The black bills. How did they get that way? Fingerprint dust, right? Silver nitrate.
Apparently not.
See comments from Brian Ingram in the screenshots.
What could have caused the blackening of the bills in such a manner? Per Brian, they were darkest at the top and bottom of each packet, getting lighter towards the Center of the packet. And he describes how his mother was able to wash/lightened or restore them to ‘normal colour’, when put in bleach (after the fabric softener). That rules out being burned, or potential ash from the St Helen’s eruption, I’d think?
It seems Tom Kaye among others were unaware that the bills were found that way.