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The construction of a constant-volume gas thermometer for use between 10 K and 300 K is described. The thermometer features gas-flow temperature control and the capability for continuous operation. Relative PV isotherms giving values for thermodynamic temperature and the second virial coefficient for 4He were measured at 27 K, 43 K, 54 K, 63 K and 84 K referenced to 20 K on NPL-75 and at 172 K referenced to 273.15 K. Further measurements at the isotherm temperatures referenced to 273.15 K were used to redetermine the reference temperature at 20 K. Constant-volume gas-thermometry measurements were carried out at 72 temperatures between 13.81 K to 287 K. The results agree well with NPL-75 from 13.81 K to 27.1 K but differ from IPTS-68 significantly from 27.1 K to 273.15 K.

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