The international temperature scale and a redefinition of the kelvin scale

The Tenth General Conference of Weights and Measures has accepted a redefinition of the Kelvin (absolute) temperature scale in terms of one fixed point, the triple point of water, to which a value of 273.16° K has been assigned. The International Temperature Scale continues to be defined in terms of 100° between the ice point (0.0100° C below the triple point of water) and the steam point. The relationship between the scales, and the approved designations are set out in a table. Work is being carried out with a view to future improvement of the international scale. It is hoped that it may be found possible to extend the range covered by the resistance thermometer both above and below its present limits of 630.5° C and -182.97° C, the latter temperature being the present lower limit of the international scale. If the resistance thermometer scale can be carried up to 1063° C (the freezing point of gold), it will be possible to eliminate the thermocouple as a standard instrument and so improve both the continuity and reproducibility of the scale.