io6 
Journal of Agricultural Research 
Vol. 26, No. 3 
Table XVII.— Ph of suspensions and extracts of fuller's earth , also titrations and 
calcium content of extracts , and calcium adsorbed from Ca(OH) 2 
Calcium added. 
Suspension. 
Extract. 
Titer 0.05N 
HC 1 . 
Calcium in 
extract. 
Calcium not 
adsorbed. 
Calcium 
adsorbed. 
Mgm. 
Pr 
Ph 
Cc. 
Mgm. 
Mgm. 
Mgm. 
O. . . . 
4. 82 
6. 23 
— O. I 
4.4 
O. O 
O. O 
4 . 
7. 08 
7. 62 
. I 
5 - 2 
.8 
3-2 
8. 
7.76 
7.76 
. 2 
7. 0 
2. 6 
5*4 
12. 
8. 17 
7. 86 
. 2 
8. 0 
3-6 
8.4 
l6. 
8.37 
8. 00 
. 2 
8.2 
3-8 
12. 2 
20. 
8. 61 
8. 27 
•4 
8.8 
4.4 
15.6 
28. 
8. 91 
8.57 
.6 
9.6 
5-2 
22. 8 
36 . 
9.11 
9. 11 
1.8 
11. 1 
6.7 
29-3 
48 . 
9. 28 
9 - 3 i 
2-5 
11. 8 
7-4 
40. 6 
60. 
9.48 
9 - 45 
2.9 
12-3 
7-9 
52.1 
The P H values obtained on the water suspension and the water extract 
of fuller’s earth show that the hydrogen-ion concentration in both was 
greater than that obtained in an extract of soil, and, like the soil, that the 
hydrogen-ion concentration was greater in the suspension than in the 
extract. The acid-forming substance in fuller's earth was more soluble 
than it was in soil. This means a greater intensity of acidity in the 
former. The fuller’s earth had a comparatively large amount of calcium 
in the water extract, which makes it difficult to calculate calcium adsorp¬ 
tion except relatively. Since the ratio of the amount of calcium adsorbed 
to the amount added was as great with the largest as with the smallest 
quantity added, the adsorptive capacity was probably not reached. The 
adsorptive capacity of fuller’s earth for calcium was greater than that of 
Oswego silt loam. The titration figures show that a comparatively small 
amount of calcium was present in the extract as hydroxid or carbonate. 
Some may have been present as a silicate in colloidal form, some as the 
soluble compound formed with the acid-forming substance in fuller’s 
earth, and some as redissolved from the adsorption compound. 
The reactions of fuller’s earth with Ca(OH) 2 were found to be very 
similar to those of soil, except in degree. The acid-forming substance in 
fuller’s earth is probably an aluminum silicate, and by inference it might 
be concluded that the acid-forming substance in soil is of a similar nature. 
EXPERIMENT 18.—FULLER’S EARTH-f-CALCIUM HYDROXID+POTASSIUM CHLORID 
This experiment was conducted in the same manner as Experiment 17, 
except that KC 1 was also added. The data obtained are given in Table 
XVIII. 
Table XVIII.— Ph on suspensions and extracts of fuller's earth-\-Ca(OH) 2 -\-KCl, also 
titration and calcium content of extracts , and calcium adsorbed from Ca(OH) 2 
Calcium added. 
Suspension. 
Extract. 
Titer 0.05N 
HC 1 . 
Calcium in 
extract. 
Calcium not 
adsorbed. 
Calcium 
adsorbed. 
Mgm. 
p B 
Ph 
Cc. 
Mgm. 
Mgm. 
Mgm. 
O . 
5. 06 
5-43 
0. 00 
1.8 
O. 0 
O. O 
4. 
6. 68 
. 00 
6. 0 
A 2 
. O 
8. 
7 - 15 
7 - 25 
•15 
9.9 
*r * 
8. 1 
. O 
12. 
7. 66 
7. 62 
• 15 
I 3 - 5 
11. 7 
*3 
16. 
8. 06 
7. 90 
•25 
17.1 
15-3 
•7 
20. 
8. 27 
8. 06 
•35 
20. 5 
18. 7 
2-3 
28. 
8. 64 
8-34 
•65 
25-5 
23- 7 
4-3 
36. 
8. 94 
8. 67 
i *35 
29. 1 
27-3 
8.7 
48. 
9. 21 
9 - 15 
1. 65 
33 - 0 
31. 2 
16.8 
60. 
9 * 35 
9. 21 
2. 80 
35-8 
34 * 0 
26. 0 
