fusso
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Speculating how early humans discovered the 7 metals of antiquity?
"The metals of antiquity are the seven metals which humans had identified and found use for in prehistoric times: gold, silver, copper, tin, lead,
iron, and mercury."
How did early humans discover them?
Gold and silver occur frequently in their native form so early humans can obviously discover them.
But how did they figure out the "obvious" way to reduce the other metals' ores back to the metal? Mercury would be boiled away while being smelted, so
how did they discover and collect it using only simple tools at that time? How did they cast stuff out of iron without advanced heating methods? How
did they found out that blue compounds could be reduced to a red metal? How did they figure out that metals can be obtained from sulphide ores when
SO2 smell is so discouraging?
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DraconicAcid
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Copper can also be found as native copper. I'm sure that someone probably found that using blue or green rocks to line their campfire would do weird
things to the rocks, so they tried a bunch of rocks to see what would happen.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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desman
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You mix Iron oxides with carbon then you can get the pure metal & carbon dioxide.
Excess of carbon can burned in contact with air.
I think this also applies to Cooper/Lead/Tin.
Fe2O3 + C -> Fe + CO2
C + O2 -> CO2
The Iron sulphide can be decomposed to Iron oxide at 680 °C.
FeSO4 → Fe2O3 + SO2 + SO3
You need a furnace, so the heat wont easily escape.
[Edited on 9-10-2018 by desman]
[Edited on 9-10-2018 by desman]
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fusso
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Quote: Originally posted by desman  | You mix Iron oxides with carbon then you can get the pure metal & carbon dioxide.
Excess of carbon can burned in contact with air.
I think this also applies to Cooper/Lead/Tin.
Fe2O3 + C -> Fe + CO2
C + O2 -> CO2
[Edited on 9-10-2018 by desman] |
The question is: how did they discover carbothermic
reduction?
[Edited on 18/10/09 by fusso]
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desman
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Trial & Error.
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macckone
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they used wood which forms charcoal for the fires.
when they used certain rocks to surround the fire, it formed metals.
Most iron in prehistory was probably in native form.
Iron working wasn't widespread until more recently.
The first iron was wrought iron.
Mercury was actually commonly used before iron.
It was probably discovered by heating rocks containing mercury sulfide in a closed ceramic container.
There is actually a lot of stuff on this in ancient alchemy books and history of chemistry books.
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diddi
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i suspect that one of the great drivers of invention in prehistoric days was that of advantage in war or conflict. when there is sufficient desire to
gain advantage then experimentation is encouraged. it is still true today. when the first explosives were discovered, i bet the government did not
say "hooray! now farmers can remove trees with a new found ease" or at the onset of the nuclear age there was an declaration of "cheap electricity for
all."
and also i would think that the observation of metals being associated with certain environments would point inventors in certain directions. so for
example, tiny beads of liquid silver are to be found on a crimson coloured rock. lumps of native copper are often coated in blue green powders if
exposed to the weather. some rocks are blue on the inside and green on the outside. so the metal points to the rock having some property worth
exploring
Beginning construction of periodic table display
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mayko
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Mercury occurs natively:
https://www.minerals.net/mineral/mercury.aspx
Native iron is very rare, but deposits exist and were apparently used by some Inuit. Meteoric iron was more commonly used before smelting technology
was developed:
https://www.sciencedirect.com/science/article/pii/1044580392...
https://en.wikipedia.org/wiki/Meteoric_iron#Cultural_and_his...
IIRC, the first few chapters of Asimov's "Search for the Elements" covers this pretty well
al-khemie is not a terrorist organization
"Chemicals, chemicals... I need chemicals!" - George Hayduke
"Wubbalubba dub-dub!" - Rick Sanchez
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clearly_not_atara
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Mercury is easily distilled. No reductant is necessary; the oxide decomposes. Silver is the same: silver ore is heated to obtain the pure metal.
Heating rocks isn't obviously useful, but it was probably done anyway, since this is done in the firing of clay. One day, somebody heated a rock and
got silver.
With copper, a reductant is necessary, so that was a big step. But fuels are reductants, so if you are already accustomed to heating rocks, simply
throwing the rock in the fire is the next logical step, and that will suffice to produce copper, tin, and lead, which do not (easily) form carbides.
Iron was next, and it will form cementite if you do that. But continued experimentation with the copper process probably gave the Hittites hints to
unlocking the secret of iron.
https://en.wikipedia.org/wiki/Ferrous_metallurgy#Iron_smelti...
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elementcollector1
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Lead, at least, I can give a possible answer for: I've noticed that melting lead in a wood fire tends to boil the lead, making vapors condense on any
surface above the fire (in my case, it was a tent that now has a permanent silvery stain on it).
I was taught that copper was first discovered when an ancient someone tried to melt malachite (a fairly common copper ore), and instead found that the
carbon of the fire had reduced it to molten copper.
Elements Collected:52/87
Latest Acquired: Cl
Next in Line: Nd
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Mr. Rogers
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Copper can be found as nuggets, some fairly large.
