  We present the results of a study of specific heat on a single crystal of
Pr$_{0.63}$Ca$_{0.37}$MnO$_3$ performed over a temperature range 3K-300K in
presence of 0 and 8T magnetic fields. An estimate of the entropy and latent
heat in a magnetic field at the first order charge ordering (CO) transition is
presented. The total entropy change at the CO transition which is $\approx$ 1.8
J/mol K at 0T, decreases to $\sim$ 1.5 J/mol K in presence of 8T magnetic
field. Our measurements enable us to estimate the latent heat $L_{CO}$
$\approx$ 235 J/mol involved in the CO transition. Since the entropy of the
ferromagnetic metallic (FMM) state is comparable to that of the charge-ordered
insulating (COI) state, a subtle change in entropy stabilises either of these
two states. Our low temperature specific heat measurements reveal that the
linear term is absent in 0T and surprisingly not seen even in the metallic FMM
state.
