XC. A laboratory investigation of electrosmosis in soils

A study has been made of the phenomenon known as electrosmosis in which, when an electric current is passed through a mass of wet soil, the soil is dried out around the anode and water is expelled from the cathode. The effect was investigated by means of a simple laboratory method in which a small electric current was passed through a cylindrical specimen of wet soil, the current density being kept low enough to eliminate appreciable errors due to Joule heating. Moisture movements were found to be greater in sandy than in clay soils. For a given soil the amount of water expelled at the cathode was proportional to the quantity of electricity passed through the specimen, up to the point when the soil at the anode became too dry to act as a conductor. On the assumption that the moisture movement is due to ions carrying water molecules from the anode to the cathode, calculations showed in the case of one of the soils that the number of water molecules transported per ion was 88.