The "1958 He Scale of Temperatures": Part 1. Introduction.

The generally used practical scale of temperatures between 1° and 5.2° K is the He vapor pressure scale based on an accepted vapor pressure equation or table. In Sèvres (near Paris), October 1958, the International Committee on Weights and Measures recommended for international use the "1958 He Scale" based on a vapor pressure table arrived at through international cooperation and agreement. This table resulted from a consideration of all reliable He vapor pressure data obtained using gas thermometers, and paramagnetic susceptibility and carbon resistor thermometers. The theoretical vapor pressure equation from statistical thermodynamics was used with thermodynamic data on liquid He and the vapor equation of state to insure satisfactory agreement of the vapor pressure table with reliable thermodynamic data.