Abstract
The melting behavior of histamine was investigated by AC calorimetry. The sample consisted of both crystalline solids, with regular ordered arrays of components held together by uniform intermolecular forces, and amorphous solids, which are not arranged in regular arrays. The melting point of histamine was about 84℃. The specific heat became a frequency-dependent complex quantity at and around the melting point. The specific heat was determined to be a “dynamic” specific heat. The frequency dependence of the measured dynamic specific heat was described by the Debye relaxation function. With temperature increases, the relaxation time became faster, from 28s to 7s. This indicated that the progress of the melting transition was slow and that the intermolecular force was strong. At temperatures below the melting point (61℃-67℃), we observed a thermal anomaly. Therefore, it was considered that both endothermic and exothermic reactions occurred in the amorphous solids.
