Theory of Elect rocapillarity. 383 



The experimental determination of a/t 2 — \Jr, presents some 

 difficulties caused by the lack of mobility of the capillary 

 meniscus, especially at low concentrations. The results ob- 

 tained do not pretend therefore to a high degree of accuracy. 

 Nevertheless, we may see from Table II. that the value of 

 the displacement with SO/' and 01' is approximately equal to 



T?T 



— ^r1o£ — at low concentrations, whereas with an active anion 



like F much greater displacements are observed. The same 

 phenomenon is shown to a less degree with the 01' ion in a 

 concentrated solution. 



The data for H 2 S0 4 were obtained in the same way as the 

 data for KN0 3 and Ba(N0 3 ) 2 in Table I., a correction for the 

 potential difference between H 2 S0 4 and the n/10 KC1 of the 

 calomel electrode being made ; the approximate data for 

 INaCl and KI were calculated from the measurements of 

 Gouy *. 





Table II. 







H 8 S0 4 . £ = 20°. 





7- 



M-l/10 n. 



1/10 n-l/lOO n, 



95-0 



0-042 



0-031 



900 



0-038 



0-028 



85-0 



0032 



0-022 



80-0 



0027 



0023 



750 



0-027 



0-023 



700 



0027 



NaCL t=18°. 



... 



90-0 



009 



KI. *=18°. 



005 



900 



0-15 



0-11 



75-0 



009 

 III. The maximum. 



... 



In the neighbourhood of the maximum T A and T K are 

 quantities of the same order of magnitude, and no definite 

 inference can be drawn from (5 a). A very interesting 

 attempt to find out the equation of that portion of the electro- 

 capillary curve was made by Chapman f. Assuming that 

 the ions in the surface-layer are in equilibrium under the 



* Ann. ehim. phys. (7) xxix. p. 145 (1903). 

 + Loc. cit. 



