Calomel, also known as rose powder, rose Dan, rose white and rose medicine. Small flake luster crystal. Chinese medicine shops sell them, but doctors in charge generally don't sell them separately. The main component of mercuric chloride is formed by strong thermal sublimation of salt, mercury and mirabilite, which is very toxic. Identification: take a little powder, put it on aluminum foil, add a little water and rub it gently. It is true only after the aluminum foil is discolored and perforated.