One person's trash is another's treasure. But what of his waste?

The Smithsonian has unexpectedly shared five unexpected uses for urine -- including whitening your teeth and making own gunpowder.

"For modern scientists, the golden liquid can be, well, liquid gold," wrote the museum's Surprising Science columnist. "But a quick look back in history shows that urine has always been important to scientific and industrial advancement."

Here's a few historic uses for urine that will have you saying, gee whiz!

1. Pee gives you a bright white smile

Before whitening strips, ancient Romans used urine to brighten their pearly whites.

The Roman poet Catullus wrote, "Egnatius, because he has snow-white teeth, smiles all the time...in the country of Spain what each man pisses, he’s used to brushing his teeth and red gums with, every morning, so the fact that your teeth are so polished just shows you're the more full of piss."

While it's clear that Catullus was not a fan of the man he wrote about, he also revealed that people used urine to clean and whiten their teeth. Talk about bad morning breath.

2. Softening leather

Before scientists were able to synthesize chemicals in the lab, urine was a rich source of urea, a nitrogen-based compound that when set aside for long periods decays into ammonia.

Ammonia acts as a weak base when in water, making it the perfect substance for the ancients to use when softening and tanning animal hides to make leather.

Soaking the animal skins in urine also made the process of removing hair and bits of unwanted flesh from the skin. Gross.

3. Cleansing agent

Next time you are cleaning, check the label of the cleaning product of your choice. Ammonia is a prominent ingredient in many household cleaners as it is is a powerful cleansing agent and helps fight dirt and grease.

Ammonia is also found in urine and the early Europeans often preferred pee to soap when cleaning their homes.

In ancient Rome, vessels were placed on streets as urine collectors. After the buckets were full from people passing by to relieve themselves, the vats were taken to a laundry and used to wash dirty clothes.

We'll stick to soap.

4. Dying fabric

Apparently stale urine was popular with 16th century Brits. During the 1500's, families dedicated chamber pots to collecting their pee to be used in developing brighter colors when dying fabric.

Urine was so important to the booming textile industry in England that an "estimated amount equivalent to the urine steam of 1,000 people for an entire year were shipped across the country to Yorkshire" to be used in dying fabric according to the Smithsonian.

5. Pee makes things go boom

Urine as a teeth whitener not your thing? Why not use your pee to make gunpowder?

Charcoal and sulfur used in small quantities to make gunpowder are easily found. But the main ingredient, potassium nitrate was only made available on a large-scale in the early 1900's. Until then, gunpowder manufacturers used the nitrogen found in urine to make their product.