BLACK DYE AND INK.
The following is a process for the preparation of a black dye, for which a patent was taken out at Vienna by M. Honig:—Logwood is to be boiled several times in water, and a little sub-carbonate of potash to be added to the decoctions, the quantity being so moderated that it shall not change the colour to blue; the stuff to be dyed is then to be plunged into this bath. This stuff may be either animal or vegetable. When it is well impregnated with colouring matter, it is to be withdrawn, and, without being exposed to air, is to be introduced into a solution of green-vitriol, and left there until it has obtained the desired black hue. In preparing the ink, the decoction of logwood is used in place of the infusion of galls.