2494
J. Phys. Chem. 1982, 8 6 , 2494-2498
weighted according to ion mobilities. These effects are in, perhaps fortuitously, good agreement with predictions of the Hubbard, Colonomos, and Wolynes molecular theory of kinetic polarization decrements with ion-solvent dipole interactions included in the correlation function potential. The results are encouraging, but further experiments and calculations of effects for other salts and solvents are clearly needed. The indication from the results in part 1 that large decrements are more closely related to solvent molecule dipole moments than to solvent static permittivity should be so tested. Conditions for specificity of ion effects in methanol and other solvents should be further defined, by measurements of fluoride salts on the one hand and substituted ammonium salts on the other, for example. Possible contributions to dielectric polarization from ionion interactions are inadequately defined experimentally
and there is no good theory except at very low concentrations. Much the same is true of dielectric saturation and salt effects, as discussed by Wolynes et al.4312 Despite the incompleteness of experimental evidence and approximate theoretical predictions, the recent progress in improving both situations seems to be leading to better understanding of dielectric effects and hopefully further work will contribute to a still better understanding of them and of electrolyte dynamics generally. Acknowledgment. This work was supported by the National Science Foundation, in part by Grant CHE 7822209-A02 and in part by the Materials Science Program at Brown University. (12) Wolynes, P. G . Annu. Reu. Phys. Chem. 1980, 31, 345.
Deuterium-Protium Isotopic Fractionation between Liquid Water and Gaseous Hydrogen J. H. Rolston' and I
