Fire is impartial and equally treats all,

It serves or burns, without bias one and all.

The first and second partial derivative of pressure with respect to density at constant temperature are also constrained to be zero at the above critical point. These constraints are quite easily made with essentially no detrimental effect to the P_V_T surface of the equation of state in other areas; however, even with the above constraints imposed upon the equation of state, the behavior is still not qualitatively correct at or near the critical point.