1438. ---------------. [HOFER, L. J. E., AND COHN, E. M.] Thermomagnetic Determination of Hägg Carbide in Used Iron Fischer-Tropsch Catalysts. Am. Chem. Soc., 117th Meeting Abs., March-April, 1950, p. 36-J; Anal. Chem., vol. 22, 1950, pp. 907-910.

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Literature Abstracts

1438. ---------------. [HOFER, L. J. E., AND COHN, E. M.] Thermomagnetic Determination of Hägg Carbide in Used Iron Fischer-Tropsch Catalysts. Am. Chem. Soc., 117^th Meeting Abs., March-April, 1950, p. 36-J; Anal. Chem., vol. 22, 1950, pp. 907-910.

Being capable of measuring the Curie points and magnetic moments of ferromagnetic materials, the magnetic balance is suitable for relatively rapid qualitative and quantitative determination of the ferromagnetic phases in used Fe Fischer-Tropsch catalysts. Because of the nature of the samples and the method, special consideration must be given to the magnetic field strength, elastic effects, remanent force, sampling technique, shape of sample, and heating schedule. These points are discussed, and it is shown how a composite thermomagnetic curve may be resolved into its components when their characteristic magnetic constants are known. In connection with X-ray and chemical analyses, and by means of a few simple equations, the relative abundance of ferromagnetic phases can be calculated. This procedure is illustrated for the 3-component system Fe₂C – Fe₃O₄ – a – Fe, and the significance of the magnetically nondetectable Fe is discussed.