When Benjamin Franklin moved to Philadelphia in 1723, he found the beginning of a risky new experiment: Pennsylvania had just begun printing words on paper and calling it money.
The first American paper currency appeared on the market in 1690. Metal coins did not last long in the 13 colonies as payment for imported goods, flowing in a steady stream to England and elsewhere. Many colonies began printing pieces of paper in place of coins, saying that within a certain time period, they could be used locally as currency. The system worked, but slowly, colonies were soon discovered. Print too many bills, and the money becomes worthless. And counterfeiters often find it easy to counterfeit bills, leading to a flood of counterfeits that devalue the real ones.
Franklin, who began his career as a printer, was a great inventor who also created the lightning rod and bifocalsPaper currency seemed attractive. In 1731, he won a contract to print £40,000 for the Pennsylvania Colony, and he applied his penchant for innovation to currency.
During his printing career, Franklin produced a stream of baroque, often pretty pennies. He made a copper plate of sage leaves to be printed on money to thwart counterfeiters: the complex pattern of veins could not be easily copied. He influenced many other printers and experimented with creating new paper and ink.
now in A study published on Monday In Proceedings of the National Academy of Sciences, a team of physicists has revealed new details about the composition of the ink and paper used by Franklin, raising the question of which of his innovations served as a defense against counterfeiting. and which were only new uses of printing technology.
The study is based on more than 600 artifacts held by the University of Notre Dame, said Khachatur Manukyan, a physicist at that institution and author of the new paper. He and his colleagues looked at 18th-century American currency using Raman spectroscopy, which uses laser beams to identify specific substances such as silicon or lead based on their vibrations. He also used various microscopy techniques to examine the paper the money was printed on.
Some of what they saw confirmed what historians had long known: Franklin’s paper notes contained pieces of mica, also known as muscovite or isinglass. Jessica Linker, a professor of American history at Northeastern University who studies paper money from this era and was not involved in the study, said the shiny patches were likely an attempt to deal with counterfeiters who did not have access to this particular paper. . Of course, that didn’t stop him from trying.
Dr. Linker said, “They come up with very good counterfeits by sticking mica to the surface.”
In the new study, researchers found that the mica in bills from different colonies came from the same geological source, indicating that the same mill produced the paper. The Philadelphia area is notable for its schist, a flake mineral that contains mica; It is possible, Dr. Manukyan said, that Franklin or the printers and paper makers associated with him collected the materials used in their paper locally.
However, when they examined the black ink on some of the bills, the scientists were surprised to find that it contained graphite. For most of the printing work, Franklin used a black ink made from burnt vegetable oils, known as lampblack, said James Green, emeritus librarian of the Library Company of Philadelphia. He suspects that graphite must have been hard to find.
“So Franklin’s use of graphite in printing money is very surprising, and his use on bills printed as early as 1734 is even more surprising,” Mr. Greene said in an email.
Could the use of graphite ink be a way to distinguish real money from counterfeits? Mr Green said the difference in color between graphite and lampblack is likely to be so subtle that it will become a difficult task. Instead, we can see another example of Franklin’s creativity.
“This suggests to me that from almost the beginning he was using his money printing contracts as an opportunity to experiment with a range of new printing techniques,” he said.
To more clearly understand Franklin’s intent, more analysis of printed documents from that era would be helpful, said Joseph Edelman, professor of history at Framingham State University in Massachusetts.
Dr. Edelman said, “The comparison I would like to see would be with other Franklin publications.” “To really test this theory – did Franklin have this separate reservoir of ink?”
In future research, Dr. Manukyan hopes to collaborate with scholars who have access to large collections of early American paper currency. These techniques can be enormously valuable in the study of history, Dr. Linker said, if scientists and historians can work together to identify the best questions to answer.
“I have questions about a whole bunch of ink. There’s a really weird green color on some of the New Jersey bills,” he said, referring to money printed by a Franklin contemporary. “I’d love to know what that green ink was made of.”
