  Finite size scaling (FSS) analysis of the liquid gas criticality is
complicated by the absence of any broken symmetry. This, in particular, does
not allow a straightforward finding of the coexistence line and the critical
point. The numerical flowgram (NF) method is adapted for a controlled
determination of the coexistence line and the critical point, with the critical
indices $\mu,\, \nu$ measured within 1-2% of the total error. The approach
based on the NF for measuring the non-analytical corrections to the diameter -
the mean density of the liquid and gas phases along the coexistence line - is
outlined. Our analysis is a first step toward a general evaluation of isolated
critical and multicritical points.
