Singularities of the thermodynamic functions at condensation points

The role played by vapor fluctuations in the form of liquid drops in the process of a phase transition is investigated and it is shown that although these fluctuations affect only a negligibly small fraction of the matter allowance for them leads to the appearance of the singularities on the phase equilibrium curves predicted by the theory of Lee and Yang. It is also shown that the presence of such a singularity does not prevent one describing either stable or metastable states of the matter in the framework of the classical theory of phase transitions.