November 10, 2005

Playing With Incendiaries 

If there is a non-story that I feel little inclined to write about, is the current tempest in a toilet bowl regarding the alleged use of "chemical weapons" in Fallujah (by the Americans of course; if the jihadis killed thousands with iprite, it would only gain a few raised eyebrows).

However, as Douglas Kern says, "The Internet gives liars and rumor mongers a colossal space in which to bamboozle dolts of every stripe -- but it also provides a forum for wise men from all across the world to speak the truth. Over the long run, the truth tends to win. This fact is lost on critics of the blogosphere, who can only see the exaggerated claims and gossip. These critics often fail to notice that, on the 'net, the truth follows closely behind the lies. A great many of us accept Internet rumors and hoaxes in exchange for fast access to the truth."

Out of sense of duty and allegiance to the Truth, I decided to write something about it, starting with two of my oldtime passions: military science and nasty chemicals.

Fire has always been used as a weapon: Sun-Tzu already discussed the military application of fire; the ancient Greeks and Romans used incendiary mixtures not very dissimilar to today's napalm - and so on. Fire is effective because it kills people, destroys building and vehicles, it is easy to generate and spreads spontaneously. And if you've ever seen a sizable fire up close, you'll know it is goddamn scary.

During World War I a military problem emerged: how to take out entrenched troops? Fire was an obvious response (and later poisonous gases), but if you fill a canister with gasoline, fit an igniter to it and drop the whole thing from a plane, upon impact the canister will rupture dispersing a great part of the gasoline as fine droplets that will burn very quickly; the gasoline still in liquid form instead will rapidly flow away from vertical or sloping surfaces, thus reducing the effectiveness of the fire. A lousy firebomb.

So someone came out with the idea of adding a thickener or jelling agent to the fuel in order to make it more viscous and sticky. Such a mixture sticks to all surfaces (people too) and burns for longer, maximizing the effectivness. The first thickener used for this purprose was sodium (symbol Na) palmitate, and so napalm was born (sodium palmitate and closely related chemicals can be found in common bar soap, so guess what yours truly did when he was young and wild...). Napalm is also useful in flamethrowers, because a more viscouse liquid can form a longer cohesive jet. Nowadays, jelled fuels are generally a mixture of gasoline, polystyrene and some benzene to improve the solubility of polystyrene. Napalm does not ignites spontaneously, and firebombs contain an appropriate igniter to start the fire. So yes, the Mk77 firebomb is a "napalm" bomb - but I can't see how using it against enemy forces is a war crime in itself. Napalm in itself is somewhat more toxic than gasoline; when it burns it produces soot and fumes that are as toxic as any hydrocarbon soot and fumes.

It is plain obvius that napalm is rather nasty stuff - I think that no-one lists being burned alive as a "good" way to die. But I think a lot of napalm's reputation comes from the notorious Vietnam War footage of a child running away with her back horribly burned by napalm (by the way, that child survived and last time I've heard about her, she was living in the USA). However, also standard HE munitions can and will cause horrific injuries, not to mention fires of any kind (put your hand on a wooden fire, if you don't believe me).
Nowadays, napalm is not used very often anymore: besides its bad reputation, there are anti-personnel cluster bombs, FAE munitions and precision munitions to do the same job.

Phosphorous is produced by the reduction of its ores in electric furnaces with coal, and is an element with numerous applications.White phosphorous (WP) is the α-allotrope of phosphorous: a white or yellow waxy solid, very toxic by ingestion or inhalation of vapours, which has the property of igniting spontaneously in air above 30 C; WP is normally stored under water to isolate it from air.

When ignited, phosphorous burns fiercely with a bright light, and producing a dense smoke of P2O5 and ortophosphoric acid droplets that is effective for visible and IR screening, and disrupting targeting lasers. For these reasons, WP is used militarily for illumination flares and smoke grenades or shells. In particular, the M825 smoke shell contains WP-soaked felts. WP has been used also as incendiary, because it will set fire to all flammable materials it contacts (also clothes).

Burning particles of WP will embed themselves into human flesh and continue to burn until they are in contact with air: WP is nasty stuff as well, but not banned by any treaty.

While I (fortunately) cannot vaunt experience with burnt corpses, I can state that flesh does not melt. Fat can melt, but flesh eventually burns and chars.

Update 11/11: After some research, I found one impact-bursting WP munition used by the US Military: it is the 60mm mortar cartridge M722, which as FAS states is used for marking/spotting purposes - in other words, to mark a target for an airstrike or artillery fire. Reports from Fallujah state that WP rounds have been used to drive enemy combatants out of their defensive positions.

Besides the linked papers, more information on phosporous come from the book "Hazards in the Chemical Laboratory", S.G. Luxon, Royal Society of Chemistry, Cambridge, 1992.


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