Voi,. 7, 1921 
CHEMISTRY: J. KENDALL 
59 
fewer than 96 new organic compounds have been isolated in the course 
of this work. 
Compound formation in binary organic mixtures is therefore funda- 
mentally dependent upon diversity in character (i. e., differences in positive 
or negative natures of the constituent groups) of the two components. 
Compound Formation and Ionization. — Before proceeding further, it 
was necessary to confirm a point which the above results had indicated as 
highly probable — namely, that the order of electroafnnity of different 
radicals in these organic mixtures was substantially the same as in aqueous 
solutions. This was satisfactorily established by careful conductivity 
determinations upon various systems of the types examined above. In a 
fixed ketone or ester, for example, different acids HX were found to give 
more highly conducting solutions the more electronegative the radical X. 
In a fixed acid HX, conversely, different ketones R.CO.R 1 or esters 
R.COOR 1 gave solutions of better conductivity the more electropositive 
the radicals R and R 1 . Different acids HY in a fixed acid HX, finally, 
gave more highly conducting solutions the greater the difference in the 
electroafnnity of the radicals X and Y. 
An important generalization may therefore be deduced: in a conducting 
solution, compound formation between the components and ionization 
proceed in parallel. Where compound formation is very slight, ioniza- 
tion is inappreciable; as compound formation increases in extent, ioniza- 
tion becomes evident; where compound formation is very marked, ioniza- 
tion is extensive. 
The validity of this generalization for aqueous solutions may now be 
examined. Acids and bases obviously furnish a stringent test, since 
ionization here varies very considerably. Examination of the available 
data shows that strong acids invariably give stable hydrates, while among 
the myriads of weak acids listed in Beilstein not a single example of hydrate 
formation is indicated. Quantitative confirmation of the parallelism 
between hydrate formation and ionization for acids in aqueous solution 
was obtained from freezing-point depression determinations with a series 
of acids of gradually increasing strength. With bases the data, though 
not so extensive, showed similar agreement. 
A Modified Ionization Theory. — On the basis of the above results, a 
modification of the current ionization theory has been proposed, under the 
assumption that "ionization is preceded by combination between solvent 
and solute and is, indeed, a consequence of such combination." Accord- 
ing to this view, ionization in solutions is due not to solute alone nor to 
solvent alone, but to combination between the two to form unstable 
complexes. The various factors affecting the formation and stability 
of such complexes have been critically discussed elsewhere. 3 It has been 
shown that, while in simple molecules the two radicals are in general 
attracted to each other so strongly that no dissociation is observable, yet 
