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Who proved that chlorine is a chemical element in 1810?

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A labeled diagram of the chlorine element from the periodic table shows its atomic number 17, symbol Cl, electron configuration, and atomic weight range. The box is shaded green to indicate chlorine is a halogen, with icons for orthorhombic crystal structure, gas state at room temperature, and strong acidity. A key explains the icons and colors used. — chlorine Properties of chlorine.

In 1810, the English chemist Sir Humphry Davy proved that chlorine is a chemical element.12

While the Swedish chemist Carl Wilhelm Scheele had first isolated the gas in 1774 by treating manganese dioxide with hydrochloric acid, he failed to recognize it as an element. Davy’s work demonstrated that the substance was not a compound containing oxygen, as previously theorized, but an element in its own right. He subsequently named it chlorine, derived from the Greek word chloros, meaning "yellowish green".21