There’s a story about a man (Hennig Brand) who figured since pee was yellow, and gold was yellow, maybe if you boil urine down enough you can get the ‘gold’ out of it and make lots of stacks of cash.

Unfortunately this didn’t work, but it did yield a process to create phosphorous which ended up being a valuable chemical process, of which he sold to other alchemists at the time (Who in turn tried to figure out how to turn the new found phosphorous to gold).