Physical properties of heavy-oxygen water. Part 2.—Vapour pressure

Abstract

A method has been developed for measuring small differences between the vapour pressures of two samples. V.p. differences were determined between water samples with a high concentration of oxygen-18 (H₂O¹⁸ and D₂O¹⁸) and samples with a low concentration in the temperature range 15–90°C. Differences between the vapour pressures of water containing ∼55 % O¹⁷ and samples containing high concentrations of O¹⁶ and O¹⁸ respectively, in the range 40–90°C, have also been measured. Using these results, vapour pressure ratios between the pure isotopic species were calculated.