LARS ONSAGER - The National Academies Press

LARS ONSAGER 201
acetic acid, which are only partly dissociated in solution, display
at high electric fields a conductivity in excess of the lowfield
value.
Onsager (1934,2) saw that this effect must be due to a
disturbance by the field of the rate at which associated pairs
of ions dissociate into effectively free ions, the rate of reassociation
being virtually unaffected by the field. On this bold,
simplifying assumption he derived a remarkable formula
that implied—correctly—that the effective dissociation constant
ought to be shifted by a factor proportional to the absolute
value of the field (at high fields), but independent of
the concentration. In a much later paper with C. T. Liu
(1965,1), he revised the details but not the central message
of this work. In the intervening years Onsager's theory of the
Wien effect was exploited by Eigen and DeMaeyer in their
experimental studies of very fast reactions, particularly in
biological systems. 16
The paper on dipole moments (1936,1) disturbed a number
of chemists because it called into question the Debye formula
relating the dielectric constant of a polar substance to
the molecular dipole moment. The formula had been widely
used for determining dipole moments from the temperature
variation of gaseous dielectric constants but was known to fail
for polar liquids, presumably because of molecular association
or hindered rotation. Onsager suspected that there was
a flaw in the underlying theory, since it predicted a ferroelectric
Curie point for all polar solutions, whereas no such
transition had ever been observed.
Onsager's first account of his own theory took the form
of a paper he sent to Debye for publication in the Physikalische
Zeitschrift, but Debye found the paper "unreadable" and
16 M. Eigen, "Die 'unmessbar' schnellen Keaktionen," Nobel Prize lecture, 11 December,
1967, in Les Prix Nobel 1967 (Stockholm: P. A. Norstedt & Sdner, Imprimerie
Royale, 1969), 151-80.