Calomel is a
mercury chloride
The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
with
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...
Hg
2Cl
2 (see
mercury(I) chloride
Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury(I) compoun ...
). It was used as a medicine from the 16th to early 20th century, despite frequently causing
mercury poisoning
Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashe ...
in patients.
The name derives from Greek ''kalos'' (beautiful) and ''melas'' (black) because it turns black on reaction with
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
. This was known to
alchemists
Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first ...
.
Calomel occurs as a secondary mineral which forms as an alteration product in mercury deposits. It occurs with
native mercury,
amalgam,
cinnabar
Cinnabar (; ), or cinnabarite (), also known as ''mercurblende'' is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and is t ...
, mercurian
tetrahedrite,
eglestonite,
terlinguaite
Terlinguaite is the naturally occurring mineral with formula . It is formed by the weathering of other mercury (element), mercury-containing minerals. It was discovered in 1900 in the Terlingua, Texas, Terlingua District of Brewster County, Texa ...
,
montroydite
Montroydite is the mineral form of mercury(II) oxide with formula HgO. It is a rare mercury mineral. It was first described for an occurrence in the mercury deposit at Terlingua, Texas, Terlingua, Texas and named for Montroyd Sharp who was an owne ...
,
kleinite,
moschelite,
kadyrelite,
kuzminite,
chursinite,
kelyanite,
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
,
limonite
Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as , although this is not entirely accurate as the ratio of oxide to hydroxide can vary qu ...
and various
clay minerals
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces.
Clay mineral ...
.
[The Handbook of Mineralogy]
/ref>
The type locality is Moschellandsburg, Alsenz-Obermoschel, Rhineland-Palatinate
Rhineland-Palatinate ( , ; ; ; ) is a western state of Germany. It covers and has about 4.05 million residents. It is the ninth largest and sixth most populous of the sixteen states. Mainz is the capital and largest city. Other cities are ...
, Germany
Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
.[
]
History
The substance later known as calomel was first documented in ancient Persia by medical historian Rhazes in year 850. Only a few of the compounds he mentioned could be positively identified as calomel, as not every alchemist disclosed what compounds they used in their drugs. Calomel first entered Western medical literature in 1608, when Oswald Croll wrote about its preparation in his ''Tyroncium Chemicum''. It was not called calomel until 1655, when the name was created by Théodore de Mayerne
Sir Théodore Turquet de Mayerne (28 September 1573 – 22 March 1655) was a Genevan-born physician who treated kings of France and England and advanced the theories of Paracelsus.
The Young Doctor
Mayerne was born in a Huguenot family in G ...
, who had published its preparation and formula in “Pharmacopoeia Londinensis" in 1618.
By the 19th century, calomel was viewed as a panacea, or miracle drug, and was used against almost every disease, including syphilis
Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms depend on the stage it presents: primary, secondary, latent syphilis, latent or tertiary. The prim ...
, bronchitis
Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...
, cholera
Cholera () is an infection of the small intestine by some Strain (biology), strains of the Bacteria, bacterium ''Vibrio cholerae''. Symptoms may range from none, to mild, to severe. The classic symptom is large amounts of watery diarrhea last ...
, ingrown toenails, teething
Teething is the process by which an infant's first teeth (the deciduous teeth, often called "baby teeth" or "milk teeth") appear by emerging through the gums, typically arriving in pairs. The mandibular central incisors are the first primary te ...
, gout
Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of pain in a red, tender, hot, and Joint effusion, swollen joint, caused by the deposition of needle-like crystals of uric acid known as monosodium urate crysta ...
, tuberculosis
Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...
, influenza
Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These sympto ...
, and cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...
. During the 18th and early 19th centuries pharmacists used it sparingly; but by the late 1840s, it was being prescribed in heroic doses—due in part to the research of Benjamin Rush
Benjamin Rush (April 19, 1813) was an American revolutionary, a Founding Father of the United States and signatory to the U.S. Declaration of Independence, and a civic leader in Philadelphia, where he was a physician, politician, social refor ...
, who coined the term "heroic dose" to mean about taken four times daily. This stance was supported by Samuel Cartwright, who believed that large doses were "gentlest" on the body. As calomel rose in popularity, more research was done into how it worked.
