Abstract
Aqueous dextran solutions contained within tall (20 cm) dialysis cells reach a state of sedimentation equilibrium in less than 10 hr, under gravity. Experiments were performed in which the solute was transported downward or upward, giving always the same final result. Calculation of molecular weights (M̄
w) of two well-defined dextran samples and of bovine thyroglobulin, using the vertical concentration gradients measured in the equilibrated solution columns, gives results in agreement with other methods. The well-known kinetic limitations to solute transport under gravity are thus effectively removed by coupling solvent osmotic currents to solute sedimentation.