Measurement of Absolute Water Density, 1 °C to 40 °C

The absolute density of Standard Mean Ocean Water (SMOW) has been determined over the range 1 °C to 40 °C by weighing a hollow sphere of known volume in air-free water samples of measured isotopic content. The volume of the sphere as a function of temperature is known as a result of a combination of interferometric and mechanical measurements. The measured densities are tabulated. A formula (as proposed by Thiesen et al ) and a fifth-order polynomial in temperature have been fitted to the tabulated data by least-squares analysis. The density calculated from the polynomial is estimated to have a standard uncertainty ranging from 0,64 parts in 10 6 at 15 °C to 1,4 parts in 10 6 at 1 °C and 40 °C. Comparisons are made with published data.