This classic account stresses the role of time-scales in determining the nature and extent of state space, an approach that makes clear the unity of classical, kinetic, statistical, and process thermodynamics. "Superb....It has no equal....Should be read by anyone who wants to understand what thermodynamics--regarded as a branch of physics--is all about....No one concerned with thermodynamics, and not merely that of fluid systems, can afford to be without this book, be he undergraduate student, graduate student or research worker."--Journal of Fluid Mechanics