Napalm is usually a mixture of gasoline with suitable thickening agents. The earliest thickeners were soaps, aluminum, and magnesium palmitates and stearates. Depending on how much thickener is added, 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.