Hg2Cl2, commonly known as mercurous chloride or calomel, is a chemical compound composed of mercury and chlorine. It has the formula Hg2Cl2, indicating that it contains two mercury atoms and two chlorine atoms. Calomel appears as a white or yellowish powder and is insoluble in water, making it useful in various applications. Historically, Hg2Cl2 was used in medicine, particularly as a laxative and antiseptic. However, due to the toxicity of mercury, its use has declined significantly. Today, calomel is primarily utilized in laboratory settings and as a reference electrode in electrochemistry.