Noun
Mild chloride of mercury, Hg2Cl2, a heavy, white or yellowish white substance, insoluble and tasteless, much used in medicine as a mercurial and purgative; mercurous chloride. It occurs native as the mineral horn quicksilver.
Source: Webster's dictionaryAnother good example of such chemistry is the way in which the saturated calomel reference electrode ( SCE ) works. Source: Internet
These treatments included multiple doses of calomel (a cathartic or purgative ), and extensive bloodletting (with at least 2.365 total liters of blood being taken, which is slightly less than half of a normal adult's blood volume). Source: Internet