Doing so pushed the urea, oxygen from the surrounding air, and hydrogen in the water to form solid percarbamide crystals. The crystals were then filtered from the water, ready for use as a fertilizer.

So he made up a mouthwash of carbamide (synthetic urea crystals). The crystals are colorless and odorless, taste cool and salty. He gave the mouthwash to 100 patients to use on their toothbrushes ...