How the cat invented iodine. An accidental discovery


Bernard Courtois, a French chemist and pharmacist, discovered iodine in 1811. But most likely the discovery would have been delayed had it not been for Bernard Courtois’ beloved cat. The story of the discovery is told by Courtois’ friends.

The cat liked to sit on Courtois’ shoulder during lunch. Courtois often ate lunch in the lab. One ordinary day, Courtois was having lunch as usual with his cat in the lab. During the meal, the cat got spooked by something and jumped to the floor. Not calculating its trajectory, the cat hit the bottles that were near the table. One of the bottles contained a suspension of algae ash (containing sodium iodide) in a standard, and the other bottle contained sulfuric acid.

A chemical reaction began and clouds of blue-violet vapor began to rise from the floor. The vapor settled into small black-purple crystals. This was the new chemical element iodine. That’s how the cat came up with iodine.

cat invented iodine