Chemistry. — “A Thermo-electrical Differential Method for the 
Determination of Transition Points of Metals at Comparatively 
Low Temperatures’. By Prof. A. Smits and J. Spuyman. 
(Communicated by Prof. P. Zeeman). 
(Communicated at the meeting of December 18, 1920). 
This paper should be considered as a continuation of the publi- 
cation “The Thermo-electrical Determination of Transition Points 1” ©). 
In the latter paper it was already stated that the very favourable 
results obtained by us on application of the thermo-electrical method 
in the investigation of the combination, iron-tin, and copper-tin, 
induced us to examine also other important metals in the same way, 
starting with copper. Our purpose was to examine in the first place 
whether copper shows a point of transition in the neighbourhood 
of 70°. The arrangement which we used at first for this purpose is 
represented in outline in the subjoined figure. 
Cull Ag Cul Cull 
q 
Fig. 1. 
The combination pure silver-pure copper (Cu 1), of which the 
copper wire is passed through a glass capillary, was placed in a 
wider tube 6, filled with an electrolyte, with which silver and copper 
were in electromotive equilibrium. For this purpose we took a 
solution of copper-sulphate, because the electrolyte, which is in 
1) These Proc. Vol. XXIII, 5, p. 687. 
