APPARATUS TO SHOW CAPILLARY ATTRACTION OF SOILS FOR WATER. ] The observations may be discontinued after one hundred and twenty hours, but even then the water will not have reached its maximum height. It is recommended by some experimenters to cut the tubes, after the above determination is completed, into pieces ten centimeters in length, and to determine the per cent of water in each portion. =155. Statement of Results.=—The following table illustrates a convenient method of tabulating the observed data as given by König.[108] Number of sample 1 2 3 4 5 6 ─────────────────────────────────────────────────────────────────────── Height of 24 hours. 27.3 38.0 16.7 36.4 8.0 28.8 centimeters. moisture column after: „ 48 „ 35.9 50.8 24.5 49.2 11.9 40.5 „ „ 72 „ 41.5 59.5 30.0 57.9 15.2 49.1 „ „ 96 „ 44.4 66.2 33.5 63.8 17.5 55.2 „ „ 120 „ 46.7 70.0 36.3 68.5 19.2 60.5 „ =156. Inverse Capillarity.=—In tubes filled with fine earth, as described in paragraph =154=, water is quickly poured, the same quantity into each tube of the same diameter, or such quantities in tubes of different diameters as would form a water column of the same depth over the surface of the sample. The rate at which the water column descends in each tube, the time of the disappearance of the water at the surface and the final depth to which it reaches, are the data to be entered. =157. Statement of Results.=—The points to be observed in the determination of inverse capillarity are the number of hours required for the total absorption of a column of water of a given height, the depth of the moisture column at that moment, and the total depth to which the moisture column finally reaches. The data of observations with six samples with a water column four centimeters high are given by König[109] as follows: Number of sample 1 2 3 4 5 6 ───────────────────────────────────────────────────────────────────────── Number of hours required for water to disappear 4.3 1.8 10.3 3.0 21.0 4.3 Depth of moisture at time of disappearance of water 11.0 12.0 11.4 13.3 11.7 12.0 centimeters. Total depth of moisture 13.0 18.1 13.0 19.0 12.0 16.5 „ =158. Determination of the Coefficient of Evaporation.=—The coefficient of evaporation is the number of milligrams of water evaporated from a square centimeter of soil surface in a given unit of time. It is evident that this number will vary with the physical state of the soil, the velocity of the wind, the saturation of the air with aqueous vapor and the temperature. In all statements of analyses these factors should appear. The process may be carried on first (a) with soil samples kept continually saturated with water and (b) with samples in which the water is allowed to gradually dry out.