The materials of Group IIA in the Periodic Table show a slight tendency to form complexes and hydrates, though this tendency becomes less marked on passing to the heavier elements of the Group. Increasing tendency to form hydrates is accompanied by increasing solubility of the salts in water, except in the cases of salts of the weak acids, in which cases the solubilities decrease. Thus one is led to expect some evidence of complex formation and hydration in the case of barium salts, but less marked than members of the Group of lower atomic weight would be expected to show. Salts produced by reaction of a weak acid like acetic acid , with a strong base like barium oxide, might be expected to hydrolyse in aqueous solutions. Reference to the literature on barium acetate, and acetic acid showed that work had been carried out bearing on the system BaO - Ac₂O - H₂O.