The Baghdad Battery.
Ancient Device that Produces a 2 Volt Electrical Current!

When the German archaeologist William Koenig became director of the Museum in Baghdad in 1937, he noticed that one of the objects could have been used as a battery. The yellow clay pot was dated from around 200 BC, the Parthian era. However the Parthians weren't known for any cultural or scientific achievements as they were mainly warriors. Others have noted that the pot is Sassanian and that there may have been some misidentification of the age or the place it was originally found. It was a 6 inch high clay pot, which had a cylinder of sheet copper measuring 5 inches by 1.5 inches on the inside. This was welded by a 60-40 lead-tin alloy to the bitumen (or asphalt) top. The bottom of this cylinder was capped with a crimped in copper disk and was also sealed with bitumen. The rod showed some evidence of having been eroded with an acidic agent, which gave rise to the idea of it being a battery. Obviously they had to test the idea. In the 70 they tried to add plain old pineapple juice (as it would have been the most probable acid people could have used in ancient times) and found that it yielded about 1.5V. In later experiments with vinegar and other weak acids up to about 2V were measured.

So what did the ancients do with batteries? Again, after going through history and scraping together what little knowledge we have from those peoples lives, It was most likely used for gilding. Yes, putting sheet gold onto cheap silver statuettes or vases. Other ideas were the use of low voltage for health purposes (i.e. in connection with acupuncture). However as no other vessels like the Baghdad battery have been found, some archaeologist say it was a "one off". Me personally I don't think so. It was obviously build deliberately and it would be a little coincidence to find "the only one ever made". The truth is that there were so many that we could easily find one even though most others are now lost or destroyed. So with more than one you can crank your Voltage up to really useful levels. Whatever we believe it was used for, we are probably wrong, you don't invent a functioning pen just to stir your soup with... Nici

Sitting in the National Museum of Iraq is a earthenware jar about the size of a man's fist. Its existence could require history books throughout the world to be rewritten.

According to most texts the "voltic pile," or electric battery, was invented in 1800 by the Count Alassandro Volta. Volta had observed that when two dissimilar metal probes were placed against frog tissue, a weak electric current was generated. Volta discovered he could reproduce this current outside of living tissue by placing the metals in certain chemical solutions. For this, and his other work with electricity, we commemorate his name in the measurement of electric potential called the volt.

The little jar in Baghdad suggests that Volta didn't invent the battery, but reinvented it. The jar was first described by German archaeologist Wilhelm Konig in 1938. It is unclear if Konig dug the object up himself or located it within the holdings of the museum, but it is known that it was found, with several others, at a place called Khujut Rabu, just outside Baghdad.

The jars are believed to be about 2,000 years old and consist of an earthenware shell, with a stopper composed of asphalt. Sticking through the top of the stopper is an iron rod. Inside the jar the rod is surrounded by a cylinder of copper. Konig thought these things looked like electric batteries and published a paper on the subject in 1940.

World War II prevented immediate follow-up on the jars, but after hostilities ceased, an American, Willard F. M. Gray of the General Electric High Voltage Laboratory in Pittsfield, Massachusetts, built some reproductions. When filled with an electrolyte like grape juice, the devices produced about two volts.

Not all scientists accept the "electric battery" description for the jars. If they were batteries, though, who made them and what were they used for?

Khujut Rabu was a settlement of a people called the Parthians. While the Parthians were excellent fighters, they had not been noted for their technological achievements and some reseachers have suggested they obtained the batteries from someone else. A few people have even suggested that this someone else was a space traveler that visited Earth during ancient times.

As romantic a notion as this is, there is nothing about the Baghdad batteries that is high-tech. All the materials used are common in origin and the manufacture was well within the ability of many of the peoples of that era. What is surprising about the jars is that somebody figured out how to put the right materials together in the right way to make a device that has a function which was not obvious. It is likely that the batteries (if that is what they are) the result of an isolated and accidental development.

What might they have been used for? German researcher Dr. Arne Eggebrecht used copies of the batteries to electroplate items. The electroplating process uses a small electric current to put a thin layer of one metal (such as gold) on to the surface of another (such as silver). Eggebrecht suggests that many ancient items in museums that are thought to be gold may actually be gold-plated silver.

So are these devices batteries? It certainly is a strong possibility. Even if they are, Count Volta need not be worried. We are unlikely to change the term used for electrical potential at this late date. His place in history is assured.