The topological isomorphism is shown to exist in solubility diagrams at T, p = const, plotted in the variables water activity and the Jänecke ion index, for quaternary systems with solid solutions. The same is shown for the solid-melt diagrams of ternary systems with solid solutions plotted in temperature-property spaces, as well as for liquid-vapor phase diagrams of ternary systems also in temperature-property spaces at a constant pressure or in pressure-composition spaces under isothermal conditions. It is proven that the analogs of the first, second, and third Gibbs-Konovalov laws hold when the system moves along partial solvent activity extreme curves in the solid solution fields in the isothermal-isobaric solubility diagrams of the quaternary (reciprocal) systems plotted as the water activity against the Jänecke index of the salt or ion added to a ternary alyzotrope (for the Jänecke indices of other salts or the second ion, the laws do not hold). The deduced tendencies are confirmed by sample calculations of the solubility diagram at 25°C for quaternary reciprocal system K+,NH4+∥Cl-,Br--H2O, in which different types of solid solutions crystallize. Copyright © 2005 by Pleiades Publishing, Inc.