Aurantia (Imperial Yellow), the ammonia salt of hexanitrodiphenylamine (NO2)3C6H2.NH.C6H2(NO2)3 is formed when diphenylalamine is exposed to nitric acid, forms a brick-red powder, dissolves in water and dyes silk, wool and leather orange. It is said to have an adverse effect on the skin of some individuals, but is rarely used anymore.

Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909