Volts before Volta
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Sino-Platonic Papers is pleased to announce the publication of its three-hundred-and-seventy-seventh issue:
“The Baghdad Battery: Experimental Verification of a 2,000-Year-Old Device Capable of Driving Visible and Useful Electrochemical Reactions at over 1.4 Volts,” by Alexander Bazes.
ABSTRACT
The “Baghdad Battery” has posed an archaeological enigma for over eighty years. Discovered at the Parthian site of Khujut Rabu (first century ce), this famous artifact’s utilitarian yet highly specific design tailors so clearly to the requirements of an electrochemical cell that it is difficult to conceive of another use for it. Although efforts have been made to recreate this battery (König 1938, Keyser 1993, MythBusters 2005), prior experiments have failed to (1) account for all aspects of the artifact’s design and (2) make a device that has enough power to be evidently useful for people two thousand years ago. The result of these previous recreations has thus been to cast doubt upon whether the Baghdad Battery was, in fact, a battery at all. The present study’s recreation dispels this doubt by accounting for two previously neglected aspects of the artifact’s design, namely the use of solder and the function of the ceramic jar, which together form a previously unrecognized second source of voltage for the device: an aqueous tin-air battery. This “outer cell,” which is integrally connected in electrical series with the device’s already well-understood “inner cell” (comprising copper and iron), enables the Baghdad Battery to generate over 1.4 volts: an electric potential capable of driving a number of useful (and highly noticeable) electrochemical reactions, including electroplating, etching, and the electrolysis of water into hydrogen and oxygen gas. The present study’s result therefore provides the strongest evidence to date for people in the Near East having had a working knowledge of electrochemistry nearly two millennia before Alessandro Volta’s experiments with the voltaic pile.
Keywords: Baghdad Battery, Parthian Galvanic Cell, tin-air battery, aqueous metal-air battery, ancient electrochemistry
Selected readings
- "Unit utility" (6/25/25) –in the comments
- "Annals of word rage" (5/2/09)
- "The dormitive virtue of root-power quantities" (8/29/13)
Alexander Bazes said,
January 4, 2026 @ 2:46 pm
As a possible direction for future research, I find it intriguing that the Baghdad Battery and similar artifacts date from the time and place where the earliest Syriac writings on alchemy were emerging. The opening of the Emerald Tablet, for example, strikes me as describing a spiritual theory of electrical phenomena in both the atmosphere and in living beings, with strong parallels to Taoist writings on qi. A battery may be mundane to us now, but I believe 2,000 years ago it could have had profound implications for people's understanding of the universe and their place within it.
Alexander Bazes said,
January 4, 2026 @ 3:47 pm
The opening of 内業 (Inward Training), for example, I have always found to be quite evocative of the Emerald Tablet:
1. The vital essence of all things:
2. It is this that brings them to life.
3. It generates the five grains below
4. And becomes the constellated stars above.
5. When flowing amid the heavens and the earth
6. We call it ghostly and numinous.
7. When stored within the chests of human beings,
8. We call them sages.
凡物之精
此則為生
下生五穀
上為列星
流天地間
謂之鬼神
蔵於胸中
謂之聖人
Roth, Harold David. 内業: Inward Training (nei-yeh) and the Foundations of Taoist Mysticism. Columbia University Press, 1999. (46-47)
For comparison, here is a 1929 translation of a version of the Emerald Tablet from Jabir ibn Hayyan:
0) Balinas mentions the engraving on the table in the hand of Hermes, which says:
1) Truth! Certainty! That in which there is no doubt!
2) That which is above is from that which is below, and that which is below is from that which is above, working the miracles of one.
3) As all things were from one.
4) Its father is the Sun and its mother the Moon.
5) The Earth carried it in her belly, and the Wind nourished it in her belly,
7) as Earth which shall become Fire.
7a) Feed the Earth from that which is subtle, with the greatest power.
8) It ascends from the earth to the heaven and becomes ruler over that which is above and that which is below.
14) And I have already explained the meaning of the whole of this in two of these books of mine.
