'Radio-Activity: An Elementary Treatise, from the standpoint of the disintegration theory', by Frederick Soddy MA (1877-1956), lecturer on physical chemistry and radioactivity at the University of Glasgow. Soddy conducted chemical research into radiactive materials, and is best known for his development of the theory of isotopes, the idea that some elements exist in forms that have different atomic weights but which cannot be distinguished from each other chemically. Although Soddy could not explain it (as the neutron was not discovered until 1932), this was due to different atoms of an element having different numbers of neutrons in their atomic nuclei. Nevertheles, Soddy's work earned him the Nobel Prize for Chemistry in 1921.
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