Baghdad Battery
Did the ancients invent a source of electrical power? Yes. Sort of. Maybe.
At first, nobody much cared about a handful of plain five-inch-tall clay jars archaeologists found outside Baghdad in 1936, estimated to be about 2,000 years old. But two years later, German archaeologist Wilhelm König noticed something astonishing – each jar contained a vertical iron rod surrounded by a copper cylinder. Both were mounted in an asphalt stopper that insulated one from the other. König reasoned that if the jar were to be filled with an electrolytic solution (vinegar, for example), it could function as a low-voltage battery. He went on to publish a paper suggesting that ancient Iraqis might have used the batteries for electroplating.
In 1948 a GE engineer built faithful replicas of the jars, filled them with vinegar, and tested them. They generated a two-volt output. Their maximum current was quite small – less than one-tenth that of a AAA battery. However, the engineer believed that if a number of these devices were joined, they could be used to electroplate a thin layer of gold on silver.
There are no ancient records discussing the jars’ function. Some people claim they were used to store valuable scrolls, but that cannot explain the iron-copper-asphalt configuration which is too much of a coincidence to ignore. Perhaps they were indeed used for electroplating, a method in practice in Iraq today. Or perhaps they were used to administer low-level electrical shocks for medical or religious healing.
Ongoing studies of these ancient objects face a serious obstacle – batteries are not included. The Baghdad batteries were on display in Iraq’s National Museum, but Iraqi looters ransacked the museum during the 2003 US invasion. The batteries either were destroyed or are currently decorating someone’s living room.
