From the History Channel:
3. Vikings used a unique liquid to start fires.
Clean freaks though they were, the Vikings had no qualms about harnessing the power of one human waste product. They would collect a fungus called touchwood from tree bark and boil it for several days in urine before pounding it into something akin to felt. The sodium nitrate found in urine would allow the material to smolder rather than burn, so Vikings could take fire with them on the go.
My favorite thing about stuff like this is imagining how the people came up with a particular solution.
Picture this: a Viking raiding party returns from sacking some Celtic village. They’re celebrating around a huge bonfire, quaffing jugs of mead, when one of them gets up to go relieve some internal pressure.
Runolf stops him, “Ho Magnus! Don’t leave us in the midst of all this merriment! Here, piss in this here kettle.”
Magnus obliges his friend, emptying his bladder into the kettle. Boys being boys, the others take their cue and start following suit.
“You lily-livered parsnips!” shouts Thorvald, “Look at you standing around pissing in a pot like a bunch of old women. Vikings don’t do that.”
Thorvald proceeds to pick up the kettle and put it on the massive fire. “Piss in your pot now, you trout-knuckled rutabagas!”
The group takes Thorvald up on his challenge, trying to arc their piss into the kettle without getting themselves burnt. Naturally, with all the alcohol they’ve been drinking, there are a few accidents. A few singe their pubic hair, but Bjarni suffers the worst, stumbling forward and roasting his hot dog.
Still, despite these incidents, the men continue the pissing contest, not wanting to seem weak. Eventually they actually succeed in filling the kettle to the top.
As they pass around fresh jars of mead to celebrate this latest accomplishment, Olaf says, “Let’s cook something in it.”
But what to cook? They don’t want to waste any of their actual food on something so stupid.
“I know,” says Thorvald, “Grab some of the stuff growing on the side of that tree. We’ll cook it and give it to Sigurd when he wakes up. Tell him it’s a Celtic delicacy.”
The men throw a large chunk of the fungus into the kettle, and sit around watching it for a while. Eventually, they all pass out from their drunkenness.
The next day, Sigurd dies from alcohol poisoning. The joke isn’t carried out. The women tend to the fire, keeping it going, though at a much lower flame than the night before. They don’t touch the kettle. It stinks too badly, and they don’t have a need for it at the moment. The men, though, continue to practice pissing into it, and manage to keep it filled as the heat evaporates the contents. They make a game of hitting the blob floating in the center.
After three days, though, the women finally need the kettle for a feast. They knock the kettle over, spilling the contents into the fire. After the flames recover, the men notice that their former practice target isn’t burning as it should. It smolders instead of catching afire. Thorvald, being the great thinker that he is, pulls the fungus out from the fire. This could prove to be useful.
And that is how the Vikings invented their firestarter.