How to detect counterfeit currency with a refrigerator magnet

Great hack from Cy Tymony's piece in Make magazine.

Here's what he wrote:

"Legitimate [U.S.] currency has iron particles in the ink. Fold a bill so half of it stands up vertically — if the top edge moves toward your magnet, it's the real deal. If not, phone the Secret Service!"

I sent my crack research team out back to our skunk works to check this out.

You know how skeptical we are around here.

But I digress.

Sure enough, Tymony's tip is spot-on.

But in order to shorten your learning curve (I realize how busy you are), let me note that the fridge magnet will demonstrate its attractive effect only within approximately 1/8" (2-3mm) of the bill.

So just holding up a magnet and expecting a bill in someone's bag or wallet across the room to explode out is asking a bit much.

Also — the effect is not demonstrable if there is an appreciable air current in the vicinity.

Do not attempt this maneuver on a windy hilltop and then say I'm so wrong.

Try it indoors, then say it.