(A.) Inks for writing on metallic surfaces may be made as follows: - (a) 1 part verdigris (acetate of copper), 1 part sal-ammoniac, 1/2 part soot, 10 parts water; stir well; write with a quill. (6) 1 gr. sulphate of copper dissolved in 20 gr.' water; add 2 drops hydrochloric acid, and enough solution of gum-arabic to make the ink adhesive. To make the writing appear at once, add a little pyrogallic acid. Write with a copper pen. (c) Dissolve 2 oz. shellac in 1 pint alcohol, filter through chalk, and mix with finest lampblack; forms a jet-black lustreless ink, insoluble in water. (d) Take 1/2 lb. of nitric acid and 1 oz. muriatic acid. Mix and shake well together, and then it is ready for use. Cover the place you wish to mark with melted beeswax; when cold, write your inscription plainly in the wax clear to the metal with a sharp instrument. Then apply the mixed acids with a feather, carefully filling each letter. Let it remain 1 to 10 hours, according to the appearance desired; then wash and remove the wax. (e) Make a saturated solution of sulphate of copper in gum-water. Write with a quill pen.
When quite dry, give the labels a coat of white hard varnish, the labels being slightly warmed before application. (/) Chloride of platinum, 1/4oz.; soft water, 1 pint; to be kept in glass and used with a quill pen. (g) Verdigris, sal-ammoniac, and levigated lampblack, of each 1/2 oz.; common vinegar, 1/4 pint; mix thoroughly. (f) is the better, but rather expensive; both will do for zinc, iron, or steel.
(B.) Gold and silver inks are made as follows: - (a) 24 leaves gold, 1/2oz. bronze gold, 30 drops spirits of wine, 30 gr. honey, 4 dr. gum-arabic, 4 oz. rain-water; rub the gold with the honey and gam, and having mixed it with the water, add the spirit. (6) 1 part gold, 3 parts aqua regia; mix, and evaporate till all the chlorine is given off; cool, and mix well with ether; thicken with naphtha or essential oils. (c) For gold ink it is best to employ genuine gold-leaf, but owing to the expense this is seldom used; sometimes mosaic gold (sulphide of tin) or iodide of lead is employed, but almost always Dutch leaf. Owing to the relatively low price of silver, genuine silver-foil is used for silver ink; false silver-foil is seldom used, and is not so good. For other metallic inks, commercial bronze powders are employed. The genuine and false foils are also sold in a finely-pulverized state; they are made from the waste of the gold-beaters by rubbing it in metallic sieves to an impalpable powder. In consequence of the beating between gold-beaters* skin, it has particles of grease and other impurities attached to it, which must be removed before it can be used for ink.
For this purpose, the whole sheets, or the commercial bronze powder, are triturated with a little honey to a thin magma on a glass or porphyry plate with a pestle, as carefully as possible, as the beauty of the ink depends essentially on this. The finely-rubbed paste is rinsed into a thin glass beaker, boiled for a long time with water containing a little alkali, frequently stirred, decanted, well washed with hot water, and dried at a gentle heat. By boiling this powder with water containing sulphuric, nitric, or hydrochloric acid, different shades can be imparted. Next, a solution of 1 part of white gum-arabic in 4 parts of distilled water is mixed with 1 part of potash water glass, and triturated with the requisite quantity of purified metallic powder. Gold ink will bear more liquid than silver ink, since gold covers much better; on rough paper, more metal is necessary than on sized paper; on light paper, more than on dark, to make the colour of the ink appear equally intense. In general 1 part of foil is enough for 3 or 4 parts of the above liquid. In preparing large quantities of ink, a low porcelain measure is used for transferring it to the small glass vessels where it is to be kept, and it must be continually and thoroughly stirred so that it will always keep well mixed.
It requires frequent stirring also when in use. It is best to mix the dry powder with the liquid immediately before using. The ink can be used with a common steel pen, and flows very well when writing slowly, but it is better to use a pencil. The use of potash water glass is of much importance. It greatly increases the metallic lustre on paper, prevents its looking dead, protects the writing from being discoloured by the action of the atmosphere, and prevents its penetrating too far into the pores of the paper, without rendering it very viscid. Although the writing of itself possesses a high metallic lustre, it may be increased by gently polishing with a polishing steel. Inks made with mosaic gold, mosaic silver, iodide of lead, etc, are not nearly so beautiful. (C. H. Viedt.)
(C.) Inks for Writing on Glass. - (a) A solution of hydrofluoric acid applied to glass previously coated with wax, and the matter scratched through with a style. (6) 3 parts barium sulphate, 1 part ammonium fluoride, and sufficient sulphuric acid to decompose the ammonium fluoride and make the mixture of a semi-fluid consistence. It should be prepared in a leaden dish, and kept in a gutta-percha or leaden bottle.
(D.) Burnishing Ink. - 4 oz. shellac, 1 oz. borax, sufficient water. Boil to the consistence of syrup, and add a few drops of strong ammonia water. A small amount of soap is sometimes also introduced. Add a sufficient quantity of this to the ink to obtain the desired result. Instead of the above, soap is often used alone, or with a trace of glycerine, ammonia, or gum-arabic.
(E.) Shoe-finishers' - Make a strong decoction of logwood, preferably in soft water, by boiling; then add green vitriol at the rate of 2 oz, to the gal., with 1/2 oz each bichromate of potash and gum-arabic. Powder the last 3 ingredients, and even the logwood if you like, as it will take the colour out quicker; or you can use the prepared extract of logwood at the rate of 1 oz. to a gal. of water.
(F.) Bookbinders' Ink. - A very good red ink may be made in the following manner: - Infuse 1/4 lb. of Biazil-wood raspings in vinegar for two or three days. Boil the infusion gently for an hour, and filter it while hot. Put it again over the fire and dissolve in it, first, 1/2oz. of gum-arabic, and afterwards of alum and white sugar, each J oz. A little alum will improve the colour. The blue is a solution of indigo or Prussian blue.
(G.) Obliterated Ink.-(a) Wash in warm water to remove salt if the paper has been immersed in sea-water, and then soak in a weak solution of gallic acid, say 3 gr. to the oz. (b) Wash in clean water and soak in solution of proto-sulphate of iron, 10 gr. to the oz. (c) Apply a solution of potassium ferro-cyanide with a brush, when the writing will appear in blue, if any iron is left of the original ink.
(H.) Falsified Writing. - Gobert has found that if writing is ever so carefully scratched out, there are still left sufficient traces of the oxide of iron in the ink to become visible in a photographic copy. Light reflected from paper that has not been written on acts in a different way on the photographic materials from that reflected from places which have been once covered with ink. By this means the genuineness or otherwise of a document can always be ascertained. (Stummer's fngenieur.)