6. Red Inks.—Steep one pound of powdered Brazil wood, and one ounce of powdered cochineal, in two gallons of vinegar. Let them macerate for twelve hours. Then put the whole on to a slow fire, with four ounces of alum, and one ounce of lump-sugar, in a pewter vessel, until a good red colour is obtained. When the ink is settled it may be decanted, pouring it through a piece of cloth into bottles, and preserved for use. Cochineal is a very expen sive article, and although it is usual to recommend its introduction into red ink, on account of the richness of its colouring matter, we know from experience that it is by no means a necessary ingredient, and that a beautiful and very permanent red may be obtained without it. We have before us a recipe, written fifteen years ago in the identical red ink it is descriptive of the process of making ; the colour is extremely beautiful, nor in the least deteriorated by the lapse of time. The process differs only from the above recipe in using no cochineal, but it contained as much alum as the liquid would dissolve in its cold state; the Brazil wood was macerated during a night, and was very gently boiled in an unglazed earthen pot on the next day, for half an hour ; afterwards one pound of ,Senegal gum, and a quarter of a pound of lump-sugar, were added. With so large a proportion of mucilage asjust mentioned, and so much alum, it is probable that vinegar may be dispensed with, and that water alone, which is a good menstruum for the colouring matter of Brazil wood, will answer very well, and materially cheapen the ink. Care should be taken to discontinue the boiling after the full bright red is obtained, as by continuing it the colour darkens ; also, that copper or iron vessels should not be used, unless they are perfectly coated with tin in every part. A solution of tin heightens the red colour, and tends to restore it if it has acquired a purple tint.
7. Indestructible Red Ink may be made by dissolving one ounce of copal in seven ounces of oil of lavender, and adding thereto three ounces and a half of pure vermilion. If found too thick for the pen, add a little more oil of lavender.
8. Blue Ink.—Take sulphate of indigo (indigo dissolved in sulphuric acid, it may be had of the dyers), and dilute it with water till the desired tint is obtained. It is with this sulphate, very largely diluted, that the faint blue lines of ledgers and other books are ruled. If the ink were used strong, it would be necessary to add chalk to it to neutralize the acid.
. 9. Yellow Ink.—Half a pound of French berries, boiled with a little alum in a quart of water, or vinegar and water.
10. Green and other coloured Inks.—A mixture of the above blue and yellow inks will make a green; a mixture of the red and yellow will make an orange ; of the blue and red, a purple; of the black and yellow, a brown. Inks of all colours may, however, be very readily obtained by rubbing down with water any of the water-colours prepared in cakes, for artists; or by using a strong decoction of any of the ingredients used in dyeing, with a little alum and gum.
11. Marking Linen.—Mr. