 
Cc. 
3. 12 
3.25 
I2 * 5 
25.0 
50. 0 
Mgm. 
2. 5 
5 -o 
10. 0 
20. 0 
40. 0 
Ph. 
4 - 95 
5 - 43 
7. 22 
5 - 46 
3.86 
Pn. 
5. 80 
7 - 83 
7 - 83 
4- 07 
2. 42 
Cc. 
5 
2.9 
7-3 
12. 6 
31.0 
Mgm. 
0.8 
1. 2 
2. I 
3 - 2 
4 - 9 
Pn- 
5 - 39 
Pn. 
8. 00 
7 . 93 
8. 27 
3. 20 
2. 55 
Cc. 
i. 8 
4. 1 
8. 1 
17. 0 
35-9 
Mgm. 
O. 7 
• 7 
1. 1 
i- 7 
2. 1 
Ph- 
7. 95 
8. 13 
8. 27 
7. 42 
5 - 73 
Ph- 
8- 37 
8. 03 
8. 00 
7. 90 
3. 30 
Cc. 
O. 4 
1. 6 
2. 4 
8. 1 
21. 8 
Mgm 
3.6 
3-4 
3-4 
4.6 
6.8 
5. 80 
3 - 76 
2. 48 
The increase in the hydroxyl-ion concentration with the smaller 
amounts of oxalic acid can be accounted for by the fact that a salt of 
a weak acid and a strong base has an alkaline reaction in a water solution. 
1 his is due to the formation of the highly ionized hydroxid of the base 
and the feebly ionized acid. The hydrogen ions and the hydroxyl ions 
come from the water. When oxalic acid is added to soil, oxalates are 
ormed. If the quantity added to soil is small these oxalates are in 
excess, and there are more hydroxvl-ions than hydrogen ions. When 
larger amounts of oxalic acid are added the reverse condition occurs, 
lne initial reaction and the calcium content of the soil appear to de¬ 
termine the amount of oxalic acid required to produce an excess of 
hydrogen ions. With Bates loam, a neutral soil with a relative higher cal¬ 
cium content, the excess of the hydroxyl ions persists for a larger amount 
of oxalic acid than is the case with the other two soils. 
* s added to the extract a part is used in basic exchange 
with the oxalates and part to neutralize the free oxalic acid. Bates 
loam neutralized a larger portion of oxalic acid than the other two soils. 
1 i/u r S mo , re calc . ium » an d therefore more insoluble calcium oxalate 
could be formed. This would appear to indicate that the quantity of 
an organic acid, such as oxalic, which a soil is able to neutralize is a 
measure of the potential alkalinity. 
The effect of oxalic acid on soil, as shown in this experiment, explains a 
facf well known to agriculturists, namely, that barnyard manure reduces 
the acid condition of the soil. The acids which result from the decay 
of organic matter combine with the bases of the soil, forming salts of 
weak acids and strong bases. The effect of adding organic acids to soil 
deserves further study, particularly those which form soluble com¬ 
pounds, such as acetic acid. 
GROUP B.—-INFLUENCE OF CALCIUM HYDROXID AND POTASSIUM CHLORID 
ON THE P H WHEN USED ON WASHED SOIL, IGNITED SOIL, ACID-TREATED 
SOIL, AND ACID-TREATED SAND, ALSO ON THE TITRATION AND CALCIUM 
CONTENT OF THE EXTRACT 
EXPERIMENT II.—WASHED SOIL + CALCIUM HYDROXID 
In this experiment Ca(OH) 2 was added to washed soil in the same 
manner as m Experiment 5. In washing, part of the colloidal clay was 
removed. The method of washing was as follows: One kgm. of soil was 
