There is reason to believe that in certain cases such complex ions do exist, and interfere with the results of the differing ionic velocities.
An alternative hypothesis is given by the idea of complex ions.
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.
The results go to show that, where the existence of complex ions is not indicated by varying transport numbers, the observed velocities agree with those calculated on Kohlrausch's theory.
There is a reaction between the aluminum oxide and the cryolite to produce a range of complex ions involving aluminum, oxygen and/or fluorine.