Dozens of authors have obtained experimental thermal curves of solid-solid reactions, carried out in bulk. Different mathematical functions were used to obtain fits to the thermal curve data. Polynomials were found to give the best fits to the data. The data may be divided into three types on the basis of the shape of the curves, with one peak, with two peaks and with three peaks. In this preliminary report we present one fitted curve of each of the three types as specimen. The importance of the Thermal Curves is briefly pointed out. A detailed discussion of the large amount of the available data may be taken up later.