J. Annesley was one of the first to write about the differing effects of calomel when taken in small or large doses. Through experimentation on dogs, Annesley concluded that calomel acted more like a laxative on the whole body rather than acting specifically on the vascular system or liver as previous physicians believed. In 1853, Samuel Jackson described the harmful effects of calomel on children in his publication for Transactions of Physicians of Philadelphia. He noted that calomel had harmful effects causing gangrene
Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. If the ga ...
on the skin, loss of teeth, and deterioration of the gums. On May 4, 1863, William A. Hammond, the United States' surgeon-general, stated that calomel would no longer be used in the army as it was being abused by soldiers and physicians alike. This caused much debate in the medical field, and eventually led to his removal as surgeon-general. Calomel continued to be used well into the 1890s and even into the early 20th century. Eventually calomel’s popularity began to wane as more research was done, and scientists discovered that the mercury in the compound was poisoning patients.
Calomel was the main of the three components of the pill number 9 of the British army during the First World War.
Electrochemistry
Calomel is used as the interface between metallic mercury and a chloride solution in a saturated calomel electrode, which is used in electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between Electric potential, electrical potential difference and identifiable chemical change. These reactions involve Electron, electrons moving via an electronic ...
to measure pH and electrical potentials in solutions. In most electrochemical measurements, it is necessary to keep one of the electrodes in an electrochemical cell at a constant potential. This so-called reference electrode allows control of the potential of a working electrode.
Chemical properties
Calomel is a powder that is white when pure, and it has been used as a pigment in painting in 17th century South Americas art and in European medieval manuscripts. When it is exposed to light or contains impurities it takes on a darker tint. Calomel is made up of mercury and chlorine with the chemical formula Hg2Cl2. Depending on how calomel was administered, it affected the body in different ways. Taken orally, calomel damaged mainly the lining of the gastrointestinal tract. Mercury salts (such as calomel) are insoluble in water and therefore do not absorb well through the wall of the small intestine. Some of the calomel in the digestive system will likely be oxidized
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
into a form of mercury that can be absorbed through the intestine, but most of it will not. Oral calomel was actually the safest form of the drug to take, especially in low doses. Most of the calomel ingested will be excreted through urine and stool.
Powdered forms of calomel were much more toxic, as their vapors damaged the brain. Once inhaled, the calomel enters the bloodstream and the mercury binds with the amino acids
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the Proteinogenic amino acid, 22 α-amino acids incorporated into p ...
methionine, cysteine, homocysteine and taurine. This is because of the sulfur group these amino acids contain, which mercury has a high affinity for. It is able to pass through the blood brain barrier and builds up in the brain. Mercury also has the ability to pass through the placenta
The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...
, causing damage to unborn babies if a pregnant mother is taking calomel.
Calomel was manufactured in two ways - sublimation and precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...
. When calomel first started being manufactured it was done through sublimation. Calomel made through sublimation tends to be a very fine white powder. There was some controversy over the sublimation of calomel. Many argued that the more times calomel was sublimed, the purer it got. Opponents believed that the repeated sublimation made calomel lose some of its therapeutic ability. In 1788 chemist Carl Wilhelm Scheele
Carl Wilhelm Scheele (, ; 9 December 1742 – 21 May 1786) was a Swedish Pomerania, German-Swedish pharmaceutical chemist.
Scheele discovered oxygen (although Joseph Priestley published his findings first), and identified the elements molybd ...
came up with the mechanism to make precipitated calomel. This became rapidly popular in the pharmaceutical industry because it was both a cheaper and safer form of production. Precipitation also tended to form very pure calomel salts.
Medicine
Calomel was a popular medicine used during the Victorian period
In the history of the United Kingdom and the British Empire, the Victorian era was the reign of Queen Victoria, from 20 June 1837 until her death on 22 January 1901. Slightly different definitions are sometimes used. The era followed th ...
, and was widely used as a treatment for a variety of ailments during the American Civil War
The American Civil War (April 12, 1861May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States between the Union (American Civil War), Union ("the North") and the Confederate States of A ...
