  Preliminary experimental data for particle number ratios in the collisions of
Au+Au at the BNL AGS (11$A$ GeV/$c$) and Pb+Pb at the CERN SPS (160$A$ GeV/$c$)
are analyzed in a thermodynamically consistent hadron gas model with excluded
volume. Large values of temperature, T=140--185 MeV, and baryonic chemical
potential, $\mu_b=590$--270 MeV, close to the boundary of the quark-gluon
plasma phase are found from fitting the data. This seems to indicate that the
energy density at the chemical freezeout is tremendous which would be indeed
the case for the point-like hadrons. However, a self-consistent treatment of
the van der Waals excluded volume reveals much smaller energy densities which
are very far below a lowest limit estimate of the quark-gluon plasma energy
density.
