The sodium chloride, the common kitchen salt, and the sodium carbonate are known since Antiquity. The first is probably a vital need and it was probably used in the food since immemorial times, while the second, besides occurring naturally, constitutes a considerable portion of the ashes of marine algae, being already known and used by the ancient Egyptian.
Metallic sodium was first isolated by Sir Humphrey Davy in 1807 using the electrolysis of solid sodium hydroxide. At that time, sodium and potassium hidroxides were considered elementary substances and were called fixed alkalis. Davy also obtained metallic potassium; in a letter to a friend, he wrote concerning its discovery:
"I decomposed and I recomposed the fixed alkalis and discovered that its bases were two new very inflammable substances similar to metals; but one of them is lighter than the other and very reactive. There are like this two decomposed bodies and two new discovered elementary bodies".