An important part of inorganic chemistry is the study of the behaviour of chemical elements and their compounds. If this behaviour is to be explained with any confidence, it needs first to be described in quantitative language. Thermodynamics provides such a language, and Dr Johnson's 1982 book is concerned with the theoretical explanations that become possible after the translation into thermodynamic language has taken place. This book will continue to be of interest to advanced undergraduate and postgraduate students of chemistry, as well as teachers of chemistry in both schools and universities.