It can also be experimentally demonstrated that on taking two recipients separated by such a partition, and both containing nitrogen mixed with varying proportions of hydrogen, the last-named gas will pass through the partition in such a way that the concentration--that is to say, the mass of gas per unit of volume-- will become the same on both sides.

Only then will equilibrium be established; and, at that moment, an excess of pressure will naturally be produced in that recipient which, at the commencement, contained the gas with the smallest quantity of hydrogen.
This experiment enables us to anticipate what will happen in a liquid medium with semi-permeable partitions.

Between two recipients, one containing pure water, the other, say, water with sugar in solution, separated by one of these partitions, there will be produced merely a movement of the pure towards the sugared water, and following this, an increase of pressure on the side of the last.

But this increase will not be without limits.

At a certain moment the pressure will cease to increase and will remain at a fixed value which now has a given direction.