Iodine Science

54924855_bernard_courtois01Like most other discoveries, the discovery of Iodine was a fortuitous accident. Bernard Courtois discovered Iodine in 1811. His story about the discovery of Iodine was an interesting and ironical one. While most scientists discovered something when trying to help people to save their lives, Courtois discovered Iodine when he was trying to kill people. Bernard Courtois was serving in Napoleon’s army. On account of continuous wars, Napoleon’s army required enormous quantities of gun powder. Saltpeter also spelled as salpeter (potassium nitrate – KNO3) was the principal component in gunpowder. The manufacture of potassium nitrate required potassium carbonate that is generally extracted from wood ashes. Since the sources of willow wood had nearly run out, they wanted some alternative sources of potassium carbonate.

seaweed-gatherers-1889-by-paul-gauguinAs per some suggestions, Napoleon’s army resorted to burning dried seaweed, which was found in large quantities in the coasts of Brittany and Normandy. While the Napoleon’s army was with its mission of making saltpeter, enormous quantities of sulfur compounds also evolved as byproducts. They had to add sulfuric acid to their compounds to clean them up.

iodine vaporThey said that one day the workers of the factory where Bernard Courtois was conducting his experiments ran after a cat and on the its way the cat accidentally dropped the jar with the   sulfuric acid  on the left overs of the saltpeter production which gave out a dense violet vapor cloud that got condensed onto the surfaces of colder metal objects forming highly lustrous crystals.

Courtois jumped in ecstasy at the realization that the cat had accidentally created something new. Courtois’s experimentation with this new element/compound revealed that it could combine well with a few metals, hydrogen and phosphorous, but didn’t react easily with carbon or oxygen. In addition, he discovered that the new element/compound demonstrated explosive properties on mixing with ammonia, but didn’t decompose while subjected to burning.

iodine1He had to conclude that what he accidentally created was not a compound; it was a new element, pure in form. Napoleon’s wars had emptied the government coffers. Also, there was the pressure of newer wars. Therefore, Courtois couldn’t continue with his findings. Courteous passed on his discovery to French scientists Charles-Bernard Désormes and Nicolas Clément. For some reason, Courtois had also given a sample of the new element to Louis-Joseph Gay-Lussac and André M. Ampère, who carried forward the experiment parallel to the other pair.

Iodine gets its name from the Greek word “iodes” which means “violet.”

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