Experimental Study of the Absolute Temperature Scale. XI. Deviation of the International Practical from the Kelvin Temperature Scale in the Range 0° to 444.6°C

Abstract

The deviations of the International Practical Temperature Scale from the thermodynamic Celsius scale were determined at eleven temperatures in the range 0° to 444.6°C by a comparison of the indications of four platinum resistance thermometers with those of two constant-volume nitrogen-gas thermometers in a stirred-liquid thermostat. In each gas thermometer several different ice-point pressures were used to permit corrections to be made for the imperfection of the thermometric fluid. The arithmetic means of the observed differences between temperatures on the thermodynamic Celsius scale as it was defined in 1954 and those on the IPTS at the eleven temperatures, each weighted in accordance with the number of observations, are represented by the equation t(therm.)−t(Int.)=[−0.0060+(0.01t−1)(0.04106–7.363×10−5t)](0.01t),where t in the right-hand member is on the IPTS. The standard deviation of a determination of Δt of unit weight from the equation is 18×10−4 deg.