Coloured 19c engraving of Humphry Davy using electrolysis to isolate the metallic element in alkalis and alkaline earths. He is shown experimenting at the Royal Institution in 1807. Davy used a combination of Voltaic batteries to give the highest electrical power he could obtain and ran an electrical current through a solution of potash which caused the isolation of potassium. This was the first metal to be isolated by electrolysis. He discovered that alkalis and alkaline earths are compound substances formed by oxygen combined with metallic bases. Using electrolysis he went on to isolate sodium, strontium, magnesium, calcium and barium. Humphry Davy is on the right. The Voltaic batteries are seen on the table in front of him, to the left is a double-barrelled air pump.