Galvanism^ from ^Galvani to Ohm. 79 



The hypothesis of Grothuss and Davy was attacked in 1825 

 by Aiiguste De La Kive* (6. 1801, d. 1873) of Geneva, on the 

 ground of its failure to explain what happens when different 

 liquids are placed in series in the circuit. If, for example, a 

 solution of zinc sulphate is placed in one compartment, and 

 water in another, and if the positive pole is placed in the 

 solution of zinc sulphate, and the negative pole in the water, 

 De La Rive found that oxide of zinc is developed round the 

 latter; although decomposition and recomposition of zinc 

 sulphate could not take place in the water, which contained 

 none of it. Accordingly, he supposed the constituents of the 

 decomposed liquid to be bodily transported across the liquids, 

 in close union with the moving electricity. In the electrolysis 

 of water, one current of electrified hydrogen was supposed to 

 leave the positive pole, and become decomposed into hydrogen 

 and electricity at the negative pole, the hydrogen being 

 there liberated as a gas. Another current in the same way 

 carried electrified oxygen from the negative to the positive 

 pole. In this scheme the chain of successive decompositions 

 imagined by Grothuss does not take place, the only molecules 

 decomposed being those adjacent to the poles. 



The appearance of the products of decomposition at the 

 separate poles could be explained either in Grothuss' fashion 

 by assuming dissociations throughout the mass of liquid, or 

 in De La Rive's by supposing particular dissociated atoms 

 to travel considerable distances. Perhaps a preconceived 

 idea of economy in Nature deterred the workers of that time 

 from accepting the two assumptions together, when either of 

 them separately would meet the case. Yet it is to this apparent 

 redundancy that later researches have pointed as the truth. 

 Nature is what she is, and not what we would make her. 



De La Rive was one of the most thoroughgoing opponents 

 of Volta's contact theory of the pile ; even in the case when 

 two metals are in contact in air only, without the intervention 



* Annales de Cnimie, xxviii, 190. 



