56 Mi; s. W. J. SMITH ON THE NATURE OF ELECTROCAPILLARY PHENOMENA. 



In order to determine whether the depolarization is the sole cause of the olxserved 

 flattening of the direct curve, an accurate knowledge of the relation between the 

 graphite resistance and the internal resistance of the electrometer would be necessary. 

 But an approximate knowledge of this relation is quite sufficient to show that the 

 depolarization must soon affect the form of the curve. Thus, to take an example, the 

 horizontal distance between the direct and indirect descending branches for a surface 

 tension corresponding to 150 is not less than 64 horizontal divisions (see fig. 1), 

 equivalent to a potential difference of 1600 (= 1/6 X '28 volt), and even if the 

 electrometer resistance is not above 50,000 ohms, the effect of the latter will be a 

 displacement of the direct curve to the right to the extent of one-third of a horizontal 

 division a quite perceptible amount due to the potential fall within the electro- 

 meter. As the actually observed displacement is considerably greater than the above, 

 it seems probable that the flattening in the upper portion of the curve is not due to 

 de|K)larization alone. This is rendered still more probable when the curve for such a 

 substance as hydrochloric acid (in which the ascending branch is very much steeper 

 than the descending) is considered." 



Fig. 3. 



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3 gives a portion of another pair of direct and indirect curves, showing how 

 the depolarization increases when the potential difference applied, between the 

 terminals of the electrometer is reversed in sign. 



In order to show how the depolarization for kathodic polarization of the small 

 electrode varies with the nature of the kation, curves (corresponding to those above 

 described) are given for a dilute solution of caustic potash (fig. 4). 



The curves show that in this case, for a given surface tension, the depolarization IB 



than when the kation is hydrogen of the same order of concentration. 



known, the magnitude of the depolarization in an electrolytic cell depends 



