[HN Gopher] Pompeii fixed potholes with molten iron (2019)
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Pompeii fixed potholes with molten iron (2019)
Author : strict9
Score : 57 points
Date : 2024-06-28 19:23 UTC (3 hours ago)
(HTM) web link (www.smithsonianmag.com)
(TXT) w3m dump (www.smithsonianmag.com)
| Dr_Birdbrain wrote:
| I'm annoyed they don't include pictures of the iron fillings.
| grugagag wrote:
| This article is a bit better on photos
|
| https://www.ancient-origins.net/news-history-archaeology/rom...
| elwell wrote:
| Plenty of ads though.
| roschdal wrote:
| Show me the proof please.
| grugagag wrote:
| https://www.ancient-origins.net/news-history-archaeology/rom...
| onetimeuse92304 wrote:
| Call me sceptical.
|
| That would have been astronomically expensive given the enormous
| supply chain needed to produce charcoal to get that iron in those
| times.
|
| I am sceptical on how they figured out iron stains are pothole
| fillings. I think much simpler explanation would be everyday
| items or metal pieces of carts getting stuck between stones.
| jl6 wrote:
| I do find this quite hard to believe. Iron would be considered an
| expensive material to use in roadbuilding even today. The
| pictures aren't all that convincing.
|
| > But lead author Eric Poehler of the University of Massachusetts
| Amherst writes that stray iron drops found on the street suggest
| that the molten metal was carried from a furnace to the repair
| site.
|
| If the hypothesis is that they were capable of carrying molten
| metal from a furnace to the road, isn't it more likely that these
| are splashes or spills from molten iron en route to a blacksmith?
| yard2010 wrote:
| You say "even", as if the Roman empire wasn't on par with the
| western empire today. I disagree. Even though we're at the tip
| of the ice berg, the human history is episodic in a way.
| sushisource wrote:
| > as if the Roman empire wasn't on par with the western
| empire today
|
| Huh? I mean, no, technologically it... definitely wasn't.
| Remind me how many teraflops the most powerful Roman computer
| was capable of?
|
| The Romans were plenty advanced, sure, but that's just a
| nonsense statement.
| thriftwy wrote:
| They had huge stadiums, though.
|
| Modern people had very little idea why you would have a
| stone stadium until around XX century.
| adriand wrote:
| I'm currently reading a book about Cleopatra [1] (it's superb)
| and I've been absolutely boggled by the productive capacity of
| the nation states of her era. Whether it was building ships,
| growing and transporting grain or raising armies, these were
| highly sophisticated bureaucracies that knew how to make, grow
| and transport huge quantities of stuff.
|
| I'm at work and don't have the book on me, so I may have this
| slightly wrong, but IIRC, in Cleopatra's day Alexandria (where
| she resided with her court) was consuming 300 tons of grain per
| day, which arrived on ships via the Nile. Or consider the ability
| of Rome to draft and train legions of highly-skilled soldiers: it
| was at a scale similar to that of modern-day Russia.
|
| 1: https://www.goodreads.com/book/show/7968243-cleopatra
| lukan wrote:
| I am somewhat sceptical, as iron was very expensive back then.
| And they do not come up with a working idea how they possibly
| could have done it in an economic way. Portable smelters were not
| really a thing. And building an oven next to every hole does not
| sound too practical either. At least not easier, than just fixing
| the holes with stones.
|
| Also shouldn't we have found other instances, where it was done?
|
| "The researchers found that repairs using liquefied ore were
| being carried out just before the city's destruction."
|
| So my first (uneducated) guess would rather be, that hot lava
| might have tampered with the evidence.
| jl6 wrote:
| I also thought "hang on a minute. Pompeii? As in volcano
| Pompeii?" but apparently the city was never flooded with lava,
| but rather ash, which was cooler than would melt iron (still
| fatally hot though).
| lukan wrote:
| The eruption was a violent explosion with molten rocks flying
| around. Some of them probably hit the city and some of them
| contained lots of iron would be my guess.
| meindnoch wrote:
| Elemental iron is not present in rocks on Earth.
| lukan wrote:
| But iron ore is. And TFA literally talks about "liquified
| molten ore".
|
| And this is speculation, but I assume a molten ore rock
| from inside the vulcano shot outwards, might have enough
| energy and time to purify itself a bit (different
| elements have different density, centrifugal principle).
| LightHugger wrote:
| Elemental iron is in fact present in some rare geology on
| earth. However, that's unlikely to be related to this
| issue, since they found the iron localized to main
| roadways and not splattered all over.
