If the temperature at which this dense spontaneous shower of crystals is found be determined for different concentrations of solution, we can plot a "supersolubility curve," which is found generally to run roughly parallel to the "solubility curve" of steady equilibrium between liquid and already existing solid.
If a solution, let us say of sugar, be confined in a closed vessel through the walls of It is probable that in both these solutions complex ions exist at fairly high concentrations, but gradually gets less in number and finally disappear as the dilution is increased.
In such salts as potassium chloride the ions seem to be simple throughout" a wide range of concentration since the transport numbers for the same series of concentrations as those used above run Potassium chloride 0.5 1 5, 0.515, 0.514, 0.513, 0.509, 0.508, 0.507, 0.507, 0.506.
The forces between the ions of a strongly dissociated solution will thus be considerable at a dilution which makes forces between undissociated molecules quite insensible, and at the concentrations necessary to test Ostwald's formula an electrolyte will be far from dilute in the thermodynamic sense of the term, which implies no appreciable intermolecular or interionic forces.
It is evident that the undissociated part of each acid must eventually be in equilibrium with the free hydrogen ions, and, if the concentrations are not such as to secure this condition, readjustment must occur.