1. The results show that humic acid sol obtained from coal is heterogeneous in character. Part of it is in true solution while the remaining part is in colloidal suspension. 2. The humic acid sol has some intrinsic acid character and which is quite independent of dissolved acids present in it. 3. The degree of dissociation as calculated from the ratio of free acidity to total acidity shows that the humic acids (including that from coal) are very weakly dissociated in contrast to results from potentiometric titration. 4. Both conductometric and potentiometric titration indicate that humic acid prepared from coal is tribasic in character. The base-exchange capacity depends on the nature of base used. So the cationeffect predominates over the pH effect. © 1957 Verlag von Dr. Dietrich Steinkopff.