=149. Accuracy of Results.=—A sample of soil from the beet sugar station, in Nebraska, gave the following duplicate results: First trial 45.75 per cent water. Second trial 44.85 „ „ „ Muck soils from Florida, containing varying proportions of sand, gave the following numbers: Soil number one, 144.85 per cent, and 145.43 per cent; soil number two, 109.13 per cent, and 107.93 per cent; soil number three (very sandy), 46.86 per cent, and 46.51 per cent. =150. Method of Wollny.=[105]—A zinc tube, ninety centimeters long and four centimeters internal diameter, carries at each end, at right angles to the axis, a flattened rim 1.5 centimeters broad. The lower end of the tube is closed with a strong piece of coarse linen. The soil to be examined is then filled in little by little, with gentle tamping. On the upper end two glass tubes are placed, each ten centimeters long and four centimeters internal diameter. These tubes are furnished at each end with cemented brass cylinders which are expanded to a circular, evenly ground rim, 1.5 centimeters wide, also at right angles to the axis of the main tube. These rims are greased and placed together, one on the other, and held together by wooden clamps. The glass tube in immediate connection with the zinc tube is also firmly filled with the soil sample, while the second tube is only partly filled, so that any settling which may take place in the soil on the addition of water may still find the first glass tube full of the sample. The empty part of the upper glass tube is now filled with water and additional quantities of water are added from time to time until the soil is saturated. In order to be able to observe when this takes place there is a slit at the lower end of the zinc tube which is closed with a piece of glass. This slit should be about two centimeters broad and ten centimeters long. The lower end of the zinc tube is set on a glass plate to prevent evaporation. As soon as the water shows itself at the lower end of the zinc tube, the excess of water in the upper glass tube is at once removed by a pipette and a stopper inserted through which a glass tube passes drawn out into a fine point above. The object of this is to avoid evaporation on the upper surface. The apparatus is then left at rest for thirty-six hours. At the end of this time the clamps are removed and the column of moist earth cut with a piece of platinum foil, and the two ends of the glass tube, next to the zinc tube, covered with glass plates. It is then weighed and the weight of moist earth determined by deducting the weight of the tube and its glass covers. The moist earth is carefully removed to a large porcelain dish and dried at 100°. Before weighing it is allowed to stand twenty-four hours in the air. The data obtained are used to calculate the water content to volume per cent. The volume of the glass tubes should be determined by careful calibration.