Its existence as "potash" or "vegetable alkali" (potassium carbonate), "caustic potash" (potassium hydroxide), etc., had long been known, but it was not isolated as an element until 1807, by Sir Humphrey Davy. | Its existence as "potash" or "vegetable alkali" (potassium carbonate), "caustic potash" (potassium hydroxide), etc., had long been known, but it was not isolated as an element until 1807, by Sir Humphrey Davy. |