Resistivity of Very Pure Th and Th—Rare-Earth Alloys

Resistivity data are given for pure thorium samples with a resistivity ratio [Γ=ρ₃₀₀^∘Kρ4.2^∘K] greater than 1000. At high temperatures, deviations of the resistivity from the Block-Gr\"uneisen relation correspond closely to the anomaly which is found in the specific heat. The resistivity at 300^∘{}K is found to be 15.8 {μ}{Ω}-cm. Thorium---rare-earth alloys show no resistance minimum of the type discussed by Kondo, to an accuracy of 0.001 {μ}{Ω} cm.