126 
Journal of Agricultural Research 
Vol. VII, No. 3 
the views of Cameron (5) concerning soil acidity, that it is generally due 
to the selective absorption of bases. They also are in opposition to the 
recent conclusions of Rice (26) and Harris (15), that water-soluble 
acids are not characteristic of acid soils. 
Table II. — Hydrogen-ion concentrations of suspensions oj unground soil 
Soil No. 
Quantity 
of soil. 
Water. 
Readings on 
voltmeter. 
H-ion concentra¬ 
tion (gram-mole¬ 
cules per liter). 
Gm. 
C. c. 
I. 
2. O 
30 
0.763 
O. 4Xio“ 7 
2. 
2. O 
3 ° 
• 7 S 3 
. 6 Xio“ 7 
3 . 
2. O 
30 
• 759 
. 5X10- 7 
4 . 
2. O 
30 
• 763 
. 4X10 -7 
5 . 
2. O 
30 
• 759 
.5X10- 7 
2. O 
30 
• 753 
. 6X10 -7 
7 . 
2. O 
30 
. 761 
. 5X10- 7 
8. 
2. O 
30 
• 7 S 2 
. 6X10 7 
2. O 
30 
* 752 
. 6Xio“ 7 
2. 0 
30 
. 742 
. 9Xio“ 7 
2. O 
30 
. 760 
• SXio- 7 
2. O 
30 
• 77 ° 
.3 Xio~ 7 
2. O 
30 
• 550 
. 2X10 -3 
2. O 
30 
• 753 
. 6Xio~ 7 
2. O 
50 . 
a. 590 
.4X10- 4 
15 . 
* 5-0 
30 
• 565 
. 1Xio“ 3 
. I 
50 
. 627 
.9X10- 5 
2. O 
50 
a . 648 
.4X10- 5 
S-o 
50 
. 642 
• 5X10-* 
10. 0 
50 
.623 
. 1X10- 4 
15.0 
30 
.628 
.9X10- 5 
17 *. 
. 1 
50 
. 619 
. 1X10- 4 
17 .. 
2. 0 
50 
a. 605 
■ 2XlO~* 
17 . 
5 -o 
5 ° 
• 59 6 
• 3XIO- 4 
10. 0 
50 
. 582 
• SXlO- 4 
i 7 -. 
25.0 
50 
. 582 
.5XIO- 4 
18. 
2. 0 
50 
. 704 
.4X10^ 
18. 
7 5 -o 
50 
. 710 
•3XIO- 4 
*9 .. 
2. 0 
SO 
. 638 
.6XIO- 5 
. 1 
50 
.638 
. 6XIO” 6 
2. 0 
So 
a. 630 
.8XIO- 5 
S-o 
50 
• 633 
. 7X10- 5 
10. 0 
50 
.628 
.9X10-* 
i 5 -o 
30 
• 633 
• 7XlO- 4 
5 -o 
100 
.605 
• 2XIO- 4 
2. 0 
5 ° 
. 605 
. 2XlO~' 4 
23. 
5-o 
50 
• 87s 
• SXio-» 
5-o 
50 
.898 
.2X10—« 
a Average of several determinations. 
It is also evident from the data presented in Table II that there is a 
considerable range in the H-ion concentration of the soil suspensions. 
A number of soils known to be fertile show strikingly similar reactions, 
slightly alkaline, as indicated by an H-ion concentration of slightly less 
than 1 X io“ 7 . Alkali soils, presumably containing sodium carbonate, 
show alkalinity corresponding to an H-ion concentration of 0.2 X io -9 . 
