History of Potassium

Potassium, which is the seventh-most abundant metal on earth, cannot retain its free form due to its highly-reactive nature. The pure metal in its free form, is very soft and silver-white in color. It has to be stored in mineral oil or kerosene, in order to prevent its disintegration. It is isolated from its compounds by the method of electrolysis.

Status of Potassium before the 18th Century

Before the eighteenth century, people were familiar with potash, as they used it for cleaning purposes. Potash is a potassium compound, which was then made from wood ashes. People used to wash wood ash with water, in order to dissolve the potash in it. This water was collected in large iron pots and evaporated to recover a white substance called potash. The name potash is derived from the pots used in the process and the ash-like residue in it. It was known in the name of vegetable alkali (vegetable refers to plants that gives wood and alkali refers to the property of the material). This vegetable alkali was a harsh chemical used for cleaning purposes.

People at that time, used a similar substance called mineral alkali, with almost same properties, as of vegetable alkali. Mineral alkali was obtained from some rocks and was known as soda ash. This chemical was also used for cleaning. Nobody could differentiate between vegetable alkali and mineral alkali. The only difference between the two substances was their source.

Discovery of Potassium

By the end of the eighteenth century, chemists came to the conclusion that the vegetable alkali and the mineral alkali contained some new elements that they had never seen. They tried various methods to isolate these elements from their compounds. In 1807, Humphry Davy, a British chemist started working on isolating the elements. He first made water solutions of potash and soda ash and then passed electric current through it. This method did not yield any results, as the elements, soon after their isolation from the compounds, reacted with the water. Hence, Davy could not see any free element as such.

Soon, Davy realized his folly and decided to exclude water from his experiments. He passed electric current through the molten solution of potash, which led to the emergence of tiny droplets of the metal. He named it potassium after potash. This feat was achieved on October 6, 1807 and potassium was the first metal isolated by electrolysis. A few days later, he discovered sodium, using the same method. Now, it is a known fact that the alkali extracted from wood ashes, termed as potash by our ancestors, was actually potassium carbonate. Similarly, the compound known as soda ash was sodium carbonate.

Earlier, people used to cut down trees in large numbers and burn them, to produce wood ash, which in turn, was used for making potash. Now, potassium is produced by the electrolysis of its hydroxides or through thermal methods using potassium chloride. The compounds of this metal are found abundantly in the deposits formed by the evaporation of water in ancient lakes and seabeds. Potash is mined from Saskatchewan in Canada, Germany and the three states in U.S. namely, California, New Mexico and Utah. Though the metal is non-toxic, anybody dealing with the pure form of potassium should take sufficient precautions to ensure safety, as it is highly reactive.

Today, potassium is widely used in making soaps, glass, fertilizers, medicines, explosives and fireworks. It is also an essential nutrient for the human body. Mankind will always be thankful to Humphry Davy for discovering this alkali metal, which is beneficial in many ways.