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Thus the radio elements formed strange and cruel families in which each member was created by spontaneous transformation of the mother substance: radium was a "descendant" of uranium, polonium a descendant of radium.

Ève Curie (1937). “Madame Curie: a biography”
Thus the radio elements formed strange and cruel families in which each member was created by spontaneous transformation of the mother substance: radium was a descendant of uranium, polonium a descendant of radium.