Hydrolysis of Aluminum(III) Ion in Sodium Nitrate Medium.-The EMF data of the hydrolysis of 1.0-78.0 mM Al3+ ion in 3.0 NaNO3 medium within the pH range 2.0-4.5 show that at definite pH the extent of hydrolysis increases with increasing Al3+ concentration, indicating the presence of the polynuclear hydrolytic complexes Al2(OH)4+ 2, Al2( OH)2+ 4, and Al3(OH)5+ 4. Their composition and stability constants are determined by minimizing the error square sum. The trimeric complex is predominant.-(MILIC, N. B.; BUGARCIC, Z. D.; DJURDJEVIC, P. T.; Can.