Davy's electrolysis trough, 1810.
© Science Museum / Science & Society Picture Library
Replica made in 1931 of the original object in the Royal Institution Collection. The original was made by James Powell and Sons of Whitefriars. Electrolysis is a technique in which electric current is pased through solutions or molten materials. This method can separate compounds into their elements by supplying or removing electrons from the outer shell of their atoms. It was pioneered by the English scientist Humphry Davy (1778-1829), who pased electricity through potash and soda to discover potasium and sodium.