Identifier: plat61492301909124124unse (find matches)
Title: Platinum resistance thermometry at high temperatures
Year: 1909 (1900s)
Authors:
Subjects: thermometry, pyrometry and calorimetry Heat flow, thermal and thermodynamic processes
Publisher: National Bureau of Standards
Contributing Library: NIST Research Library
Digitizing Sponsor: NIST Research Library

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s, the relation of the scales defined bythese thermometers to the standard gas scale of the Physikalisch-Technische Reichsanstalt being known. The correction foremergent stem of the thermometer, which amounted to 1 °.5 to 30,was determined by means of a Mahlke fadenthermometer. Aconical radiation screen of thin sheet iron, as shown in Plate VIII,was used. Rothe found for the S. B. P. 4440-7 on the constantvolume scale of the air thermometer. With two thermocouplesthat were calibrated on the scale of the Holborn and Day constantvolume (Pt-Ir bulb) nitrogen thermometer, the standard hightemperature scale of the Reichsanstalt, but which was not pri-marily intended for the highest attainable accuracy at the lowerrange of temperatures, Rothe found for the S. B. P. 445 °.o. Variation of S. B. P. with Pressure.—The following relationsfor the variation in temperature of the S. B. P. with pressurehave been used: Waidner. 1Burgess. J Platinum Thermometry at High Temperatures. PLATE VIII 187
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ELECTRICALLY HEATED S.B.P. APPARATUS 0 cm GAS HEATED S.B.P. APPARATUS 10 188 Bulletin of the Bureau of Standards. ivoi. 6, No. 2.t = t760 +0.082 (p-760) (1) * = *760 +O.O88 (p - 760) (2) * = £760+0.090 (p-760)+0.0002 (p-760)2 (3) t = t760+ 0.0912(p-760) -0.000042 (p-760)2 (4) / = *760+0.0904^-760) -0.0000519 (p-760)2 (5) Equations (1) and (2) were deduced from Regnaults observa-tions, the former by Griffiths from observations including a widerange of pressures, and the latter by Chappuis and Harker fromthe observations nearest atmospheric pressure. Equation (3) wascomputed by Chree57 from a large number of observations of thesteam points of platinum thermometers carried out at differenttimes at Kew Observatory, the total range of barometric pres-sure being, however, only about 30 mm. Equations (4) and (5),the former given by Holborn and Henning130 and the latter by theHarker and Sexton127, are the results of experiments especiallyplanned with a view to the determination of the temper

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