2075.     LE CLERC, G., AND LEFEBVRE, H.  [Comparison of Catalytic Activity of Allotropic Varieties of Nickel.]  Compt. rend., vol. 208, 1939, p. 1650-1651; Chem. Abs., vol. 33, 1939, p. 5732.

        Reduced Ni gradually loses catalytic power when the mixture CO+2H₂ is passed over it at 175°, but this is recovered on heating the Ni to 250° in a vacuum or in N₂.  A similar loss of catalytic power is shown in the hydrogenation of C₆H₆ to C₆H₁₂ or of Me₃CO to Me₂CHOH.  This loss of power is accompanied by transformation of the Ni from the ferromagnetic cubic to the nonmagnetic hexagonal form.  No such loss of catalytic or magnetic power is shown in the similar transformation of Co; the change in Ni would, therefore, appear to be connected with a change in its electronic structure.