The English chemist and natural philosopher Sir Humphry Davy (1778-1829) isolated and named the elements of the alkaline-earth and alkali metals and showed that chlorine and iodine were elements.

Humphry Davy was born on Dec. 17, 1778, in Penzance, Cornwall. He was apprenticed when he was 16 to an apothecary in Penzance, where he evinced a great interest in chemistry and experimentation, using as his guide Lavoisier's famous work, Traité élémentaire de chimie. His obvious talents attracted the attention of Gregory Watt and Davies Giddy (later Gilbert), both of whom recommended him to Dr. Thomas Beddoes for the position of superintendent of the newly founded Pneumatic Institution in Bristol. He worked there from October 1799 to March 1801.

The Pneumatic Institution was investigating the idea that certain diseases might be cured by the inhalation of gases. Davy, sometimes perilously, inhaled many gases and found that the respiration of nitrous...