3614.     WATASE, T.  Heat of Formation of Cementite.  Sci. Repts. Tôhoku Imp. Univ., vol. 17, 1928, pp. 1091-1109; Chem. Abs., vol. 23, 1929, p. 1046.

        Cementite prepared by subjecting plates of C steel (2% C) to electrolysis with N HCl and a current density of 0.075 amp. per cm.,² was burned in a Berthelot-Mahler bomb calorimeter, and its heat of combustion was determined.  From the observed amount of heat evolved and the composition of the combustion residue, the heat of the reaction Fe₃C+3 O₂=Fe₃O₄+CO₂ was found in the literature for the formation of Fe₃O₄ and for CO₂, the heat of formation of cementite is calculated to be -4.8 kcal. at 20°.