Ancient Exploding Cannonballs

Planetes writes "There is a story on MSNBC about some surprise archaeology. Apparently, cannonballs from shipwrecks are "exploding" (more like heating up and cracking open) when they are exposed to air. At least one reacted so violently it reached several hundred degrees. Talk about a booby trap. I'd never have seen this one coming." Heat from oxidation (that's "rusting", if you haven't taken chemistry) has started many fires in cargo ships carrying iron.

Comments

Great Balls of Fire!!

[savage_panda]

This information is great to know if ever your stranded on a desert island with a coral reef around it, which has caused some shipwrecks of vintage warships with cannonballs. It would be a way to cook coconuts, a way to heat your hut at night, and start fires without matches, not to mention the other basic uses of a cannonball like lawn bowling and basketball.

Re:Great Balls of Fire!!

[1WingedAngel]

Also, you can use them to power the next coconut radio The Professor makes. Or just half-submerge them in a small lake for your own private hot tub with Ginger and Mary Ann.

TIm

Re:Great Balls of Fire!!

[Anonymous Coward]

Habouji?

Nub gle wa?

definition of ancient?

[tps12]

When I read "ancient," I was thinking Greeks, Romans, or Moslems. I was all, "whoa, they had cannon, that's tight." But it looks like they are actually considerably more recent.

:(

Re:definition of ancient?

[Anonymous Coward]

Denoser... haha, that's excellent.

-Gabe

Interesting...

[deque_alpha]

But not much to say, other than that they need some video of one of those things spontaneously combusting a table, that would be cool...

Cross your legs

[hij]

The combination of oxygen and sea salt caused rapid oxidation resulting in the balls? ?exploding? open and crumbling into bits.

This is why I don't like to pull them out into the open air.

Basic chem

[Gamasta]

Probably under high pressure the reaction occurs not as, for example, the decomposition of carbonic acid to water and carbon dioxide (H2CO3->H2O+CO2, occurs only under 3atm, above that in the opposite direction) and combined with cloride ions eating balls wall, yeah, for sure it's not safe to bring them up by use of hands...

Re:Basic chem

[Anonymous Coward]

What? Your post is incomprehensible. Now that you know basic chemistry, try learning how to write a coherent sentence.

Re:Basic chem

[Cenam]

yeah that may be true nut thats high air pressure, not sea, it wasn't happening because of the crystal lattice(if u read the article) that formed around the ball insulating it..and if you know chem you will also know wht a crystal lattice is..

Re:Basic chem

[Anonymous Coward]

Actually, there is not such a thing as carbonic acid in reality. We, the chemist (I am a chemist), tell you there is such a thing in the college freshman chemistry classes (and anything below that level), but in reality, carbon dioxide really disolves in water, not forming carbonic acid.
The only condition you would have carbonic acid is under high pressure (gas pressure):

CO2(g) <===> CO2(aq)

Another point I would make is that chloride (it should be spelled "chloride," not "cloride") ion would not eat iron easily. In fact, if you remember anything from solubility chapter in chemistry, you should remember that anything containing chloride ion will completely dissociate:

MCl(s) --> M+(aq) + Cl-(aq)

where M is any metal such as iron. What this means is that all the chloride ion containing substances are soluble in water. Therefore, even if you mix any metal ions with chloride ion, chloride will never precipitate out (reacting with the metal ion). Since chlorine have very strong electronagativity, it will always want to stay as ion rather than staying as pure substance (chlorine gas), it will never react with the ball (which is made of iron).

Re:Basic chem

[PD]

We, the chemist (I am a chemist), tell you there is such a thing in the college freshman chemistry classes (and anything below that level), but in reality, carbon dioxide really disolves in water, not forming carbonic acid.

Do you lie to students in order to make them better chemists?

Frankly, I'm a little disturbed by this. I recall that my teachers and professors did NOT lie to us about carbolic acid. And nothing bad happened to me. So why exactly do you do this?

