ABSTRACT
The existence of a heavy isotope of hydrogen had been suspected even though F. W. Aston in 1927, from mass spectrometric evidence, had discounted the presence of the heavier isotope at specific hydrogen abundance ratio. H. C. Urey, F. G. Brickwedde, and their colleagues had knowledge of the differences in nuclear spins, as well as magnetic and quadrupole moments, between isotopes of the same element. They probably estimated the chemical differences among isotopes to be small, perhaps too small to be measured by contemporary experiments. Any successful separation, therefore, was likely to be achievable largely by virtue of the difference in masses of isotopes of the same element. A suspected isotope of hydrogen had a mass two or three times that of the predominant hydrogen. The search for a hypothetical hydrogen isotope caused great excitement and led to a high-stakes competition among laboratories.
