... Assume that gas is a thermodynamic system in the state of local equilibrium, that is, it is satisfied the relation [2] [pic] (1) There [pic],[pic] and [pic] are the temperature, the pressure and the gas volume, [pic], [pic] are entropy and internal energy per unit volume. ... Let us consider the first-degree form [pic]. ... Since the evolutionary relation is not identical, from this relation one cannot get the state differential [pic] that may point to the equilibrium state of the material system. ...