Re:Basic chem

[PD]

Crap. CARBONIC. I typed carbolic by accident. Carbolic acid is different.

Re:Basic chem

[Anonymous Coward]

It's a good apporximation for students. That is why. We (again, the chemists) do this quite often. For example, there is not such things as resonance structure, ball-and-stick model molecules. However, in terms of visualizing, they are great models. Better known one would be hydrogen ion. This really doesn't exist, but we treat as if it really exists (of course, many text books tell you that it really is H3O+). In chemistry, you see all the sorts of different models explaining the same system. Just to take examples, to explain acid-base system, you typically learn at least three different models: Arrhenius, Bronstead, and Lewis. While Physicists go insane about having so many different models explaining the same system, Chemists have no problem with it, as we choose the most appropriate one as we needed. In many areas of chemistry, it consists of many different models describing the same system. Sometimes, we take some approximated approach to these problems, specially when we are teaching to the first time (or near first time) students, as using these approximated models make a lot of sense for them to understand without making them confused. In this case, carbonic acid, we don't really tell you that really doesn't exist, as you need to have a good understanding of equilibrium and gas laws to understand that carbonic acid doesn't really exist under 1 atm (and carbonic acid is typically introduced in nomenclature chapter in very early on). Think it just like what physicists do in the college level general physics. They never really talk about air friction and the likes in classical mechanics chapters, as it will complicate the system a lot. They do this, because it is a good approximation of the system, and for the most part, they work just fine. In fact, it turned out, even if you include all the terms, just by using the classical mechanics method will give you slightly different answer, as it does not take into account of modern mechanics, but they never tell you that in general physics. That is because in order to understand that, you need to learn modern physics, which will complicate the matter big time when you are learning for the first time (by the way, I have taken modern physics in college, as well as some upper level physics, if you are wondering). I believe something like this is not totally unusual in many science area. We aren't exactly lying, as there were a time that we believed that particular subject was correct, and we found that it is easier to exmplain than telling you the truth. As you study more, you will often find that there are different explanation to the subject, and sometimes, what you learned in the first level is not the complete truth.

Exploding or cracking

[Anonymous Coward]

I like how at the begining of the article it's Cannonballs retrieved from ancient shipwrecks are wreaking thunderous havoc and by the end, they are using exploding in quotes as if they don't really explode but crumble into bits.

Use this link

[Anonymous Coward]

For fewer advertisements and no MS, you might as well go to the source.

Somehow seems appropriate.

[hackwrench]

One could not be a successful scientist without realizing that, in contrast to the popular conception supported by newspapers and mothers of scientists, a goodly number of scientists are not only narrow-minded and dull, but also just stupid. - J. D. Watson, "The Double Helix"

Re:Somehow seems appropriate.

[SecretFire]

I agree. Way too many people view scientists as a singular body, and critisize them as such. Suprisingly many fail to realize that "scientists" are a group of people, and have their fair share of idiots, cranks, and lunatics. Always annoying when people use generalizations like "scientists say".

Rust at work

[R2.0]

There's a road in the northwest that was closed because it was effecively on fire. The state specified ground-up tires be used in the fill under the road in an eco-friendly gesture. Groundwater started the steel belts in the fill rusting, the heat started the rubber burning, and now smoke is coming out of the ground.

Re:Rust at work

[Anonymous Coward]

Prove it. Gimme a Link. Couldn't find it on google with any obvious search terms.

Re:Rust at work

[R2.0]

Here ya go smartass: http://www.metrokc.gov/procure/green/rubber.htm

Like in KSR's Mars trilogy

[MagikSlinger]

One of the theories I've always heard is that if Martian soil was ever exposed to signficant water (i.e., enough to thoroughly wet it), the soil of Mars could start reacting violently because it's mostly iron that hasn't had the advantage of water to ensure the iron is fully rusted.

