can be rearranged as Z = 1 + ( B 0 − − A 0 R T − − c T 3 ) ρ ρ − − ( B 0 b − − A 0 a R T + B 0 c T 3 ) ρ ρ 2 + ( B 0 b c T 3 ) ρ ρ 3 The Benedict-Webb-Rubin equation of state of 1940 represents better isotherms below the critical temperature: Z = 1 + ( B 0 − − A 0 R T − − C 0 R T 3 ) ρ ρ + ( b − − a R T ) ρ ρ 2 + ( α α a R T ) ρ ρ 5 + c ρ ρ 2 R T 3 ( 1 + γ γ ρ ρ 2 ) exp ⁡ ⁡ ( − − γ γ ρ ρ 2 )