Temperature Measurement in Thermogravimetry

Abstract

A method is described whereby the temperature of a sample in a thermobalance may be determined directly without the large uncertainty that usually accompanies these measurements. The procedure consists of using a unijunction transistor relaxation oscillator with a thermistor as the resistive part. The entire primary circuit including the power supply is made part of the balance suspension and is weighed along with the sample. The frequency of oscillation which is a function of sample temperature is relayed to an events-per-unit-time meter via a mutual inductance between two suspended coils. The nonlinearity of the thermistor is removed to a considerable extent by a compensating circuit.