Discovery of selenium

Selenium was discovered in 1817 by the Swedish chemist Jons Jacob Berzelius and his colleague Johan Gottlieb Gahn. They were examining a reddish-brown sediment in the lead chambers of a sulfuric acid factory at Gripsholm and at first suspected that it contained tellurium, because it gave off a similar smell of rotten radish when heated. Further analysis showed that it was a new element. Berzelius named it selenium after Selene, the Greek goddess of the Moon, since tellurium had been named after the Earth. Selenium conducts electricity better when exposed to light, a property that led to its use in early photocells, light meters and photocopiers. It is an essential trace nutrient for humans and animals, though it is toxic in larger amounts.

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