6o4 
CHEMISTRY: W. D. HARKINS 
Proc. N. a. S. 
though it is a powerful tool in many calculations where the premises are 
sufficiently known. In the end the complete ionization theory will un- 
doubtedly be forced to consider in this case that the uni-univalent ion is 
often associated with the bivalent ion, and so will lead to the same con- 
ception as the older theory; but it may in the end be able to overcome the 
imperfections in the latter which are due to the fact that it ignores too 
greatly the kinetics of the phenomena, though it should be recognized 
that many of those who use the older theory are fully aware of the statisti- 
cal features of the problem. In a certain sense it is probably nearer the 
truth to say that there is only one theory which is supported by the most 
advanced workers in the field, but that some of them pay attention to one 
set, and others to another set, of the features of the general theory, which 
will not be even approximately satisfactory until it is put much more 
completely into the form of partial differential equations. 
Even though many physical chemists may dislike such a use of the 
term, it may be possible that the work ion will be used most largely in the 
sense in which it has been used by Noyes and Maclnnes. In order to 
preserve some of the more valuable features of the older use of the term, 
in case this should occur, I wish to suggest that then a distinction be 
made, according to the suggestion made earlier in the paper, between 
ionization, and dissociation, the former term to be used whenever the 
particle becomes charged, the latter only when there is an obvious separa- 
tion. Of course this does not surmount the difficulty that there are all de- 
grees of separation, so there will be actually no such thing as a certain 
percentage dissociation. However, it may be said that the apparent 
percentage dissociation as determined by the conductivity or the ther- 
modynamic method, has a definite value, which may, in certain cases, 
depend not only upon the experimental method employed, but also upon 
the additional hypotheses used in the calculation. What has been styled 
the unionized salt, may be called the undissociated salt. Intermediate 
or complex ions under the old nomenclature, may keep their older designa- 
tions, or may be termed ion associates or complexes. 
Unless those who speak of the complete ionization of all strong elec- 
trolytes do something of this sort, they will be plunged into difficulties 
if they attempt to use the energy concept (activity) to describe such 
phenomena as those in which the mercury and cadmium complexes seem, 
according to the commonly accepted view, to play an important part. 
They will have to explain also the slightly dissociated electrolytes, and 
those electrolytes in formic acid, which, although largely dissociated, 
follow the mass law, as has been found by Schlesinger. 
It is always best when possible to devise new terms to express new 
ideas, since otherwise the point of view of all of the older literature is 
confused. It may be preferable, as has been suggested to the writer 
by Professor Stieglitz, to consider a gaseous salt molecule as made up of 
