56 
TRANSACTIONS OF THE TEXAS ACADEMY OF SCIENCE. 
49* 
Insoluble matter. 88.177 
Soluble silica. 2.151 
Potash.298 
Soda.081 
Lime.413 
Magnesia.343 
Manganese.040 
Iron. 2.076 
Alumina. 2.508 
Phosphoric acid.094 
Sulphuric acid.020 
Water and organic. 2.735 
* Cotton Production. Tenth Census, p. 45. 
9S.936 
The character of the soils of the different rivers in their course across 
the Black Prairies is given in the analyses below. 
No. 51 is from the first bottom of Red River, Indian Territory, oppo¬ 
site Lamar county. No. 52 is from the Trinity, two miles west of Dallas. 
No. 53 is from the Colorado bottom, four miles east of Austin, and by 
its percentage of lime shows the influence of the soft limestones of the 
Cretaceous just north of it. 
50* § 
51* 
52* 
Insoluble matter. 
68.050 
36.065 
62.306 
Soluble silica. 
9.863 
16.553 
10.357 
Potash. 
.345 
.509 
.591 
Soda. 
.066 
.225 
.118 
Lime. 
1.116 
16.344 
7.793 
Magnesia. 
1.217 
1.602 
1.379 
Manganese. 
.126 
.054 
.126 
Iron . 
5.274 
3.857 
2.934 
Alumina . 
8.367 
5.205 
3.288 
Phosphoric acid... 
.209 
.152 
.207 
Sulphuric acid. 
.030 
.158 
.033 
Carbonic acid. 
.952 
12.008 
5.075 
Water and organic. 
4.906 
6.270 
5.028 
100.521 
99.002 
99.225 
* Cotton Production, Tenth Census, pp. 43, 44, 47. 
The analysis No. 53 is a red loam soil from the Brazos bottom four 
miles west of Hearne, and No. 54 is a valley loam from the Colorado at 
Bastrop. 
