Starting from ten eutectic binary phase diagrams, the heat absorbed to melt completely a binary mixture from its solid state was plotted as a function of the mole fraction of one of the two components of the system. Surprisingly, a linear relationship was found for all the studied systems. The extrapolated total heat values at pure component composition (ie. x = 0 and x = 1) obtained via the heat capacity experimentally determined for each compound were interpreted as the melting enthalpies of the pure components at the eutectic temperature, for each binary system. A mathematical model is proposed that takes into account an ideal liquid state and an enthalpy in the liquid state independent of the temperature.