1059.    FORESTIER, H., AND LONGUET, J.  [Formation of Cupric Ferrite at Low Temperature.]  Compt. Rend., vol. 208, 1939, pp. 1729-1730; Chem. Abs., vol. 33, 1939, p. 5764.

       By precipitation of a suitable mixture of ferric and cupric salts with NaOH, a mixture of Fe(OH)₃ and Cu(OH)₂ in molecular proportions was obtained.  On boiling this mixture in H₂O, ferromagnetism began to appear after ½ hr. and gradually increased, the limit being reached after about 24 hr., when it equaled that of CuO·Fe₂O₃ heated above 400°.  The Curie point was 455°.  X-rays indicated that the precipitate was at first amorphous and gradually became crystalline with boiling, developing the spinal structure of Cu(FeO₂)₂.  This is confirmed by the fact that KCN solution dissolves the Cu from the unboiled precipitate, but is without action on the ferromagnetic product.  The production of Cu(FeO₂)₂ takes place only in the presence of H₂O and between the anhydrous oxides.