Potassium ferrocyanide has a large range of niche applications. Its most common use is as an anti-caking agent for both road salts and table salts. It is produced industrially from hydrogen cyanide, ferrous chloride, and calcium hydroxide, then rated with potassium salts and potassium carbonate. It is used in the purification of tin and the separation of copper from ore and in the production of wine and citric acid. It can be used in salts and its substitutes and also in animal feed. Potassium ferrocyanide is used widely in the laboratory to determine the concentration of potassium permanganate and as a buffer for beta-galactosidase, and as an agent for identification in the lab as a regent, because it turns blue when it reacts with iron. Potassium ferrocyanide can be used as a fertilizer for plants.