Douhle-Layer of Solid and Liquid Bodies. 

 Table II. — Intrinsic potentials and Atomic radi 



307 



I. 



Element. 



c... 



II. 

 Valency 



4 



III. 



Atomic 



weight 



A. 



IV. 

 Specific 

 weight 



c. 



V. VI. 



Intrinsic Atomic 

 potential radius r 

 (observed;. Kcalculated ). 



VIL 

 ^ inter- 

 atomic 

 distance R. 



VIII. 

 r 

 R" 



12 



1-80 



4-55 volt s.iOGoX 10 ~ 8 



ro.ixio -8 



0-03 



Ta 



5 



181 



166 



4-51 



0-74X10 -8 



1-24X10" S 



0-60 



Mo 



6 



9G 



9 



4-59 



0-67 Xl0" 8 



1-21 x 10" 8 



0-55 



W 



6 



184 



191 



4-48 



0-61 x 10 " 8 



1-18x10"* 



052 



Os 



■8 



191 



22-5 



±< 



0-52 x 10 ~ 8 



l : 13xl0~ 8 



0-46 



Pt 



8 



195 



21-4 



■VI 0-57x10 



1 



1-16 X 10" S 



0-49 



The values of r in column VI. are of the right magnitude 

 and decrease with k, with the exception of that for carbon, 



which is too small: this does not, however, affect the ratios -^ 



(column VIII.), which regularly decrease as k increases, 

 being approximately equal to -J. The values of V, calcu- 

 lated on the assumption r = R (as in Table I.), would have 

 been thus about four times larger than the observed ones. 



We have hitherto taken no account of the effect of the 

 partial ionization of the metallic atoms, revealed by the 

 presence of free electrons. This effect may be just as well 

 negative as positive, depending possibly on the temperature. 

 It is clear, however, that it may be considerable only when 

 k is small (in the case of mono- and di-valent atoms). But 

 as the ionization depends upon the intensity of the inter- 

 atomic forces (as proved b}' the fact that it disappears in 

 metallic vapours) it may be much less for the superficial 

 atoms, exposed to such forces from one side only, than for 

 the internal ones. Whatever it may be, the results of this 

 theory, which are equally applicable both to metals and 

 dielectrics, seem to support the view that the ionization has 

 no sensible effect upon the surface layer (see below). 



§ 5. Let us imagine an equipotential surface, enclosing as 

 tightly as possible that of the metal, without, however, 

 penetrating into the double-layer, and call ifs potential </>, 

 the external potential of the metal. If there were no double- 

 layer, <fi would be equal to the potential of the internal 

 points. The action of the double-layer consists in increasing 

 the latter by a fixed value V, and we shall call the sum 

 <£ + V the internal potential of the body, j 



