The thermal and electrical conductivity of copper at low temperatures

Following previous work on sodium, the thermal and electrical conductivity of copper has been measured continuously between 90 and 2° K . The specimen was of spectrographic purity, and had been found to have a pronounced minimum in the electrical resistance at about 10° K . A similar, but smaller, anomaly was observed in the thermal resistivity with a corresponding small deviation from the Wiedemann-Franz law at the lowest temperatures. As in the case of sodium, marked disagreement with theory was found in the temperature variation both of the thermal conductivity and of the Lorenz number.