Coloured inks may be divided into two classes, those in which the colouring matter is derived from coal-tar, and those in which it is not.

A. Without Coal-Tar Colours. - Blue

(a) Dissolve 2 to 3 oz. sulphate of indigo in 1 gal. water. (6) Rub together 1 oz. oxalic acid and 2 oz. fine Prussian blue, and add 1 qt. boiling water; the excess of iron in the Prussian blue must first be removed by a strong mineral acid; then wash in rainwater, (c) 2 oz. Chinese blue, 1 qt. boiling water, 1 oz. oxalic acid; dissolve the blue in the water, and add the acid; it is ready for use at once.

Green

(a) Calcine acetonitrate of chrome; dissolve the green powder in sufficient water. (6) Dissolve sap green in very weak alum water, (c) 2 oz. verdigris, 1 oz. cream of tartar, 1/2 pint water; boil till reduced to one-half, and filter.

Green-Black

Boil 15 parts bruised galls in 200 parts water for about 1 hour; strain; to the liquor add 5 parts sulphate of iron, 4 fine iron shavings, and a solution of 1/2 pint powdered indigo in 3 pints sulphuric acid. This ink flows readily; it writes green, but turns black after a few days.

Purple

(a) To a decoction of 12 parts Cam peachy wood in 120 parts water, add 1 part subacetate of copper, 14 parts alum, and 4 parts gum-arabic; let stand for 4 to 5 days. (6) To a strong decoction of logwood add a little alum or chloride of tin.

Red

(a) 4 oz. ground Brazil-wood and 3 pints vinegar, boiled till reduced to 1 1/2 pint, and 3 oz. powdered rock-alum added. (6) 1/4 lb. raspings of Brazilwood, infused in vinegar for 2 to 3 days; boil the infusion for 1 hour over a gentle fire, and filter while hot; put it again on the fire, and dissolve in it, first, 1/2 oz. gum-arabic, then 1/2 oz. alum and white sugar, (c) Boil 2 oz. Brazil wood in 32 oz. water; strain the decoction; add 1/2 oz. chloride of tin and 1 dr. powdered gum-arabic; then evaporate to 16 fl. oz. (d) Dissolve 1 dr. carmine in 1/2 dr. liquid ammonia, sp. gr. 0.880; dissolve 20 gr. powdered gum-arabic in 3 oz. water; mix the two solutions, (e) Mix 2000 parts Brazil-wood, 3.salt of tin, 6 gum, and 3200 water; boil till reduced to one half, and filter. (f) 2 parts Brazil-wood, 1/2 alum, 1/2 cream of tartar, 16 water; boil down to 1/2, and filter; add 1/2 part gum. (g) To an ammoniacal solution of cochineal add a mixture of alum and cream of tartar, till the required tint is obtained. (A) Digest 1 oz. powdered cochineal in 1/2 pint hot water; when quite cold, add 1/2 pint spirit of hartshorn; macerate for a few days, then decant the clear portion. (i) Dissolve 20 gr. pure carmine in 3 fl. oz. liquid ammonia; add 18 gr. powdered gum. (j) Best ground Brazilwood, 2 oz.; diluted acetic acid, 1/2 pint; alum, 1/4 oz.

Boil them slowly in an enamelled vessel for half an hour, strain, and add 1/2 oz. of gum. (A) 1 qt. of white wine vinegar, 2 oz. of Brazilwood, and 1/2 oz. of alum, bottled and well shaken for a fortnight; then let simmer in a saucepan, and add 3/4 oz. of gum-arabic. Let the whole stand for a few days, filter, and it will be ready for use. (l) Boil 4 oz. of Pernambuco-wood with 16 oz. of dilute acetic acid, and an equal quantity of water, until 24 oz. remain. Add an ounce of alum, and evaporate again to 16 oz.; add gum-arabic 1 oz. and strain; and lastly, add to the cold liquid 1 dr. protocol oride of tin. (m) The solubility of carmine lake in caustic aqua ammonia; is attended with this disadvantage: that in consequence of the alkaline properties of ammonia, the cochineal pigment will in time form a basic compound which, in contact with a steel pen, no longer produces the intense red, but rather a blackish colour. To avoid this evil, prepare the ink as follows: - Triturate 1 oz. of pure carmine with 15 oz. of acetate of ammonia solution, and an equal quantity of distilled water, in a porcelain mortar, and allow the whole to stand for some time.

In this way a portion of the alumina which is combined with the carmine dye is taken up by the acetic acid of the ammonia salt, and separates as precipitate, while the pure pigment of the cochineal remains dissolved in the half-saturated ammonia. It is now filtered, and a few drops of pure white syrup added to thicken it. In this way an excellent red drawing-ink is obtained, which holds its colour a long time. A solution of gum-arabic cannot be employed to thicken this ink, as it still contains some acetic acid, which would coagulate the bassorine, which is one of the natural constituents of gum-arabic. (n) Bottger rubs up carmine and silicate of soda, and then adds to this mixture a concentrated silicate solution till the whole is of sufficient consistency to write well. The product gives a very brilliant ink when dry, and dries quickly. It must be kept out of contact of air in a well-closed vessel.

Violet - (a) Boil 8 oz. logwood in 3 pints water, till reduced to 1 1/2 pint; strain, and add 1 1/2 oz. gum and 2 1/2 oz. alum. (6) Mix 1 oz. cudbear, 1 1/2 oz. pearlash, and 1 pint hot water; allow to stand for 12 hours; strain, and add about 2 oz. gum. If required to keep, add 1 oz. spirit of wine.

B. With Coal-Tar Colours

The colouring matters derived from coal-tar may all be employed for writing purposes. These inks possess bright colours, do not precipitate their colour, and dry quickly. When dried up or thickened, they can be put right by simple dilution with water. On the other hand, they are readily destroyed by chemical reagents. They must not be used with pens which have been employed in writing with other inks. They do not require any addition of gum; but if desired, 1 part dextrine may be added to every 100 parts ink. Almost all tints may be produced by mixtures, in varying proportions, of the following principal colours: -

Blue

1 part soluble blue (night blue) in 200 to 250 parts hot water; if the ink dries with a coppery hue, more water must be added.

Green

1 part iodine-green in 100 to 110 parts hot water. Gives a bluish-green writing; for a lighter tint, add a little picric acid.

Red

(a) 1 part magenta in 150 to 200 parts hot water. (ft) Dissolve 25 parts (by weight) safranine in 500 parts warm glycerine; then stir in carefully 500 parts alcohol, and 500 parts acetic acid; dilute in 9000 parts water, containing a little gum-arabic in solution, (c) Get a small quantity of magenta crystals - as many, for instance, as will lie on a sixpence, or at most on a shilling - place them in an egg-cup, and cover them with water. In a short time you will have a solution of a fine magenta colour. A little Indian ink well rubbed up, with a few drops of Judson's dye (Oxford blue) added, will intensify the colour.

Violet

1 part violet-blue in 200 parts hot water.

Yellow

1 part picric acid in 120 to 140 parts water. This is not very successful.