Data were obtained in a flat-plate continuous-flow thermogravitational column to check the theories developed by Furry et al., and Yeh and Chu. Separations of benzene-n-heptane mixtures were measured, with flow rate, feed concentration, and temperature difference being varied in the experiments. Yeh and Chu's work are in excellent agreement with the experimental data, while the agreement of Furry et al.'s work with the experimental results is fair for equi-fraction solution and poor for high and low values of feed concentration.