In 1938 a number of small jars were found in the collection of the National Museum of Iraq. These jars, previously overlooked, were found to be quite unique. Each contained copper and iron, and was sealed with asphalt.
It was hypothesized based on the various components, that they were a type of battery, possibly used to electroplate metals. Since they were noticed long after they had been taken from outside of their archeological context, not much else is known about them.
Mythbusters, the television show, recreated them and found that they were able to hold a charge and electroplate quite effectively. However, just because something could have been done, doesn’t mean it was done. The jars also very closely resemble jars designed to hold sacred scrolls.
We may never know their true nature, but no doubt people will continue to speculate on the purpose of the Baghdad battery for a long time to come.
Some of the original 12 Baghdad Batteries can be seen at the National Museum of Iraq, which is currently closed due to the 2003 looting which saw nearly half it’s collection stolen.