Manufacturer and builder 5, 1871
The well-known gum catechu, used in medicine as an astringent, and by steam-engineers as a preventive against boiler-scale, gives a yellow dye. In order to obtain it, the brown catechu is pulverized, covered with nitric acid, and kept at a temperature of 112° Fahrenheit, till no more nitrous vaports arise. The yellow dye obtained, when dissolved in water, colors silk yellow at once, wool slowly, and both cold, without the application of heat. The dye reacts chemically like picrid acid, but is much more soluble.