Naphthenic acid by a general formula CH O, where "n" indicates the carbon number and "z" specifies a homologous series. The "z" is equal to 0 for saturated, acyclic acids and increases to 2 in monocyclic naphthenic acids, to 4 in bicyclic naphthenic acids, to 6 in tricyclic acids, and to 8 in tetracyclic acids. Salts of naphthenic acids, called naphthenates, are widely used as hydrophobic sources of metal ions in diverse applications.Aluminium salts of naphthenic acid and palmitic acid were combined during World War II to produce napalm. The word "napalm" is derived from the words naphthenic acid and palmitic acid.
High-explosive incendiary are fired from various platforms, including aircraft, anti-aircraft cannons, and anti-missile systems, as well as common battlefield howitzers, though the latter has gone through a recent decline in use. HEI ammunition has also been used on the battlefield against tanks and other armoured vehicles, but this has become impractical due to the invention of modern armour systems such as Chobham and explosive reactive armour, which can absorb most high-explosive rounds currently used. Recently, APIS (armour piercing incendiary shells) have been used; these penetrate the target using the kinetic properties of the round before the incendiary round goes off, smothering the