1. Craig, H., Science, 133, 1833 (1961).
2. Conley, R. F., and Bundy, W. M., Geochim. et Cosmochem. Acta, 15, 57(1958).
3. In this experiment the observed value of the fractionation factor was 1.0065, higher than in the other cases reported in Table 1; this could be due to the small amount of water in proportion to the calcium sulphate and to the bad stirring of the resulting mixture. This could perhaps be responsible for the fact that isotopic equilibrium between gypsum and the mother-water was not completely attained.
4. Taube, H., J. Phys. Chem., 58, 523 (1954).
5. Baertschi, P., Helv. Chim. Acta, 36, 1352 (1953).