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.

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Literature Abstracts

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.