34 HISTORY OF CHEMISTRY. [LECTURE XVI. 



of those who believed that untold treasures lay here which 

 should one day be disclosed. 



The modern subject of electro-chemistry forms a con- 

 tinuation to those older discoveries, and to the important 

 investigations of Hittorf and of Kohlrausch (already mentioned 

 on p. 325) which were now for the first time fully understood; 

 and it leads to successive new discoveries. 



In this connection, accumulators may first of all be men- 

 tioned here, since they have come into very general use, and 

 without them it would scarcely be possible to employ electricity 

 to advantage. Their introduction is the outcome of the dis- 

 covery of polarisation by Ritter,' 28 and of the very exhaustive 

 researches of Plante, which extend as far back as the year 

 i859. 29 Plante constructed very powerful examples of the 

 so-called secondary batteries ; and these were afterwards im- 

 proved upon in important particulars by Faure. 30 



The devising by Lippmann of the capillary electrometer, 31 

 which depends upon the change produced in the surface 

 tension of mercury by polarisation, is also worthy of mention. 



The theory of the voltaic pile, for which we are indebted 

 to Nernst, 3 - is very important. It is founded upon the theory 

 of diffusion, which was "advanced by Nernst himself, and upon 

 the idea of solution tension deduced from van 't Hoff's theory 

 of solution. Nernst also developed the theory of concentration 

 cells in the same way, and in doing so arrived at the same 

 conclusions that Helmholtz 33 had already reached by thermo- 

 dynamical investigation. 



These matters must, however, be disposed of here by merely 

 alluding to them, since they really belong more to the domain 

 of physics than to that of chemistry. 



Turning now to subjects that concern us more immediately, 



138 Voigt's Magazin. 6 (1803) 105 ; compare also Gautherot, Sue, Hist. 

 du Galvanisme. 2, 209. '* Comptes Kendus. 49, 402 ; $0, 640 ; Re- 

 cherches sur 1'electricite, Paris 1879. :} German Patent, 1881. 31 Pogg. 

 Ann. 149, 546 (1873). *' Z. physik. Chem. 2, 613 ; 4, 129. ^ Berlin. 

 Akad. Ber. 1877, 713. 



