When Benjamin Franklin moved to Philadelphia in 1723, he witnessed the beginning of a dangerous new experiment. He had just started printing letters on paper in Pennsylvania and calling it money.
The first American banknotes appeared on the market in 1690. Metal money did not stay long in his 13 colonies, flowing incessantly to England and elsewhere as payment for imports. Some colonies began printing scraps of paper to substitute for coins, stating that within a certain period of time the coins could be used as local currency. The system was working, but soon stopped when a colony was discovered. Printing too much banknotes made money worthless. And counterfeiters often decided that banknotes were easy to copy, devaluing the real value with a flood of fakes.
Franklin, who started his career as a printer, was an avid inventor who also created lightning rods and lightning rods. bifocal glasses, was fascinated by banknotes. In 1731 he won a contract to print his £40,000 for the Pennsylvania colony, applying his taste for innovation to currency.
During his printing career, Franklin created a succession of baroque, often beautiful banknotes. He made copperplates of sage leaves and printed them on money to deter counterfeiters. The complex pattern of veins could not be easily imitated. He influenced many other printers, experimenting with new paper making and ink formulations.
now A study published on Monday In the Proceedings of the National Academy of Sciences, a team of physicists revealed new details about the composition of the ink and paper Franklin used, and which of Franklin’s innovations were aimed at defending against counterfeiting, and which were merely new. It raises the question whether it was an experiment in technology. printing technology.
The study is based on more than 600 artifacts in the University of Notre Dame’s collection, said Khachatur Manukyan, a physicist at the university and author of the new paper. He and his colleagues studied 18th-century American currency using Raman spectroscopy, which uses laser light to identify certain substances, such as silicon and lead, based on their vibrations. They also used various microscope techniques to examine the paper on which the banknotes were printed.
Some of their observations confirm what historians have long known. Franklin banknotes contain flecks of mica, also known as muscovite or isin glass. Northeastern University American history professor Jessica Rinker, who studied banknotes from this era and was not involved in the study, said these glossy patches were meant to combat counterfeiters who had no access to this special piece of paper. said it was most likely an attempt to Of course, that didn’t stop them from trying.
“They come up with a very good counterfeit with mica on the surface,” says Dr. Linker.
In a new study, researchers find that the mica in banknotes from different colonies appears to have come from the same geological origin, suggesting that a single mill produced the paper. The Philadelphia area is famous for schist, a flaky mineral containing mica. Dr. Manukyan said it is possible that Franklin, or a printing and paper company associated with Franklin, locally collected the materials used in the paper.
But when examining the black ink on some banknotes, scientists were surprised to discover that it supposedly contained graphite. For most of his printing work, Franklin tended to use a black ink made by burning vegetable oil known as lamp black, according to James Green, librarian emeritus of the Philadelphia Library Company. Graphite would have been difficult to find, he surmises.
“It is therefore very surprising that Franklin used graphite in printing banknotes, and even more surprising is the use of graphite in banknotes printed as early as 1734,” Greene said in an email. said in an email.
Was the use of graphite ink a way to distinguish real money from fakes? The color difference between graphite and lamp black was subtle enough to make it difficult, Green said. Instead, we may be looking at another example of Franklin’s creativity.
“It suggests that almost from the beginning he was using the banknote printing contract as an opportunity to experiment with different new printing technologies,” he says.
Joseph Adelman, a history professor at Framingham State University in Massachusetts, said further analysis of printed documents from the period would help to understand Franklin’s intentions more clearly.
“The thing I’m most interested in comparing is Franklin’s other publications,” Dr. Adelman said. “Having put this theory to the test, does Franklin have another reservoir of ink?”
In future research, Dr. Manukyan hopes to work with academics who have access to larger collections of early American banknotes. Dr. Linker said that identifying the best questions for scientists and historians to work together could be of great value in historical research.
“I have a question about the large amount of ink. There’s a really strange green thing on the New Jersey banknotes,” she said of the banknotes she printed during the Franklin era. “I want to know what that green ink is made of.”