was discovered by Bernard Courtois in 1811. Courtois, who was born at Dijon in 1777, was apprenticed to a pharmacist at Auxerre named Fremy, grandfather of the noted chemist of that name, and was afterwards associated as assistant with Seguin, Thénard, and Fourcroy. He had worked with the first-named of these in the isolation of the active principle of opium, whereby Seguin so nearly secured the glory of the discovery of the alkaloids. In 1811 Courtois was manufacturing artificial nitre, and experimenting on the extraction of alkali from seaweed. He had crystallised soda from some of the mother liquor until it would yield no more crystals, and then he warmed the liquor in a vessel to which a little sulphuric acid had been accidentally added. He was surprised to see beautiful violet vapours disengaged, and from these scales of a grayish-black colour and of metallic lustre were deposited. Courtois was too busy at the time to follow up his discovery, but he brought it to the notice of a chemist friend named Clement. The latter presented a report of his experiments to the Academy of Sciences on November 20th, 1813, two years after Courtois’s first observation. No suggestion was made by Courtois or Clement of the new substance being an element. This deduction became the occasion of an acrimonious dispute between Gay-Lussac and Humphry Davy. The English chemist happened to be in Paris (by special favour of Napoleon) at the time when Clement read his paper. He immediately commenced experimenting, and was apparently the first to suspect the elementary nature of iodine. His claim was confirmed by a communication he made to Cuvier. But Gay-Lussac forestalled his announcement in a paper he read at the Academy on December 6th, 1813. Davy complained of the trick Gay-Lussac played him, and Hofer, who investigated the circumstances, came to the conclusion that Davy was certainly the first to recognise iodine as a simple _body_, and to give it its name from the Greek, Ion, violet. Ion was originally Fion, but had lost its initial. The Latin viola was derived from the original word. Jean Francois Coindet, of Geneva (an Edinburgh graduate), suspected that iodine was the active constituent of burnt sponge, which had long been empirically employed in goitre and scrofula, and having proved that this was the case, was the first physician to use iodine as a remedy. The pharmaceutical forms and the medical uses of iodine have been very numerous during the century which has almost elapsed since its introduction, but it would be impossible even to detail them here. Iodoform was first prepared by Serullas about 1828, and its chemical composition was elucidated by Dumas soon after. It was first used in medicine by Bouchardat in 1836, and then dropped out of practice for about twenty years, when it again appeared in French treatises, and its use soon became general as an antiseptic application.