Reproducibility of the Boiling Point of Oxygen and Its Pressure-Temperature Relation near 1 Atmosphere

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Abstract
The accuracy of the realization of the oxygen point has been investigated through calibration of two platinum resistance thermometers of capsule type against the vapour pressure of oxygen of which the purity has been strictly checked. From 65 measurements ranging from 660 to 860 mmHg of pressure, the International Practical Temperature t int,1948 has been found to be expressed by t int,1948=-182.97+9.5425(p/p 0-1)-3.686(p/p 0-1)2+2.28(p/p 0-1)3 where p 0 is 1 standard atmosphere, and the reproducibility attained has been ±0.00022 degree in terms of the standard deviation. The interpretation of the same data in the CCT64-scale of temperature is also given. Although the temperature value derived from resistance thermometers depends slightly on the characteristics of thermometers in use, it is concluded that the equation derived here are more accurate than that given in the text of the IPTS 1948.