Using the theory of polarizable fluids, we investigated the dispersion attraction of electrons solvated in metal-ammonia solutions. We have found that the dispersion attraction results in a negative osmotic coefficient and a negative mean force potential between excess electrons and provides a phase separation at intermediate metal concentrations. Our analysis indicates that the dispersion attraction determines dielectric properties of solution. It is responsible for the experimentally observed shift of the maximum in the conductivity spectrum. Another effect of the dispersion attraction is a sharp enhancement of the microwave dielectric constant, leading to a nonmetal-metal phase transition. (C) 2012 Elsevier B. V. All rights reserved.