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Literature Abstracts

 1410.    HERROUN, E. F., AND WILSON, E.  Magnetic Susceptibility of Certain Natural and Artificial Oxides.  Proc. Phys. Soc. (London), vol. 33, 1921, pp. 196-206; Chem. Abs., vol. 15, 1921, p. 3023.

        Susceptibility of Fe2O3, as occurring in nature, varies through a wide range, but in the case of artificial preparations the range of variation seems to be much greater.  The highest susceptibility exhibited by Fe2O3 occurs when either FeO or Fe3O4 is oxidized at a high temperature in the anhydrous condition.  From hydrated Fe3O4, the susceptibility, though considerable, is much less.  The lowest susceptibility is obtained from native hematites or naturally oxidized chalybite or by the ignition or precipitation of ferric salts.  It appears that the passage through the stage of Fe3O4 impresses more pronounced magnetic properties upon the resulting Fe2O3.  The susceptibilities of a number of ferrites were measured, of which that of Cu ferrite is most conspicuous, being higher than those of Co or Ni ferrites or any similarly constituted compound except Fe3O4 itself.  Heating feebly magnetic Fe2O3 with a basic oxide, as CaO or MgO, increases susceptibility (confirming List and others).  When higher susceptibility has been produced by heating Fe2O3 with a basic oxide, such as Ag2O or HgO, subsequent removal of the metal leaves the Fe2O3 in a magnetic condition.  The chemical compounds formed when Fe2O3 is replaced by Al2O3 show no definite increase in susceptibility, which is in marked contrast with the ferrites.  In the cases of Co and Mn the susceptibilities of the different oxides show a steady decrease with increase of O2, and, unlike Fe, there is no increase in the susceptibility of Co3O4 and Mn3O4 corresponding with Fe3O4.  Although the susceptibility of Cu is negative, that of each of its oxides is positive but small in magnitude.

       HETHERINGTON, H. C.  See abs. 150.