On the relation between diffusion, sedimentation, and friction

Since there exists in the literature some discrepancies in the formulation of the relation between diffusion, sedimentation, and friction of colloidal particles in solution, we rederive the relation between these transport phenomena in this paper. From the application of irreversible thermodynamics it is shown, that the relation between the experimentally accessible quantities like diffusion coefficient, sedimentation velocity, and osmotic compressibility can be obtained unambiguously. The relation between sedimentation velocity and frictional coefficient is discussed in detail, where we give an argumentation for the right expression between these two quantities.