On "Resistance " at the Surfaces of Electrodes. 249 



Also 



s s s 



S becomes =— ■ — - ; 81 becomes z. — ~: and S 2 becomes t— — -. 

 1 + ut 1+fit l + ott 



If, now, these results be substituted for those in formula (1), 

 the expression obtained will be theoretically correct, as the 

 empty space vanishes at t°. 

 Thus 



l+j3t 1+at 

 which, by simplification, becomes 



Vl ~ B,(l + ffi) W 



bl TT^T" 



It will be seen that (2) gives rather a larger result than (1), 

 because /3 is greater than a. This, however, is what must be 

 expected if reference is made to (1). There V is too large 

 and S is too small, so that the product V S remains unaltered ; 



W 



because S= -^ if V is the volume in cubic centimetres, 



whence VS = W; but the product VS 2 becomes greater as 

 V increases. Hence (1) gives too small a value for V 1? a 

 result which is compensated for in (2). 



XXXIV. On "Resistance" at the Surfaces of Electrodes in 

 Electrolytic Cells. By GL Gore, LL.D., F.R.S* 



IN a former paper on "Evidence respecting the Reality of 

 Transfer-resistance in Electrolytic Cells " (Proc. Birm. 

 Phil. Soc. 1886, and Phil. Mag. February 1886, vol. xxi.), I 

 have shown that the passage of an electric current into or out 

 of an electrode of sheet platinum by means of dilute nitric 

 or sulphuric acid, sets free at the surface of contact of the 

 metal and electrolyte an amount of heat which cannot appa- 

 rently be accounted for by any other cause than that of an 

 obstacle of some kind to the passage of the current at those 

 surfaces. 



And in another paper, " On the Relations of Surface-resist- 

 ance at Electrodes to various Electrical Phenomena " (ibid.), 



* Communicated by the Author, having been read before the Birming- 

 ham Philosophical Society, February 11, 1886. 



