Isopiestic measurements have been made for the systems (NaCl + BaCl2 + mannitol((sat))(aq)} and (KCl + glycine + mannitol((sat))(aq)} at T = 298.15 K. The results agree well with the linear relations for the saturated systems published previously and indicate that if the unsaturated subsystem ((B + C)(aq), where B and C represent the unsaturated solutes} conforms to Zdanovskii's rule and the Stokes and Robinson relation, then the saturated system {(B + C + A(2(sat)))(aq), where A(2) denotes the saturated solute) obeys the relations for the saturated systems.