374 Prof. Oliver Lodge on the Seat of the 



atom of HC1, at the same time combining with the electricity 

 contained in this atom ; in the same way the hydrogen of the 

 second atom — [the welcome letters u. s. f. are now not far 

 ahead, and we will let them serve for the next fifteen or six- 

 teen lines]. 



" It is evident that in this process there occurs a continual 

 loss of vis viva, since the elements of the binary compound 

 rushing up to the metal move with a definite velocity to the 

 metal, and then are reduced to rest, either with formation 

 of ZnCl or by being set free (H). This loss of vis viva is the 

 equivalent of the heat which is evolved by the obviously occur- 

 ring chemical process, which essentially is the solution of an 

 equivalent of zinc in the acid. The same value must like- 

 wise be the work applied in effecting the redistribution of 

 electricity. 



" When, therefore, electricity begins to flow, work must 

 be done, during the solution of Zn and liberation of an eq. of 

 H from the liquid in the whole circuit, whether it be in the 

 form of heat or of external work, which is equivalent to the 

 heat-production attending that chemical process. 



" The electrical shearing-force B is an accelerating force, 

 so its work A in unit time is equal to its product with the 

 quantity of electricity moved in unit time, m, and the distance 

 s which the same travels, or 



A=E,ms. 



The product ms expresses the quantity of electricity which 

 travels per second through the cross section of the conductor. 

 " If we have different combinations, as Zn, HC1, Cu ; or 

 Mg, H 2 S0 4 or NaCl,Cu; or &c, we suppose that the same 

 quantity of E travels per equivalent .... [a long appeal to the 

 facts underlying Faraday's law is made to prove this] ; hence 

 ms= const., 



.". A = const. .E ; 



or the E.M.F. is directly proportional to the heat generated 

 by the decomposition of an equivalent of the binary compound 

 and the solution of the zinc. 



" For the production of steady currents, that electrical force 

 can alone be active which depends on the unequal attraction 

 and polarization of the atoms of the binary compound in the 

 exciting liquid of the cell ; the electrical force at the contact- 

 place of the metals which no mechanical changes can prelude 

 must, on the other hand, be inactive. That this latter, if it 

 perhaps opposed the metal liquid E.M.F. (as by immersion 

 of zinc and lead in KCy solution), is not compensated by 

 a definite part of the tension force, is proved by the afore- 



