181.    BEECK, O., SMITH, A. E., AND WHEELER, A.  Catalytic Activity, Crystal Structure and Adsorptive Properties of Evaporated Metal Films.  Proc. Roy. Soc. (London), vol. 177, 1940, A, pp. 62-90; Chem. Abs., vol. 35, 1941, p. 2061.

                 Metal films of high reproducible catalytic activity were obtained by condensation of their vapors on glass at any desired temperature.  The catalytic activity was measured by the hydrogenation of C₂H₄.  The crystal structure of these films was investigated by electron diffraction.  By controlling the pressure of an inert gas N₂, A, and others, during evaporation of the metals, unoriented and oriented films could be produced at will, and their catalytic activities were compared.  Completely oriented Ni films were obtained with an inert-gas pressure of 1 mm., the (110) plane, the least dense of the planes, lying parallel to the backing and the 2 remaining axes showing random distribution.  Fe films were oriented with their (111) plane parallel to the backing, again the least dense plane thus oriented.  Low-pressure adsorption of H₂ at room temperature and of CO at liquid-air temperature revealed that the oriented gas-evaporated Ni films have 2 times the available surface/gm. of randomly oriented high-vacuum films, but 10 times the activity.  The oriented films have therefore 5 times the activity of unoriented films.  Oriented films of an available surface equal to unoriented but of 5 times the activity could also be obtained in high vacuum by evaporation onto oriented films previously produced by evaporation in an inert gas.  The activity/unit weight of the films was constant; this indicates ready accessibility to the interior of the film by the reacting gases.  Adsorption of H₂ was found to be immeasurably fast in all cases.  Adsorption isotherms on Ni films were obtained for C₂H₄, CO, N₂, H₂, and O₂; and the effect of catalyst poisoning by CO and O₂, as well as the effect of sintering, was studied.  Loss of activity, decrease of H₂ adsorption, and amount of poison were found to be proportional.  The most extensive studies were made on Ni films, but films of Fe, Co, Pd, Pt, and Cu were also investigated, and with the exception of Cu similar results were obtained.  The enhanced activity of oriented films appears to be associated with the larger distances in the (110) plane of Ni or the (111) plane of Fe.  The bearing of the results on the definition of active centers and on the general problem of adsorption is discussed.

                  BEERY, D. W.  See abs. 15a.

                  BÉGUI, Z. E.  See abs. 550.

                  BELETSKIĬ, M. S.  See abs. 3371.