The adsorption of oxygen on a high-temperature superconductor is not inhibited by superconducting forces. The equilibrium adsorption isotherms of oxygen and nitrogen on superconducting YBa2Cu3O7-x and (Bi,Pb)2Sr2Ca2Cu3Ox at 77 K are equivalent. Moreover, the equilibrium adsorption of oxygen on superconducting YBa2Cu3O7-x and (Bi,Pb)2Sr2Ca2Cu3Ox and on nonsuperconducting SiO2 at 77 K are equivalent. These results agree with theoretical arguments that predict the magnetic repulsion of oxygen from a superconductor to be significant over a distance of angstroms. At these distances, the magnetic forces are constrained by the superconductor's penetration depth and no Meissner effect is observed, contrary to the results of past reports.