Eq. 8 can never be zero unless T=Tc*. It is similar to the definition of internal energy in the conventional thermodynamics. As discussed above, for a symmetric molecule, 𝐻 𝑣 ∅ is constant, irrespective of temperature and pressure. However, for an asymmetric molecule, B is different due to the different packing status of molecules in the liquid at various temperatures. Hence, ∆𝐻 𝑣 ∅ is variable. However, the variation is generally slight except for water below M.P. For example, in Fig. (9) Reminiscent of the pressure at saturation, 𝑙𝑛𝑃 -𝑙𝑛𝑃 𝑐 * = 𝑙𝑛𝑥 2 (10) Thus, provided that A and ∆𝐻 𝑣 ∅ are independent to the temperature,