The freezing-point of rhodium

• Published in: Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences Mathematical and physical sciences, 1939-11, Vol.173 (952), p.117-125, Article 117
• Main Authors: Barber, C. R., Schofield, F. H.
• Format: Article
• Language: English
• Subjects: Crucibles; Gold points; Ingots; Labor standards; Palladium; Physics; Platinum; Pyrometers; Rhodium; Temperature scales
• ISSN: 0080-4630; 2053-9169
• DOI: 10.1098/rspa.1939.0132

The International Temperature Scale, which has been in force since 1927 (Bureau International des Poids et Mesures 1927, 1934), is based on certain values assigned to the boiling- and freezing-points of pure substances and on specified means of interpolation between, or extrapolation beyond, these points. The highest basic point of the scale is the freezing-point of gold, defined as 1063-0° C, while for extrapolation from this temperature use is made of the Wien law of radiation with a certain value of the constant c2. Though any temperature above 1063° C is thus completely defined without reference to further fixed points, determinations of such points are of considerable value. In particular, they serve to indicate the degree of reproducibility of the scale and, when well authenticated, to provide secondary standards for its realization in cases where this is more convenient than a primary calibration. A good example of the use of secondary fixed points is the establishment by the National Bureau of Standards, U.S.A., of a scale of colour temperature (Wensel, Judd and Roeser 1934), based on the freezing-points of platinum (1773° C), rhodium (1966° C) and iridium (2454° C).