Thermomagnetic and Galvanomagnetic Effects in Arsenic

Thermomagnetic and galvanomagnetic effects—The following coefficients expressed in absolute e.m.u. are determined at 20°C in a single plate of arsenic distilled in vacuum:—specific resistance, 4.6×${10}^4$; thermal conductivity, 3.68×${10}^6$; Peltier heat against lead, 3.80×${10}^5$; Thomson heat, 3.33×${10}^3$; Hall coefficient, 4.52×${10}^{-2\mathrm{}}$; Nernst coefficient, 2.25×${10}^{-3\mathrm{}}$; Ettingshausen coefficient, 1.75×${10}^{-7\mathrm{}}$; Righi-Leduc coefficient, 4.15×${10}^{-7\mathrm{}}$. Between 0° and 170°C the temperature coefficient of resistance is 0.00435 and the thermal e.m.f. against copper is $+(7.91\mathrm{} t+0.051\mathrm{} t^2)\times {10}^{-6\mathrm{}}$ volts. None of these coefficients shows variation with magnetic field strength. Thermodynamic relations between different effects are checked as to order of magnitude but the difference between observed and computed values often differs by a factor of two. The thermomagnetic and galvanomagnetic effects of arsenic, antimony and bismuth show increase with atomic number; the thermal conductivity decreases. The thermal and electrical conductivity of arsenic deviates markedly from the Wiedemann-Franz ratio. When a longitudinal temperature gradient of 10°C/cm existed in the plate, a field of 8000 gauss caused a drop in temperature of 0.4°C. This temperature change is proportional to the square of both temperature gradient and field strength.