Humphry Davy. Portrait of English chemist Sir Humphry Davy (1778-1829). In 1800 he discovered nitrous oxide, also known as laughing gas, which was the first chemical anaesthetic used. Davy is better known for his research on electrolysis. In 1807 he was able to isolate potassium and sodium by driving an electric current into solutions containing potash and soda respectively. Using a similar method, Davy obtained other metals such as barium, strontium, calcium and magnesium in the following year. In 1815 he invented the Davy lamp which, thanks to a special device, could be safely used in gassy coalmines.