Isotope Effect in the Solution of Oxygen and Nitrogen in Distilled Water

The isotopic fractionations of nitrogen and oxygen in water have been measured in the range 2°—27°C. The extrapolated values at 0°C of k′/k, the ratio of Henry's Law constants, are 1.00085 (±0.00010) for nitrogen and 1.00080 (±0.00015) for oxygen in the sense of the heavier species being more soluble. Several possible sources are recognized for the observed effects which are, however, of the magnitude to be expected from the motion of point masses in ``iceberg'' cavities of reasonable dimensions.