Appearance: Black grain with glitter. Water solubility: Soluble in water, the aqueous solution is blue-purple, and the sodium hydroxide solution is added to produce brown-purple precipitation. Solubility: Soluble in ethanol, blue. It is also blue in concentrated sulfuric acid, turns purple after dilution, and precipitates. Application Use 1: Mainly used for dyeing wool and silk, but also for leather dyeing (usually chromium mediated), coloring and manufacturing ink for paper, wood products, soap, aluminum electrochemical. Use 2: Mainly used for dyeing leather, silk and woolen fabrics, and can also be made into color deposition for colored paper and printing