An equation was derived relating the partial specific volume of water in a clay suspension to the clay concentration and the suspension density. By means of this equation and the observed suspension densities at different clay concentrations, the partial specific volume of water was determined to be the same as that of pure water in Li‐, Na‐, and K‐clay suspensions at concentrations up to 0.14 g. of clay per cc. (13% clay).From the above results it was possible to calculate the densities of Li‐, Na‐, and K‐clay. The respective densities were 2.71, 2.80, and 2.75.