Today in 1865 the US Secret Service formed.

It’s best known as the agency charged with protecting the president, the First Family and other high-level figures, but its first mission was to stamp out people who printed counterfeit money.

And as part of that long anti-counterfeiting effort, the Secret Service has something called the International Ink Library, with tens of thousands of vintage and modern inks to help investigators sort out what’s what.

The library started in the 1960s.

Forensic chemist Antonio Cantu started collecting inks used in pens, markers and computer printers.

And he came up with ways to verify when certain inks would have been available to the public.

That’s useful in checking whether a piece of paper money is legitimate or not, of course, but that’s only one of the library’s functions.

The Secret Service once had to check whether a letter that was supposedly written by Abraham Lincoln was the real deal or a fraud.

The scientists could use the ink library to test the type of ink used in the letter and whether it would have been available in Lincoln’s time.

The ink library is an asset in protecting the president, too, since many of the threats agents investigate are written or printed.

Chemists can study the ink for clues about where those threats came from and who sent them.

The ink scientists have worked on some of the most high profile cases of the last few decades, including the “DC sniper” case in 2002.

And while our world is turning increasingly digital, that’s actually creating more work for the scientists who use the Ink Library.

If a person can use high-tech printing equipment to put out fake money, the Secret Service will need to keep coming up with ways to tell the real bills from the counterfeit bucks.

The Secret Service uses code names to each of the people it protects.

The code names for members of a single family all start with the same letter.

Former Vice President Al Gore’s Secret Service name was Sundance.

His daughter Karenna said she was allowed to choose her own code name, as long as it started with S and was two syllables long.

She picked “Smurfette.”

Ever since that choice, she said, “I have been cringing.”

US Secret Service Laboratory Studies Ink to Solve Crimes (VOA News)

Secret Service’s ink library helps agents foil kidnappings, counterfeiters (SFGATE)

11 Great Secret Service Code Names (TIME)

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Photo by Toshiyuki IMAI via Flickr/Creative Commons