  We show that an electric field parallel to an electrically neutral surface
can generate flow of electrolytic mixtures in small channels. We term this
solvo-osmotic flow, since the flow is induced by the asymmetric preferential
solvation of ions at the liquid-solid interface. The generated flow is
comparable in magnitude to the ubiquitous electro-osmotic flow at charged
surfaces, but for a fixed surface charge density, it differs qualitatively in
its dependence on ionic strength. Solvo-osmotic flow can also be sensitively
controlled with temperature. We derive a modified Helmholtz-Smoluchowski
equation that accounts for these effects.
