The Academy Collection at the Deutsches Museum in Munich contains parts of a voltaic pile that is thought to have been made by Johann Wilhelm Ritter. In 1804, Ritter moved to Munich after being elected to the Bavarian Academy of Sciences. He created what he termed “batteries” by combining square copper plates with round zinc discs. He also experimented with materials such as bismuth to accurately determine the galvanic series, which ranks metals according to their nobility (resistance to oxidation).