In 1938, an Austrian archaeologist named Wilhelm König was poking through the basement collections of the National Museum of Iraq when he came across something that didn’t belong. Sitting among the Parthian-era artifacts — clay pots, bronze figurines, the usual detritus of a civilization two millennia gone — was a small terracotta jar, roughly the size of a man’s fist, containing a copper cylinder and an iron rod. The iron showed signs of corrosion consistent with acid exposure. The copper had been soldered shut at the bottom with a lead-tin alloy. König, who was not prone to wild claims, published a paper suggesting the object might have been a primitive galvanic cell — a battery.

He was largely ignored. Then he was ridiculed. Then, decades later, people started actually testing the idea, and the conversation got considerably more complicated.

What We’re Actually Looking At

The artifact — or rather, artifacts, since there appear to be at least a dozen similar objects — dates to somewhere between 250 BCE and 224 CE, the Parthian period of Mesopotamian history. The main specimen consists of three components: a clay jar approximately 13 centimeters tall, a copper cylinder roughly 9 centimeters long formed from a rolled sheet, and an iron rod suspended inside the cylinder, separated from it by an asphalt plug at the top. The copper cylinder’s bottom was capped and sealed with a lead-tin solder.

This is an unusual combination of materials. Iron and copper don’t naturally cohabitate in Parthian artifact assemblages without reason. The deliberate insulation of the iron rod from the copper cylinder — the asphalt plug ensures no direct metal-to-metal contact — is the detail that makes electrochemists raise their eyebrows. Because that separation is exactly what you need to create a voltaic cell. Add an acidic electrolyte — vinegar, wine, lemon juice, any of a dozen substances readily available in ancient Mesopotamia — and you get a small but measurable electrical current.

The Experiments That Muddied Everything

In 1940, Willard F.M. Gray, an engineer at the General Electric High Voltage Laboratory in Pittsfield, Massachusetts, built a replica using copper sulfate as an electrolyte and reportedly generated about half a volt. The experiment was informal, and Gray’s notes are sparse, but the result was real enough.

More rigorous tests followed. In the early 1980s, Dr. Arne Eggebrecht, then director of the Roemer and Pelizaeus Museum in Hildesheim, Germany, constructed replicas and used grape juice as an electrolyte. He claimed to have generated sufficient current to electroplate a thin layer of gold onto a small silver figurine. Eggebrecht argued this explained a longstanding mystery: certain ancient Iraqi artifacts appear to have gold plating so thin and uniform that conventional explanations — fire gilding, gold leaf application — don’t satisfactorily account for the quality of the finish.

The television show MythBusters replicated the experiment in 2005 with ten Baghdad Battery replicas connected in series, generating roughly 4 volts — enough to produce a slight tingling sensation on the skin and to electroplate a small coin.

So the basic electrochemistry works. Nobody seriously disputes that. Fill the jar with an acidic solution, and you get a current flowing between the dissimilar metals. The physics is straightforward — Luigi Galvani stumbled onto the same principle with frog legs in 1780. The question isn’t whether it can produce electricity. The question is whether anyone in ancient Mesopotamia knew it did, and if so, what they did with it.

The Scroll Jar Hypothesis

The dominant counter-explanation, championed most prominently by Dr. St John Simpson of the British Museum, is that the objects are simply scroll jars — containers for storing sacred texts or small papyrus documents. Simpson has pointed out that similar-looking vessels from the Seleucia region were used for exactly this purpose, and that the copper cylinder could have served as a protective housing for a rolled document.

It’s a reasonable argument, and Simpson is a serious scholar. But it has gaps.

First, no traces of papyrus, parchment, or any organic document material have ever been found inside any of the Baghdad Battery specimens. Proponents of the scroll jar theory argue that organic materials would have decayed over two thousand years, which is fair — but the absence of evidence is not itself evidence. The asphalt seal and the lead-tin solder cap are also hard to explain under the scroll jar model. Why would you solder shut a document container with a metallic cap? Why would you seal it with asphalt, a waterproofing agent? Scroll jars from other regions and periods — the Dead Sea Scroll jars from Qumran, for instance — don’t exhibit anything like this level of material complexity. They’re simple lidded vessels, because that’s all you need to protect a rolled document.

Second, the iron rod. What is an iron rod doing inside a scroll container? Simpson has suggested it might be a structural support, but iron is a strange choice for supporting a papyrus scroll — it corrodes, it’s heavy relative to the task, and it would be in direct contact with the document. Wood or bone would serve far better and were abundantly available.

