PHYSICAL ANALYSES OF TYPICAL SOILS. ==============================+=====+=========================+====== | | Silt. |Sand, | +------------+------------+2.0 to |Clay.| Fine, | Coarse, |64 mm. | | <.25 to |.5 to 2. mm.|h. v. | |.5 mm. h. v.| h. v. | ------------------------------+-----+------------+------------+------ No. 233. Morano sandy soil | 2.82| 3.03 | 3.49 |89.25 No. 1197. Gila bottom soil | 3.21| 5.53 | 15.42 |72.05 No. 198. Ventura silty soil |15.02| 15.24 | 25.84 |45.41 No. 1697. Berkeley adobe soil |44.27| 25.35 | 13.47 |13.37 ------------------------------+-----+------------+------------+------ The most striking feature in this diagram is the very rapid[74] and high ascent in the combination of sediments represented by the Gila bottom soil. It outstrips at once both the sandy soil from Stanislaus, which contains a trifle less of clay, and the silt soil from Ventura, from which at first sight it does not seem to differ widely, but which contains considerably more clay. It is doubtless the latter which so greatly retards the motion of the water, as is still farther seen in the case of the clay or adobe soil. It will be noted that on the second and third days, the Gila soil had raised the water nearly twice as high as the adobe, and that it took only 18 hours to raise it nearly the same height as that attained by the Ventura silt in so many days. But it ceased to rise after the 125th day, while the Ventura soil, continuing for 195 days, finally rose 3 inches higher. The adobe also continued its rise, but did not reach the same height as the Gila soil by nearly two inches. There can be no doubt that the energetic and high rise of the latter proves an important factor in the culture of these lands. [74] The ascent is of course most rapid, in the large tubes almost instantaneous, when the capillary space is entirely clear; but in the complex system of connected air spaces in soils, the curved paths and the friction obstruct the movement. The coarse sandy soil reached its highest limit, 16½ inches, within six days, when the silty Gila soil stood at about double that height. [Illustration: FIG. 38.—Columns showing heights to which water will rise by capillarity in soils of different physical composition, and rates of ascent.] [Illustration: FIG. 39.—Capillary Rise of Water in Soil Sediments of different Diameters.]