The book contains the very latest information on all aspects of heat capacities related to liquids and vapours, either pure or mixed. The chapters, all written by knowledgeable experts in their respective fields, cover theory, experimental methods, and techniques (including speed of sound, photothermal techniques, brillouin scattering, scanning transitiometry, high resolution adiabatic scanning calorimetry), results on solutions, liquids, vapours, mixtures, electrolytes, critical regions, proteins, liquid crystals, polymers, reactions, effects of high pressure and phase changes. Experimental methods for the determination of heat capacities as well as theoretical aspects, including data correlation and prediction, are dealt with in detail. Of special importance are the contributions concerning heat capacities of dilute solutions, ultrasonics and hypersonics, critical behavior and the influence of high pressure.