When the properties of solid coal are compared with those of other common substances, coal seems in many ways unusual and mysterious. For example, almost any set of measurements of coal properties will exhibit time-dependent variation. This dynamic behaviour, commonly referred to as weathering, is known to affect adversely the physical and chemical properties which make coal valuable or desirable as an energy resource or basic material for the chemical industry. This book deals with the molecular-level origins of commonly observed time-dependent variations in the physical properties and chemical constitution of coal which are associated with the weathering process. Primary attention is devoted to the description of what are judged to be among the most important physical phenomena, their conceptual interpretation, and their relationships to various technical aspects of coal utilization, transport, and storage. The text is copiously referenced and indexed so as to make the material as accessible as possible. Chemistry of Coal Weathering is an ideal complement to standard textbooks dealing with coal science and technology, materials science, geochemistry and physical chemistry.