90.     ARWELL, J. C. AND BARSS, W. M.  Comparison of the X-Ray Diffraction and Nitrogen Adsorption Surface Areas of Carbon Blacks and Charcoals.  Canadian Jour. Research, vol. 26, sec. A, 1948, pp. 236-242.

                Surface areas, as determined from X-ray diffraction and low-temperature N adsorption data, were compared for a number of C-blacks and activated charcoals.  Comparative data were obtained also on samples of charcoal at various stages of activation and after calcination.  The X-ray diffraction data indicated that all the samples examined were composed of small, graphite-like crystallites of the same order of magnitude, which had specific surfaces of about 2,500-3,000 m.² per cc.  The N adsorption surface of a highly activated charcoal was found to be about equal to the X-ray surface.  It is suggested that the crystallite surface represents the potential-adsorption surface of a carbonaceous material; and, providing that crystal growth does not occur during activation, the activation process makes these surfaces available to external adsorbate.

                ASCHE, W.  See abs. 1610.