illiniumn.

1926 J. A. Harris et al. in Nature 5 June 792/2 X-ray analysis confirmed the theory and showed the presence of element number 61 in those fractions... The name assigned to the element is Illinium (Il).

1926 Chambers's Jrnl. 480/2 In honour of the university where it was discovered, the new element has been called Illinium.

1931 E. N. da C. Andrade in Observer 18 Oct. 22/4 In 1926 the rare earth 61 was discovered in America, and named Illinium.

1939 Nature 9 Dec. 959/1 The existing data about No. 61, which is called illinium or florentium, are derived from X-ray spectral lines in the L- and K- series.

1947 Nature 4 Jan. 8/2 The names ‘masurium’ and ‘illinium’ are so firmly rooted in text-books and tables that recent work on artificial isotopes of the elements 43 and 61 is sometimes referred to as the production of species of masurium and illinium.

1951 J. R. Partington Gen. & Inorg. Chem. (ed. 2) xvi. 436I Promethium, an artificial element, fills the place of atomic number 61 missing in the natural rare-earth series, the supposed natural ‘illinium’ not having been confirmed.

1962 F. A. Cotton & G. Wilkinson Adv. Inorg. Chem. xxxi. 871 As early as 1926, several groups of workers reported optical and X-ray evidence for the existence of element 61 in various lanthanide concentrates, and the names Illinium, Il, and Florentium, Fl, were proposed by workers at the Universities of Illinois and Florence.