Reanalysis of the density of liquid water in the range 0–150 °C and 0–1 kbar

The change of density of liquid water under pressure has been calculated from the speed of sound u by fitting u−2 as a polynomial in temperature and pressure, integrating with respect to pressure, and allowing for the difference between isothermal and adiabatic compressions. By comparing calculations done by different methods on the same data and on different data it appears that the densities so obtained are accurate to about 20 ppm at 1 kbar. These densities are about 100 ppm greater than the densities obtained by us some years ago by direct measurement of the compressions in the range 0–150 °C and 0–1 kbar relative to a stainless steel vessel. It seems likely that the compressibility of the vessel used in this work is too high by about 0.1 Mbar−1. A correction to the compressibility of the vessel is proposed to bring the densities in the range 0–100 °C and 0–1 kbar into agreement with the values from the speed of sound. The same correction should apply in the range 100–150 °C, and the corrected values ...