Feinwanderung an elektrischen Kohle-Kohlekontakten

On carbon-carbon contacts operated with d.c. the author has observed carbon transfer in normal direction i.e. from the anode to the cathode, if the contact load does not exceed a certain value. This is the same direction as the well known "bridge transfer" in metal-metal contacts, although a liquid bridge cannot be formed in the gap of carbon-carbon contacts. This phenomenon is explained by the local heating of the anode, effected by electrons emitted from the cathode through the gap. Thus the anode is vapourized and carbon vapour condensed on the colder cathode. Anomalous transfer i.e. from the cathode to the anode may result, if the cathode is subjected to additional heat.