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42 -P»'o/. A. C. Brown on the Ions of Electrolysis. [Jan. 31, 



I had also thought of saying something as to the atomic character 

 of electricity, and the compounds of electricity with what we may 

 venture to call the other chemical elements, and had even some idea 

 of poaching on Lord Kelvin's domain of "Aepinus atomised," but 

 time has saved me from this. 



I have been describing the history of the theory of electrolysis 

 from the time of Faraday, in such a way as is possible within the 

 limits of an hour. I have necessarily omitted mention of many 

 active, able and successful workers, and I cannot in every case justify 

 the omission except by referring to the time limit. I have as far as 

 I could explained the evidence which we have for the theories 

 described, but I have not intended to argue for or against the essen- 

 tial truth of them. I have sometimes been asked in reference to the 

 theory of electrolytic dissociation. Do you really believe it to be true ? 

 My answer to that question is, I believe it to be an eminently useful 

 theory. It has led to a great deal of most valuable experimental 

 work. It has enabled us to group together things that without its 

 help seemed very little connected. It has led to the discussion of 

 problems that could scarcely, without its suggestion, have occurred 

 to any one. It does not seem to be exhausted, and I look forward 

 to much good to be got from it yet, and therefore I am willing to take 

 it as a guide. But I do not look on it as an infallible guide ; we 

 cannot expect, we do not need, an infallible guide in physical science. 

 A long life may be anticipated for this theory ; if that be so, we may 

 be sure that it will undergo modifications, for if it is to act, it will be 

 acted on. 



Nothing but good can come from the fullest discussion, either of 

 the theoretical basis or of the experimental evidence for or against a 

 theory. No great principle in science or in law can be satisfactorily 

 settled without full argument by competent advocates on both sides, 

 and the eager hunt for evidence by those who attack and by those 

 who defend, will lead to a more complete investigation of the whole 

 field than would be attained without such — shall we call it partisan 

 — interest. 



[A. C. B.] 



