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Leather, Ink, and Miscellaneous: Hence

Modern inks of this sort are improved by the addition of a little free sulphuric acid, which prevents the tannate of iron from forming a precipitate or powder. Hence they are true solutions. The addition of a little indigo, carmine, or aniline blue is also an improvement. This is one of the reasons why modern inks cannot be removed by old-fashioned recipes, the acids which take out the stain of tannate of iron having no effect on the modern coal-tar colors. Inks of this class are made commercially from Aleppo nutgalls and copperas, or from green vitriol. The nutgalls contain 60 to 70 per cent tannic acid and 3 to 5 per cent gallic acid. The galls are crushed, steeped in hot, not boiling, water, and strained.

The infusion is mixed with a solution of copperas containing free sulphuric acid. Indigo and aniline blues are added, and also a solution of gum arabic, the last ingredient enabling the writer to make light strokes with the pen and to prevent the ink from spreading too quickly. An antiseptic, usually carbolic or salicylic acid, is added to prevent mold.

Some experiments will be required to make a good ink of this class, as the amount of tannin contained in nutgalls varies, and the amount extracted by inexperienced persons varies still more. Recipes will be given for the use of nutgalls, but for homemade inks it will be found more convenient, when possible, to buy tannic and gallic acids ready made than to extract them from nutgalls. We recommend for a good homemade ink the following:

Five ounces of tannin, 4 ounces of copperas, ounce of indigo, carmine, or aniline blue, and 10 drops of sulphuric acid.

Or 5 ounces of gallic acid, 74 ounces of copperas, ounce of indigo, carmine, or aniline blue, and 12 drops of sulphuric acid. The latter formula gives a finer quality of ink than the former, but it does not turn black so quickly. Hence a still better formula is a mixture of the two.

Or 5 ounces of tannin, 5 ounces of gallic acid, 11½ ounces of copperas, 1 ounce of indigo, carmine, or aniline blue, and 20 drops of sulphuric acid; or, for smaller quantities, the same proportions by weight. This mixture will be found an excellent ink for schools, offices, and domestic purposes.