To isolate Fe3C, the sheet is placed in a neutral FeCl2 bath and used as an anode at the lowest possible current density. The bath is the same as used in the preparation of electrolytic iron. [p. 1490.] In this way very pure Fe3C is left behind as a coarsely crystalline gray powder. It is washed with dilute acetic acid, water, alcohol and ether, and dried in vacuum.
Alternate methods: a) Iron carbide may also be isolated quantitatively while measuring the anode potential; see E. Houdremont, P. Klinger and G. Blaschczyk, Techn. Mitt. Krupp, Forschungsber. 4, 311; Arch. EisenMitteinw. 15, 257 (1941).
b) Solution of white, low-Si pig iron in 1N acetic acid; see O. Ruff and E. Gersten, Ber. dtsch. chem. Ges. 45, 64(1912).
c) For the preparation of almost pure fused Fe3C, see F. Wever, Mitt. KWI Eisenforschung 4, 67 (1923).