2745.     PREUNER, G.  [Equilibrium Between Iron, Ferrosoferric Oxide, Hydrogen, and Water Vapor.]  Ztschr. physik. Chem., vol. 47, 1904, pp. 385-417; Jour. Chem. Soc., 1904, II, p. 317.

        According to the equation 3 Fe+4 H₂O=Fe₃O₄+4 H₂, p₁/p₂, where p₁ is the water vapor pressure after equilibrium has been reached and p₂ the H₂ pressure under the same conditions, should be a constant for a given temperature.  This was found to be the case at 3 temperatures, 900°, 1,025° and 1,150°, the mean values of p₁/p₂ being 0.69, 0.78, and 0.86, respectively.  In these experiments, p₁ was varied between 8.8 and 49.3 mm.  The heat effect of the reaction 3 Fe+4 H₂O=Fe₃O₄+H₂, obtained by inserting the values of the equilibrium constants in van’t Hoff’s equation, is calculated to be 11,900 cal. at 960°, while calculations from calorimetric data give 42,890 cal.  When used in calculating the heat of formation of ferrosoferric oxide, the value 11,900 cal. gives a result much more in harmony with Baur and Glaessner’s work than does the value of 42,890 cal.

        PRIBYTKOVA, N. A.  See abs. 2916.