Gunpowder, seaweed and the accidental discovery of iodine

Bernard Courtois, the man linked with the invention of iodine. It’s not only a name, but an inventor who revolutionised the world of chemistry. Yet, this unassuming Frenchman made a discovery that would change science and medicine forever.
His life, marked by modest beginnings and the chance of discoveries, offers a fascinating glimpse into the world of chemistry in the early 19th century.
Courtois grew up being often found surrounded by the workings of science. His father was a saltpetre manufacturer, a key ingredient for gunpowder, and Bernard naturally followed in his footsteps.
He became a pharmacist and chemist, working in an era where France’s demand for gunpowder boomed, especially during the Napoleonic Wars. His involvement in the saltpetre industry connected him to the larger chemical community.
However, Courtois’ discovery of iodine in 1811 was an accident, one of those fortunate serendipities that often drive scientific breakthroughs. At the time, he was working with seaweed ash to extract sodium and potassium compounds for gunpowder production.
Seaweed was abundant along the French coast and had become a crucial resource for the nation. During one of Bernard’s routine experiments, he added too much sulphuric acid to the seaweed ash, and suddenly, violet-coloured vapours started to rise.
These vapours condensed into dark crystals, which would later be identified as iodine.
At first, Courtois didn’t realise the significance of his discovery. He simply noted the strange substance but did not have the means or scientific recognition to explore it further.
However, he shared his findings with other prominent chemists of the time who were shocked after looking at it, including Charles Bernard Desormes and Nicolas Clément, notable figures in the field of chemistry, who confirmed that iodine was indeed a new element.
Iodine’s significance quickly spread to the land of Europe and later to other parts of the world and became apparent. In medicine, it became essential for treating goitre, a thyroid disorder caused by iodine deficiency.
It was also found to be a powerful antiseptic, a discovery that would later save countless lives.
Chemists across Europe began to study its properties, and it soon became a staple in laboratories and medical practices alike.
Despite his groundbreaking contribution, Courtois did not achieve lasting fame or wealth during his lifetime. He remained relatively obscure, working in his small laboratory in Paris.
His discovery of iodine was celebrated by others in the scientific community, but he never received the full credit or financial rewards that could have accompanied such an important breakthrough.
Courtois lived modestly, dedicated to his craft but struggling with financial difficulties. His passion for chemistry never wavered, but his recognition as the man behind iodine’s discovery was overshadowed by other scientists who continued to explore the element’s uses.
Bernard Courtois passed away on September 27, 1838, largely forgotten by the broader public. Yet, his legacy endures through the myriad applications of iodine in science, medicine, and industry.
Though his life may not have been filled with accolades, the impact of his discovery is immeasurable. From the treatment of thyroid disorders to its role in disinfectants and pharmaceuticals, iodine remains one of the cornerstones of modern chemistry, and Courtois’ accidental discovery continues to save lives to this day.
In a world driven by methodical research, Bernard Courtois reminds us that sometimes, the greatest discoveries come not from planned experiments, but from moments of chance.