_Elutriation of Clayey Soils._—Hilgard found that by churn elutriation no satisfactory results could be obtained on clay without long boiling and subsequent kneading of the finer sediments. Osborne examined a sample of clay by his method after previous boiling for twenty-three hours. When the sediments were examined by the microscope they were found to contain many aggregations of particles which broke into dust under the pressure of the thin glass slide-cover. These sediments were then gently crushed in the beaker with the help of a soft rubber stopper with a glass rod for a handle, the grinding together of the particles being, as much as possible, avoided. This pestling was continued with clear water as long as it occasioned turbidity. Comparison of the analyses shows that practically identical results were obtained on this soil whether it was boiled or not and indicates that the sediments are reduced to their elements by gentle pestling alone. For such soils, therefore, it is demonstrated that pestling is a much safer treatment than boiling. The same remark may be applied to the fertile prairie soil of Mercer County, Illinois, where boiling proved quite insufficient and in which the pestling process proved completely successful. The general conclusions arrived at from the results obtained by Osborne are as follows: 1. On sands and silts of pure quartz or similar resistant material Hilgard’s method and beaker elutriation give practically identical results. 2. With coarse sands and silts upon whose grains finer matter has been cemented by silicates, etc., and with soils containing soft slaty detritus, the churn elutriator with preliminary boiling may give results too low for the coarse and too high for the finer grades. In these cases beaker elutriation with pestling yields more correct figures. 3. Some loamy soils containing no large amount of clay or of extremely fine silt, as well as prairie soils rich in humus, cannot be suitably disintegrated by twenty-four hours’ boiling, but are readily reduced by pestling. 4. Beaker elutriation preceded by sifting, gives results in five or six hours with use of two to three gallons of pure water, which, in churn elutriation, require several days and consume eight to ten gallons of pure water. 5. Hilgard found that practically 0.25 millimeter is about the lowest velocity of water current per second available within reasonable limits of time in his elutriator. Such a current carries over particles up to 0.015 millimeter diameter and hence the silts of less dimensions cannot be conveniently separated by churn elutriation. In beaker elutriation there is no difficulty in making good separations at 0.01 millimeter and at 0.005 millimeter.