| loufe wrote:
| You do get some very large deposits of mostly pure iron,
| all of which in Europe would be fully mined out by now.
| Here's a mine in Northern Canada near my own which has
| 60-70% pure iron ore (truly astronomically high purity
| compared to ores for other metals).
| gus_massa wrote:
| Where, so I can take a look for more details.
|
| Natural iron minerals are made of oxizized iron, that
| includes oxigen or sulfur.
|
| The chemical process to deoxidize iron requires a lot of
| energy.
| littlestymaar wrote:
| Even with Lava, you're not going to melt iron, even when'
| it's just leaving the volcano it's not generally hot enough,
| and by the time it reaches the city it's even colder.
|
| The melting point of iron is very high, and that's why for a
| long time iron was never molten even during the production
| process (slag was, but not the iron)
| 0cf8612b2e1e wrote:
| Also from the Wikipedia, I learned that people died of the
| heat and not suffocation. Which means that episode of
| Stargate lied to me where they claimed the opposite.
| A multidisciplinary volcanological and bio-anthropological
| study[53] of the eruption products and victims, merged with
| numerical simulations and experiments, indicates that at
| Pompeii and surrounding towns heat was the main cause of
| death of people, previously believed to have died by ash
| suffocation.
| yard2010 wrote:
| Apparently, using ships ballast was a common practice
| throughout the last 500 years. You have to have it on the ship
| anyway.
| swatcoder wrote:
| > And they do not come up with a working idea how they possibly
| could have done it in an economic way.
|
| ... are you sure about that? I haven't pulled the paper, but
| the abstract suggests that doing exactly that was central to
| the research.
|
| https://www.ajaonline.org/article/3863
| lukan wrote:
| I probably should get the actual paper, yes. The articles are
| not that great, one has to read between the lines, that they
| talk about iron ore and not pure iron. Or rather iron slag.
| The byproduct of melting.
|
| But I meant the economics of getting the liquid iron (or
| slag) to the holes. If there were many furnaces nearby, maybe
| they just used that and carried it some meters, but longer
| distances?
| ricree wrote:
| Unless I'm mistaken, this strikes me as a really incredible
| claim. To the best of my knowledge, Rome didn't make much use out
| of cast iron. Iron has a very high melting point, it's not
| something that people were just casually melting. There were a
| few exceptions, but my understanding is that Europe mostly didn't
| use cast iron until late in the middle ages.
|
| The idea that some random resort town was casually melting iron
| and hauling it around to fill cracks strikes me as really
| implausible. Some other, more easily melted metal perhaps, but
| not iron. Not unless my understanding of Roman metallurgy is
| really mistaken.
| gfxxxx wrote:
| Not only that, but the thermal stress of pouring molten iron on
| wet, cold and cracked stone.... call me skeptical
| jandrese wrote:
| Count me as skeptical as well. Not only would it have been wildly
| impractical, but iron is prone to rusting and expands when it
| rusts. Plus it is slippery when wet. It's just not a good pothole
| filler.
| blacksmith_tb wrote:
| Also seems like the stone around it would wear more quickly and
| then instead of potholes you'd have iron bumps in the road, not
| much of an improvement.
| dukeofdoom wrote:
| They lived in really nice villas too. Frescos on the wall and
| mosaic floors. Better constructed than modern ones in some
| regards. No sqeeky floors for example. Surrounded by organic
| gardens with lemons and oranges and fragrant spices
| kragen wrote:
| > _most of the streets in the bustling seaside city were paved
| with silex, a type of cooled lava stone_
|
| 'silex' is a rather old-fashioned word; nowadays it's more
| commonly called 'flint', which is a sedimentary rock, not an
| igneous one. https://en.wikipedia.org/wiki/Silex
|
| > _processing taconite, a type of low-grade iron ore_
|
| taconite is typically 30%-35% iron, but it's true that most iron
| has historically been made from higher-grade ores than that
| (though throughout history iron has usually been made from
| _lower_ -grade ores, just in much smaller quantities)
|
| it is indeed fairly surprising to find cast iron in a roman town.
| china had cast iron from around 2500 years ago, but i thought the
| technology only reached europe during medieval times, and even
| later in western europe
| OnlyMortal wrote:
| Flint like "churt" used to make tools way back when?
| kragen wrote:
| yes
| Modified3019 wrote:
| Huh, I would have bet $10 that flint was igneous. Given how
| glasslike it can be I thought it was related to obsidian.
