Gas-adsorption chromatography has been used to calculate adsorption isotherms and isosteric heats of adsorption (q_st) for the reactants and products of oxychlorination at low coverage on CuCl₂ and CuCl. The heat of adsorption at zero coverage of ethylene on CuCl₂ is 65 ± 5 kJ mol^–1, indicating chemisorption. On CuCl, ethylene is only physically adsorbed (q_st= 13 kJ mol^–1, heat of liquefaction = 14.45 kJ mol^–1). The adsorption of C₂H₄ is shown to be unaffected by the alumina support or by oxygen, but an excess of HCl appears to decrease the adsorption. The unsaturated nature of the adsorbate is evidently a vital factor; ethane and 1,2-dichloroethane give heats which are close to the heats of liquefaction, but with ethylene and propene (55 kJ mol^–1) the heats are considerably higher and with acetylene and buta-1,3-diene chlorination occurs.

The technique of gas-adsorption chromatography is successfully extended to the injection of liquids at sufficiently high temperature that vapourisation is instantaneous. The heat of adsorption of water vapour on CuCl₂ is 64 kJ mol^–1(the heat of liquefaction is 40.6 kJ mol^–1).