1943 steel cent coins. The copper cents differ from their steel counterparts in four ways: In an error similar to the 1943 cents, a few 1944 cents were struck on steel planchets left over from 1943. There are two explanations given for why this happened. One explanation is that steel planchets were left in the press hopper and press machines from the previous year mixed in with copper planchets. Another explanation credits the error to the production of 25 million Belgian two franc pieces by the Philadelphia mint after that country's liberation from the Nazis. These coins were of the same composition and
Bell metal (representing Absolute and Relative Truth) is also sometimes used. A similar alloy is employed for the gongs, saron, demung, and numerous other struck metallophones of the Indonesian gamelan ensembles. In this case the tin:copper ratio is traditionally given as 3:10 by weight. Whereas bells are cast and then left to cool, the metal of Indonesian gongs and metallophones is cast as rough blanks which are then hot-forged to their final shape with hammers. Bell metal was used to cast many early Spanish, Portuguese and "Malay" cannon, most notably the Malay cannon known erroneously as "Rentaka". In Java, bell metal mixtures