The meta silicate, K2SiO3, is used in water glass . Potassium permanganate, KMnO4, a purple-black, crystalline compound that forms deep purple, aqueous solutions, is used in the chemical laboratory as a powerful oxidizing agent and in medicine as an antiseptic and disinfectant. Substances containing potassium impart a purple color to a flame. It is the seventh most abundant element in the earth's crust and the sixth most abundant of the elements in solution in the oceans. It is found in mineral waters, brines, and salt deposits.
Potassium is an essential nutrient for plants and animals.
The metal may be produced electrolytically from fused potassium hydroxide, but, unlike sodium and lithium, it reacts with carbon electrodes and may form explosive compounds. Potassium was discovered in 1807 by Humphry Davy , who decomposed potash with an electric current.