The activities of HCl, HBr and HJ were determined in 10−2‐M solutions of the hydrogen halides in water‐acetic acid mixtures ranging from 0 to 99,9% CH3COOH using the galvanic cell:
From the potentials the quantity pw⊕ was derived as a measure of acidity and compared with HAMMETT'S acidity function determined with the aid of p‐nitraniline and o‐nitraniline. Acidity measurements were also carried out in 10−2−M HClO4; 10−2−M HCl + 10−2−M HClO4; 10−2‐M HClO4 + 10−1‐M(CH3)4Cl; 10−2‐M NaOH + 10−1‐M N(CH3)4Cl, using the same series of solvents.