Zero coverage thermodynamic properties of adsorption on Sterling FT graphite at 60-degrees-C obtained by using gas-solid chromatography are presented for the five adsorbates from neopentane through carbon tetrachloride resulting from sequential substitution of a chlorine atom for a methyl group. Enthalpies of adsorption (as well as of vaporization of pure liquid) are reproduced by a simple model that ascribes a fixed attractive energy to each of the C-CH3 and C-Cl bonds, and a third contribution proportional to the square of the molecular dipole moment of the adsorbate. The role of the C-Cl dipole in the total attraction of adsorbate for the surface is compared with its role in mutual attraction in the liquid state, and it is found to be significantly weaker in the former. It is estimated that neopentane loses about 6% of its rotational freedom upon adsorption, while the adsorbates containing from one to four chlorine atoms lose from 11 to 15%.