Iodine was discovered in 1811 by Bernard Courtois who was the manufacturer of saltpeter (potassium carbonate) and soap. Since old ages alkaline metals carbonates (soude de varech or salin de varech in French), crucially necessary for gunpowder manufacture were extracted in France and other countries from seaweed (varech in French) gathered at the coasts of Normandy and Brittany. For this purpose seaweed was burned and the ash then washed with water. After the process, the remaining wastes were destroyed by adding sulphuric acid. In 1811 Courtois accidentally added excess sulphuric acid resulting in a violet vapor cloud that condensed on colder objects forming dark, lustrous crystals, which as Courtois suspected, belonged to a new element.
Louis-Joseph Gay-Lussac and Andre M. Ampere also investigated the new element, after which Gay-Lussac offered to name it iode. Ampere had given his sample to Sir Humpry Davy, who visited Paris travelling to Italy. He sent off a paper to the Royal Society of London in 1813 describing his experiments and recognizing the similarities between the new substance and chlorine. He named it iodine, after the Greek ιοειδης [ioeides] = violet coloured (from ιον [ion] = violin), which was analogous to chlorine and fluorine, the name, which is now fully accepted in English-speaking environment. |
| Iodine is the least abundant of the halogen elements, approximately 4x10-5% on average of the Earth& |