Davy, Humphry (1778-1829)

English chemist. He discovered, by electrolysis, the metallic elements sodium and potassium in 1807, and calcium, boron, magnesium, strontium, and barium in 1808. In addition, he established that chlorine is an element and proposed that hydrogen is present in all acids. He invented the safety lamp for use in mines where methane was present, enabling miners to work in previously unsafe conditions. Davy's experiments on electrolysis of aqueous solutions from 1800 led him to suggest its large-scale use in the alkali industry. He theorized that the mechanism of electrolysis could be explained in terms of species that have opposite electric charges, which could be arranged on a scale of relative affinities - the foundation of the modern electrochemical series. His study of the alkali metals provided proof of French chemist Antoine Lavoisier's idea that all alkalis contain oxygen. Davy was born in Penzance, Cornwall, and apprenticed to an apothecary. As a laboratory assistant in Bristol in 1799, he discovered the respiratory effects of laughing gas (nitrous oxide). He moved to the Royal Institution, London, 1801. In 1813 he took on Michael Faraday as a laboratory assistant. Davy introduced a chemical approach to agriculture, the tanning industry, and mineralogy; he designed an arc lamp for illumination and an electrolytic process for the desalination of sea water.