Bernard Courtois
The French chemist who stumbled upon the element iodine in his vat of seaweed ash, revolutionizing medicine and industry.
1777–1838 (age 61)·19th-century French chemist·Birthday: February 12
Biography
Bernard Courtois's moment of discovery was born from mundane necessity and wartime scarcity. The son of a saltpeter manufacturer, he learned chemistry in the family business, which supplied potassium nitrate for gunpowder to Napoleon's armies. When saltpeter supplies ran low, Courtois turned to burning seaweed, whose ash (called 'varec') was a traditional source of soda and potash. In 1811, while cleaning a copper vat used to extract these salts, he added too much sulfuric acid. To his astonishment, a stunning violet vapor erupted and condensed into dark, crystalline sheets. Courtois, a careful experimenter, recognized he had found a new substance. He passed his samples to other chemists who confirmed it was a new element, which they named iodine. This accidental find in a workshop, not a university lab, became a cornerstone of thyroid medicine, early photography, and chemical analysis, though Courtois himself never profited greatly from it.
#1 When Bernard Was Born
The biggest hits of 1777
Bernard's Life & Times
The world at every milestone
1777Born
1782Started school
1790Became a teenager
1793Could drive
1795Could vote
1798Turned 21
1807Turned 30
1817Turned 40
1827Turned 50
1837Turned 60
1838Died at 61
Key Achievements
- First isolated the element iodine from the ash of seaweed in 1811.
- His discovery provided the critical chemical for effective thyroid disease treatment.
- The iodine compounds he identified became essential in early photographic processes (daguerreotypes).
- Ran a successful saltpeter manufacturing business that supplied the French military.
Did You Know?
He served as a pharmacist's assistant in his youth and later worked for Antoine-François de Fourcroy, a famous chemist.
After his discovery, he struggled financially and briefly ran a factory making iodine-based compounds for medicine.
The French Academy of Sciences awarded him a prize of 6,000 francs in 1831 for his contribution to science.
He initially thought the violet vapor might be a compound of chlorine.
“The violet vapor from seaweed ash revealed a new element.”
