Effect of Gravity near a Critical Point in Binary Mixtures

The effect of gravity is calculated near a critical point in binary fluid mixtures including azeotropic critical points. It is shown that a gravity field produces density gradients very similar to those it produces in a pure substance. For small deviations the density is a linear function of the height with a slope which diverges like $t^{\mathrm{‐\; \gamma }}$ . The available experimental evidence supports this prediction.