Abbot's and Bishop's pee was best for gunpowder because they were wine drinkers. I think I got that from a Hornblower novel.

James Bond used it for invisible ink....

My dad once used it in his motorbike carbide lamp when nothing else was available. His girlfriend,-later my mum- was not impressed, but she married him anyway.

"Chammily'll poison you, my old man.
Chammily'll poison you, come cuddle me, my Dan."
Fermented urine as bleach.

'Stumbling' Jack Elliot.