The fifth edition of Thermodynamic and Transport Properties of Fluids incorporates two new tables: other material is being retained essentially as in the fourth edition, although tables beyond p.11 will be on different pages.The new tables are as follows: Data of Refrigerant 134a (tetrafluoroethane - CH2F-CF3) are being added because this refrigerant is environmentally more acceptable than Refrigerant 12 which it replaces. The table of R12 is being retained, however, because R12 will survive in much equipment for a long time. At present it is still uncertain whether R134a is a medium-term substitute, or will be used for much longer than a decade.Figure 15.11 from Engineering Thermodynamics, Work and Heat Transfer (Rogers & Mayhew, Longman 1992) is being included. The table contains, for selected substances, molar enthalpies and molar Gibbs functions of formation, and Equilibrium constants of formation, as well as molar heat capacities and absolute entropies.