History and Composition of Napalm "Napalm" is actually now a general term for jellied gasoline. There are many prescriptions for how to jelly the gasoline, and hence the resulting products can differ dramatically. In particular, napalm made poorly or with incomplete mixing can end up being very similar to gasoline, with its attendant hazards.
Gasoline, being a volatile, easily ignited compound with a high energy density, was immediately used as a weapon in war. In World War I, both Germany and the Allies used it in flame throwers, but it burned itself too quickly to be very effective at igniting the target of the flame throwers. As you might imagine, intensive research to slow down the burning was funded by the U.S. government, and in 1942 Harvard University scientists and the U.S. army chemical warfare service found a way to jelly gasoline that worked quite well.
They found that mixing an aluminum soap powder of naphthene and palmitate (hence na-palm), also known as napthenic and palmitic acids, with gasoline produced a brownish sticky syrup that burned more slowly than raw gasoline, and hence was much more effective at igniting one's target. The napalm was mixed in varying concentrations of 6% (for flame throwers) and 12-15% for bombs mixed on site (for use in perimeter defense).
This mixture was a big hit with the allied forces, who used it extensively in World War II in flame throwers and fire bombs in the latter part of the war. (The incendiary bombs that rained on Dresden were probably mostly made with phosphorus, not napalm, but I have not been able to find an authoritative source online describing the incendiary material.) Napalm bombs burned out 40% of the area of Japanese target cities. In the Korean war, 165 gallon napalm bombs were dropped on enemy troops, with very effective "results".
Popular weapons continue to be refined and developed, of course, and napalm was no exception. With many more compounds available after World War II, a safer and just as effective napalm compound was developed. After all, gasoline is a pretty nasty substance, and of course is extremely flammable (see below). The safer napalm is known as "napalm-B", super-napalm, or NP2, and it uses no napalm at all! Instead, polystyrene and benzene are used as a solvent to solidify the gasoline.
Napalm-B has a huge advantage over the original napalm - its ignition can be well controlled. Hence soldiers smoking around napalm-B face no hazard at all. (I'm told that workers at the Fallbrook Naval Weapons Station used napalm to put out their cigarettes!) Yet a reliable igniter can be used to start napalm-B burning exactly when you want it to do so. Since the military would much prefer that the napalm burn opposing forces rather than their own forces, the military quickly adopted napalm-B, and it was this form of bomb-grade napalm which was used for aerial bombardment in Vietnam and which is currently stored in Fallbrook.
The above information comes from the Encyclopedia Brittanica article on napalm, and from Scott E. Harrigan, who kindly provided me with information about the various types of napalm as described in Incendiary Weapons by Malvern Lumsden.
The rest of this page talks only about the napalm manufactured for the Navy that is stored in Fallbrook.
The Hazards of Napalm To a first approximation, the Fallbrook napalm is basically gasoline, only less flammable due to the addition of plastics. Hence the basic hazard of napalm is less than the hazard of gasoline.
To be precise, the Fallbrook napalm is a mixture of 46 parts polystyrene, 33 parts gasoline and 21 parts benzene. Let's examine these items one by one.
a.. Polystyrene is best known by the trademark name "styrofoam". You hold polystyrene in your hand everytime you drink coffee from a styrofoam cup. If you have ever eaten off a "paper" plate made of plastic, you've eaten off a styrofoam product. The hamburger meat you buy at the grocery store on a plastic tray is sitting on polystyrene. Further, your house is filled with polystyrene products, since most polystyrene is used to make durable goods such as television cabinets, appliances, and furniture. This is the "normal" form of polystyrene, a hard, rigid plastic. Styrofoam is the "expanded" version, which is also used as protective packaging in the boxes in which these durable products made out of normal polystyrene come ("peanuts" and styrofoam molds). One third of all the plastic around you is polystyrene.
b.. Everyone knows what gasoline is, but most people don't realize that it is one of the most dangerous substances we come into contact with in our daily lives. Gasoline itself is a very hazardous substance which would never be allowed to be introduced into our society if we hadn't gotten used to it in the "dark ages" of environmentalism. Gasoline is a witch's brew of organic chemicals, many of which are toxic, but whose major danger is that it is an extremely flammable substance. People die regularly from gasoline. They die horribly in fires ignited by gasoline in many different ways. People use gasoline as solvents to clean parts and die when a careless cigarette or a spark ignites the vapors. Open containers of gasoline catch fire in garages and workshops when vapors reach pilot lights. We all drive around with 10-20 gallon bombs of gasoline or diesel fuel in the fuel tanks of our vehicles. These bombs sometimes go off in automobile accidents that often cause people to die in accidents that would have otherwise survived.
It's worth mentioning another hazardous effect of gasoline that fortunately is going away. Lead pollution caused by leaded gasoline was so large, causing significant impairment of children's learning abilities, that the Reagan administration, not a known bastion of environmentalists, banned leaded gasoline and paint! (Remember James Watt, who single-handedly doubled the membership in the Sierra Club?)
c.. Benzene is already contained in gasoline. In fact, the "natural" content of benzene in gasoline is often boosted to around 2% in order to raise the octane rating. Benzene is known to cause a specific form of leukemia in humans, but other than that, little is known about the effect of weak concentrations of benzene on human health. However, there are two ongoing experiments to find out the health hazards of benzene:
a.. cigarette smoke contains levels of benzene far in excess of any other source. Unfortunately, smoking cigarettes kills people too quickly to measure the effects of benzene.... b.. city air contains benzene from our automobiles burning gasoline and spewing benzene into the air. Because the half-life of benzene in air is only a half day, country air has little benzene contamination. Thus if benzene were quite hazardous at low concentrations, city dwellers would show the effects. Because of the known leukemia connection, the latest clean air acts reduce the allowable percentage of benzene in gasoline to 1%.
Like thousands of toxic chemicals, benzene is found in small amounts as a naturally occurring metabolic product in fruits, vegetables, dairy products, meats, and eggs. Fortunately, our livers work quite well at detoxifying small concentrations of toxic chemicals. After all, our livers can even detoxify large amounts of toxic alcohol for years before succumbing....