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.