Abstract: A calorimeter that includes a sample cell, a reference cell, a pressure system that applies a variable pressure to the sample cell, and a pressure controller that controls the pressure applied by the pressure system to the sample cell. By applying identical pressure perturbations to both the sample and reference cells over a range of temperatures, the calorimeter can be used to accurately calculate both the thermal coefficient of expansion of various substances, and the volume change of molecules undergoing a structural transition.