  Earlier it was shown that the entropy of an ideal gas, contained in a box and
moving in a gravitational field, develops an area dependence when it approaches
the horizon of a static, spherically symmetric spacetime. Here we extend the
above result in two directions; viz., to (a) the stationary axisymmteric
spacetimes and (b) time dependent cosmological spacetimes evolving
asymptotically to the de Sitter or the Schwarzschild de Sitter spacetimes.
While our calculations are exact for the stationary axisymmetric spacetimes,
for the cosmological case we present an analytical expression of the entropy
when the spacetime is close to the de Sitter or the Schwarzschild de Sitter
spacetime. Unlike the static spacetimes, there is no hypersurface orthogonal
timelike Killing vector field in these cases. Nevertheless, the results hold
and the entropy develops an area dependence in the appropriate limit.
