Further experiments with liquid helium. H. On the electrical resistance of pure metals etc. VII. The potential difference necessary for the electric current through mercury below 4°.19 K.

Abstract

In a previous Communication (No. 124c of Nov. 1911) we related that special phenomena appeared when an electric current of great density was passed through a mercury thread at a temperature below 4°.19 K., as was done to establish a higher limit at every temperature for the possible residual value of the resistance. Not until the experiments had been repeated many times with different mercury threads, which were provided with different leads chosen so as to exclude any possible disturbances, could we obtain a survey of these phenomena. They consist principally herein, that at every temperature below 4°.18 K. for a mercury thread inclosed in a glass capillary tube a “threshold value” of the current density can be given, such that at the crossing of the “threshold value”¹¹ the phenomena change. At current density below the “threshold value” the electricity goes through without any perceptable potential difference at the extremities of the thread being necessary.