"Gay-Lussac was one of the most brilliant of the French chemists, and spent his whole life in research. His principal subjects of investigation [included]... Iodine and its compounds. ...Gay-Lussac's Memoir on Iodine appeared in 1814. This substance had been discovered three years previously by Bernard Courtois. Davy, in respect of its analogy to chlorine, had declared it to be an elementary body. Gay Lussac, doubting this conclusion, made a careful investigation of iodine, and described its peculiar properties and those of its compounds. This substance was shortly afterwards recognised as an element."