Humphry Davy. Caricature of the British chemist and physicist Humphry Davy (1778-1829), holding a Davy lamp. The Davy lamp was a safety lamp designed for use in coal mines. It comprised a candle surrounded by a fine metal gauze. The flame heated the gauze but not above the ignition temperature of methane gas, explosions of which had cost many lives. Davy discovered the euphoriant effects of nitrous oxide, and used the newly invented battery to separate the components of salts by electrolysis.