355.     BRILL, R., AND MARK, H.  [Röntgenographic Studies on the Structure of Complex Iron Cyanides.]  Ztschr. physik. Chem., vol. 133, 1928, pp. 443-445; Chem. Abs., vol. 22, 1928, p. 3073.

       (NH₄)₄[Fe(CN)₆] and S of the substances resulting from its stepwise reduction at 400° with time were subjected to diffraction analysis.  3 crystalline phases were found, and in some cases many more.  Besides the initial compound and the final a-Fe, another compound certainly was (Fe(CN₂))_n, cubic, d₁₀₀=15.9 Å. U., molecular formula (Fe(CN)₂)₃=Fe₂[Fe(CN)₆].  Hence the reduction mechanism must be:  (NH₄)₄[FeCN)₆]→(Fe(CN)₂)₃→Intermediate carbides, nitrides, etc., →a-Fe.  The supposition is made that the appearance of certain extra lines in the diffraction pattern of the product obtained when H₂ and N₂ act on ammonium ferrocyanide at 400° is due to a carbide of unknown structure.