Stability of convection in a vertical binary fluid layer with an adverse density gradient

When a horizontal temperature gradient is imposed across a vertical layer o f a binary fluid with a negative Soret coefficient, the coupling of convect ion and the Soret effect give rise to a steady-state adverse density gradie nt along the layer. In this paper we shall experimentally analyze, using di fferent mixtures of ethanol and water, the stability of this situation. We find that it remains stable for density gradients several orders of magnitu de higher than the critical value corresponding to an isothermal fluid prov ided that the Grashof number exceeds a critical value. The stability diagra m is delineated. [S1063-651X(99)00101-4].