Discrepancies in the Isotopic Weight of ¹²C

Abstract

OF some forty isotopic weights so far determined by the doublet method, more than half depend on that of ¹²C as a substandard. As chairman of the International Committee on Atoms, I am anxious that some agreement should be reached on this isotopic weight to enable a satisfactory table to be adopted. Ill-health has prevented me making any further measurements for the past year, but Mattauch has recently published results¹ indicating that my value 12.00355 ± 0.00015 is too low. He gives as his own 12.003876 ± 0.000032, closely agreeing with Bainbridge and Jordan's latest value, 12.00398 ± 0.00009. Much as I regret being compelled to criticize the results of other workers, I feel it may be well to explain some of the reasons which prevent me accepting the high value with entire confidence.