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Ubya
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well you never throwed a rock in a fire out of boredom? since i was a child i like making campfires, and i always tried to burn everything hahahaha, a
green stick, some dirt, a piece of metal , glass, A ROCK, just out of boredom, i look at a fire and throw stuff in it, might as well been the same for
ancient people, just stare at a fire to keep warm, and throw stuff inside it, and maybe if you throw the right rock you get something cool after, like
red shiny metal (copper) if you used a green rock, a heavy shiny rock like galena would produce little spheres of molten lead inside a fire. pretty
much everything was discovered by accident, and after that intelligent humans made a connection, "i threw a green rock in the fire and i got red
metal, if again i put green rocks in the fire i will get more red metal" then you test which green rock works and which not. how do you think people
knew what berries or foods are poisonous? someone ate them and died 
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feel free to correct my grammar, or any mistakes i make
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VSEPR_VOID
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For you
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unionised
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It is obviously useful if you want hot water to cook, but don't have metal saucepans to heat water over a fire.
You put hot rocks in a container of water.
You can boil water in a wooden tub this way which is a very useful thing to do.
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DraconicAcid
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I'm sure people learned pretty quickly that they should put rocks around their fire if they didn't want it spreading. Eventually, someone used a
greenish-blue rock, and the rest is prehistory....
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Morgan
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| Quote: Originally posted by DraconicAcid |
I'm sure people learned pretty quickly that they should put rocks around their fire if they didn't want it spreading. Eventually, someone used a
greenish-blue rock, and the rest is prehistory.... |
Maybe a greenish-blue rock imparted a color to a flame, creating a curiosity to explore them more.
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Gearhead_Shem_Tov
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Heating rocks goes back long before metallurgy was discovered. Flint is
more easily and consistently worked with a bit of heat treatment, and lithic technology is arguably the only technology humans evolved to get to be
good at during over 94% of our time since we became anatomically modern 130,000 years BP (not counting the minimum of half million years or so of
lithic tech used by previous hominin species). Banging rocks together and then the more delicate techniques of pressure flaking made us who we are.
The first evidence of any sort of smelting doesn't show up until maybe 7000 years BP. Stone tools are still in daily use in some parts of the world to
this day.
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VSEPR_VOID
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Was smelting copper part of their plan?
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Heptylene
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Of course!
 Did you watch The Dark Knight Rises recently?
One a more serious note, I wonder how they managed to turn the metal into useful shapes. Did they have to melt it again or did they managed to make
large single pieces in one step from the ore?
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Morgan
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Possible stairsteps ...
"Many archaeologists believe that these techniques for smelting copper were discovered in the process of firing ceramics in early kilns. Pottery
making technology was reasonably well developed before 4000 B. C., and the potters had by that time learned much practical chemistry through their use
of glazes. Though they understood it but little, they were using the properties of silicates to control whether their pottery was of the high fired
type (like fine bone china today) or a medium fired variety (like a terra - cotta plant pot or roof tile) or even a low fired type (fired just enough
so that it doesn’t turn into mud when it gets wet). High and low here refer to the temperature and length of time the piece was kept in the kiln and
determine to what degree the particles of kaolin or other clay fuse together to form glass. The chemistry of glazes was another entire field
altogether and it was through controlling the temperature and the amount of oxygen present (these were closely guarded secrets) that the color,
texture, and pattern of the finish were controlled. The glazes containing copper compounds were used to create the brilliant blue, aqua, and green
finishes which were quite as popular with the ancients as they are today. If fired correctly, they formed a hard glass coating on the piece."
"The reason for the foregoing discussion of pottery is that many researchers today believe that the discoveries of smelting techniques came about when
ancient potters found bright bits of pure copper in their kilns when removing the pieces of fired pottery after the kilns cooled off. They were
accomplished practical if not theoretical chemists in that they knew how to control fire and oxygen in order to produce a desired look to their
finished pieces. The authors of the Time - Life Metalsmiths book used as the principal source of information in this article express wonder in print
how long it took the potters to catch on that their glazes were the source of metallic copper found in their kilns. The author of this article would
take a different path down the road of conjecture and what if. He contends that these were the keepers of the most advanced and complex technology of
their day, and were quite experienced in the use of their powers of observation when it came to some new phenomenon associated with their firing
techniques. Furthermore, their work would be in high demand by the aristocratic and ruling classes, the consumers or art and beautiful objects. It was
probably part of good professional practice for these craftsmen to be on the lookout for some potentially useful or desirable byproduct of their
operations. On the contrary, many were probably deliberate experimenters. What would be surprising would be if they did not make a connection between
the most brilliant blue and green minerals used in their glazes and the work of their contemporary metalsmiths who were taking similarly colored
malleable rocks, hammering off the green malachite scale covering them, and cold forming copper weapons and jewelry. It is simply human nature to
wonder about the possible implications of a curiosity or a discovery, and to make connections with other little bits of knowledge that come their
way."
http://www.jaysromanhistory.com/romeweb/glossary/timeln/t09....
[Edited on 14-10-2018 by Morgan]
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