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A d escription is given of an apparatus used for d etermining t h e t hermal conductivities o f solids in t h e temperature range 4 K to 300 K. The apparatus is especially suited to the determination of thermal condu ctivity over a la rge temperature interval , enabling coverage of t h e temperatures between t he normal boil ing points of liquefi ed gases. Illustrati ve res ults ar e given for an insulator, poiytetrafiuoro ethylene, and for a high-conduct ivity co mmerci al coalesced copper. The thermal conductivity of the insulator increases monotonically from 0.56 milliwatt per centimeter p er degree K at 5 K , to 2.32 at 80 K. The t h ermal conductiv ity of the copper has a maximum of 24.9 watts p er centimeter p er d egr ee K at 21 K , and a value of 8. 15 at 5 K. The m ethods of data analys is a nd estimat ion of errors are given.
Powell et al. (1957) studied this question.