One for Earl: The Romans used urine, liquid gold, to clean their teeth and keep them healthy; they not only traded in pee collected from public urinals, but those who traded in urine were taxed.
Urine-soaked leather makes it soft, and soaking animal skins in urine made it easier for leather workers to remove hair and bits of flesh from the skin.
Early Europeans knew about soap, though many launderers used urine for its ammonia content to remove stains from cloth. In ancient Rome, vessels for collecting urine were commonplace on streets, passers-by would relieve themselves into them and when full the vats and their contents were taken to a fullonica (a laundry), diluted with water and poured over dirty clothes; workers would stand in the tub of urine and stomp on the clothes, similar to modern washing machine’s agitator.
Even after conventional soaps became more prevalent, urine was often used as a soaking treatment for tough stains.
Ammonia, found in urine, is one of the ingredients in many household cleaners, which neutralises dirt and grease which are slightly acidic.
Urine not only makes whites cleaner, but colours brighter. Urine was so important to the textile industry of 16th century England that casks of it, each estimated to hold the equivalent urine of 1000 people for an entire year, were shipped from across the country to Yorkshire, where it was mixed with alum to form an even stronger mordant than urine alone.
Bored with cleaning, tanning, and dyeing? Then why not use your pee to make gunpowder! Gunpowder recipes call for charcoal and sulphur in small quantities, which are easy enough to find, but the main ingredient (potassium nitrate), saltpeter, was only synthesized on a large-scale in the early 20th century. Prior to that, makers of gunpowder took advantage of the nitrogen naturally found in pee to make the key ingredient for ballistic firepower.
Different regions of the world had their own recipes for gunpowder, but the scientific principle is the same: Ammonia from stagnant pee reacts with oxygen to form nitrates. These nitrates, negatively charged nitrogen-bearing ions, then search for positively charged metal ions to bind with. Thanks to the ash, potassium ions are in abundance, and after a little filtering you have potassium nitrate.