Hugh Aldersey-Williams has more to say about the spelling episode of alumin(i)um :
America and France may have pioneered the development of aluminium, but they disagreed over its spelling. Even the great editor H. L. Mencken is at loss to explain this. In the American Language he is forced to confess: ‘How aluminium, in America, lost its fourth syllable I have been unable to determine, but all American authorities now make it aluminum and all English authorities stick to aluminium.’ Other sources suggest it may have been the doing of Charles Hall. The patents he took out while his commercial publicity material touted the merits of ‘aluminum’, whether by intent or typographical error is not known. The shorter word spread and stuck in the United States; in France, Britain and the rest of Europe, the extra syllable remained.
The extra syllable was also around in the U.S. until 1925 . Then the American Chemical Society officially decided to use the name aluminum in their publications. Ever since, scientists and engineers are doomed to live with a dual spelling policy for alumin(i)um—switching between aluminum and aluminium depending on which journals they read and where they publish. Fortunately, the element symbol Al is undisputed!
Keywords: chemical element, renaming, history, orthography, typography.
References and more to explore
 David R. Lide (Editor): Handbook of Chemistry and Physics. CRC Press, Boca Raton, 88th Edition 2007-2008; page 4-3.
 Hugh Aldersey-Williams: Periodic Tales: a cultural history of the elements, from arsenic to zinc. Harper-Collins Publisher, New York, NY 10022, 2011; page 260 [www.harpercollins.com/Srch/index.aspx?search=periodic tales].