  We examine phase separation in aqueous mixtures at fixed amounts of
hydrophilic monovalent ions. When water is the minority component, preferential
solvation can stabilize water domains enriched with ions.
  This ion-induced precipitation occurs in wide ranges of the temperature and
the average composition where the solvent would be in one-phase states without
ions. The volume fraction of such water domains is decreased to zero as the
interaction parameter $\chi$ (dependent on the temperature) is decreased toward
a critical value for each average composition.
