This is the fourth edition of an established textbook of chemical thermodynamics used by university and technical college students of chemistry and chemical engineering. The text covers the same ground as previous editions, presenting the general theory of chemical equilibrium, including its statistical development, and illustrating its many applications in the laboratory and industry. This edition has been extensively revised in the light of recent contributions to the literature. Many new references have been added; the re-writing of certain passages, especially of those concerning the statistical interpretation of entropy and the present understanding of order-disorder transitions, also reflects changes of emphasis.