Baghdad Battery

The Baghdad battery, also known under the name of the Parthians battery or battery of Khu - jut Rabuah, is a clay pot, which was found in 1936 by William King in excavations of a Parthian settlement in place of the hill Khujut Rabuah near Baghdad. Since it contains a copper cylinder and an iron rod, there is speculation that it is - with the same kind connected together - could have served as early as 2000 years ago as a battery when electricity according to current knowledge actually was still unknown.

The vessel

The Baghdad Battery is approximately 14 cm high vase- shaped clay pot, the largest diameter is about 8 cm. It includes a closed end at the bottom, approximately 9 cm long copper cylinder with a diameter of 26 mm. This was, by a kind of stopper made ​​of asphalt (bitumen mass ) noted a strongly oxidized rods of iron. The upper end stood out about 1 cm above the plug and was covered by a yellow-gray oxidation layer. There is no conductive contact between two metals.

In 1978, the vessel in Geneva and subsequently exhibited in the Roemer and Pelizaeus Museum in Hildesheim and shown with the label "apparatus" and described in the catalog. In particular, the Hildesheimer presentation of the exhibit led to a flurry of speculation about the now Parthian Battery -called archaeological object. This was confirmed there was not, however, so far.

Finds

Found in 1936, only one object with that exact arrangement of the two metals. Locality was the hill of Khujut Rabuah ( Khujut Rabbou'a ) near Baghdad, in the uncovering of a historic Parthersiedlung from the years 250 BC - 225 AD Due to heavy rain the first traces of settlement have been discovered by accident.

The at that time working for the Iraqi National Museum in Baghdad archaeologist Wilhelm König has this documented outside the village center clay container found under a building. Similar and to be distinguished above all by its contents vessels had already been found previously and examined in more detail:

• Under the leadership of archaeological Leroy Waterman, University of Michigan, 1930 four sealed pottery excavated at Seleucia. Three of these in the late Sassanid era (5th - 6th century AD) dated the finds were sealed with bitumen compound. These vessels in turn contained a sealed bronze cylinder in which there was a pressed- papyrus roll. Although none of these characters were able to largely disintegrated fiber rolls are demonstrated and these clay containers but had been marked out with up to four sunken in the ground metal rods made ​​of bronze and iron, it is concluded that the cultic meaning and use. The fourth also sealed vessel contained broken glass.

• A group led by Ernst Kühnel German -American excavation expedition found in 1931 in the immediately adjacent Ctesiphon six other pottery vessels, including three sealed found objects, each with a coiled three and ten bronze and sealed rolls. Within this bronze winding, there were already severely disintegrated cellulose fibers. Another clay pot contained three sealed bronze cylinder. In the other two and also sealed vessels were in a Fund specimen with lead carbonate coated tablets made originally pure lead; in the other ten heavily corroded iron nails, where traces of a wrapped organic fiber material could be detected. Although reminds a round winding of metal foil and paper to the construction typical feature of eg constructed with a soaked paper electrolytic capacitor, but there are for these excavated as well as in Seleucia findings because offenkundlich missing counter electrode not immediately tangible electro-physical function basis.

William King represented since 1938, believes that it may be at the handleless clay container found in Khujut Rabua only to a galvanic cell or a battery. On this view refers to a series of controversial today abhandelnder posts.

Batteries hypothesis

King Wilhelm information about the design and suitability of the Parthian Galvanic cell battery as were in 1962 by Walter Winton, a historian at the Science Museum London, confirmed. Winton had reorganized at this time the Iraqi National Museum and studied there an existing exhibit closer. Thus, it is in the Fund type described by King is a closed, fixed with a bituminous mass and sealed structure, which is seen both several times scientific and popular media articles as electrode unit of a battery. Following their interpretation as the main component of a galvanic cell, the closed structure described by King could keep both from drying out and contamination even in unfavorable environmental conditions a reactive under partial filling electrolyte ( including, for example, lemon or dilute acetic acid).

As can be deduced from the electrochemical series of the elements, the result for copper and pure iron as well as a galvanic pair of electrodes a potential difference of more than about 0.79 volts. However, a generally dependent on the electrolytic properties and is thus also low to induce beating cell voltage can not be represented, because a hedged conclusion is not present on any of the knitted at their metal surfaces reaction carrier or is possible for the image captured by King copy and other finds variants.

Application hypotheses

The physicist George Gamow and the historian Christopher Kelly (University of Cambridge ) are among the most skilled scientists who are related to the electrochemical metal finishing favored by William King. The working for the British Museum archaeologist Paul Craddock notes however that there are no traditions or clearly interpretable Fund findings available to prove such a practiced in Parthia method. Nevertheless leads Craddock, who worked as an expert for metallurgical Fund analyzes the Middle East, with an applied in the Parthian stimulation current stimulation another hypothetical application example. Already king postulated, also without hedged historiographical knowledge, electro-therapeutic treatments.