POTENTIALS AT PHASE BOUNDARIES 213 



With other materials the effect produced was less and not so 

 regular, for example. 



rri .1 „. Ccdctdaled maximal 



Turtle carapace: g^gct 



KCl N/IO and N/50 0.010 volts ] 



N/50 andA^/250 0.015 volts f 0.040 volts 



Ar/250 andiV/1250 0.021 volts J 



Human finger nails: 



NaCl 10 N/8 and A^/8 0.017 volts ] 



N/8 and A^/80 0.023 volts I , 



N/80 and iV/800 0.028 volts f "•"^' ^ ^"""^ 



iV/800 and iV/8000 0.030 volts J 



In muscles a much smaller effect was obtained: 



KCI N/8 and N/40 0.002 volts ] 



N/40 and iV/200 0.006 volts [ 0.040 volts 



iV/200 and AT/IOOO 0.008 volts J 



(6) An E.M.F. must also be produced when two uninjured places 

 are connected by means of solutions of the same concentration but 

 of different electrolytes. The influence of the ions in the negative 

 direction must follow in the same series sequence as in the "oil- 

 chains." This point had already been demonstrated in Hober's 

 studies, which, however, could not at the time be interpreted in the 

 sense of the later experiments. It was shown that when the con- 

 necting fluid was varied at an uninjured place, the negative effect 

 of the anions was expressed in the series: 



S0=4 CI- Br- I- NO3"" SCN- 



and of the cations: 



K+ Na+ Ba++ Cu++ Mg++ 



Furthermore, for a closer conception of the phenomenon it was 

 necessary to find out whether the oil-layer represented by the apple 

 peel is a single oil phase, such as 



salt solution | oil salt solution 



which would correspond to 



salt solution 



apple peel 



Free fluid of 

 apple pulp 



