  Treating the cosmological constant as a thermodynamic pressure and its
conjugate quantity as a thermodynamic volume, we reconsider the critical
behaviour of charged AdS black holes. We complete the analogy of this system
with the liquid-gas system and study its critical point, which occurs at the
point of divergence of specific heat at constant pressure. We calculate the
critical exponents and show that they coincide with those of the Van der Waals
system.