|
| Turns out it's sedimentary, and I overlooked considering all
| the non-volcanic places it can show up naturally. I guess
| it's time to brush up on my geology and mineralogy:
| https://en.m.wikipedia.org/wiki/Flint
| jacobolus wrote:
| Your Wikipedia link says: "The word _silex_ was previously used
| to refer to flint and chert and sometimes other hard rocks. "
| Seems this was a fairly generic word.
|
| According to http://doi.org/10.3764/aja.122.4.0579 which is the
| paper this blog post was based on, "The paving stones of
| Pompeii consist of a heavy, dark basaltic lava stone, which we
| describe as 'lava stone,' or _silex_ , using the general Latin
| term. For local travertine stones, we use the common name,
| 'Sarno limestone.'"
|
| One of the authors of the paper wrote a book, _The Traffic
| Systems of Pompeii_ , which has: "When covered in gravel or
| created in beaten earth, the surface was calld _glarea_ , but
| when paved in harder stones, the term _silex_ was applied. "
| kragen wrote:
| yes, the ancients often erred in their identification of
| minerals, lacking things like the flame test and
| spectrometers, not to mention atomic theory
|
| thanks for finding the reference from the paper! it's
| puzzling that the article would describe 'heavy, dark
| basaltic lava stone' as 'a type of cooled lava stone that
| wore away relatively quickly'. basalt is one of the more
| wear-resistant rocks
| ralferoo wrote:
| > 'silex' is a rather old-fashioned word; nowadays it's more
| commonly called 'flint', which is a sedimentary rock, not an
| igneous one. https://en.wikipedia.org/wiki/Silex
|
| From the start of the wikipedia link you yourself provided:
| "Silex is any of various forms of ground stone."
| kragen wrote:
| the next sentence says, 'In modern contexts the word refers
| to a finely ground, nearly pure form of silica or silicate'
| and then it goes on to explain that it historically referred
| to either flint or things that people confused with flint
| ralferoo wrote:
| So given that there are multiple things that it has meant
| over time, the first statement that it can refer to " _any_
| of various various forms of ground stone " seems like a
| good summary.
|
| To claim it can _only_ mean silicates, when two paragraphs
| later it says "Silex is now _most commonly used_ to
| describe finely ground silicates ", seems somewhat
| disingenuous. It's not " _only used_ " but " _most commonly
| used_ ".
| kragen wrote:
| your attack on my integrity is outrageous and utterly
| uncalled for; it's entirely possible to disagree with
| people without insulting them, and i suggest you learn
| how right now
|
| i don't think 'there are multiple things it has meant
| over time' is really correct, except in the sense that
| imperial roman mineralogy was entirely incapable of
| meaning things we mean today, because they lacked much of
| our conceptual framework. they didn't know the difference
| between basalt and flint, evidently, much as many people
| today don't know the difference between nylon and
| polyethylene and consequently mistakenly call their
| polyethylene shopping bags 'nylon'
| jjk166 wrote:
| This article is incorrect. The actual claim is that the romans
| were making repairs with molten ore, ie slag, which has a
| substantially lower melting point than molten iron and would be a
| cheap byproduct of iron production.
| gfxxxx wrote:
| Thank you. I was extremely skeptical that they used molten
| iron.
| kortex wrote:
| I believe this is the article:
|
| https://www.ajaonline.org/article/3863
|
| > In July 2014, we conducted a survey of Pompeii's street network
| to document traces of iron that were observed on the stone-paved
| streets, which resulted in the identification of 434 instances of
| solid iron and iron staining among the paving stones. ...
| Pompeians were--in addition to using solid iron wedges--pouring
| molten iron and iron slag onto their streets as a method of
| emergency repair.
|
| There's a huge gulf of difference between "a civilization is
| capable of melting iron" and "molten iron is so cheap and easy
| they used it to fill potholes".
|
| Castable iron: Valuable, scarce, energy intensive, very hard to
| melt (comparatively), corrodes readily (especially on the coast)
|
| Iron and other metal _slag_ : Byproduct of iron smelting,
| basically waste, melts fairly easily, was used as ballast in
| ships, comparatively cheap, rusts superficially but is mostly a
| matrix of oxides which don't meaningfully react
|
| I'm beyond skeptical that perfectly good cast iron was used to
| fill potholes. Using slag/dross/failed smelts/other byproducts of
| metallurgy makes far better sense.
|
| It would be like far future archeologists unearthing rammed earth
| tire walls and concluding "the 20th century was so efficient at
| producing rubber they used excess tires as a building material"
| vs "they used a waste product which would have been landfill
| anyways".
| kragen wrote:
| and bloomery slag is _always_ contaminated with bits of iron
| that never melted
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