The Thermodynamic Kelvin Temperature Scale from 273.15 K to 415 K.

The investigation of the effects of sorption in a gas thermometer used to realize the Thermodynamic Kelvin Temperature Scale has been continued. By eliminating sorbable material more completely from the gas thermometer, we attained higher gas purity. So little contaminant remained that further cleanup produced no significant effect on the values of thermodynamic temperatures measured between 0 °C and 142 °C. The results are presented by giving the differences between the values on the thermodynamic scale and the International Practical Temperature Scale of 1968. The value of the steam point was determined to be 99.970 °C(therm) with an uncertainty of ±3.5 mK at the 99 percent confidence level (based on 3 times the estimate of the standard deviation).