  A critique is presented of the frequently used Bruce-Wilding (BW) mixed-field
scaling method for estimating the critical points of nonsymmetric model fluids
from grand canonical simulation data. An explicit, systematic technique for
implementing this method is set out thereby revealing clearly a fortunate,
close cancelation of contributions from the leading correction- to-scaling and
thermal scaling functions that makes the method effective for Ising-type
systems but which lacks a general theoretical basis. Pressure mixing is
considered in this work which modifies the leading behavior of the critical
density estimator while the critical temperature estimator maintains the
leading behavior asserted by BW.
