831.    EMMETT, P. H., AND KUMMER, J. T.  [Physical and Chemical Adsorption Studies on Catalysts.]  Jour. Chim. Phys., vol. 47, 1950, pp. 67-73; Chem. Abs., vol. 44, 1950, p. 6711.

      Theory for the multilayer adsorption of gases on solids (abs. 389) still appears to yield reliable values for the surface area of porous and finely divided solids, though according to Halsey (abs. 1340, it is doubtful if the assumptions of the theory are valid.  N₂²⁸ and N₂³⁰ react rapidly to form N₂²⁹ over Fe catalysts at 450°-500°, contrary to previous conclusions (abs. 1639).  Singly promoted Fe-synthetic-NH₃ catalysts rapidly catalyze the reaction H₂+D₂=2HD at –195°, even though D₂ does not remove H adsorbed at –78° or 100° from the surface at –195°.   Adsorption measurements indicate the existence of a new type of activated adsorption on Fe capable of occurring rapidly at –195°.  Chemisorption measurements, using normal CO as well as radioactive CO, indicate that Fe-synthetic-NH₃ catalysts behave as though half the surface was homogeneous and half heterogeneous.  The measurements were made by covering part of the surface with radioactive CO and the remainder with normal CO at low temperatures and then collecting and analyzing the evolved CO for radioactivity as the temperature was slowly raised.