Thermodynamics deals with energy levels and the transfer of energy between states of matter, and is therefore fundamental to all branches of science. This new edition is specifically tailored to the interests of the Earth sciences, and emphasizes throughout the use of thermodynamics to construct mathematical simulations of real systems. Many computer programs are mentioned and used throughout the text, especially SUPCRT92, a widely used source of thermodynamic data. An associated website includes links to useful information sites, computer programs and problem sets.