32 
BULLETIN 1311, U. S. DEPARTMENT OF AGRICULTURE 
and iron did not agree closely, but the determinations of lime and 
generally of magnesia showed good agreements. 
Table 9. — Solubility of tlw colloidal material in 1 per cent HC1 and 1 per 
cent NaOH 
Description of colloidal material 
Solubility in 1 per cent HC1 
Si0 2 
Ti0 2 
AI2O3 
Fe 2 3 
CaO 
MgO 
P 2 5 
<B 
» 
1 ® 
<B 

2* * 
ft 
73 ft 
■3 
ft 
ft 
B 
ft 
No 
Xame 
Color 
i °« i 
o § 
° X 
S 
a 
e 
r 
B 
*a « C3 
^O 
c3 
^C 
*»o 
!+»Oi ca 
TO 
OT _0 OT 
v,0 « 
OT 
OT 
v- « 
OT 
«_ tC OT 
o ' t» o 
85 © 
Z< 
O 
^fe 

'-'C 
O 
S3 

C Ph 
I-, -U 
!a 
U, 
Ph 
* i £ 
Ph 
Ph 
3-1. 
Ph 
Ph 
Ph 
H 
Ph 
Ph 
Per Per 
Per 
Per Per 
Per 
Per 
Per 
Per 
Per 
Per 
! Pe r 
Per 
Per 
cent cew 
cen 
cent cen' 
cen 
cent 
cen> 
cen' 
98 0. 6f 
.cen' cen 
cent 
3 
Cecil clay loam... 
Red 
4. 56 12. 6 
0.12 
19 6.80 
23.7 
8. 15 
48. 80. 50 
; 49 0. 18 
95 
6 ! Chester loam Brown 
4. 40 12. 6j . 20 
18 4.82 
17.2 
7. 16 
1.68 
45.0 
. 17 
100 
.45 
i 16 .28 
90 
11 Crowley silt loam Grayish brown 
3.11' 6.6!trace 
3.54 
12.9 
19.1 
.83 
84 
. 421 29 
.09 
64 
12 Dunkirk clay 
Yellowish olive 
5. 98 13. 8' trace 
.... 3.99 
14. 3|2. 49 
18.8 
.62 
98 
40: 17 
.27 
59 
loam. 
1 1 
20 i Lufkin clay 
Cream 
5. 98 10. 8 trace 
.... 3.99 
17.5 
2.49 
27.7 
1.56 
84 
.4( 
20 
.09 
100 
37 1 Stockton clay 
i | 
1 
adobe. Dark gray 
5. 88 12. trace 
.... 6.72 
31.2 
2. 22 16. 1 
1.39 
95 
1.0:- 
1 48 
.07 28 
Kaolinite suspen- 
. 76! 1. 6 trace 
.... .95 
2.3 
........ 
sion. 
Cecil clay loam.. 
Red 
1 1 
i 
1 
1 
Solubility in 1 per cent NaOH 
3 
15 39 
42.5 
14. 62 51. 1 
. 081 42 
6 
Chester loam... . 
Brown 
14. 45 
41.5 
14. 74 52. 8 
.18, 58 
11 
Crowley silt loam 
Dunkirk clay 
loam. 
Grayish brown 
Yellowish olive 
6. 11 
13.0. 
4.67 17.0 
1 
07 
50 
12 
3.70 
8.6, 
4.52 
16 *> 
.23 
50 
1 
?0 
Lufkin clay 
Stockton clay 
adobe. 
Cream ; 
Dark gray 
6.72 
4 40 
12.1 
9. 1 
4.05 
1.83 
17.8 
8 1 
.07 
77 
37 
.08 32 
1 
i 
Kaolinite suspen- 
5.01 
10.9 
2.30 
5.9 
1 
sion. 
1 
i 
1 
It may be seen from the table that neither the silica nor the 
alumina are completely soluble in the hydrochloric acid or the 
sodium hydroxide used. The NaOH solution dissolved considerably 
more Si0 2 and A1 2 3 from the Chester and Cecil colloids than from 
the others. A definite proportion of the colloidal matter is not dis- 
solved as such in either HC1 or NaOH, for the proportion of the 
total alumina dissolved is much greater than the proportion of the 
total silica dissolved. No definite ratio of silica to alumina has 
been dissolved, although the quantities of alumina and silica dis- 
solved from any one colloid are generally about the same. The un- 
dissolved residues of the different colloids are not constant in compo- 
sition, nor do they correspond to any definite compound of alumina 
and silica. In nearly every case the undissolved residue is consid- 
erably higher in silica than the untreated colloid. 
The kaolinite suspension was much less soluble than the soil col- 
loids in hydrochloric acid, but in sodium hydroxide it was about as 
soluble as four of the soil colloids. The silica and alumina were 
extracted by sodium hydroxide from the kaolinite in a ratio dif- 
ferent from the one in which they occur in the mineral. 
