The infamous "Baghdad battery," a clay pot dating to around the 3rd century CE and found in Iraq. Often referred to as a "battery" by significance-junkies and mystery-mongers, it obviously isn't since there were no electrical devices present in the early first millennium for which a battery would be required. But, of course, this is exactly the sort of thing the significance-junkie looks for. Suddenly, an innocuous clay pot becomes part of a grand conspiracy to which archaeologists are willing accomplices in a cover up. Ignored are the more probable explanations for such jars, one of which includes that vessels of this type were for scroll or papyrus storage. They were typically 5 inches long and contained a rolled up copper sheet and an iron rod. The ends were capped with asphalt plugs, which would have interfered with the conduction of electricity.
They would, however, have been very efficient at hermetically sealing papyrus and, since each of the "batteries" found to date have were found open to the environment while in situ, any papyrus inside would have long since deteriorated, leaving a slightly acidic residue. Experiments testing the "battery" hypothesis yielded about 25mW from one of these tested as a possible galvanic cell. A penlight requires about 1100mW. Tests were conducted since a couple of electricity-related hypotheses exist regarding the purpose of these jars: a way for electroplating metals such as gold or elektrum; and for ritualistic use by some "magical" means by a sorcerer who used a weak acid in the vessel and attached it to metal statue. Touched by believers, they would then feel a tingle, verifying his "power." The former suggestion of electroplating has fallen out of favor, however, since gilding metal by fire using mercury is far more effective. Very little gilding was able to be procured from models of the "batteries" which only produced a very weak current.