Oct. 16, 1916 
Acidity and Adsorption in Soils 
129 
EFFECT OF GRINDING SOILS ON THE HYDROGEN-ION CONCENTRA¬ 
TION OF THEIR SUSPENSIONS. 
The determination of the lime requirement of soils by the usual 
methods depends upon several factors. Among these factors the fine¬ 
ness of division has recently received some attention. Cook (9) found 
that in certain soils the lime requirement by the Veitch method in¬ 
creased with grinding, while Brown and Johnson (4) obtained opposite 
results working with another group of soils. Several of the soils already 
described were ground to pass a 200-mesh sieve. Table III shows the 
H-ion concentration of suspensions made from the ground soil. 
Table III -Hydrogen-ion concentrations in suspensions of soil ground to pass through 
a 200-mesh sieve 
Soil No. 
Quantity 
of soil. 
Water. 
Readings on 
voltmeter. 
H-ion concentra¬ 
tion (gram mole¬ 
cules per liter). 
Gm. 
C. c. 
IS . 
0. 01 
So 
O. 629 
0.8X10- 5 
IS . 
. IO 
50 
. 6x7 
.1X10- 4 
IS . 
■ 50 
So 
• 632 
. 7Xio~ 3 
IS- . 
I. O 
So 
612 
.2X10- 4 
IS . 
2. O 
So • 
“• 593 
.4X10- 4 
IS . 
5 * 0 
50 
a. 560 
.1X10- 3 
IS . 
10. 0 
50 
• 577 
. 7X10- 4 
I. 0 
So 
a * 653 
• 3X10- 5 
50 
50 
. 625 
1. 0X10- 5 
17 . 
. ox 
So 
a . 615 
. iXio -4 
17 . 
I. 0 
50 
. 624 
.iXio" 4 
17 . 
5 -o 
50 
S 97 
• 3X10 4 
20. 
2. 0 
so 
a . 623 
. 1X10 -4 
TQ.. 
1. 0 
30 
. 646 
. 4 Xio -i5 
IQ. 
2. 0 
0 
qo 
a . 634 
. 7 Xio~ 5 
* 5 
ij 
So 
• 750 
. 7Xio“ 7 
18. 
2. 0 
50 
• 748 
. 7Xio“ 7 
18. 
5 - 0 
50 
. 762 
.4X10 7 
a Average of several determinations. 
By comparing Table III with Table II it will be seen that with the 
exception of soil 18 grinding did not materially alter the H-ion con¬ 
centration of the soil suspensions. These remarks bear no reference to 
the lime requirement, which will be discussed later, but apply only to 
intensity of acidity. Apparently the anomalous behavior of soil 18 
may be explained on the supposition that the interior cores of the soil 
particles are of a different composition from the exterior, partially 
weathered layers. This hypothesis may also account for the findings of 
Brown and Johnson (4)*. 
The data of Table III also corroborate in the main those presented 
in Table II in reference to the slight fluctuations in H-ion concentra¬ 
tion due to varying the proportion of soil to water. 
