Napalm: composition, history, properties and military use

Chemistry and physical characteristics

Early napalm was made by adding a soap-like thickening agent to gasoline to create a jelly that would not splash or drain away as readily as plain fuel. During World War II a research group at Harvard, led by Louis Fieser, developed an early formula that used metal salts of fatty acids to produce the gelling action; this naming origin is reflected in the word "napalm," derived from naphthenic and palmitic acids. See a historical reference to the wartime development at World War II. Traditional gasoline and petrol fuels are commonly called gasoline in civilian usage. The original thickening ingredients included coprecipitated aluminum salts related to aluminum chemistry and fatty acids such as naphthenic and palmitic acids.

Types and modern formulations

Formulations evolved over time. What became known as napalm-B replaced earlier natural-rubber thickeners with combinations of hydrocarbon solvents and polymers. A common modern gel is made from aromatic solvents such as benzene and plastic polystyrene-type thickeners such as polystyrene, producing a cheaper, more stable incendiary gel. These mixtures remain prone to intense heat release, adhesion to targets, and long burn durations compared with unthickened fuel.

History and military use

While gelled fuel is a 20th-century technical development, incendiary weapons have a long history. Pre-modern analogues include early incendiaries such as Greek fire, and the introduction of portable flame-projecting devices occurred in the 20th century: the flamethrower was introduced in World War I and later adapted by many armies. Napalm and similar gels were adopted because they improved range, adhesion, and persistence relative to raw liquid fuels; flamethrowers and aerial-delivered incendiaries benefited from these properties. For background on flame weapons, see flamethrowers.

Effects, uses and controversies

Napalm burns at high temperature and adheres to skin and structures, causing severe burns and fires that are difficult to extinguish. In confined or densely packed environments the combustion can rapidly consume available oxygen and produce toxic gases such as carbon monoxide, presenting lethal hazards beyond thermal injury. Militaries have used napalm in various roles: to clear vegetation or fortifications, to deny terrain, and in incendiary bombs and flamethrowers. Notable wartime applications include use by the United States and allied forces in several 20th-century conflicts, including extensive use in the Vietnam War, where it was sometimes employed to clear helicopter landing zones and target positions. Public reaction to civilian harm and long-term injuries helped drive restrictions and debate about incendiary weapons.

Legal status and distinctions

Following the mid-20th century, evolving customary practice and international instruments began to restrict incendiary weapons, particularly their use against civilian populations. Today many states treat incendiary munitions differently under weapons protocols, and their employment is subject to legal and ethical constraints. It is important to distinguish napalm from other incendiary or energetic materials: for example, thermite produces high localized temperatures by an exothermic metal-oxide reaction and does not behave as an adhesive gel, while white phosphorus burns and produces dense smoke but has different chemical and physical behavior. For broader context on incendiary technology and its history, see general treatments of incendiary devices and historical antecedents such as Greek fire, and the early modern military adoption following World War I.

Summary and notable facts

• Origin of the name: "napalm" reflects early ingredients (naphthenic + palmitic acids) and the metal salts used to gel fuel.
• Primary qualities: adherent, long-burning, and able to sustain combustion where unthickened fuels would run off.
• Common modern composition: aromatic solvents with polymer thickeners; often called napalm-B in 20th-century sources.
• Humanitarian impact: cause of severe injury and subject of international concern and restrictions.

For further technical, historical, or legal detail consult specialized sources and archival accounts. Additional reading and historical documents can be found through archival repositories and technical histories of military ordnance, academic chemistry histories, and international humanitarian law summaries.

Online references for general topics mentioned: flammable liquids, war, gasoline, World War II, aluminum, naphthenic acid, flamethrowers, benzene, polystyrene, allied forces, carbon monoxide, Vietnam War, landing zones, incendiary devices, Greek fire, World War I.