Yellow prussiate of potash, also known as potassium ferrocyanide, is a bright yellow crystalline compound with the chemical formula K4[Fe(CN)6]. It is commonly used in various applications, including as a food additive, in photography, and in the production of certain dyes. The compound is soluble in water and has a slightly bitter taste. In addition to its industrial uses, yellow prussiate of potash serves as a source of potassium in fertilizers. It is important to handle this compound with care, as it can release toxic cyanide gas under certain conditions. Despite its potential hazards, it is generally considered safe when used appropriately.