(Formula presented) and CO condensed into nanoporous glasses have been investigated by vapor pressure measurements and x-ray diffraction as a function of temperature and fractional filling. The pore material is stable with respect to bulk condensation for any fractional filling. The adsorbate on the pore walls has to be distinguished from the capillary condensate in the center of the pores. This distinction can be made not only in the liquid, but also in the solid state. The solid capillary condensate is quasi-hcp at higher temperatures. (Formula presented) remains in this state down to the lowest temperatures, even in pores as large as 130 Å diameter, whereas CO transforms into the orientationally ordered (Formula presented) phase. On heating an orientationally disordered intermediate phase with a fcc center-of-mass lattice is observed.
