How was sodium first isolated by Sir Humphry Davy in 1807?

In 1807, the English chemist Sir Humphry Davy successfully isolated sodium in its elemental form by applying electrolysis to fused sodium hydroxide.1

Davy had previously theorized that chemical combinations occurred between substances of opposite electrical charges and reasoned that electrolysis—the interaction of electric currents with chemical compounds—offered the most effective method for decomposing substances into their constituent elements. Following this principle, he utilized an electrolytic cell to isolate sodium shortly after using the same method to isolate potassium earlier that year. Because sodium is extremely reactive and does not occur in a free state in nature, this electrolytic process was essential for obtaining the element in its pure form.231