taken below 42Β°K using a specimen of pyrolytic graphite heat-treated at 3250Β°K. In conjunction with zero-field resistivity and magnetoresistance data it will be shown that the "usual" Lorenz number provides an adequate description of the magnetothermal behavior of graphite. At saturation, measurements as a function of temperature yield the intrinsic phonon component of the thermal conductivity; implications from the lattice-dynamic point of view will be briefly considered. 1. C, A. KLEIN and M. G. HOLLAND, Phys. Z&m. 136, A575 (1964).
- Electrical resistivity of sofi carbon below 4.2%* R. I. Gayley and 0. K. Griflith (State University of New York at 3u,@lo, Buffalo, New York). The electrical resistivities of a series of soft carbon specimens were measured as a function of temperatures from 4.2"K down to 1.3"K. For well graphitized samples it was observed that the resistivity has a msximum in the neighborhood of 4Β°K as was suggested by earlier measurements by Reynolds, Hemstreet, and Leinhardt.(r) For less well graphitized specimens heat treated at 1000Β°C and 1200Β°C there is also a maximum in resistivity near 4Β°K and, in addition, a rise setting in below about 3Β°K which may well be exponential. For intermediate heat treatments, no m~imum was observed.