Humphry Davy isolates potassium by electrolysis

Background. Prior to 1807, the chemical status of alkali metals was uncertain, as Antoine Lavoisier had not included them in his list of elements. The hypothesis that potash and soda were distinct elements combining with anions to form salts was demonstrated when elemental potassium was isolated via electrolysis. This process confirmed the elemental nature of potassium.

Methodology. Davy utilized the most powerful electrical battery available at the Royal Institution, which he had possessed since 1802. He derived potassium by electrolyzing molten caustic potash (KOH) using the newly discovered voltaic pile. This specific process of isolating potassium metal from its hydroxide has remained largely unchanged since its initial application in 1807.

Significance. The isolation of potassium was the first instance of a metal being obtained through electrolysis. This work helped establish the new field of electrochemistry, as Davy studied the forces involved in these separations. Although the elemental status of potassium and sodium was proven by their production, universal acceptance of this view took some time.