. The medication was available in two forms, blue pills and blue masses. The blue pill was an oral form of calomel containing mercury that was often mixed with a sweet substance, like licorice or sugar in order to be taken by mouth. The blue mass was a solid form of calomel in which a piece could be pinched off and administered by any one of several possible routes ( orally, skin absorption, vapor inhalation) by a physician or other medical provider. Neither form of the medication came with a standardization of dosing. There was no way of knowing how much mercurous chloride each dose contained.
Uses
Calomel was marketed as a purgative agent to relieve congestion and constipation; however, physicians at the time had no idea what the medication's mechanism of action was. They learned how calomel worked through trial and error. It was observed that small doses of calomel acted as a stimulant
Stimulants (also known as central nervous system stimulants, or psychostimulants, or colloquially as uppers) are a class of drugs that increase alertness. They are used for various purposes, such as enhancing attention, motivation, cognition, ...
, often leading to bowel movements, while larger doses caused sedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, ...
. During the 19th century, calomel was used to treat numerous illnesses and diseases like mumps, typhoid fever, and others—especially those that impact the gastrointestinal tract, such as constipation, dysentery, and vomiting. As mercury softened the gums, calomel was the principal constituent of teething powders until the mid-twentieth century. Babies given calomel for teething often suffered from acrodynia.
Side effects
It became popular in the late 18th century to give calomel in extremely high doses, as Benjamin Rush normalized the heroic dose. This caused many patients to experience many painful and sometimes life-threatening side effects.
Calomel, in high doses, led to mercury poisoning
Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashe ...
, which had the potential to cause permanent deformities and even death. Some patients experienced gangrene
Gangrene is a type of tissue death caused by a lack of blood supply. Symptoms may include a change in skin color to red or black, numbness, swelling, pain, skin breakdown, and coolness. The feet and hands are most commonly affected. If the ga ...
of the mouth generated by the mercury in the medicine, which caused the tissue on the cheeks and gums inside the mouth to break down and die. Some patients would lose teeth, while others were left with facial deformities.
High doses of calomel would often lead to extreme cramping, vomiting, and bloody diarrhea; however, at the time, this was taken as a sign that the calomel was working to purge the system and rid the disease. Calomel was often administered as a treatment for dysentery
Dysentery ( , ), historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehyd ...
; the effects of calomel would often worsen the severe diarrhea associated with dysentery and acted as a catalyst
Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...
in speeding up the effects of dehydration.
One victim was Alvin Smith, the eldest brother of Joseph Smith
Joseph Smith Jr. (December 23, 1805June 27, 1844) was an American religious and political leader and the founder of Mormonism and the Latter Day Saint movement. Publishing the Book of Mormon at the age of 24, Smith attracted tens of thou ...
, founder of the Church of Jesus Christ of Latter-day Saints
The Church of Jesus Christ of Latter-day Saints, informally known as the LDS Church or Mormon Church, is a Nontrinitarianism, nontrinitarian Restorationism, restorationist Christianity, Christian Christian denomination, denomination and the ...
. Alvin was suffering from a " bilious colic" better known as abdominal pain.
It was also used by Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
to treat his mysterious chronic gastrointestinal illness, which has recently been attributed to Crohn's disease
Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the ...
.
Discontinuation
By the mid-19th century, some physicians had begun to question the usefulness of calomel. In 1863, the Surgeon General of the U.S. Army forbade calomel from inclusion in army medical supplies, a decision that angered many practicing doctors. The use of calomel gradually died out over the course of the late 19th and early 20th centuries, although its use persisted longer in the American South
The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, Dixieland, or simply the South) is census regions United States Census Bureau. It is between the Atlantic Ocean and the ...
and American West
The Western United States (also called the American West, the Western States, the Far West, the Western territories, and the West) is census regions United States Census Bureau
As American settlement in the U.S. expanded westward, the mea ...
.
Citations
General bibliography
* Palache, P.; Berman H.; Frondel, C. (1960). ''Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc.'' (Seventh Edition). John Wiley and Sons, Inc., New York, pp. 25–28.
{{authority control
Halide minerals
Mercury(I) minerals
Withdrawn drugs
History of medicine
Mercury poisoning