CONSTANT-VOLUME GAS THERMOMETRY BETWEEN 4-K AND 100-K

Gas-thermometer measurements between 4 K and 100 K have been performed as part of the preparatory work in several institutes for a future, revised, International Practical Temperature Scale. Gas-thermometer temperatures are compared, between 13. 8 K and 100 K, with platinum resistance thermometers calibrated on IPTS-68 and, between 4. 2 K and 27. 1 K, with rhodium-iron resistance thermometers calibrated. Results of the measurements, with NPL-75 at 20. 3 K as a reference temperature for the gas thermometer, show agreement with NPL-75 within 0. 3 mK over most of the range.