550.    CHEVALIER, R., AND BÉGUI, Z. E.  [Thermomagnetic Properties of Ferric Oxide.]  Bull. Soc. Chim., vol. 4, No. 5, 1937, pp. 1735-1742; Chem. Abs., vol. 32, 1938, p. 3219.

                  Coefficients of magnetization, _X at 20° and 720°, were measured by Curie’s method, for some 20 Fe₂O₃ samples differing in preparation.  For these the Curie point is remarkably constant between 690° and 700°.  Above this temperature, _X is constant, with a mean value of 19X10^-6 at 720°, even when the oxides contain traces of impurities.  This value appears to be a lower limit for the susceptibility of Fe₂O₃ and characterizes a-Fe₂O₃.  It is the value for very fine, artificial oxide at ordinary temperature, for very finely pulverized hematite, for hematite along the crystal axis, as well as for all the oxides above the Curie point.  The different preparations at 20° gave widely differing values of _X.