2. Verdigris and sal ammoniac, of each 1⁄2 oz.; levigated lampblack, 1⁄2 oz.; common vinegar, 1⁄4 pint; mix thoroughly. Used as the last, for either zinc, iron, or steel.
3. Blue vitriol, 1 oz.; sal ammoniac, 1⁄2 oz. (both in powder); vinegar, 1⁄4 pint; dissolve. A little lampblack, or vermilion, may be added, but it is not necessary. As No. 1; for iron, tin, or steel plate. Some of the preparations described below under ‘Incorrodible ink’ are also used by gardeners and nurserymen.
Ink, Incorro′′dible. This name has been given to several preparations of a resinous character, capable of resisting the action of damp and acids.
Prep. 1. Boiled linseed oil, ground with lampblack and Prussian blue, of each q. s. to impart a deep black colour. It may be thinned with oil of turpentine.
2. Good copal or amber varnish, coloured with either plumbago or vermilion.
3. Trinidad asphaltum (genuine), 1 part; oil of turpentine, 4 parts; colour (as last) q. s.
4. (Close.) Cobalt (in powder), 25 gr.; oil of lavender, 200 gr.; dissolve by a gentle heat, and add of lampblack, 3 gr.; indigo 1 gr. (both in impalpable powder); or vermilion, q. s.
5. (Hausmann.) As No. 3 (nearly). Resists the action of iodine, chlorine, alkalies, and acids.
6. (Sheldrake.) Asphaltum dissolved in amber varnish and oil of turpentine, and coloured with lampblack.
Coarsely powdered anacardium nuts (the fruit of the Anacardium orientale) are macerated in a well-closed bottle with petroleum ether, for some time. Upon allowing the latter to evaporate spontaneously, a syrupy residue is left, and this, when applied to linen or cotton cloth, imparts to them a brownish-yellow colour, which instantly changes to a deep black on the addition of ammonia or lime water. (Böttger.)