Napalm is an incendiary mixture of a gelling agent and a volatile petrochemical (usually gasoline (petrol) or diesel fuel). The name is a portmanteau of two of the constituents of the original thickening and gelling agents: co-precipitated aluminum salts of naphthenic acid and palmitic acid. Napalm B is the more modern version of napalm (utilizing polystyrene derivatives) and, although distinctly different in its chemical composition, is often referred to simply as "napalm".
A team led by chemist Louis Fieser originally developed napalm for the United States Chemical Warfare Service in 1942 in a secret laboratory at Harvard University. Of immediate first interest was its viability as an incendiary device to be used in firebombing campaigns during World War II; its potential to be coherently projected into a solid stream that would carry for distance (instead of the bloomy fireball of pure gasoline) resulted in widespread adoption in infantry flamethrowers as well.
Napalm burns at temperatures ranging from 800 to 1,200 °C (1,470 to 2,190 °F). In addition, it burns for a greater duration than gasoline, as well as being more easily dispersed and sticking tenaciously to its targets. These traits make it extremely effective (and controversial) in the anti-structure and antipersonnel role. It has been widely used in both the air and ground role, with the largest use to date being via air-dropped bombs in World War II (most notably in the devastating incendiary attacks on Japanese cities in 1945), and later close air support roles in Korea and Vietnam. Napalm also has fueled most of the flamethrowers (tank, ship, and infantry-based) used since World War II, giving them much greater range, and was used in this role as a common weapon of urban combat by both the Axis and the Allies in World War II. Multiple nations (including the United States, China, Russia, Iran, and North Korea) maintain large stockpiles of napalm-based weapons of various types.
