Tables of Vapour Pressure of Liquid Helium

Abstract

THE usual method of measuring absolute temperature T in the liquid-helium range is to measure the vapour pressure p of the liquid-helium bath and convert it by means of an empirically determined p—T relation. In the past, confusion has sometimes arisen owing to the existence of several determinations of the p—T relation which differ appreciably from each other; at an informal meeting between representatives of cryogenic laboratories in Holland, the United States and Great Britain held in Amsterdam in July 1948, it was decided to use an agreed relation in future, and to present this relation in the form of tables for practical use. The most reliable existing data are not wholly satisfactory ; but since they are unlikely to be superseded for some years, it was thought best to make them the basis of the agreed relation until more accurate results are available. Tables have been prepared presenting p as a function of T, and T as a function of p, prefaced by a statement about the data on which they are based. Copies of the tables may be obtained on application to the Royal Society Mond Laboratory, Free School Lane, Cambridge.