Electromotive Forces in a Voltaic Cell. 375 



said complete proportionality of the total electrical force (and 

 E.M.F.) in the closed circuit with the said heat-equivalent 

 of the chemical processes. It must then be neutralized in 

 some other way. This w T ould most simply happen on the 

 hypothesis that, by contact of the exciting fluid with the 

 metals, the E.M.F. is excited in a double way : first, by 

 an unequally strong attraction of the masses of fluid and metal 

 as a ichole for the one or the other electricity ; and, secondly, 

 by the unequal attraction of the metals for the oppositely 

 electrified components of the liquid. (This double pro- 

 perty would be quite analogous to the following : a metal (e. g. 

 zinc) can not only attract to itself by adhesion the whole mass 

 of any given fluid (HC1), but also can exert a much stronger 

 attraction for one constituent of the same (chlorine); just 

 also as a magnet attracts iron, not only by reason of gravi- 

 tation, but much more because of the magnetic polarization 

 of its individual particles.) 



" In consequence of the first unequal (mass) attraction for 

 the electricities, the decomposable liquids would behave exactly 

 according to the metallic law of tension, and in a closed circuit 

 of metals and liquids a complete neutralization of electrical 

 forces (and E.M.F.) would obtain; the second (chemical) 

 action would, on the other hand, alone produce the electrical 

 shearing-force effective in current formation and its accom- 

 panying E.M.F. 



" We will therefore in the sequel denote the total E.M.F. at 

 the various junctions with strong letters, and that portion of 

 the same of which no part engages in exciting the current 

 by italics in brackets, and by italics without brackets the 

 portion corresponding to the chemical work. In the closed 

 circuit — zinc, sulphuric acid, copper — the whole active E.M.F. 

 would then be 



Cu/S + S/Zn + Zn/Cu = Cu/S + S/Zn + ( CuJS) + (S/Zn) + (Zn/Cu). 



"The experiments of Hankel and others give the total E.M.F. 

 between the metal M and water, which we denote by M/Aq, 

 and which is compounded, according to the foregoing hypo- 

 thesis, of the E.M.F. excited by the mass action of the water 

 (M/Aq), and that excited by reason of its chemical polariza- 

 tion M/Aq. If therefore we put into water a copper and a 

 zinc plate, the total potential difference, or E.M.F. between its 

 ends, is Cu/Aq + Aq/Zn. This is the quantity we should 

 directly obtain if we connected the Cu and Zn immersed in 

 water with the same named plate of a zinc-copper condenser, 

 and after breaking the connection determined the charge of 

 the condenser. 



