Brown powder. Soluble in water and ethanol, all in yellow light brown, soluble in cellosolve (ethylene glycol ether), slightly soluble in acetone, insoluble in other organic solvents. It turns red to reddish-brown in concentrated sulfuric acid, and becomes orange precipitation after dilution; it turns red in concentrated nitric acid, and then turns yellow-brown. Its aqueous solution, adding concentrated hydrochloric acid turns brown light orange; adding concentrated sodium hydroxide turns orange. When dyeing copper, the color is darker; in case of iron, the color is darker than yellow. Solubility in water (80℃) 100g/L.