The magnetic susceptibility of two polycrystalline rods of hafnium (Hf I and Hf II) was observed from 4.22°K down to 0.08°K. The electrical resistance of these specimens was also observed from room temperatures down to 0.08°K. While the magnetic measurements indicated unambiguously that no superconducting transition occurred, the electrical resistance did, however, exhibit a decrease at approximately 0.19°K for Hf I and 0.28°K for Hf II. The resistance did not fall to zero but remained finite down to the lowest temperatures obtained. The temperature at which this decrease occurred was found to be sensitive to an externally applied magnetic field. Critical field data were obtained for Hf I which indicated a ${\left(\frac{\mathrm{dH}}{\mathrm{dt}}\right)}_{T=T_c}$ of 450 gauss/degree. Magnetic and electrical measurements obtained for one of the specimens, subsequent to an anneal, indicated no marked change in these measured quantities. Both these specimens had a stated purity of 98.92%.

The magnetic susceptibility of a third specimen of hafnium was observed and a superconducting transition was noted at 0.173°K. This specimen was in the form of lathe turnings and was approximately 96% pure. A few critical field points were obtained which yield a value for ${\left(\frac{\mathrm{dH}}{\mathrm{dT}}\right)}_{T=T_c}$ of 130 gauss/degree.

From a consideration of all the available data concerning the superconductivity of hafnium, it is felt that pure hafnium is probably not a superconductor down to a temperature of 0.08°K.

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