Napalm
Napalm is the name given to any of a number of flammable liquids used in warfare, often jellied gasoline. Napalm is actually the thickener in such liquids, which when mixed with gasoline makes a sticky incendiary gel. Developed by the U.S. in World War II by a team of Harvard chemists led by Louis Fieser, its name is a combination of the names of its original ingredients, coprecipitated aluminium salts of naphthenic and palmitic acids.  These were added to the flammable substance to cause it to gel.
One of the major problems of early incendiary fluids was that they splashed and drained too easily. The U.S. found that a gasoline gel increased both the range and effectiveness of flamethrowers, but was difficult to manufacture because it used natural rubber, which was in high demand and expensive. Napalm provided a far cheaper alternative, solving the issues involved with rubber-based incendiaries.
Modern napalm is composed primarily of benzene and polystyrene, and is known as napalm-B.
Napalm 878 was used in flamethrowers and bombs by the U.S. and Allied forces, to increase effectiveness of flammable liquids. The substance is formulated to burn at a specific rate and adhere to materials. Napalm is mixed with gasoline in various proportions to achieve this. Another useful (and dangerous) effect, primarily involving its use in bombs, was that napalm "rapidly deoxygenates the available air" as well as creating large amounts of carbon monoxide causing suffocation. Napalm bombs were also used in the Vietnam War.
Though napalm was a 20th century invention, it is part of a long history of incendiary materials in warfare. However, historically, it was primarily liquids that were used (see Greek fire). An infantry-based flammable liquid fuel weapon, the flamethrower, was introduced in World War I by the Germans, variations of which were soon developed by other nations in the conflict.

# Usage in warfare
On July 17, 1944, napalm incendiary bombs were dropped for the first time by American P-38 pilots on a fuel depot at Coutances, near St. Lo, France. Howard Zinn relates how he participated in a napalm bombing of German soldiers (and French civilians) who were awaiting the end of WWII in France about two weeks before the end of the war. Napalm bombs were first used in the Pacific Theatre during the Battle of Tinian by Marine aviators; however, its use was complicated by problems with mixing, fusing and the release mechanisms. In World War II,  The USAAF bombed cities in Japan with napalm, and used it in bombs and flamethrowers in Germany and the Japanese-held islands. It was used by the Greek National army against the Democratic Army of Greece (DSE) during the Greek Civil War, by United Nations forces in Korea, by France against the Viet Minh in the First Indochina War, by Mexico in the late 1960s against guerrilla fighters in Guerrero and by the United States during the Vietnam War.
The most well-known method of delivering napalm is from air-dropped incendiary bombs.  A lesser-known method is the flame throwers used by combat infantry. Flame throwers use a thinner version of the same jellied gasoline to destroy gun emplacements, bunkers and cave hideouts. U.S. Marines fighting on Guadalcanal found them very effective against Japanese positions.  The Marines used fire as both a casualty weapon as well as a psychological weapon. They found that Japanese soldiers would abandon positions in which they fought to the death against other weapons.  Prisoners of war confirmed that they feared napalm more than any other weapon utilised against them.
Pilots returning from the war zone often remarked they would rather have a couple of droppable gasoline tanks full of napalm than any other weapon, bombs, rockets or guns.  The U.S. Air Force and Navy used napalm with great effect against all manner of targets to include troops, tanks, buildings and even railroad tunnels.  The demoralizing effect napalm had on the enemy became apparent when scores of North Korean troops began to surrender to aircraft flying overhead.  Pilots noted that they saw surviving enemy troops waving white flags on subsequent passes after dropping napalm.  The pilots radioed to ground troops and the North Koreans were captured. 
Napalm has been used recently in wartime by or against: Morocco (1976), Iran (198088), Israel (1967, 1982), Nigeria (1969), India & Pakistan (1965 & 1971), Brazil (1972), Egypt (1973), Cyprus (1964, 1974), Argentina (1982), Iraq (198088, 1991, 2003 - present), Serbia (1994),1993 Angola, France during the First Indochina War (1946-1954) and the Algerian War (1954-1962 ), and the United States.
Napalm can kill or wound by immolation and by asphyxiation. Immolation produces rapid loss of blood pressure, unconsciousness and death in a short time. 3rd degree burns are typically not painful at the time, because only the skin nerves respond to heat and 3rd degree burns kill the nerves. Burn victims do not experience 1st degree burns due to the adhesive properties of napalm that stick to the skin. Severe 2nd degree burns, likely to be suffered by someone hit with a small splash of napalm are severely painful and produce hideous scars called keloids, which can also bring about motor disturbances.
"Napalm is the most terrible pain you can imagine," said Kim Phuc, a napalm bombing survivor known from a famous Vietnam War photograph. "Water boils at 100 degrees Celsius. Napalm generates extremely high temperatures upon oxidation on the skin
Phuc sustained third-degree burns to half her body and was not expected to live after the attack by South Vietnamese aircraft. But thanks to assistance from South Vietnamese photographer Nick Ut and American doctors, and after surviving a 14-month hospital stay and 17 operations, she became an outspoken peace activist.
International law does not necessarily prohibit the use of napalm or other incendiaries against military targets, but use against civilian populations was banned by the United Nations Convention on Certain Conventional Weapons, (often referred to as the CCW) in 1980.  Protocol III of the CCW restricts the use of incendiary weapons (not only napalm), but a number of states have not acceded to all of the protocols of the CCW. According to the Stockholm International Peace Research Institute (SIPRI), states are considered a party to the convention, which entered into force as international law in December 1983, if they ratify at least two of the five protocols. The United States, for example, is a party to the CCW but did not sign protocol III.
Reports by the Sydney Morning Herald suggested the usage of napalm in the Iraq War by US forces. This was denied by the U.S. Department of Defense. In August 2003, the San Diego Union Tribune alleged that U.S. Marine pilots and their commanders confirmed the use of Mark 77 firebombs on Iraqi Republican Guards during the initial stages of combat. Official denials of the use of 'napalm' were, however, disingenuous, as the Mk 77 bomb that is currently in service at this time, the Mk 77 Mod 5, does not use actual napalm (for example, napalm-B). The last U.S. bomb to use actual napalm was the Mark 77 Mod 4, the last of which were destroyed in March 2001. The substance used now is a different incendiary mixture, but sufficiently analogous in its effects that it is still a controversial incendiary, and can still be referred to colloquially as 'napalm.'
"We napalmed both those (bridge) approaches," said Col. Randolph Alles in a recent interview. "Unfortunately, there were people there because you could see them in the (cockpit) video." (...) "They were Iraqi soldiers there. It's no great way to die," he added. (...) The generals love napalm. ... It has a big psychological effect." - San Diego Union-Tribune, August 2003
These bombs did not actually contain napalm. The napalm-B (super napalm) used in Vietnam was gasoline based. The Mk-77 firebombs used in the Gulf were kerosene based. It is, however, a napalm-like liquid in its effect.

