The freezing point of palladium

Abstract

The International Temperature Scale, which has been in force since 1927, 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 1063·0º C, while for extrapolation from this temperature use is made of the Wien law of radiation with a certain value of the constant c 2 . Though any temperature above 1063º 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 by the various users of it, and, when well authenticated, to provide secondary standards for its realization. Probably the most important of the fixed points referred to are the freezing points of palladium, platinum, rhodium, and iridium. The first-mentioned point has been the subject of considerable investigation in the past and a value of 1555º C has been assigned to it in the list of secondary points given in the appendix to the specification of the International Temperature Scale.