Dark-brown flakes discovered inside a 1,900-year-old Roman glass vial are the first direct evidence for the use of human feces for medicinal purposes, a new chemical analysis reveals. The feces were mixed with thyme to mask the smell, and the concoction may have been used to treat inflammation or infection. The researchers used gas chromatography-mass spectrometry ( GC-MS ) to identify the organic compounds in the dark-brown residue they had scraped from inside the glass unguentarium. Researchers studied the contents of a second-century glass vial discovered in ancient Pergamon, Turkey. Feces, fragrance and medicine chemical evidence of ancient therapeutics in a Roman unguentarium.