  Although its practical efficiency is unquestionable, the thermodynamic tool
presents a slight inconsistency from the theoretical point of view. After
exposing arguments, which explain this opinion, a suggestion is put forward to
solve the problem. It consists of linking the mass-energy relation d m = m
c^{2} to the laws of thermodynamics. This combination results in a
clarification of the theory and opens a bridge between thermodynamics and
gravitation. It is shown that the submicroscopic consideration, which is based
on the cellular concept of the real physical space when the space is treated as
the tessellation lattice, indeed strongly supports the idea of a variation in
mass in thermodynamic processes.
