Direct observation of capillary condensation of a solid

We describe the direct condensation of a solid from vapor in an annular mica wedge. Neo-pentanol initially condenses as a liquid from 8 to 57 degrees C (the melting point T(m)), followed by nucleation of a solid from vapor for T<45 degrees C. Menthol (T(m) = 42 degrees C) gives only liquid condensates down to 12 degrees C. The adsorbed films of neo-pentanol, which unlike those of menthol show layering transitions, and the disordered crystalline phase of bulk neo-pentanol appear to facilitate condensation of the solid phase. There is evidence for a change in the nature of the solid neo-pentanol condensate with T.