It has been shown previously that when adsorbates act as single component complexes, i.e. behave as single substances in complex force fields, volumetric mean adsorbate and mean adsorbent stress intensities can be calculated from adsorption isotherm data. When potentials of surface regions in the micropore system of a porous adsorbent are statistically independent of pore structure, linear mean stress intensities of the solid are related to volumetric means through an equation containing a structure factor which is independent of the nature and pressure of the adsorbed gas.In this paper we present adsorption extension data for an active carbon rod when exposed to helium, hydrogen, nitrogen, argon, krypton, and water at pressures up to 1600 p.s.i. The data suggest that the potentials of the capillary regions are not independent of structure. An empirical correlation factor is introduced and the resulting semiempirical equation describes the data probably within the experimental error.The results suggest that in cases of moderately strong adsorption, adsorption potentials of thick-walled capillary regions are higher than those of thin-walled regions.