Nickel in Electrochemical Series

C. Drucker placed nickel in the electrochemical series... Zn, Fe, Cd, Tl, Co, N, Pb,...; and B. Neumann,... Zn, Cd, Fe, Co, N, Pb,... G. Tammann's observations were discussed in connection with cobalt. M. Faraday, and J. C. Poggendorff observed the place of nickel in the electrochemical series in dil. sulphuric acid; S. Marianini, in sea-water with 1/100th part of sulphuric acid; M. Faraday, and A. Avegadro and V. Michelotti, in dil. nitric acid; M. Faraday, in conc. nitric acid; M. Faraday, in hydrochloric acid; J. C. Poggendorff, in a soln. of potassium cyanide, and of potassium ferrocyanide; M. Faraday, in potassium hydroxide, and potassium sulphide. M. M. Haring and E. G. van der Bosche found cobalt to be more electropositive than nickel. The subject was studied by A. S. Russell and co-workers, H. T. S. Britton, E. Dubois, G. N. Glasoe, R. Vieweg, and by C. B. Gates; and J. E. Schrader examined the effect of heat treatment on the contact difference of potential. W. J. Muller and K. Konopicky showed that nickel exhibits a motoelectric effect, in that a current is produced in a short-circuited cell, consisting of two similar electrodes, with one electrolyte, by a movement of one electrode. T. Mashimo observed that with electrodes in a M-soln. of ferric chloride, with agitation at one electrode, the potential at the disturbed electrode was positive, and at the undisturbed electrode, negative. S. Procopiu found the e.m.f. of nickel electrodes moving in water, in 0.2N-H₂SO₄, and 0.2N-HNO₃ to be, respectively, 0.010, 0.072, and 0.054 volt. C. E. Mendenhall and L. R. Ingersoll found that globules of metal on a Nernst's glower move against the current.

O. Erbacher studied the ionic exchange with nickel and a soln. of a nickel salt; and H. Brintzinger and co-workers, the hydration of complex ions. A. Heydweiller found the ionic mobility of nickel, ½N^••, to be 44.2 at 18°. A. Feiler gave 50.5; K. Murata, 45.1 at 18°, and 53.0 at 25°; E. Rona, 48.0 at 18°; W. Althammer, 50.1 for the chloride, 51.1 for the bromide, and iodide; and W. Riedel gave for soln. with a mol of the salt per 21.5 and 300, the respective values 0.3616 and 0.3960. W. Ostwald calculated the heat of ionization, Co→Co^••, to be 68 kilojoules on the assumption that the heat of ionization, H₂=2H^•, is zero. J. D. Bernal and R. H. Fowler calculated for the ionization energy of the Co^••-ions, 580 Cals. per gram-ion.