[Holmyard 1923: 562.]
Peter Grubtal said,
January 5, 2026 @ 3:35 am
The wiki page on this will need updating then, because it's uniformly negative on the battery hypothesis, with apparently cogent technical arguments.
Hopefully those who edited the current wiki page will check the technical arguments in the platonic papers article, because they're above my and a lot of people's heads.
~flow said,
January 5, 2026 @ 8:18 am
Can recommend this thoughtful piece: "The Enigmatic 'Battery of Baghdad': This 2,000-year-old find is considered by some scientists to be an electrical power source. Did it really work?" by Gerhard Eggert (in: *Skeptical Inquirer* May/June 1996) https://cdn.centerforinquiry.org/wp-content/uploads/sites/29/1996/05/22165042/p31.pdf
Of particular interest regarding the critical treatment of the Battery hypothesis by the Wikipedia article is the observation that we don't have finds from the time that are electroplated.
Alexander Bazes said,
January 5, 2026 @ 10:18 am
~flow, thank you for that link, although let's remember that the Skeptical Inquirer has a self-stated bias and must cater to certain expectations from its readers. I believe you will find that my article addresses most of the concerns raised by Eggert.
Although I see electroplating as one possible use for this device, at 1.4 volts the Baghdad Battery would have been capable of driving any number of electrochemical processes, which would not necessarily have left direct evidence (for example, if the byproducts of these reactions were consumables such as hydrochloric or sulfuric acid). I am not a chemist, so I hope professionals will recreate my experiment and see what they can do with 1.4 volts. I speculate that something may have been done with electrolysis of water by fuming hydrogen bubbles over sulfur, etc. This was, after all, where early Syriac alchemical writing was emerging. People were absolutely experimenting with metals and salts.
The discovery that the Baghdad Battery actually functioned as two batteries in one also may explain other similar artifacts discovered where the iron rod is missing. A metal tube, lye, and a porous clay pot will get you a metal-air battery (the BB's "outer cell.")
Philip Taylor said,
January 5, 2026 @ 10:45 am
I am following this thread with considerable interest, in part because there was a time in my life when I saw my future career as being a research chemist, and I am not sceptical in the least, merely fascinated. But I have one question for Alexander, if I may ? Alexander, both in your comment above and in your original paper you make reference to "lye", which you define in your paper as potassium hydroxide (KOH). Now the word "lye" is not commonly used in British English, so although I thought I knew what was meant, I wanted to be sure. And Google (amongst other "authorities") tells me that "lye" can be KOH or NaOH (sodium hydroxide). My question is therefore simply "(a) do we know which of these two compounds (if either) was used in the Baghdad battery, and (b) if the other were used, would it make any significant difference ?".
Alexander Bazes said,
January 5, 2026 @ 10:53 am
It is also important to note that these artifacts are quite rare. With only one Baghdad Battery found (the other artifacts being of different design), I'm not sure how surprised we should be not to have physical evidence of what it was used for—whether that be electroplating or something else.
Similar artifacts found at the archaeological site of Csestiphon (several centuries later than the Baghdad Battery) were found in a magician's house, along with other ritual implements. I think that most likely these specialized devices were within the domain of magi/ritual practitioners, and that we are thus best served looking for evidence of how an ancient knowledge of electricity might have influenced the development of alchemical thought.
Alexander Bazes said,
January 5, 2026 @ 11:07 am
Hi Philip,
Thank you for your comment. I really wish the artifact had not been stolen from the Baghdad Museum during the Iraq War so X-ray fluorescence could be done—and then I can be proven totally wrong!
Potassium hydroxide, which was historically rendered from potash, is one of the oldest chemicals known to man, so that is why I thought it would be a likely/reasonable electrolyte to test out. I honestly don't know whether sodium hydroxide would work. (My understanding is that lye originally referred only to KOH and only later came also to refer to NaOH).
Alexander Bazes said,
January 5, 2026 @ 11:52 am
*Correction: "āšipu" was the term I was looking for that describes ritual practitioners.
