For others, again, it is the capillary phenomena which here act a preponderating part.
This last idea is already an old one: Jager, More, and Professor Traube have all endeavoured to show that the direction and speed of osmosis are determined by differences in the surface-tensions; and recent experiments, especially those of Batelli, seem to prove that osmosis establishes itself in the way which best equalizes the surface-tensions of the liquids on both sides of the partition.
Solutions possessing the same surface-tension, though not in molecular equilibrium, would thus be always in osmotic equilibrium.

We must not conceal from ourselves that this result would be in contradiction with the kinetic theory.
Sec.3.APPLICATION TO THE THEORY OF SOLUTION If there really exist partitions permeable to one body and impermeable to another, it may be imagined that the homogeneous mixture of these two bodies might be effected in the converse way.

It can be easily conceived, in fact, that by the aid of osmotic pressure it would be possible, for example, to dilute or concentrate a solution by driving through the partition in one direction or another a certain quantity of the solvent by means of a pressure kept equal to the osmotic pressure.

This is the important fact which Professor Van t' Hoff perceived.

The existence of such a wall in all possible cases evidently remains only a very legitimate hypothesis,--a fact which ought not to be concealed.
Relying solely on this postulate, Professor Van t' Hoff easily established, by the most correct method, certain properties of the solutions of gases in a volatile liquid, or of non-volatile bodies in a volatile liquid.