The effects of dissolved air and of natural isotopic distributions on the density of water have been determined at 1 atm by using a magnetic float densimeter. Dissolved gases were found to decrease the density by 3.0 ± 0.2 × 10-6 g cm-3 at 4°C. The apparent molal volumes of air were found to be nearly independent of saturation concentration and temperatures between 0° and 30°C....