Sir
I read with interest the material from the 13 May 1950 issue of Nature reported in “50 Years Ago”1. However, the statement “In 1940 the first isotopes of the elements 93 (neptunium) and 94 (plutonium) were produced…” is not quite correct.
The uranium sample that ultimately yielded element 94 was bombarded with deuterons in the Berkeley 60-inch cyclotron on 14 December 1940. From the bombarded sample, Glenn Seaborg and co-workers isolated a chemical fraction of element 93 (neptunium) for subsequent studies. To quote Dr Seaborg, “Element 94 was born at last, on the night of February 23–24, 1941.”2 Actually, element 94 was not named ‘plutonium’ until March 1942.
Seaborg's interest in element 94 was stimulated by Edwin McMillan's isolation of element 93 in 1940.
References
Nature 405, 131 (2000).
Seaborg, G. T. “Plutonium Revisited” in The Radiobiology of Plutonium (eds Stover, B. J. and Jee, W. S. S.) (J. W. Press, Salt Lake City, 1972).
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Richmond, C. How neptunium led to the birth of plutonium. Nature 406, 455 (2000). https://doi.org/10.1038/35020248
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DOI: https://doi.org/10.1038/35020248
