Extended List of Secondary Reference Points

The International Practical Temperature Scale of 1968 (IPTS-68), Amended Edition of 1975 includes, as did its predecessors, a table of secondary reference points (s.r.p.'s) that assigns values to phase transformation temperatures of many highly pure substances.These points are not part of the IPTS-68 per se, and the IFTS-68 makes no statement regarding the probable accuracy of the listed temperatures.When Working Group I1 (W.C. 11) of the Consultative Committee for Thermometry (CCT) was established in 1971, one of its assigned tasks was to revise, extend, and improve this list of s.r.p.'s.The revision of Table 6 of the IPTS-68 for the Amended Edition of 1975 was based upon the first two reports of W.G. 11.Recently, the CCT has been urged from many parts of the scientific community to increase the number of s.r.p.'s.In addition, since Table 6 was last revised, many new accurate determinations of phase transformation temperatures have been reported.Further, a simple listing of s.r.p.'s (such as Table 6) provides the user with no information regarding how to realize the points.For these reasons the CCT at its 1 1 th Session in June 1976 asked W.G. I1 to publish an extended list of s.r.p.'s.This extended list is intended to partially fill the