  The wetting behavior of thin films of 4'-n-octyl-4-cyanobiphenyl (8CB) on Si
is investigated via optical and x-ray reflectivity measurement. An experimental
phase diagram is obtained showing a broad thick-thin coexistence region
spanning the bulk isotropic-to-nematic ($T_{IN}$) and the nematic-to-smectic-A
($T_{NA}$) temperatures. For Si surfaces with coverages between 47 and $72\pm3$
nm, reentrant wetting behavior is observed twice as we increase the
temperature, with separate coexistence behaviors near $T_{IN}$ and $T_{NA}$.
For coverages less than 47 nm, however, the two coexistence behaviors merge
into a single coexistence region. The observed thin-thick coexistence near the
second-order NA transition is not anticipated by any previous theory or
experiment. Nevertheless, the behavior of the thin and thick phases within the
coexistence regions is consistent with this being an equilibrium phenomenon.
