POTENTIALS AT PHASE BOUNDARIES 



201 



the oil, and the potassium will be present in the oil not only as the 

 sahcylate but also, to a relatively marked degree, as the chloride. 

 In the latter case the total amount of K+ in the oil phase can no 

 longer remain independent of the HCl concentration in the water 

 phase. This is why it happens that the concentration effect ap- 

 proaches its maximal value the more closely the more dilute the 

 aqueous KCl solutions, which was experimentally confirmed, as 

 shown above. 



When NaCl was used instead of KCl the E.M.F. values shown in 

 table 31 were found. 



The concentration effect is smaller in this case, but the effect of 

 the absolute salt concentration is still quite obvious. 



TABLE 31 



Another oil-chain in which the E.M.F. values closely approached 

 the maximal effect was the following: 



Water 

 dimethyl aniline — HCl 



Ci 



Salicylic 

 aldehyde 



Water 

 dimethylaniline — HCl 



C2 



(Ci > C2) 



In this case also the acidic nature of the oily solvent is responsi- 

 ble for the constant concentration of cations (i.e., dimethylanihne- 

 ions) within it, in spite of the differences between Ci and C2. 



