In its basic form, this substance is a kind of soap, but when mixed with gasoline, it forms a deadly material used in flame throwers and incendiary bombs. What is it?

This substance's dual nature is rooted in its chemical composition. In its basic form, it is an aluminum salt of naphthenic and palmitic acids, which technically makes it a type of metallic soap. The name itself is a combination of these two components: "na" from naphthenic acid and "palm" from palmitic acid. This harmless-looking powder undergoes a dramatic transformation when mixed with a volatile petrochemical like gasoline. The soap acts as a gelling agent, creating a thick, sticky, and highly flammable substance. This resulting gel burns longer and at a higher temperature than gasoline alone, and adheres to surfaces, making it brutally effective.

Developed by a team of scientists at Harvard University in 1942, this incendiary was a response to the military's need for a more effective and safer alternative to the liquid gasoline used in early flamethrowers, which burned too quickly and was difficult to control. The creation of this gelled gasoline solved these problems, resulting in a weapon that could be projected farther and was more stable to handle. Its first use in combat was in flamethrowers during the Allied invasion of Sicily in 1943.

The substance was soon adapted for use in incendiary bombs, which were used extensively in World War II, the Korean War, and most famously, the Vietnam War. The devastating effects of these weapons (Review), which can burn at temperatures over 2,700 degrees Celsius, have made them highly controversial. While the original formula is no longer in primary use, modern variants exist, and the term has become synonymous with the horrific power of incendiary weapons.