Comments on the behaviour of some thermodynamic characteristics of   single component substance in the region defined by the line of liquid vapor   equilibrium
  It is shown that in general case may be not correct the statements of [1,2,6-8] that 1) the isochoric heat capacity on the entire thermodynamic surface, including the metastable region of states and the region defined by the spinodal, remains positive and finite except for the critical point, and 2) the isobaric heat capacity becomes negative in the region defined by spinodal. 
I. H. Umirzakov
cond-mat.other