In recent years many research workers have turned their attention to the quantitative characterization of complex compounds and reactions of complex-formation in solution. Instability constants characterize quantitatively the equili bria in solutions of complex compounds and are extensively used by chemists of widely-varying specialities, in analytical chemistry, electrochemistry, the technology of non-ferrous and rare metals, etc., for calculations of various kinds. Despite the wealth of numerical data, no reasonably full coliection of instability constants of complex compounds has been made...