3576.     ---------------.  [VON STACKELBERG, M.]  [Crystal Structures of Several Carbides and Borides.]  Ztschr. Elektrochem., vol. 37, 1931, pp. 542-545; Chem. Abs., vol. 25, 1931, p. 5812.

        In order to form a carbide of the CaC2 type, hydrolyzing to C2H2 with H2O, a minimum metal-ion size is necessary.  The metallic properties of most carbides of this formula are due to the presence of 2 extra valence electrons.  Ca, Sr, Ba, La, Ce, and Th form borides of formula MeB6 with CsCl-type cubic lattice.