Some Precise Measurements of the Vapor Pressure of Water in the Range From 25 to 100 °C.

The vapor pressure of water was measured at seven temperatures in the range from 25 to 100 °C using the boiler and precision manometer with which standard resistance thermometers were calibrated at the NBS in the 1940's. A table gives measured values of pressure, adjusted to even degrees, and indicates estimates of the standard deviations of pressure and of the corresponding temperatures. Except for the measurement at 25 °C, the values of pressure were consistent within one part in 50 000. The temperature measurements had an estimated standard deviation of 0.000 40 degree.