124 Professor Faraday [May 25, 



nature and chemical proportions of the bodies in which it occurs ; 

 and it is considered as varying in degree {i. e. in facility) with the 

 affinities of the constituents belonging to these bodies ; tiiere are, 

 however, other circumstances which evidently, and indeed very 

 strongly affect the readiness of transfer, such as temperature, the 

 presence of extraneous matters, &c. Conduction proper differs as 

 to facility by degrees so far apart, that that quantity of electricity 

 which could pass through a hundred miles of one substance, as 

 copper, in an inappreciably small portion of time, would require 

 ages to be transmitted through the like length of another sub- 

 stance, as shell-lac ; and yet the copper with its similars offers 

 resistance to conduction ; and the lac, and its congeners, conduct. 



The progress and necessities of science have rendered it important 

 within the last three or four years, and especially at the present 

 moment, that the question " whether an electrolyte has any degree of 

 conduction proper " should be closely considered, and the experiments 

 which are fitted to probe the question have been carried to a very 

 high degree of refinement. Buff",* by employing the electric 

 machine, and Wollaston terminals, i. e. platinum wires sealed into 

 glass tubes, and having the ends only exposed, has decomposed water 

 by a quantity of electricity so small that it required four hours to 

 collect gas enough to fill a little cylinder only -j^L-th of an inch in 

 diameter, and the yth of an inch in length ; yet the decomposition 

 was electrolytic and polar ; and therefore the conduction was 

 electrolytic also. When one pole only was in the water, and the 

 other in the air over it, still the decomposition, and therefore the 

 conduction, was electrolytic ; for one element appeared at the pole 

 in the water, and the other in the air or gas over the water at the 

 corresponding pole. Buff" concludes that electrolytes have no con- 

 duction proper. Many other philosophers have supported, with 

 more or less conviction, the same view, and believe that electrolytic 

 conduction extends to, and includes cases, which formerly were 

 supposed to depend upon conduction proper. Soret advances certain 

 experimental results, "f but reserves his opinion from being absolute. 

 Von Breda and Logeman adopt the more general view unreservedly. J 

 De la Rive, I think, admits that a very little may perhaps pass by 

 conduction proper, but that electrolytic conduction is the function 

 of electrolytes.§ Matteucci has at one time admitted a little con- 

 duction proper, but at present, I believe, denies that any degree exists. 

 On the other hand, Despretz,|| Leon Foucault,1[ Masson,** and 

 myself, have always admitted the possibility that electrolytes possess 

 a certain amount of conduction proper — small indeed, but not so 

 small as to prevent its being evident in certain forms of experiments : 



* MS. letter. f Annales de Chimie, xlii. 257. % Phil. Mag. viii. 465. 

 § Bibl. de Geneve, xxvi. 134, 144 ; xxvii. 177. || Comptes Rendus, xxxviii. 897. 

 \ Comptes R., xxxvii. 580 ; or Bibl. de Geneve, xxiv. 263 ; xxv. 180 ; xxvi. 126. 

 *♦ Prize Essay, Haarlem Trans., xi. 78. 



