569.    CHUFAROV, G. I., AND VILESOVA, G. F.  [Influence of the Crystalline Lattice of an Oxide Upon the Speed of Reduction With Hydrogen.]  Teoriya I Prakt. Met., No. 4, 1936, pp. 10-17; Chem. Abs., vol. 30, 1936, pp. 8115-8116.

      Experiments were performed with grains of 0.5-1.0 mm. and with cubes of 5 x 5 x 5 mm. prepared from natural crystals of hematite and magnetite.  Artificial oxides were prepared from piano wire.  Reduction with H₂ was conducted at all possible temperatures up to 800°-900°.  Above 600° the ultraporosity and microporosity of the magnetite reduction products is small.  This blocks the penetration of the gas and the reduction is hindered.  Below 600° the magnetite is sometimes reduced faster than the hematite.  At higher temperatures the small crystal structure favors reduction, but at low temperatures it may hinder it because of its great adsorption of the reduction products.

     CINES, M.  See abs. 828.