Surface Forces of Soils within the Range of Hygroscopic Moisture

1. Various soils are shown to hold moisture when at their hygroscopic coefficient with a force uniformly equivalent to about 25 atmospheres, as measured by the seed-soil equilibrium method of Shull. 2. For at least the two loam soils investigated, the surface soil forces within the range of hygroscopic moisture are shown to be constant for any given soil moisture content, expressed as percentage of the maximum hygroscopic moisture capacity of the soil, that is, to be functions of the hygroscopic coefficient. 3. Sand does not follow the same laws in regard to moisture holding forces as do soils. 4. The curve for soil forces given previously is shown to indicate too high values for the force with which water is retained through that portion of the hygroscopic moisture range near saturation with water vapor.