Establishment of a temperature scale for the calibration of thermometers between 14 degrees and 83 degrees K

Abstract

Seven resistance thermometers (six Pt; one 90Pt:10Rh alloy) have been calibrated on the thermodynamic scale by comparison with a helium gas thermometer. The boiling point of oxygen was taken to be 90.19° K, and computations were made in such a w ay as to secure continuity between the International Temperature Scale and the scale being established. On the latter scale the triple point of normal h ydrogen was found to be 13.96° K and the boiling point 20.39° K. Tables have been prepared by means of which temperatures corresponding to observed resistances may be obtained by linear interpolation.

Calorimetric properties of diphenyl ether from 0-degrees to 570-degrees-K

“…Csat .= 59.9 1D T ' (3) fitted to the h eat capacity at 18°, 20°, and 22° K . The values tabulated b etween 300° and 360° K were obtained by adjusting th e slight differen ces b etween the results wi th the low-temperature adiabatic calorimeter and th e ice calorimeter.…”

“…The initial and final t empera tures of a heating interval wer e measured by m eans of a platinum resistan ce th ermometer and a G-2 Mueller bridge. The platinum r esistan ce thermomet er was calibrated at this Bureau abo ve 90° K on the In terna tional T empera ture Scale [2] and b etween 10° to 90° K on a provisional scale [3], which consists of a set of platinum r esistance thermomet ers calibrated against a gas thermomet er . The resistance of the thermometer was frequ ently checked at the ice point, and the small fluctuations observed were too insignificant to affec t the r esults of the m easurem en ts .…”

Platinum Resistance Thermometry

“…Because the ITS^-27 [15] extended only 7 C below the normal boiling point of oxygen ( 182.962 C), the National Bureau of Standards was moti vated to develop a practical scale from the oxygen point down to approximately 11 K [28]. This scale has been variously referred to as the NBS pro visional scale, the Hoge and Brickwedde scale, and most recently as the NBS 39 scale; directly related to this scale is the NBS-55 scale (TNBS -55 ^NBS-39-0.01 K) [50], These NBS scales have had widespread use but, together with the previously mentioned international scales, have now been supplanted by the International Practical Tempera ture Scale of 1968 (IPTS-68) [51] (see Appendix A for the complete text of IPTS-68 and Appendix C for the difference in values of temperature).…”

Application of precise heat-capacity data to the analysis of the temperature intervals of the NBS (1955) and the International Practical Temperature Scales in the region of 90 °K

“…In the region from 10 to 90 oK a pro visional temp erature scale has been maintained at the National Bureau of Standards in terms of it set of platinum resistance thermometers. The thermometers now being used to maintain the NBS proyisional scale are "two generations" remo,' ed from the origi nal th ermometers that were compnred directly with a helium-gas thermometer in 1939 [2] . The present NBS provisional temperatme scale is designated NBS (1955) and is defined to be 0.01 deg lower than the NBS (1939) scale [2].…”