| Abstract | In a recent article, Kiyosawa [J. Solution Chem. 33, 323 (2004)] reports that the freezing points of isotopic mixtures of ordinary water and 17O enriched water show an unexpectedly large linear dependence on the concentration of H2 17O. Surprisingly, the constant of proportionality to the H2 17O concentration is nearly five times larger than that of H2 18O found in earlier studies by Kiyosawa [J. Solution Chem. 20, 583 (1991)]. We show that the H 2 17O result is not consistent with other data or models. For example, a recent determination of the triple point temperature dependence on isotopic composition in naturally and artificially depleted waters [White et al. in Temperature, Its Measurement and Control in Science and Industry, Vol. 7, D. C. Ripple, Ed., AIP CP 684, 221-226 (2003)] is consistent with the H 2 18O and D2O results from Kiyosawa (1991) [White and Tew in Report of the 22nd Meeting of the Consultative Committee for Thermometry, Document CCT/03-21, BIPM, Severes, France, 2003] but is inconsistent with the H2 17O results from Kiyosawa (2004). Additionally, the results from Kiyosawa (1991) are close to what would be found in ideal solutions for those isotopic forms, whereas the H2 17O proportionality from Kiyosawa (2004) is about 10 times larger than similarly predicted. One possible explanation is that the original 17O enriched water sample contained a small amount of D2O, and the sample, if available, should be subject to isotopic analysis to help resolve these inconsistencies. © 2005 Springer Science+Business Media, Inc. |
