3095.     ---------------.  [SCHMIDT, J.]  [Nonexistence of a Higher Nickel Carbide.]  Ztschr. anorg. Chem., vol. 216, 1933, pp. 85-98; Chem. Abs., vol. 28, 1934, p. 1618.

        Since Fe forms a higher carbide and since H Tutiya had reported detecting a  higher Ni carbide, (abs. 3505) Schmidt attempted to prepare it by X-ray analysis.  CO was passed over Ni (reduced by H2) for 240-465 hr. at 240°-250°.  All samples of carbide thus obtained contained 0.4-1.3% free C and 6.8-7.8% combined C.  Although the latter was higher than the theoretical (6.37%) for Ni3C, this was the only compound detected by X-ray studies.  As all the possible places for C in the space lattice of Ni3C are not filled, Schmidt assumes that the excess C takes some of these places without distorting the crystal.  The density of Ni3C computed from crystal data is 7.880 gm. per cc.; the experimental value (d254) was found to be 7.957 gm. per cc.  The excess C in the crystal may help account for the difference.  The products of decomposition with acids were CH4, C2H6, C2H4, and H2, all being evolved in varying proportions.  The results of decomposition were not reproducible.  When CH4 was passed over Ni, C was formed but no carbide.  C2H2 gave Ni3C and much C.  Bibliography.