58 
CHEMISTRY: J. KENDALL 
Proc. N. A. S. 
aqueous solutions would be better postponed, since the complexity of the 
equilibria here undoubtedly confuses the issue. Generalizations for non- 
aqueous solutions were accordingly first sought, with the idea of testing 
their applicability to aqueous solutions (where data for the purpose are 
plentiful) at as early a stage as possible. 
Ionization and Ideality. — The most significant characteristic of all 
conducting solutions is that they are non-ideal. Two non-associated 
substances, chemically inert one towards the other, never give a conducting 
solution on admixture. Ionization is consequently always accompanied 
by interactions between the " solvent" and "solute." How to connect 
the extent of these interactions with the character of the two components 
was the first problem to be attacked. 
Now the character of the two components A B and CD in a conducting 
solution, as related to ionization, may obviously be varied by varying the 
"ionization tendency" (or "electro-affinity") of the constituent radicals 
A, B, C and D. A definite experimental criterion of such variations is 
afforded by electromotive force measurements (for inorganic radicals) 
and by comparison of ionization constants (for organic radicals). The 
results obtained in these fields have therefore been utilized to investigate 
the influence of the character of the constituent radicals upon interactions 
between the components in solutions of widely different types. 
Compound Formation and Electro affinity. — The first type of system 
studied contained but one variable radical. Dimethylpyrone (a weak 
base in aqueous solution) was chosen as one component, acids of widely 
divergent character were taken as the second, and the extent and stability 
of compound formation on admixture were established for each particular 
case by examination of the freezing-point depression curves. The only 
variable factor here was the electroaffinity of the radical X of the acid 
component HX. The experimental results demonstrated that com- 
pound formation in the system regularly increased as X became more 
negative. 
Systems with more than one variable radical were next investigated. 
For example, aldehydes of widely divergent character were substituted 
for dimethylpyrone and tested against different acids. It was found that 
compound formation was uniformly more extensive the more electro- 
positive the radical R of the aldehyde R.CHO and the more electro- 
negative the radical X of the acid HX. Similarly with systems of the 
type ester-acid the extent of compound formation increased regularly 
as the radicals R and R l of the ester R.COOR 1 were made more electro- 
positive, or as the radical X of the acid HX was made more electro- 
negative. With systems of the type acid-acid, finally, it was shown that 
the weaker acid HX functioned as a base with regard to the stronger acid 
HY, the stability of the resultant salt being greater the greater the differ- 
ence in the electroaffinity of the radicals X and Y. Incidentally no 
