134.    ------------. [BAHR, H. A., AND JESSEN, V.] [Fission of Carbon Monoxide on Iron Oxide and Iron.]  Ber. deut. chem. Gesell., vol. 66B, 1933, pp. 1238-1247; Chem. Abs., vol. 28, 1934, p. 984.

                  Pure Fe₂C (9.7% C) can very probably be prepared from Fe and CO at 225° or lower; at 230°-400°, a mixture of Fe₂C, Fe₃C, with free C probably results; while above 400° only Fe₃C (6.68% C) is formed.  Carbonized products obtained by means of Fe oxide always contain O; detection of combined C by hydrogenation with H₂ is not quite trustworthy in this case and must be performed at 255°-260°.   The products obtained with Fe up to 330° are free from O; at higher temperatures, the oxidizing action of the liberated CO₂ is observed.  The hydrogenation of combined C with H₂ can take place at 280°-290°.  Carbide formation occurs relatively rapidly; subsequently, the main reaction is the separation of free C.