Iodine was discovered by accident during the Napoleonic Wars by Bernard Courtois, a French chemist, in 1811. He was helping his father to manufacture saltpetre, which is an important component in gunpowder. This compound was in heavy demand at the time. Initially, he had been using wood ash as the source of potassium nitrate that was needed to make saltpetre. But due to the shortage in wood ash, Courtois began using seaweed in its place. To isolate the sodium and potassium extracts from the seaweed, he used to burn the seaweed and wash its ash with water. Later, sulfuric acid was added and the leftover waste was removed. But once when Courtois added a little too much sulfuric acid, he noticed a cloud of violet gas. With further analysis, he discovered that this vapour would form deep violet crystals on cold surfaces when condensed.
At that time, Courtois knew that he had discovered a new element, but he did not know that it was iodine. He shared some samples with other scientists to continue the research. These scientists later confirmed that it was a new element.
Although Courtois did not name the element, he was later acknowledged as the first person to isolate iodine. He received the Montyon Prize from the Royal Academy of Sciences in 1831 for his work.
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