A friend told me last night that if you boil urine and let it cool, it’ll glow in the dark. “Well, let's do it,” I exclaimed, to which he shook his head. Naturally I was immediately suspicious, like any budding scientist would be, and accused him of lying about the glowing urine trick, but he said it wasn't an appropriate activity for two friends to share.

The reason our conversation took this potentially-amazing-but-ultimately-anticlimactic turn is because we were talking about the first matchsticks, which used white phosphorous (incredibly toxic but useful because you could strike them on any surface, and if you were a cowboy an ideal place for this would be the back of your cowboy boots).

This led us to the alchemist Hennig Brand, who tried to create gold by storing buckets of urine underneath his house and doing science to them. He ended up blowing up his house, apparently, but in the process noticed the material he was producing glowed in the dark. What Brand had created was not gold, but phosphorus!

Here’s how you do it:

• Boil urine to reduce it to a thick syrup.
  
• Heat until a red oil distills up from it, and draw that off.
  
• Allow the remainder to cool, where it consists of a black spongy upper part and a salty lower part.
  
• Discard the salt, mix the red oil back into the black material.
  
• Heat that mixture strongly for 16 hours.
  
• First white fumes come off, then an oil, then phosphorus.
  
• The phosphorus may be passed into cold water to solidify.
  
  The science of it all:

Urine contains phosphates PO43-, as sodium phosphate (i.e. with Na+), and various carbon-based organics. Under strong heat the oxygens from the phosphate react with carbon to produce carbon monoxide CO, leaving elemental phosphorus P, which comes off as a gas.

Phosphorus condenses to a liquid below about 280°C and then solidifies (to the white phosphorus allotrope) below about 44°C (depending on purity).

This same essential reaction is still used today (but with mined phosphate ores, coke for carbon, and electric furnaces)

What I am saying here is that the next time you are doing a pee, please think about how it is an incendiary weapon just waiting to happen. Thank you.