212 HYDROGEN ION CONCENTRATION 



sent non-aqueous oil-phases containing oil-soluble organic acids. 

 In order to prove Beutner's theory it is necessary to show that on 

 varying the kind and the concentration of the electrolytes in the 

 aqueous phase the resulting changes in the E.M.F. are quahtatively 

 and quantitatively the same as those obtained in artificially repro- 

 duced oil-chains containing an acid (or acidified) oil-phase. 



The electromotive forces observed in physiological systems must 

 possess the following properties in order to fulfill the conditions of 

 Beutner's theory: 



1. A potential difference also must be observed between two 

 uninjured places when they are connected by means of solutions 

 of an electrolyte of different concentrations. This is shown in the 

 following experiments: 



(a) With differing concentrations of the same electrocute. 



The E.M.F. between two uninjured parts of an apple were 

 measured, with the following solutions being used as connecting 

 liquids: 



*»-*• 



El Tf ET » J Calculated maxirnal 



E. M. F. observed concentration effect 



M/10 NaCl and M/10 NaCl. . 



M/IO NaCl and M/50 NaCl... 0.029-0.024 volts ] 



M/50 NaCl and il//250 NaCl.. . 0.042-0.036 volts !> 0.040 volts 



M/250 NaCl and M/1250 NaCl.. . 0.041-0.038 volts J 



showing that the more dilute solution is always positive. 



The agreement with the results obtained from artificial oil-chains 

 is so complete that even with the higher salt concentrations, the 

 concentration effect is well below the theoretical maximal effect 

 obtainable. With the more dilute solutions, the theoretical maxi- 

 mal effect is reached. 



With NaBr the concentration effect was more pronounced. 



Calculated maximal 



NaBrAT/S and A^/40 , 0.040 volts 1 



AV40 and A''/200 0.041 volts \ 0.040 volts 



iV/200 and A^/IOOO 0.042 volts J 



The concentration effect proved to be reversible whenever no 

 permanent injury was inflicted upon the apple peel by the stronger 

 salt solutions. 