# Composition
Napalm is usually a mixture of gasoline with suitable thickening agents. The earliest thickeners were soaps, aluminium, and magnesium palmitates and stearates. Depending on the amount of added thickener, the resulting viscosity may range between syrupy liquid and thick rubbery gel. The content of long hydrocarbon chains makes the material highly hydrophobic (resistant to wetting with water), making it more difficult to extinguish. Thickened fuel also rebounds better from surfaces, making it more useful for operations in urban terrain.
There are two types of napalm: oil-based with aluminium soap thickener, and oil-based with polymeric thickener ("napalm-B").
The United States military uses three kinds of thickeners: M1, M2, and M4.
- The M1 Thickener (MIL-T-589A), chemically  a mixture of 25% wt. aluminium naphthenate, 25% aluminium oleate, and 50% aluminium laurate, (or, according to other sources, aluminium stearate soap) is a highly hygroscopic coarse tan-colored powder. As the water content impairs the quality of napalm, thickener from partially used open containers should not be used later. It is not maintained in the US Army inventory any more as it was replaced with M4.
- The M2 Thickener (MIL-T-0903025B) is a whitish powder similar to M1, with added devolatilized silica and anticaking agent.
- The M4 flame fuel thickening compound (MIL-T-50009A), hydroxyl aluminium bis(2-ethylhexanoate) with anti-caking agent, is a fine white powder. It is less hygroscopic than M1 and opened containers can be resealed and used within one day. About half the amount of M4 is needed for the same effect as of M1.
A later variant, napalm-B, also called "super napalm", is a mixture of low-octane gasoline with benzene and polystyrene. It was used in the Vietnam War. Unlike conventional napalm, which burns for only 1530 seconds, napalm B burns for up to 10 minutes with fewer fireballs, sticks better to surfaces, and offers improved destruction effects. It is not as easy to ignite, which reduces the number of accidents caused by soldiers smoking. When it burns, it develops a characteristic smell.
Starting in the early 1990s, various websites including The Anarchist Cookbook advertised recipes for homemade napalm. These recipes were predominantly equal parts gasoline and styrofoam. This mixture closely resembles that of napalm-B, but lacks a percentage of benzene.
Napalm reaches burning temperatures of approximately 1,200 C (2,200 F). Other additives can be added, eg. powdered aluminium or magnesium, or white phosphorus.
In the early 1950s, Norway developed its own napalm, based on fatty acids in whale oil. The reason for this development was that the American-produced thickening agent performed rather poorly in the cold Norwegian climate. The product was known as Northick II.
Some weapons utilize a pyrophoric variant, known as TPA (thickened pyrophoric agent). Chemically it is a triethylaluminium thickened with polyisobutylene.

# In popular culture
Napalm itself became well-known by the American public after its use in the Vietnam war. Since then, it has been mentioned in the media and arts on numerous occasions. In the film Apocalypse Now, Airmobile Infantry Colonel Kilgore declared "I love the smell of napalm in the morning... It smells like... victory" following a nearby napalm strike. In An Officer and a Gentleman, Sgt. Foley led a quick-step march with a cadence call that had the chorus, "Cause napalm sticks to kids!", representing a cadence call common in the U.S. military at the time.