Priority of V. A. Kistyakovskii in the Discovery of Hydration

Abstract: The priority of V.A. Kistyakovskii in the discovery of hydration was substantiated. The history of D.I. Mendeleev’s chemical theory of hydrates and S. Arrhenius’ physical theory of electrolytic dissociation was considered; the Kistyakovskii concept spans these theories. The role of I.A. Kablukov in hydration research and modern aspects of the theory were discussed.