Use of the Fuoss-Onsager equation to determine A and

Modern studies use computer fitting of experimental data to the 1957 Fuoss-Onsager equation, from which values of A°, S and Ei A — 2E2 and J can be found. 

The value of J can be then compared with the theoretical values of J calculated for various assumed values of a using the expression for J in terms of a given previously. The value of a which gives the calculated value of J closest to the experimentally determined J is taken to be the true value of a. This value can then be compared with the value found from A using Stokes Law arguments, the Debye-Hiickel theory and with the appropriate crystallographic radii. 

The conclusion from the early work was that the equation was as successfid as the Debye-Hiickel theory relating to mean ionic activity coefficients was in coping with the effects of non-ideality in solutions of electrolytes. 

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