Demixing systems salt + water

While the early work on molten NH4CI gave only some qualitative hints that the effective critical behavior of ionic fluids may be different from that of nonionic fluids, the possibility of apparent mean-field behavior has been substantiated in precise studies of two- and multicomponent ionic fluids. Crossover to mean-field criticality far away from Tc seems now well-established for several systems. Examples are liquid-liquid demixings in binary systems such as Bu4NPic + alcohols and Na + NH3, liquid-liquid demixings in ternary systems of the type salt + water + organic solvent, and liquid-vapor transitions in aqueous solutions of NaCl. On the other hand, Pitzer s conjecture that the asymptotic behavior itself might be mean-field-like has not been confirmed. 

We read further in Kossel that clupein chloride is soluble in water but is separated as an oil by added NaCl. Obviously the complex relations here between colloid cation and the monovalent chlorine ion are still too weak for coacervation in the binary system clupein chloride -F HgO and without further information one cannot determine whether the demixing by added NaCl is based on increase of these complex relations, or on an ordinary salting-out process. 

Summarising we may therefore consider these and similar demixings in binary systems H2O + salt as complex coacervation reduced to its simplest form beside water only the two essential ions are present these in the case of procaine salts are only monovalent and do not even possess macromolecular structure. 

---