Thermoelectric Measurement of High Temperatures in Pressure Apparatus

Abstract

The effect of pressures up to 4000 kg/cm² upon the thermal electromotive force of chromelalumel, and of platinum‐platinum‐10 percent rhodium couples has been observed for hot‐junction temperatures up to 580°C. Within this range, the electromotive force of the chromelalumel couple is independent of the pressure, to within about 10 microvolts, or one‐quarter degree. An appreciable and regular effect is found for the platinum‐rhodium couple, amounting to a decrease of the electromotive force by about 16 microvolts, or 1.8°C at 500°, for a pressure of 4000 kg/cm². The results are presented as curves showing the decrease of electromotive force as function of temperature and pressure.