Forum on osmosis. IV. More on osmosis and diffusion.

A brief summary is presented of the Gibbsian view of chemical drives and of its mechanical interpretation, including a description of the "diffusion force" that arises from an interplay between fluctuations and dissipation. Osmotic flows are shown to be driven by diffusion forces acting at the membrane interface, and not by the effects of Hammel and Scholander's "solvent tension."