  A new method that characterizes thermal properties during a first-order phase
transition is described. The technique consists in exciting the sample by a
series of constant frequency thermal pulses which one in every N pulses (N is a
small number like four) being exceedingly large in amplitude. This pulse
induces phase transformation which is inhibited during the following smaller
pulses due to thermal hysteresis. That way the specific heat for a given
mixture of phases can be determined. The results obtained are independent of
experimental parameters like the rate and the amplitude of the pulses, unlike
what happens in other calorimetric techniques. The method also provides the
enthalpy excess by analyzing the energy balance between the dissipated heat and
the heat flowing during each pulse of measurement.
  The protocol is tested to analyze the phase transitions of a Heusler alloy Ni
50.54 Mn 33.65 In 15.82 . The paramagnetic-ferromagnetic transition for the
austenite phase is continuous and the specific heat shows a lambda anomaly. The
martensitic phase transition shows a first-order character and the specific
heat follows a step-like behaviour in contrast with previously reported
large-peak anomalies.
