Napalm is an incendiary mixture of a gelling agent and a volatile petrochemical (usually gasoline (petrol) or diesel fuel). The title is a portmanteau of the names of two of the constituents of the original thickening and gelling agents: co-precipitated aluminium salts of naphthenic and palmitic acids. Napalm B is the more modern version of napalm (utilizing styrene derivatives) and, although distinctly different in its chemical composition, is often referred to simply as "napalm".Napalm was originally developed in 1942 in a secret laboratory at Harvard University, by a team led by chemist Louis Fieser under the United States Chemical Warfare Service. Of immediate first interest was its viability as an incendiary device to be used in fire bombing campaigns during World War II, but its ability 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/combat engineer flamethrowers as well. Napalm burns at the same temperature as gasoline, and for a greater duration, 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 used to date being via air-dropped bombs in WW2 (most notably in the gruesomely effective 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 I, giving them much greater range, and was used in this role as a common (and feared) weapon of urban combat by both the Axis and 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.