669.    DAVIS, R. T., Jr., DEWITT, T. W., AND EMMETT, P. H.  Adsorption of Gases on Surfaces of Powders and Metal Foils.  Jour. Phys. and Colloid Chem., vol. 51, 1947, pp. 1232-1248; Chem. Abs., vol. 42, 1948, p. 1102.

     Adsorption isotherms for N₂, Kr, n-C₄H₁₀, 1-C₄H₈, and CHCl₂F were measured at temperatures at or below their boiling points and found to be S-shaped on Ag foil, monel ribbon, glass spheres, W powder, ZnO pigments, Al₂O₃ and SiO₂ gel.  Cross-sectional areas that had to be assigned to the various adsorbates to bring the calculated surface areas for the last 5 of these adsorbents into agreement with those obtained from adsorption isotherms for N₂ by assigning an area of 16.2 Å.² to the N₂ molecule were:  Kr, 20.8 Å.² at –195°; C₄H₁₀, 43.4 Å.² at –78° and 46.9 Å.² at 0°; CHCl₂F, 37.5 Å.² at –78° and 40.1 Å.² at 0°; and 1-C₄H₈, 42.7 Å.² at 0°.  For Ag foil and monel ribbon, these same molecule area assignments yielded absolute areas that were 10% to 60% larger than the geometric surface area when CHCl₂F, n-C₄H₁₀, and Kr were used as adsorbates.  With molecule area, assignments calculated for these 3 adsorbates from liquid density in the usual way (abs. 827) the surface areas of the Ag foil and monel ribbon obtained from Kr, C₄H₁₀, and CHCl₂F were smaller than the geometric area by as much as 25%.