738.    DOTTERWEICH, F. H., AND HUFF, W. J.  Colloidal Properties of Iron Oxide in Hydrogen Sulfide Removal.  Proc. Am. Gas Assoc., vol. 20, 1938, pp. 699-717; Gas Age, vol. 82, No. 9, 1938, pp. 43-44, 54, 56-58; Chem. Abs., vol. 33, 1939, p. 1473.

     Adsorption capacity, activity, and colloidal content of a number of Fe oxides used for removing H₂S from gas were measured.  These oxides were divided into 2 groups, (1) those containing more than 11% Al₂O₃ and (2) those containing less than that amount.  Oxides of group (1) showed increasing capacity and activity for H₂S absorption with decreasing particle size; those of group (2) showed greater activity but diminishing capacity with decreasing particle size.  Also oxides of the latter group are affected markedly in their activity by changes in alkali content.  Heating the oxides to 550° caused the particle size of all oxides to increase; this resulted in correspondingly lower activity.