Chemical clue suggests spurned account of Indian yellow’s origins might be right after all

Artists throughout the 1800s prized the pigment Indian yellow for its luminescent gold hue until synthetic pigments took its place on palettes at the beginning of the 20th century. But the pigment’s lore still fascinates. According to an account made by Indian product and resource expert Trailokya Nath Mukharji in 1883, Indian yellow was manufactured in the country’s Monghyr region by a small community who dried the urine of cows fed only mango leaves and water—a diet that produced dark yellow urine. Mukharji, the sole eyewitness to report the unusual manufacturing process, also sent samples of the raw pigment and other items involved in its preparation to the Royal Botanic Gardens, Kew. In the intervening years, scholars have cast doubt on Mukharji’s story, suggesting the pigment is purely plant based. Now, Buffalo State College’s Rebecca Ploeger and Aaron Shugar and researchers at Newfields, which includes the Indianapolis Museum of Art, have found a chemical clue that gives credence to the legend (Dyes Pigm. 2018, DOI: 10.1016/j.dyepig.2018.08.014). Using pyrolysis gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry, the team identified hippuric acid—a component of cow urine—in unrefined balls of Indian yellow pigment from several sources. The finding, Ploeger says, “supports the claims that the pigment was made from urine.”