402 



ScHOCH ') found — 0,48 V by the method described above, and 

 also when measuring in an Nj-atmosphere. 



ScHiLDBACH '), workiug according to the method Schoch, likewise 

 finds a value which is in very good agreement with that of Schoch. 



It was of importance to examine whether in a solution ofNiCl^ 

 the same influences of H, and 0, would be found. The Cl-ions 

 exerting so strong a catalytic influence on the setting in of the 

 internal equilibrium of iron, it was possible that here too the influence 

 was noticeable, and would prove to be stronger than the disturbing 

 intluence of 0, and H,. This has not appeared to be the case. 



In 2.5 n. NiCl^ in H,-atmosphere we found : 



jsjij —0.604 V, Nil I -0.600 V, H, —0.607 V 

 after addition of HCl : 



Ni 1 - 0.379 F, Nl 11 — 0.372 V, H, — 0.376 V. 



The behaviour of nickel in NiCl, is therefore quite analogous to 

 that in NiSO,. 



S U M MARY. 



The researches on the electromotive behaviour of some metals, 

 made in the Amsterdam laboratory of late years show that one of 

 the most charactei-istic properties of a metal is the velocity with 

 which it assumes equilibrium at a definite temperature and pressure. 

 At the ordinary temperature and pressure this velocity is on the 

 whole exceedingly small for a metal in dry condition. In contact 

 with an electrolyte this is, however, quite different, but at the same 

 time we meet then with complications throngh the appearance of 

 catalytic actions, both positive and negative ones, which render a 

 comparison of the behaviour of different metals ditficull. It occurs 

 namely that in the same metal the equilibrium sets in quickly in 

 one electrolyte and slowly in another ; thus iron assumes internal 

 equilibrium e.g. with great velocity, when it is immersed in a solution 

 of FeClj, and this takes place mnch more slowly in a solution 

 of FeSO,. 



There are, however, metals that also in contact with an electrolyte 

 assume internal equilibrium slowly, and nickel, which has been 

 discussed in this communication, is one of these metals. 



Now it has appeared of late, that not only oxygen, but also 

 hydrogen can be negative catalyst for the establishment of the internal 



1) I.e. 



«) Z.f. Electr. Chem. 22 [1910] 977. 



