Blacking LEATHER. In the tanning of leather it is so much impregnated with the astringent parts of oak-bark, or with that matter which strikes a black with green vitriol, that rubbing it over three or four times with a solution of the vitriol, or with a solution of iron made in vegetable acids, is sufficient for staining it black. Of this we may be convinced by dropping a little of the solution on unblacked side of common shoe-leather. This operation is performed by the currier; who, after the colouring, gives a gloss to the leather with a solution of gum-arabic and size made in vinegar. Where the previous astringent impregnation is insufficient to give due colour, and for those sorts of leather which have not been tanned, some galls or other astringents are added to the solution of iron; and in many cases, particularly for the finer sorts of leather, and for renewing the blackness, ivory or lamp-black are used. A mixture of either of these with linseed oil makes the common oil-blackening. For a shining blackening, small beer or water are taken instead of oil, in the quantity of about a pint to an ounce of the ivory-black, with the addition of half an ounce of brown sugar and as much gum-arabic. The white of an egg, substituted for the gum, makes the black more shining, but is supposed to hurt the leather, and make it apt to crack. It must be obvious, however, that all these compositions admit of a great many variations.