Mercury, also known as mercury, is a chemical element with the chemical symbol Hg and atomic number 80. It is a silver white liquid transition metal, usually in liquid form at room temperature. Mercury has been used as a material for making thermometers in history, and due to its high density and good conductivity, it is also widely used in the manufacturing of electronic and electrical products. In addition, mercury has a wide range of applications in industry and medicine due to its low toxicity and ease of forming alloys with various substances.

In traditional Chinese medicine, mercury has a long history of use as a traditional Chinese medicine, but it is less commonly used in modern times. Its aliases include White Dragon, Maiden, Dragon, Mercury, Divine Glue, Yuan Shui, Lead Essence, Flowing Pearl, Yuan Zhu, Red Mercury, Sand Mercury, Spirit Liquid, Living Treasure, etc. Mercury comes from the refining process of cinnabar ore and can also be directly extracted from mercury sulfide minerals in nature. Traditional Chinese medicine believes that mercury has disinfection, diarrhea, diuresis, insecticidal, and lice killing effects, and is mainly used to treat diseases such as skin scabies, psoriasis, and head lice. However, due to the toxicity of mercury, modern medicine no longer recommends its oral or injection use for the treatment of diseases, but instead uses topical preparations.