“…Both these effects have been discussed by Irish (1956) who concluded from measurements made on neodymium that this electron multiplier caused no mass discrimination. Analyses of terrestrial barium isotopes, which were made in conjunction with the measurement of the 137 half-life of Cs (Farrar et al, 1961), gave relative abundances in exchange column to remove cationic impurities. This water was then redistilled twice in an all-quartz still.…”