KSR has some fun with this when he described a flood released onto pristine Martian soil. Snap, crackle, pop, kids.

Re:Like in KSR's Mars trilogy

[TwP]

Isn't the soil on Mars already rusted, hence the red color?

Re:Like in KSR's Mars trilogy

[MousePotato]

hrm... If I recall correctly the Viking lander had a soil sample explode when water was added to it.

Anyone with info on the validity of this?

Re:Like in KSR's Mars trilogy

[ObviousGuy]

Yes. Take your tetanus shots before going.

Re:Like in KSR's Mars trilogy

[Anonymous Coward]

I just googled and found this article
Way offtopic and last year's news but it seems to address the thoughts of the parent post and the children...

Re:Like in KSR's Mars trilogy

[MagikSlinger]

Isn't the soil on Mars already rusted, hence the red color?

I forgot to mention that in my original post. From what I gather, only a small precentage of it is rusted (almost entirely on the surface of the rock or grain). Deep inside, there is iron just waiting for water to react with. As another poster mentioned, the Viking landers discovered "novel" chemistry when it was exposed to water. I don't know if it exploded, but it certainly did chemically react with the water.

Do it yourself pyromania

[ObviousGuy]

Toss some rags in a box and pour linseed oil on them. Put them in a quiet corner of your garage and wait for the fire department.

Imagine...

[Keyser_Lives]

...a Beowolf cluster of those.... Sorry. I really, truly am.......

Contains oxygen: handle with care.

[Observer]

Arthur C Clarke wrote a short piece about conditions on Earth as deduced from observations by astronomers of the long-extinct Martian civilisation (obtained by archeological investigations undertaken by early scientific expeditions from Earth in the early 21st century, IIRC - one of his early pieces). The Martian scientific consensus was that intelligent life could not possibly evolve on Earth, because 20% of its atmosphere was made up of the dangerously reactive element oxygen. Any life that did exist would have to be heavily armoured and shielded from exposure to such a corosive substance, and even then, there was evidence of sporadic large-scale chemical reactions on the surface of the planet, a terrifying natural phenomenon for which the scientists had invented the technical term "fire". Clearly, no life at all could possibly survive such events....

ACC was quietly ignoring the question of what was maintaining the level of such a reactive substance in the atmosphere in the first place, but he was also making a good point: most people do underestimate how reactive oxygen can be outside the everyday circumstances that we're familiar with. Wood burns, but we can make stoves out of iron, so iron doesn't burn easily, right? Wrong. Stuff an iron pipe with iron rods, blow pure oxygen down it and heat the open end for a while with an oxy-acetylene torch and you get one of the more powerful cheap cutting flames around. The cannon-balls had apparently had lots of fine channels corroded into them by years of exposure to sea-water so there was a large surface area unprotected by a covering of rust: in the cases where the iron combusted sufficient area of unprotected iron became exposed as or after the water evaporated which was enough to get the reaction started.

And Primo Levy commented in one of his books (Periodic Table, perhaps? I don't have it to hand to check) about how treacherously ready sawdust could be to spontaniously combust. A more obviously flammable example than iron, but a similar situation: with more surface area and less nearby mass to absorb heat from any reaction that does start, sawdust is that much more liable to behave dangerously that timber in bulk.

Ancient explosive ordinance

[j_w_d]

The older explosive ordinance was packed with black powder and fused so that it would ignite when fired from a gun. The problem with black powder is that while wet, it is perfectly safe. When it dries out it is unstable. I have participated in archaeological monitoring where the UEO guys were working to locate and safe ammunition ranging in age from Viet Nam War back to the Civil War. That ammunition occasionally still contained black powder that WOULD detonate (actually deflagrate I suppose) when dry. "Ancient exploding cannon balls" could very well ruin your whole day if not treated with some real respect.

Steel wool

[t]

I'm suprised no one has mentioned steel wool. If you've never played with some, it is incredibly flammable.

t.