experiments. For this purpose the glass tubes were filled with 100 
grams of soil, covered with distilled water, and each 100 cubic centi- 
meters of filtrate analyzed. 
Phosphoric acid removed from the soils by distilled water. 
[Expressed in parts per million of PO< in the percolate.] 
Percolates of 
100 cc. each. 
Soil No. 
292. 
Soil No. 
448. 
SoU No. 
428. 
SoU No. 
474. 
Percolates of Soil No. 
100 cc. each. 292. 
Soil No. 
448. 
Soil No. 
428. 
Soil No. 
474. 
100 
6.4 
3.2 
3.8 
4.4 
3.8 
4.4 
500 5.6 
600 11.2 
700 12.0 
800 10.8 
2.8 
2.0 
2.0 
3.6 
4.6 
4.4 
6.0 
20.0 
7.0 
200 
10.8 
300 
8.8 
3.8 
5.2 
400... 
3.2 
5.0 
11.2 
The general tendency of these soils is to yield a solution of fairly 
constant concentration. This is in direct harmony with what should 
be expected, namely that the phosphoric acid is so firmly retained 
by Hawaiian soils that the first leachings should not yield a more 
concentrated solution than those following. 
The following table shows the absorbing power of the soil for phos- 
phoric acid in monopotassium phosphate (KH 2 P0 4 ) : 
Absorption of phosphoric acid from a solution of monopotassium phosphate (KH 2 P0 4 ). 
[Expressed in parts per mUlion of PO* in the percolate.] 
SOLUTION CONTAINED 175 PARTS PER MILLION PO,. 
Percolates of SoU No. 
100 cc. each. 292. 
Soil No. 
448. 
Soil No. 
428. 
Soil No. 
474. 
Percolates of 
100 cc. each. 
Soil No. Soil No. Soil No. 
292. 448. ; 428. 
Soil No. 
474. 
100 45.6 13.6 11.2 17.2 '. 2,100 
200 35.2 29.0 13.2 40.0 2,200 
300 52.0 10.4 17.2 44.0 2,300 
400 38.0 13.6 i 34.0 49.0 2,400 , 
500 39.0 9.6 19.4 36.0 2,500 
600T 48.0 11.2 15.6 I 39.0 2,600 
700 57.0 15.6 16.8 I 42.0 2,700 
800 ! 27.0 36.0 36.0 55.0 2,800 
900 20.0 5.8 20.8 35.6 2,900 
1,000 17.8 5.8 27.8 41.6 i 3,000 
1,100 1 71.2 5.2 12.0 24.8 3,100 
1,200 ! 37.2 6.8 13.2 40.0 3,200 
1,300 1 72.0 6.4 I 14.0 34.4 j 3,300 
1,400 , 60.0 10.0 i 16.8 20.8 3,400 
1,500 ' 76.0 .7.2 I 12.0 52.0 3,600 
1,600 72.0 5.6 | 11.6 56.0 3,800 
1,700 i 42.0 13.6 j 12.0 24.0 4,000 
1,800 64.0 9.6 8.0 20.0 4,200 
1,900 ! 66.4 4.4 | 4.4 18.0 4,400 
2,000 54.4 4.0 4.0 14.8 
SOLUTION CONTAINED 140 PARTS PER MILLION P0 4 . 
I j j j j 
4,600 40.0 6.0 7.6 24.0 5,000 34.4 I 4.0 
4,800 24.8 6.8 8.4 23.2 
62.8 
4.0 
5.2 
60.0 
5.2 
4.8 
60.0 
4.0 
4.0 
66.4 
5.6 
6.0 
62.8 
4.8 
4.8 
56.0 
4.8 
4.8 
44.0 
4.0 
4.8 
28.8 
4.0 
4.8 
31.2 
3.6 
4.0 
39.2 
4.4 
4.4 
21.6 
4.0 
4.0 
6.8 
5.6 
5.6 
33.6 
5.6 
5.6 
25.6 
10.0 
29.6 
20.8 
8.0 
8.8 
46.6 
10.0 
9.6 
29.6 
4.4 
6.4 
46.4 
5.2 
12.4 
34.4 
4.8 
8.0 
25.6 
38.4 
22.4 
22.4 
31.2 
16.8 
32.0 
28.8 
35.2 
32.0 
24.0 
26.4 
44.0 
36.8 
29.6 
31.2 
34.4 
48.0 
48.0 
4.0 
24.0 
Summary of above table. 
SoU No. 
PO, 
added to 
100 gm. 
soU. 
PO< 
fixed by 
100 gm. 
soU. 
Per cent 
ofP0 4 
fixed. 
292 
Gram. 
0.8540 
.8540 
.8540 
.8540 
Gram. 
0.6872 
.8146 
.7977 
.6882 
80.6 
448 
95.5 
428 
93.3 
474 
80.7 
