During some experiments which I have been making on the unequal resistance to the deposition of a metal upon cathodes of different metals in the same solution by the same current (see “Some New Phenomena of Electrolysis”), I have been led to investigate the resistance of cathodes of different metals to the passage of the current into them. I have found that by taking a good conducting electrolyte, immersing in it a positive sheet of zinc, and a smaller negative one of another metal, connecting the plates with a galvanometer of low resistance, reducing all the other resistances in the circuit to the minimum except that of the negative plate; then making a series of measurements of strengths of current of different couples formed by the zinc and about twelve other metals, during removal of polarisation by stirring the liquid; also making another series of measurements of the electromotive forces of the same couples during stirring; calculating from these data the total resistance in each case, then deducting the portion of resistance due to the galvanometer, also that due to the liquid itself, and to opposing contact-potential, and thermo-electric and voltaic action at the cathode and external junction, very different amounts of resistance, large in some cases, remain, and are exercised by different metals as cathodes, and those differences of resistance are only to a small extent due to heat and current absorbed in liberating hydrogen, and can only in a few cases be partly accounted for by chemical action, films, or absorption of gases at the cathode.