=151. Method of Heinrich.=[106]—The soil to the depth turned by the plow is dug out and in the hole a lead vessel without bottom, twenty centimeters in diameter and forty centimeters high, is placed. The soil is then thrown back around and outside the lead vessel until the latter appears buried in the fragments. The rest of the soil is passed into the lead vessel, through a sieve having four meshes to the centimeter, using for this purpose enough water to thoroughly moisten it. Care should be taken not to use enough water to cause any separation of the fine from the coarse particles. By this process all coarse stones, sticks, etc., are separated. In sandy soils the flask is left for a few hours while in clay soils a much longer time is necessary. When the excess of water has disappeared the lead cylinder is removed, and a piece cut out of the center of it placed in a weighed drying flask and dried at 100°. =152. Effect of Pressure on Water Capacity.=[107]—The increasing capacity of soil to hold water developed by shaking or pressure, is determined by Henrici in the following way: Into a glass cylinder of twenty millimeters internal diameter are poured twenty cubic centimeters of water. A given quantity of soil is next added, and after standing until thoroughly saturated, the residual water is measured by pouring off, or better, by graduations on the side of the tube. The increase in the volume of the clear water is also measured, after shaking, in the same way. The data of a determination made as above described follow: Water in cylinder 30 cubic centimeters. Water and saturated soil 40 „ „ Volume of unsaturated soil = e = 10 „ „ Volume of saturated soil = e + w = 20.5 „ „ Water contained therein = w = 10.5 „ „ By repeated shaking the volume of e + w, the content of w therein, and the relative values of e/w were found to be as follows: Cubic Cubic Cubic Cubic centimeters. centimeters. centimeters. centimeters. e + w 20.5 16.0 15.7 15.0 w 10.5 6.0 5.7 5.0 ───────────────────────────────────────────────────────── w/e 1.05 0.60 0.57 0.50 If e′ represent the volume of the saturated soil then e′ = e + w, and this gives the relation to the volume of dry earth represented by the equation e′/e = 1 + w/e. This indicates that the relative volume of the saturated soil is equal to unity increased by the relative content of water.