=147. Method of A. Mayer.=[104]—A glass tube, one and seven-tenths centimeters in diameter, composed of two pieces, seventy-five centimeters and twenty-five centimeters in length, is united by a piece of rubber tubing. The lower free end of the seventy-five centimeter piece is closed with a piece of linen. The tube is filled, with gentle jolting, to the depth of one meter with fine earth, the earth column thus extending twenty-five centimeters above the point of union of the two pieces. Thus prepared, a quantity of water is poured into the upper tube sufficient to temporarily saturate the whole of the soil. During the sinking of the water in the tube there is thus effected a moistening of the material before it is wholly filled with water. After waiting until the water poured on top has disappeared the tube is separated at the rubber tube connection and a sample of the moist soil taken at that point. This is at once weighed and then dried at 100°. The loss in weight gives the water absorbed. The number thus obtained is calculated to the standard by volume, by use of the number representing the apparent specific gravity of the fine earth. For sand of different degrees of fineness the following numbers were found: Degree of fineness 2 3 4 Per cent water absorbed 7.0 13.7 44.6 The numbers thus obtained are taken to represent the absolute water capacity of a mineral substance in powder. The full water capacity, _i. e._, the power of holding water when the powder is immersed in water, the excess of which is then allowed to flow away is much greater than the absolute number. This difference is shown in the following data: Quartz, size three. Clay, size three. Full water capacity 49.0 per cent 46.8 per cent Absolute water capacity 13.7 „ „ 24.5 „ „ In general the absolute is markedly inferior to the full water capacity. Only in the finest dust do the two numbers approach each other. =148. Volumetric Determination.=—A convenient apparatus for this determination has been devised by Mr. J. L. Fuelling, of the Chemical Division, Department of Agriculture. It is shown in Fig. 18. It consists of an ordinary percolator the diameter of which decreases slightly towards the lower end, a thick-wall rubber tube and an ordinary burette, divided in tenths. A rubber stopper is fitted to the mouth of the percolator and perforated twice—in the middle and at the side, the former for a small tube provided with pinch-cock and the latter for the neck of a small funnel. The whole is supported on a convenient stand, the clamp holding the percolator being placed above that supporting the burette, both clamps arranged to slide on the stand-rod. [Illustration: FIGURE 18. FUELLING’S APPARATUS. ] The method is as follows: