Humphrey Davy (1778-1829), British chemist. A pioneering chemist, Sir Humphrey Davy used electrolysis in 1807 to isolate potassium and sodium from their compounds. Later he discovered barium, strontium, calcium and magnesium in a similar way. However he remains best known for his invention of the Davy lamp, a miner's safety lamp which could be safely used in coal mines without igniting any flammable gases (such as methane). It worked because he realised that, to ignite, the gases must be first heated to an ignition temperature. He kept his lamp cool by spreading its heat over a metal gauze. Taken from a book published in 1849.