Max Planck

“ The only difference with respect to the cases treated earlier is this, that here, in the presence of a separating membrane between two phases, the pressure in the first phase may be different from the pressure in the second phase, whereby by “pressure,” as always, is to be understood the ordinary hydrostatic or manometric pressure.
The proof of the applicability of equation is found in the same way as this equation was derived above, proceeding from the principle of increase of entropy. ”

“ An experimental test of the equation of equilibrium is possible on account of the connection between the degree of dissociation and electrical conductivity of the solution. In accordance with the electrolytic dissociation theory of Arrhenius, the ratio of the molecular conductivity of the solution in any dilution to the molecular conductivity of the solution in infinite dilution is:
since electric conduction is accounted for by the dissociated molecules only. It follows then, with the aid of the last equation, that:
With unlimited decreasing , increases to . ”

“ The more complicated the systems considered are, the more apparent becomes the advantage of this method, and there is no doubt in my mind that in chemical circles it will be more and more employed, especially, since in general it is now the custom to deal directly with the energies, and not with cyclic processes, in the calculation of heat effects in chemical changes. ”

“ Also, the dependence of the degree of dissociation upon the temperature is indicated here in quite an analogous manner to that in the example considered above, of the dissociation of water.
III. Vaporization or Solidification of a Pure Liquid. ”