The properties of Heusler's alloy, and the true specific heat of manganese and its discontinuity

The physical properties of a sample of Heusler's alloy made in Prof. F. C. Thompson's laboratory at the University of Manchester have been examined. The experiments, which were always carried out on the same specimen, comprised determinations of density, intensity of magnetization, critical temperature, Curie's constant, electrical resistivity and its temperature coefficient, thermoelectric power and mean and true specific heat. A determination has also been made of the true specific heat of the metal manganese and a large discontinuity has been found about 350°C., which is near to the critical temperature of Heusler's alloy. It was further found that the heat-capacity of the alloy is the sum of the heat-capacities of its constituents both below and above the critical temperature, thus following Regnault's rule, and the same rule can be applied to magnetite.