The Baghdad Battery | Hacker News Reader

The Baghdad Battery

en.wikipedia.org

76 pointsneom19 comments

"The Discovery Channel program MythBusters built replicas of the jars to see if it was indeed possible for them to have been used for electroplating or electrostimulation. On MythBusters' 29th episode (March 23, 2005), ten hand-made terracotta jars were fitted to act as batteries. Lemon juice was chosen as the electrolyte to activate the electrochemical reaction between the copper and iron. Connected in series, the batteries produced 4 volts of electricity. When linked in series, the cells had sufficient power to electroplate a small token and deliver a minor electric shock to MythBusters co-host Adam Savage. Archaeologist Ken Feder commented on the show noting that no archaeological evidence has been found either for connections between the jars (which were necessary to produce the required voltage) or for their use for electroplating."

4V is not enough for any sort of "electric shock", much less be perceptible.

What is the cutoff between 4V and 9V then? Because a fully charged 9V battery on the tongue is most definitely perceptible!

Why is it imperceptible when you drop down to 4 volts?

It has to do with the resistance between the two terminals. Every person is different, so the cutoff will be different between every person

It also depends on the sensitivity of the tissue. Take the tongue for example where 4V is enough to feel a bite.

when cells are linked in series, voltage is additive. 2 jars linked positive-to-negative would provide 8 volts, 10 jars about 40, which is definitely enough to get a shock or electroplate.

I think you misread it --- the sentence is saying 10 cells in series provided 4V, which means ~0.4V/cell and far closer to what the chemistry would predict for a copper-iron cell:

https://en.wikipedia.org/wiki/Standard_electrode_potential_(...

edit: see near the bottom of page 4 of this: http://www.mrloader.com/uploads/3/2/2/1/32218311/electrochem...

That says 0.43V for a copper-iron cell.

Unfortunately it looks like the battery was looted from the Baghdad museum during the 2003 invasion of Iraq and remains missing (according to a small snippet at the bottom of this article).

Also of interest, Moche electroplating.

https://www.cambridge.org/core/journals/american-antiquity/a...

http://resources.conservation-us.org/osg-postprints/postprin...

https://www.britannica.com/topic/Moche

This reminds me of a mean prank the cast of Mythbusters pulled on Adam Savage[0]. According to Adam, the team was forced into doing this by someone who wasn't with the show anymore (2015)[1].

[0] https://www.youtube.com/watch?v=U0SEBFGGEcI

[1] https://www.reddit.com/r/IAmA/comments/3cfqzf/i_am_adam_sava...

It's all very well to prove they would not have been useful as cells in a battery for electroplating, but it gets us no closer to what they really were meant for. You don't need a copper jacket or iron rod to store a scroll in a sealed jar: you just need to seal the jar.

> You don't need a copper jacket or iron rod to store a scroll in a sealed jar

This is not a strong argument, on the basis that there's apparently no limit to the desire of humans to be superstitious about shit they don't understand, and want to decorate stuff.

You may not think you need a copper jacket and iron rod to store a scroll in a sealed jar, but Uncle Nasim the Ctesiphonian may have had some trenchant beliefs on both the aesthetics of document storage, and how to keep the Djin away.

...and maybe these actually were batteries used for a lot of things. Your argument amounts to "people might have done it for superstition", which isn't a strong argument either which was ops original gripe.

https://en.wikipedia.org/wiki/Aeolipile

https://en.wikipedia.org/wiki/Antikythera_mechanism

https://en.wikipedia.org/wiki/Su_Song

More generally, out-of-place artifacts:

An out-of-place artifact (OOPArt) is an artifact of historical, archaeological, or paleontological interest found in an unusual context, that challenges conventional historical chronology by being "too advanced" for the level of civilization that existed at the time, or showing "human presence" before humans were known to exist.

From https://en.wikipedia.org/wiki/Out-of-place_artifact

Not as out of place as popular media would have you believe. Ancient civilizations had analog computers, automatons, steam engines etc the Romans were responsible for destroying most of it, they were only interested in weapons tech, set us back at least two thousand years.

Further reading: https://press.princeton.edu/titles/14162.html

Your reference only says that their myths proposed some advanced ideas not that they executed or realized those ideas.

tldr: The physical construction makes it pretty much impossible to use as a battery, it might have been used for electroplating but it seems more likely that it held scrolls.

Erik von Daniken had a field day with this in his "Chariots of the Gods" hoax back in the 70's.

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