Philip Taylor said,
January 5, 2026 @ 2:01 pm
Fine, thank you Alexander, and all understood. And I join with you in deploring the theft of this remarkable artifact from the Baghdad Museum during the Iraq War.
Victor Mair said,
January 5, 2026 @ 10:02 pm
More TK (from the nonpareil Penn Museum).
Alexander Bazes said,
January 10, 2026 @ 2:22 pm
Philip, by the way– please be skeptical! Perhaps I should have made it clear that skeptical inquiry is obviously always to be encouraged; my limited experience with articles from the "Skeptical Inquirer," however,
is that they consider skepticism to be an a priori assumption that nothing weird or unexpected has ever actually happened and a duty to assure their readers of this comforting fact.
William B. Hafford said,
January 22, 2026 @ 1:52 pm
The drawing that Wilhelm Koenig made and published in 1938 is what has been recreated in this article (as in all attempts to reconstruct the 'Baghdad battery'). Koenig, the director of the laboratory at the Iraq National Museum, was convinced that the artifact he saw in the museum was a battery. It had three museum numbers, one for the jar, one for the copper cylinder, and one for the iron nail. This fact, along with the photograph that Koenig published, show that the artifact was already in pieces when he examined it. Thus, he did not make a drawing of the actual arrangement of the artifact as found, but of the arrangement he believed would work as a battery. And work it does, if you add a caustic substance and assume that the bitumen seal allowed you to make contact with the metal parts to complete the circuit (presumably using wires, for which there was no evidence).
The excavation of Khujut Rabu'a was never published as far as I can tell, but Koenig probably had access to field notes from that dig (conducted by Iraq Department of Antiquities archaeologists in 1936). He claims that the iron rod protruded above the bitumen sealing around the jar neck, but sealed jars are common and the sealing typically covers the entire opening. In fact, some of the comparable objects found at Ctesiphon and Seleukia were sealed completely and the iron rod, along with several bronze rods, was found stuck in the ground outside, apparently holding the jar itself in place. These jars typically contained multiple copper cylinders (rather than just one, which would be required for a good battery to work), and no jar has revealed direct evidence of a caustic substance. Of course, acid would be hard to detect in the archaeological record and very little scientific analysis of these objects has been done. One study does mention lead carbonate and the iron and copper are certainly corroded, but these materials naturally corrode in the salty soils of Iraq. Over nearly 2000 years, water filters down and into the jars through their porous outer surface and corrosion naturally occurs.
Most importantly, the archaeological evidence speaks pretty strongly against the battery hypothesis. We have no contextual information for the Khujut Rabu'a artifact, but several of the Tell Umar (Seleukia) jars (with copper cylinders and external nails) were found along with incantation bowls. Such bowls are very well studied and stretch over a long period across many cultures and language groups. They had spells written on their interiors and were then placed upside down in the foundation of a building. Their purpose was expressly revealed by the spells–they were meant to trap demons or evil spirits that tried to enter the building. From this we can see that the jars with copper cylinders (most of which had the remains of papyrus-like material inside) were almost certainly deposited in the foundation along with the bowls, never meant to be touched or used by humans. They likely had prayers or spells written on the papyrus, rolled up in the cylinder, and placed inside the jar for burial. In some ways, these objects appear similar to much later witch bottles, mostly found in Europe from the 17th to 19th centuries CE. These were glass or ceramic containers that often held nails and other materials, intended as magical objects that were believed to be active as long as they remained buried and out of sight.
Most likely the 'Baghdad battery' was a ritual object meant to protect a building, or perhaps to curse an enemy. Some sort of effect that occurs between different metals may have been noted by ancient alchemists and this may have been a reason for the inclusion of different metals in the ritual, but I believe that there is not enough evidence to show that the jars found at Khujut Rabu'a, Ctesiphon, and Seleukia were ever used as batteries.
For the best discussion of the original objects, see Paszthory, "Stromerzeugung oder Magie" in Antike Welt 1985 Vol. 16 pp. 3-12.