82 Mr. J. Brown on the Theory of 



because I had no magnetometer at my disposal for compari- 

 son, and because the experiments had to be carried on in a 

 building containing a dynamo and other masses of iron. 

 There seems no reason to doubt, however, that with a gal- 

 vanometer whose constant had been carefully determined, the 

 method would give reliable results. 



VIII. On the Theory of Electrolytic Conduction of Clausins ; 



and on some recent Evidence for the Dissociation Theory of 

 Electrolysis. By J. Brown*. 



THE original theory of Clausius regarding the mechanism 

 of electrolytic conduction is contained in a paper en- 

 titled " Ueber die Electricitatsleitung in Electrolyten/' 

 published in Poggendorff's Annalen, ci. p. 338, 1857 f . 



As it forms the basis of the modern dissociation theory, 

 any attempt to comprehend the latter would properly begin 

 with a studv of the former. In discussing the views of 

 Clausius we may conveniently consider, first, the reasons given 

 for the inadequacy of the then commonly accepted theory of 

 Grotthus, and, second, the probability of the new hypothesis 

 put forward in its place. 



Clausius objects to the Grotthus theory chiefly for two 

 reasons. He explains in detail in § 5 that considering, for 

 instance, the anode, the negative part-molecules are here 

 retained while their positive partners decompose the next 

 stratum of adjacent molecules, and so on; and that this results 

 in a surplus of positive part-molecules implying a surplus of 

 positive electricity in the liquid, which, as he has previously 

 shown, is inadmissible. In like manner the action at the 

 cathode would result in a surplus of negative electricity 

 equally inadmissible. 



Now, though it be admitted that this reasoning may 

 be correct when applied to each pole separately, it fails, I 

 think, when both are taken together. The two charges of 

 opposite sign would then combine and, in fact, may be said to 

 constitute the current produced. 



In other words, the Grotthus molecular chains do not end 

 in the interior or at the free surface of the electrolyte, but 

 only at the electrodes, so that the action may be said to be 

 here reciprocal and complete. 



The second objection to the older . hypothesis (§ 6) is 



* Communicated by the Electrolysis Committee of the British Associa- 

 tion, having- been read at the meeting of the Association in August 1891. 

 t Also Phil. Mag. [4] xv. p. 94. 



