https://en.wikipedia.org/wiki/Uranyl_acetate
- so easily distinguished from espresso. OTOH...
https://www.google.com/search?q=far+side+comic+culture+of+am...
https://en.wikipedia.org/wiki/Uranyl_acetate
- so easily distinguished from espresso. OTOH...
https://www.google.com/search?q=far+side+comic+culture+of+am...
Funny, on that page it also lists oolong tea as a staining agent.
So, coffee, tea and Uranyl acetate...