In addition to the earlier data for the specific gravity of oxygen-18 water: d=1.112±0.001 and 1.113±0.001, obtained from measurements on water samples in which oxygen-18 was depleted, there have appeared in the last two years new observations made on samples with moderately and highly concentrated oxygen-18. Zhavoronkov and coworkers gave d=1.10723±0.00002, while