The suggestion by Sharp et al. (Biochemistry 30 (1991) 9686) that a vo
lume correction should be made to the standard chemical potential of a
non-polar solute molecule in water is examined by re-deriving their r
esults using an exact statistical mechanical procedure and comparing t
hem with those of a couple of other similar schemes. It is shown that
their suggestion is equivalent to choosing a standard state based on t
he ideal gas behavior.