Lewisite is an organoarsenic compound
Organoarsenic compound
Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fungicides. In general these applications are declining in...

, specifically an arsine
Arsine is the chemical compound with the formula AsH3. This flammable, pyrophoric, and highly toxic gas is one of the simplest compounds of arsenic...

. It was once manufactured in the U.S. and Japan as a chemical weapon
Chemical warfare
Chemical warfare involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from Nuclear warfare and Biological warfare, which together make up NBC, the military acronym for Nuclear, Biological, and Chemical...

, acting as a vesicant (blister agent) and lung
The lung is the essential respiration organ in many air-breathing animals, including most tetrapods, a few fish and a few snails. In mammals and the more complex life forms, the two lungs are located near the backbone on either side of the heart...

 irritant. Although colorless and odorless, impure samples of lewisite are a yellow or brown liquid with a distinctive odor that has been described as similar to scented geranium
Pelargonium is a genus of flowering plants which includes about 200 species of perennials, succulents, and shrubs, commonly known as scented geraniums or storksbills. Confusingly, Geranium is the correct botanical name of a separate genus of related plants often called Cranesbills. Both Geranium...


Chemical reactions

The compound is prepared by the addition of arsenic trichloride to acetylene:
AsCl3 + C2H2 → ClCHCHAsCl2

Lewisite, like other arsenous chlorides, hydrolyses in water to form hydrochloric acid:
ClCHCHAsCl2 + 2 H2O → "ClCHCHAs(OH)2" + 2 HCl

This reaction is accelerated in alkaline solutions, with poisonous (but non-volatile) sodium arsenite
Sodium arsenite
Sodium arsenite is a compound with formula NaAsO2. It is the sodium salt of arsenous acid. It is a crystalline solid consisting of sodium cations, Na+, and catena-arsenite anions, [AsO2], which are infinite -O-As- chains, similar in structure to selenium dioxide, SeO2.It is a pesticide....

 being the coproduct.

Mode of action as chemical weapon

It can easily penetrate ordinary clothing and even rubber; upon skin contact it causes immediate pain and itching with a rash and swelling. Large, fluid-filled blister
A blister is a small pocket of fluid within the upper layers of the skin, typically caused by forceful rubbing , burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid called serum or plasma...

s (similar to those caused by mustard gas exposure) develop after approximately 12 hours. These are severe chemical burn
Chemical burn
A chemical burn occurs when living tissue is exposed to a corrosive substance such as a strong acid or base. Chemical burns follow standard burn classification and may cause extensive tissue damage. The main types of irritant and/or corrosive products are: acids, bases, oxidizers, solvents,...

s. Sufficient absorption can cause systemic poisoning leading to liver
Hepatotoxicity implies chemical-driven liver damage.The liver plays a central role in transforming and clearing chemicals and is susceptible to the toxicity from these agents. Certain medicinal agents, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure...

Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...

 or death.

Inhalation causes a burning pain, sneezing, coughing, vomiting, and possibly pulmonary edema
Pulmonary edema
Pulmonary edema , or oedema , is fluid accumulation in the air spaces and parenchyma of the lungs. It leads to impaired gas exchange and may cause respiratory failure...

. Ingestion results in severe pain, nausea, vomiting, and tissue damage. The results of eye exposure can range from stinging and strong irritation to blistering and scarring of the cornea. Generalised symptoms also include restlessness, weakness, subnormal temperature and low blood pressure.

Chemical composition

Lewisite is usually found as a mixture, of 2-chlorovinylarsonous dichloride as well as bis(2-chloroethenyl)arsinous chloride ("lewisite 2"), and tris(2-chlorovinyl)arsine ("lewisite 3").


Lewisite is named after the US chemist and soldier Winford Lee Lewis
Winford Lee Lewis
Winford Lee Lewis was a US soldier and chemist best known for his invention of the chemical warfare agent, Lewisite, in 1917.- References :http://www.time.com/time/magazine/article/0,9171,790772,00.html...

 (1878–1943). In 1918 he found the thesis of Julius Arthur Nieuwland at Maloney Hall
Maloney Hall
The Martin Maloney Chemical Laboratory of The Catholic University of America was built in November, 1917. Maloney Hall was named for Martin Maloney, a papal marquis from Philadelphia, Pa., who gave $120,000 for main building and $100,000 for the auditorium....

, a chemical laboratory at The Catholic University of America
The Catholic University of America
The Catholic University of America is a private university located in Washington, D.C. in the United States. It is a pontifical university of the Catholic Church in the United States and the only institution of higher education founded by the U.S. Catholic bishops...

, Washington DC in which Nieuwland detailed the synthesis by allowing arsenic trichloride
Arsenic trichloride
Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.-Structure:AsCl3 is a...

 to react with acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...

 in the presence of a hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

 solution of mercuric chloride.

It was developed into a secret weapon at Nela Park
Nela Park
Nela Park is the headquarters of GE Lighting, and is located in East Cleveland, Ohio, United States. Today, GE Lighting is a part of GE's Consumer and Industrial business headquartered in Louisville, Kentucky...

 (a facility located in Cleveland, Ohio
Ohio is a Midwestern state in the United States. The 34th largest state by area in the U.S.,it is the 7th‑most populous with over 11.5 million residents, containing several major American cities and seven metropolitan areas with populations of 500,000 or more.The state's capital is Columbus...

 at East 131st Street and Taft Avenue) and given the name "the new G-34" to confuse its development with mustard gas. It was not used in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

, but experimented with in the 1920s as the "Dew of Death."

After World War I, the US became interested in lewisite because it was not flammable. It had the military symbol of M1 up into World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, when it was changed to L. Field trials with lewisite during World War II demonstrated that casualty concentrations were not achievable under high humidity due to its rate of hydrolysis and its charactistic odor and lacrymation
Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....

 forced troops to don masks and avoid contaminated areas. The United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 produced about 20,000 tons of lewisite, keeping it on hand primarily as an antifreeze
Antifreeze is a freeze preventive used in internal combustion engines and other heat transfer applications, such as HVAC chillers and solar water heaters....

 for mustard gas or to penetrate protective clothing in special situations.

It was replaced by the mustard gas variant HT (a 60:40 mixture of sulfur mustard and O Mustard), and declared obsolete in the 1950s. It is effectively treated with British anti-lewisite (dimercaprol
Dimercaprol or British anti-Lewisite , is a compound developed by British biochemists at Oxford University during World War II. It was developed secretly as an antidote for lewisite, the now-obsolete arsenic-based chemical warfare agent. Today, it is used medically in treatment of arsenic,...

). Most stockpiles of lewisite were neutralized with bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...

 and dumped into the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

, but some remain at the Deseret Chemical Depot
Deseret Chemical Depot
The Deseret Chemical Depot is a U.S. Army chemical weapon storage area located in Utah, 60 miles southwest of Salt Lake City. It is related to the Tooele Chemical Agent Disposal Facility.-History:...


In 2010, lewisite was found in a World War I weapons dump in Washington, DC.

Controversy over Japanese depots of lewisite in China

In mid 2006, China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

 and Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

were negotiating disposal of stocks of lewisite in northeastern China, left by Japanese military during World War II. Residents of China have died over the past twenty years from accidental exposure to these stockpiles.
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