When Benjamin Franklin moved to Philadelphia in 1723, he witnessed the beginning of a perilous new experiment: Pennsylvania was just beginning to print words on paper and call them money.
The first American paper money hit the market in 1690. Coins never survived in the Thirteen Colonies, flowing in a steady stream to England and elsewhere, as payment for imported goods. Several colonies began printing bits of paper to exchange for coins, indicating that, within a certain time, they could be used locally as currency. The system worked, but the colonies were soon discovered. Print a lot of bills, and the money becomes worthless. And counterfeiters often found the money easy to duplicate, devaluing the real stuff with a flood of fakes.
Franklin, who began his career as a printer, was an established inventor who could also create a lightning rod and BifocalsAnd I found paper money wonderful. In 1731 he won a £40,000 printing contract for the colony of Pennsylvania, and applied his penchant for innovation to currency.
During his printing career, Franklin produced a stream of baroque, often beautiful prints. He created a copper plate from a sage leaf to imprint on the money to thwart counterfeiters: the intricate pattern of the veins could not be easily imitated. He influenced a number of other printers and experimented with producing new paper and converting inks.
At the moment study published 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 Franklin used, raising questions about which of his innovations were intended as defenses against counterfeiting and which were simply experiments with new printing techniques.
Khachour Manukian, a physicist at that institution and author of the new paper, said the study draws on more than 600 artifacts in the possession of the University of Notre Dame. He and his colleagues studied 18th-century American currency using Raman spectroscopy, which uses a laser beam to identify specific materials such as silicon or lead based on their vibration. They also used a variety of microscopy techniques to examine the paper on which the money was printed.
Some of what they observed confirms what historians have long known: Franklin’s banknotes contain flecks of mica, also known as muscovite or isinglass. These shiny patches were likely an attempt to combat counterfeiters, who did not have access to this particular paper, said Jessica Linker, a professor of American history at Northeastern University who studies paper money in this era and was not involved in the study. Of course, that didn’t stop them from trying.
“They came up with really good fakes, with mica sticky on the surface,” said Dr. Linker.
In the new study, the researchers found that the mica in different colonies’ bills appeared to have come from the same geological source, indicating that a single mill produced the paper. The Philadelphia area is known for the presence of schist, a flaky mineral containing mica; It is possible, Dr. Manukian said, that Franklin or the printers and paper makers associated with him collected the material for their papers locally.
When they examined the black ink on some of the papers, the scientists were surprised to find that it appeared to contain graphite. For most printing jobs, Franklin tended to use black ink made from burnt vegetable oil, known as soot, said James Green, librarian emeritus of the Library Company of Philadelphia. He suspects that graphite was hard to find.
“So Franklin’s use of graphite in printing money is very surprising, and its use in printed bills since 1734 even more surprising,” Green said in an email.
Could the use of graphite ink be a way to distinguish between real and fake money? The differences in color between graphite and soot are likely subtle enough to make this task difficult, Mr. Green said. Instead, we might look at another example of Franklin’s creativity.
“It suggests to me,” he said, “that almost from the beginning he was using money-printing contracts as an opportunity to experiment with a range of new printing techniques.”
To understand Franklin’s intention more clearly, Joseph Adelman, a history professor at Framingham State University in Massachusetts, said it would be helpful to conduct further analyzes of printed documents from the era.
“The comparison I’d like to see would be Franklin’s other publications,” said Dr. Adelman. “To really test this theory – does Franklin have this separate store of ink?”
In future research, Dr. Manoukian hopes to collaborate with scholars who have access to larger collections of early American paper money. These techniques could be very valuable in the study of history, said Dr. Linker, if scholars and historians can work together to determine the best questions to answer.
“I have questions about a whole bunch of inks. I’d like to know what that green ink is made of,” she said, referring to money printed by a contemporary Franklin.