98 Haynes.—A Criticism of Beutner s Theory of the 
A 
B 
+ Na in water 
(Na o 
Na cone. — Na dil. 
‘ oil ’ solution 
eate) (NaCl) 
Na in water — 
and the Nernst system : 
+ Ag metal | Ag° cone. — Ag 1 dil. | Ag metal — 
and regards the former as a system reversible in respect to sodium ions, 
while he limits the effect of free acid in the ‘ oil ’ phase to that which 
it produces by increasing the solubility of the sodium salt. This is to 
ignore the fact that unless the ions of an electrolyte are completely insoluble 
in one of the two phases—an impossible assumption here—the distribu¬ 
tion of these ions must affect the potential at the boundary, and this more 
especially where organic acids are concerned, since the partition coefficient 
between organic liquid and water is likely to be far higher for organic 
anions than for hydrogen ions. 
In Beutner’s systems the matter is further complicated by the nature of 
the salts in contact with the acid oil. Not only must the distribution 
of these, salt ions be taken into account, but also the possibility of reaction. 
We may consider the case of an ‘ oil * very frequently used by 
Beutner—a solution of salicylic acid in salicylic aldehyde. As salicylic 
acid is not insoluble in water as he supposes, it will react with the salts with 
which it is in contact, and double decomposition will take place at both 
boundaries. At A salicylic acid, oleic acid, sodium salicylate, and 
sodium oleate will be present ; at B salicylic acid, hydrochloric acid, 
sodium salicylate, and sodium chloride. At A, therefore, there will be 
a decrease of hydrogen ion concentration ; at B an increase. The effect of 
free hydrochloric acid is entirely ignored by Beutner, and his reasons for 
neglecting so potent a factor are discussed in the sequel. Here it will merely 
be pointed out that a solution of salicyclic acid will increase in acidity 
by admixture with sodium chloride, since salicylate ions will be removed 
as undissociated sodium salicylate and the concentration of hydrogen 
ions will consequently increase. When considerable quantities of undisso¬ 
ciated salt are present this effect becomes important, and this has been 
shown by the writer 1 to be the case in buffer solutions. An ‘ oil ’ in which 
undissociated salt is soluble will evidently produce a very similar effect, and 
in the system under discussion there will therefore be a difference of. con¬ 
centration of acid on the two sides ; work will be done by the transference 
of hydrogen ions from a region of greater to one of less concentration, and 
on this account a difference of potential will arise. 
Before going farther into this matter consideration must be given 
to the effect of diffusion potential. Beutner discusses this in connexion 
with the work of Haber and Klemensiewicz 2 and of Cremer 3 on diphasic 
1 Biochem. Journ. xv. 440 (1921). 
3 Zeitsch. f. Biologie, xlvii. 1 (1906). 
2 loc. cit. 
