What does calomel mean?
Calomel is the common name for mercurous chloride, a heavy, white, tasteless compound of mercury with the formula Hg₂Cl₂. From roughly the sixteenth century until the early twentieth century it was one of the most heavily prescribed drugs in Western medicine, administered as a purgative, a diuretic, and a treatment for syphilis; its name derives from Greek roots meaning 'beautiful black', an alchemist's allusion to its behaviour in chemical reactions. Because mercury is toxic, heavy calomel use caused salivation, tooth loss, and other symptoms of mercury poisoning, and the drug gradually fell out of medical favour. Today the word survives mainly in two settings: histories of medicine, where 'calomel' evokes the harsh heroic therapies of earlier centuries, and chemistry, where the calomel electrode remains a standard reference electrode for measuring electrical potential.
nounCalomel is mercurous chloride (Hg₂Cl₂), a white, tasteless powder formerly widely used in medicine as a purgative, diuretic, and treatment for syphilis, and still used in chemistry, notably in the calomel reference electrode.
- Mercurous chloride (Hg₂Cl₂), a white powder historically used in medicine as a purgative, diuretic, and antisyphilitic.
- The same compound as used in electrochemistry, especially in the calomel reference electrode.
"Nineteenth-century doctors dosed their patients with calomel so freely that many suffered mercury poisoning as a result."
"The physician prescribed a dose of calomel to purge the patient's bowels."
"The pH of the solution was measured against a saturated calomel electrode."
As a mass noun denoting the substance, calomel is normally uncountable. A plural form exists only when referring to individual doses or preparations, e.g. in historical accounts of pharmacy.
"The ship's surgeon dispensed calomels and jalap to the feverish crew."
Victorian doctors handed out calomel by the spoonful as a cure-all — and quietly poisoned generations of patients with mercury in the process.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of calomel
The word calomel entered English in the late seventeenth century, borrowed from New Latin, and was formed from Greek kalos, meaning 'beautiful', and melas, meaning 'black' — a reference apparently coined by alchemists in connection with the compound's reactions. The same Greek roots give English a wide family of words: melas underlies melanin, melancholy, and melanoma, while kalos appears in calligraphy and kaleidoscope.
How calomel is actually used
Calomel is a technical and historical term. In modern medical writing it appears almost exclusively in discussions of the history of medicine and of mercury poisoning, since its therapeutic use was abandoned in the twentieth century. It remains current vocabulary in chemistry laboratories, particularly in electrochemistry.
Easily confused with calomel
A calumet is a ceremonial tobacco pipe of Native American peoples, whereas calomel is a chloride compound of mercury used in medicine and electrochemistry.
Caramel is burnt sugar used for flavouring and colouring food, while calomel is a toxic mercury compound; the two resemble each other in sound but share nothing else.