ELECTROLYSIS AND ELECTRO-CHEMISTRY. 227 



JEledrolysis and Electro-chemistry. — Report of the Committee, consisting 

 of Mr. W. N. Shaw (Chairman), Mr. E. H. Griffiths, Rev.T. 0. 

 FiTZPATRiCK, My. W. C. J). Whetham (Secretary), on the present 

 state of our knowledge in Electrolysis and Electro-chemistry. 



Appendix. — The Tlieory of the Migration of Ions and of Specific Ionic Velo- 

 cities. By W. C. Dampiee Whetham, M.A page 227 



The experiments upon the electrical properties of solutions, in relation to 

 their thermal properties, towards the expenses of which a grant of 50?. 

 was made, are in progress. The apparatus for the measurement of the 

 resistance of solutions has been designed, constructed, and tested. It has 

 been proved to work satisfactorily by test experiments with pure water 

 and with solutions of potassium chloride. 



The cost of the apparatus, the essential parts of which had to be madfr 

 of platinum, has exceeded the amount of the grant. 



The expenses incidental to the completion of the experiments are 

 estimated by the Secretary at 35?., and the Committee desire that that, 

 sum be placed at their disposal in the ensuing year. 



The section of the report on electrolysis treating of the theory of 

 migration of ions and of specific ionic velocities prepared by Mr. 

 Whetham last year is printed as an appendix to this report. 



The Committee regret that the pressure of other engagements has 

 prevented further progress with the compilation of the report. 



The Committee ask for reappointment, with a grant of 35?. 



APPENDIX. 



(f) The Theory of the Migration of Ions and of Specific Ionic Velocities^.. 

 By W, C. Dampier Whetham, M.A. 



The liberation of the products of electrolysis at the electrodes, and at 

 the electrodes only, shows that a continuous passage of the opposite ions in 

 opposite directions through the liquid must be going on. Whether the 

 ions are free from each other during their passage, or accomplish their 

 journey by means of continual decomposition and recombination of mole- 

 cules, does not matter for our present purpose. The numbers of the ions 

 in the middle portion of the liquid do not change, but, while the current 

 passes, a constant excess of anions is delivered at the anode, and of 

 kations at the kathode. 



If the opposite ions move with equal velocities, the result of the 

 passage of the current will be that, while the composition of the middle 

 portion of the solution remains unaltered, the products of the decomposi- 

 tion, which appear at the electrodes, are taken in equal proportions from 

 the solution surrounding the anode, and from that round the kathode. 



If, however, one of the ions travels faster than the other, it will get 

 away from the portion of the solution whence it comes more quickly than 

 the other ion enters. The concentration of this region will therefore fall 

 faster than that of the liquid round the other electrode, and the ratio 



Q2 



