An attempt has been made to separate the colloids of a number of Canadian soils of medium texture into groups and fractions as proposed by Tyulin (Soil Sci. 45, 343-357, 1938). Details of the separations are given. Group 1 included those colloids that were dispersed in dist. water after being saturated with Na ions. Group 2a contained those colloids which, following the removal of Group 1, were dispersed in 0.004 N NaOH. Group 2b consisted of those that were dispersed in weak alkali following the removal of group 2a and subsequent treatment of the residual soil with weak acid. Results in general have agreed with those obtained by Tyulin. The amts. of group 1 colloids varied from 1.1 to 19.3% in 7 soils. The soil residues, after separation of the colloid groups, retained from 30 to 60% of the capacity to adsorb bases possessed by the original soil.