Dyeing black is accomplished either by brushing on a table, or by "ridging" or folding, grain-side outwards, and drawing quickly through baths of the mordant and colour. To prepare them for the colour, stale urine is generally employed. A deeper colour, and one less likely to strike through the skin, is obtained by adding 1/4 lb. potash bichromate to 4 gal. urine; or the following mixture may be substituted with advantage, viz. 1/2 lb. Marseilles soap dissolved in boiling water, 5 or 6 egg-yolks added, and the whole made up to 4 gal. with water and 1/4 lb. potash bichromate. The colour used is infusion of logwood or its extract, or J logwood, which is best extracted by stale urine or old soak liquor, with addition of a small quantity of soda (1 lb. to 25 lb. dye wood). It is fixed and darkened by a wash of iron-liquor (1 of iron protosulphate in 75 cold water). After being again dried, the skins are grounded with the moon-knife, and rubbed over on the grain with a composition containing oil, wax, etc, and are finally ironed with a flat iron to give them a fine and smooth surface. Eitner gives a recipe for the gloss: - 1 lb. gum-arabic, 1/2 lb. yellow wax, 1/2 lb. beef tallow, 3/4 lb. Marseilles soap, 2 lb. strong logwood infusion, and 1 gal. water.

The water is brought to a boil in an earthen pot, and then the soap, wax, gum, and tallow are added successively, each being stirred till dissolved before adding the next, and lastly the logwood. After boiling for an hour, it is allowed to completely cool, being incessantly stirred during the whole process. (Spons' Encyclopaedia.)