For many thermodynamic calculations in oceanography it is necessary to know the effect of pressure (or depth) on various thermodynamic properties. … Recently, a new equation of state for sea-water (Millero et al., 1980; Millero and Poisson, 1981) has been adopted by the UNESCO/ICES/IAPSO joint panel on oceanographic tables and standards. By appropriate differentiation of this equation of state, it is possible to determine the pressure derivatives for the specific volume of seawater solutions. To estimate the effect of pressure on the partial molal thermochemical properties (Millero and Leung, 1976), it is necessary to know the partial molal volumes of"sea salt" and water as a function of pressure. This can be accomplished by fitting the apparent molal volumes (c{>,,) of seawater solutions to a function of pressure...