Third, the corrosion patterns. Paul Keyser, a classicist at the University of Alberta, published a detailed 1993 paper in the Journal of Near Eastern Studies arguing that the corrosion on the iron rod is consistent with prolonged exposure to an acidic electrolyte, not with the slow atmospheric oxidation you’d expect from simple storage. Keyser didn’t claim the batteries were used for electroplating — he proposed they might have been used to produce a mild electrical sensation for medicinal or ritual purposes, analogous to the use of electric fish (torpedo rays) in Greek and Roman medical practice. Scribonius Largus, a Roman court physician, prescribed the shock of a torpedo fish for headaches and gout as early as 47 CE. The idea that a culture might seek to replicate that effect artificially is not outlandish.

What the Scroll Jar Explanation Can’t Account For

The real problem with the scroll jar hypothesis isn’t any single objection — it’s the accumulation of design features that make no functional sense for document storage but make perfect sense for electrochemistry.

The deliberate separation of dissimilar metals. The waterproof seal. The corrosion patterns. The solder cap. Each of these, individually, might be explained away. Taken together, they describe an object that looks remarkably like it was designed to hold a liquid in contact with two different metals while preventing those metals from touching each other. That is, by definition, a galvanic cell.

Simpson and other skeptics have rightly noted that there is no known textual evidence — no cuneiform tablet, no inscription, no ancient manual — describing electrical phenomena in Mesopotamia. This is a significant objection. The Parthians left administrative records, religious texts, commercial documents. Nowhere do they mention electricity, current, or anything resembling the concept.

But absence of textual evidence in the ancient Near East is a shaky foundation for an argument. We have enormous gaps in the Parthian textual record. The Parthians wrote predominantly on perishable materials. Entire categories of Parthian knowledge — their medical practices, their metallurgical techniques, their religious rituals — are poorly attested or unattested in surviving texts. Arguing that they didn’t understand a phenomenon because they didn’t write about it in documents that largely haven’t survived is circular.

The Electroplating Question

Eggebrecht’s electroplating claim remains the most dramatic interpretation, and also the most contested. Skeptics have pointed out that fire gilding and mercury amalgam gilding were well-established techniques in the ancient world and could account for the thin gold layers on Mesopotamian artifacts. This is true. But as Robert Bianchi, an Egyptologist, has noted, some of the gold layers on certain artifacts from this region are extraordinarily uniform and thin — thinner than what fire gilding typically produces. Electroplating would explain this quality, though it doesn’t prove it occurred.

The voltage output of a single Baghdad Battery is too low for efficient electroplating. You’d need multiple cells connected in series, and while the existence of multiple specimens suggests this was possible, we have no direct evidence of such an arrangement. The gap between “could have” and “did” is wide enough to drive a chariot through.

What We’re Left With

Here is what we can say with confidence: the Baghdad Battery artifacts are real, they are ancient, and they are capable of producing an electrical current when filled with an acidic solution. The scroll jar explanation accounts for the shape of the vessel but fails to explain the specific combination and arrangement of materials inside it. The battery hypothesis explains the materials and their arrangement but lacks direct evidence of application.

König died in 1940, shortly after publishing his initial paper, and never had the chance to conduct systematic experiments. The original artifacts were looted from the National Museum of Iraq during the 2003 invasion and their current whereabouts are unknown — a loss that makes further direct analysis impossible. We are arguing, in some sense, about objects we can no longer examine.

What strikes me about the Baghdad Battery debate is not the question of whether ancient Parthians had electricity — framed that way, it sounds like cable television pseudoarchaeology. The real question is subtler and more interesting: is it possible for a civilization to discover an empirical phenomenon, use it for a narrow practical or ritual purpose, and never develop the theoretical framework to understand what they’d found? We treat the history of science as a story of progressive revelation, each discovery building on the last. But what if some discoveries are dead ends — observed, exploited in a limited way, and then lost, not because the civilization collapsed, but because no one ever connected the observation to a larger explanatory framework?

The torpedo fish was known to produce a shock for centuries before anyone understood why. Is it so difficult to imagine that someone, somewhere in the workshops of Ctesiphon or Seleucia, noticed that a particular combination of metals and vinegar produced a strange tingling sensation — and built a device to reproduce it, without ever knowing they’d stumbled onto one of the fundamental forces of nature?