The vapour pressure of liquid oxygen

Abstract From a thermodynamic equation the temperature dependence of the pressure of the saturated vapour of liquid oxygen was calculated using available experimental information. Simultaneous measurements of the vapour pressure of liquid oxygen and of the resistance of a number of platinum thermometers were carried out in two different apparatuses. The platinum thermometers were previously calibrated on the gas thermometer scales of NBS, PSU, PRMI and NPL respectively. Temperatures derived from the pressure measurements using the thermodynamic p - T relation were compared with temperatures derived from the platinum thermometer readings. The temperatures are nearly equal. Fig. 5 shows that their difference can be represented by a smooth curve. The triple point of oxygen was also measured. We found for the vapour pressre at the triple point 1.097 5 mm Hg at 0°C and standard gravity and for the vapour pressure 54.350°K. A formula for the p - T relation of oxygen is proposed and a table has been calculated.