In June of 1936 workers moving earth for a new railway uncovered a
ancient tomb from the
Parthian period. Among the usual
pottery,
engraved bricks, and metal
trinkets found in the tomb was a
clay jar containing a
copper tube with one closed end and an
iron rod.
After examining the artifact in Britain, physicist Walter Winton suggested that should someone pour an acid, such as vinegar, into the copper tube, the result would be a simple battery which would generate voltage. Several of these jars placed in series would generate enough current to drive a small electric motor. The discovery of several other jars in the Parthian ruins of Cresiphon seemed to strengthen this hypothesis, and experiments in the United States using replica jars produced a battery that generated a 1/2 volt current for almost three weeks.
Without any other explanation, archaeologists began to wonder why the ancient world use batteries. It was well known that the Babylonians used electric fish as an anesthetic. It's quite possible that these batteries served as a substitute. It is also possible that the batteries were used for electroplating jewelry, as the amount of current is definitely sufficient, and primitive techniques for electroplating still exist in Iraq.
Whatever their purpose, these "Baghdad Batteries" still remain an intriguing mystery to the archaeological community.