408 



SCIENCE. 



[N. S. Vol. XXIV. No. 613. 



duction and the reasons for its action. The 

 best explanation is summed up in Professor 

 Oliver J. Lodge's * Modern Views of Elec- 

 tricity,' chapter four on ' Electrolytic Con- 

 duction,' as follows : 



1. Electrolytic conductioii is invariably accom- 

 panied by chemical decomposition, and in fact only 

 occurs by means of it. 



2. The electricity does not go through, but with 

 the atoms of matter, which travel along and con- 

 vey their charges something after the manner of 

 pith balls. 



3. The electric charge belonging to each atom of 

 matter is a simple multiple of a definite quantity 

 of electricity, which quantity is an absolute con- 

 stant quite independent of the nature of the partic- 

 ular substance to which the atoms belong. 



4. Positive electricity is conveyed through a 

 liquid by something equivalent to a procession of 

 the electro-positive atoms of the compound, in 

 the direction of the current; and at the same 

 time, negative electricity is conveyed in the op- 

 posite direction by a similar procession of the 

 electro-negative atoms. 



5. On any atom reaching an electrode, it may 

 be forced to get rid of its electric charge, and, 

 combining with others of the same kind, escapes 

 in a free state ; in which case visible decomposition 

 results. Or it may find something else handy 

 with which to combine, say on the electrode or 

 in the solution; and in that case the decomposi- 

 tion, though real, is masked, and not apparent. 



6. But, on the other hand, the atom may cling 

 to its electric charge with such tenacity as to 

 stop the current; the opposition force exerted by 

 these atoms upon the current being called polar- 

 ization. 



7. No such opposition force, or tendency to 

 spring back, is experienced in the interior of a 

 mass of fluid; it occurs only at the electrodes. 



The first three of these statements constitute a 

 summary of Faraday's Laws of Electrolysis. 



The claim was made, immediately upon the 

 application of this apparatus, that the elec- 

 tricity coming from the anode, which in this 

 installation was of cast iron but which ordi- 

 narily would be of carbon, would short-circuit 

 on to the very ends of the tubes instead of 

 passing through the tubes to the several points 

 which might be exposed to galvanic action. 

 This, however, does not seem to be the case, 

 and in fact is entirely accounted for by the 



following remarks from the above-mentioned 

 work on ' Modern Views of Electricity ' : 



But it may be asked, ' If the atoms in each 

 molecule cling together by their electrostatic at- 

 tractions, and, as there are an enormous number 

 of atoms between the two electrodes, how comes it 

 that a feeble electromotive force can pull them 

 apart and effect decomposition; moreover, how can 

 the electromotive force needed to effect decom- 

 position help varying directly with the thickness 

 of the fluid between the plates ? ' It does not de- 

 pend upon anything of the kind; the length of the 

 liquid between the electrodes is absolutely im- 

 material. This proves that throughout the main 

 thickness of the liquid no atoms are torn asunder 

 at all. Probably, they frequently change partners, 

 one pair of atoms not always remaining united 

 but occasionally getting separated and recombined 

 with other individuals. During these interchanges 

 there must be moments of semi-freedom during 

 which the atoms are amenable to the slightest 

 directive tendency, and it is probably these mo- 

 ments that the applied electromotive force makes 

 use of. 



The reality of such a state of continual inter- 

 change between molecules has been forced upon 

 chemists by the facts of double decomposition, 

 such facts as the interchange of atoms between 

 strongly combined salts where their solutions are 

 mixed so as to form very much weaker com- 

 pounds ; the proof that such compounds are formed 

 being very clear in the case when they happen to 

 be insoluble. 



The fact that the most infinitesimal force is 

 sufficient to effect its due quota of decomposition 

 has been proved most clearly and decisively by 

 the experiments of Helmholtz. 



Moreover, electrolytic conduction is perceived to 

 be scarcely of the nature of true conduction: the 

 electricity does not slip through or among the 

 molecules; it goes with them. The constituents of 

 each molecule are free of each other, and while one 

 set of atoms conveys positive electricity, the other 

 set carries negative electricity in the opposite di- 

 rection; and so it is by a procession of free atoms 

 that the current is transmitted. The process is of 

 the nature of convection: the atoms act as car- 

 riers. Free locomotion of charged atoms is essen- 

 tial to electrolysis. 



Professor Lodge also says : 



For any element, whatever, the number of atoms 

 liberated in any time is equal to the number of 



