Conditions of the Constitution of Electrolytes. 165 



cerned in the phenomena (474?.), and that other bodies much 

 surpass it in some of the effects supposed to be peculiar to 

 that substance. 



671. Water, from its constitution and the nature of its ele- 

 ments, and from its frequent presence in cases of electrolytic 

 action, has hitherto stood foremost in this respect. Though 

 a compound formed by very powerful affinity, it yields up its 

 elements under the influence of a very feeble electric current ; 

 and it is doubtful whether a case of electrolyzation can occur, 

 where, being present, it is not resolved into its first princi- 

 ples. 



672. The various oxides, chlorides, iodides, and salts (402.), 

 which I have shown are decomposable by the electric current 

 when in the liquid state, under the same general law with 

 water, illustrate in an equally striking manner the activity, in 

 such decompositions, of elements directly and powerfully op- 

 posed to each other by their chemical relations. 



673. On the other hand, bodies dependent on weak affi- 

 nities very rarely give way. Take, for instance, glasses : many 

 of those formed of silica, lime, alkali, and oxide of lead, may 

 be considered as little more than solutions of substances one 

 in another*. If bottle-glass be fused, and subjected to the 

 voltaic pile, it does not appear to be at all decomposed (408.). 

 If flint-glass, which contains substances more directly op- 

 posed, be operated upon, it suffers some decomposition ; and if 

 borate of lead glass, which is a definite chemical compound, be 

 experimented with, it readily yields up its elements (408. # ). 



674. But the result which is found to be so striking in the 

 instances quoted is not at all borne out by reference to other 

 cases where a similar consequence might have been expected. 

 It may be said, that my own theory of electro-chemical de- 

 composition would lead to the expectation that all compound 

 bodies should give way under the influence of the electric 

 current with a facility proportionate to the strength of the 

 affinity by which their elements, either proximate or ultimate, 

 are combined. I am not sure that that follows as a conse- 

 quence of the theory ; but if the objection be supposed one pre- 

 sented by facts, I have no doubt it will be removed when we 

 obtain a more intimate acquaintance with, and precise idea o£ 

 the nature of chemical affinity and the mode of action of an 

 electric current over it (518. 524.)): besides which, it is just 

 as directly opposed to any other theory of electro-chemical 



* Philosophical Transactions, 1830, p. 49. 



f These numbers, and the others referred to from 380. to 449., both in- 

 clusive, belong to the Fourth Series of these Researches, noticed in Lond. 

 and Edinb. Phil. Mag. vol. iii. p. 449. — Edit. 



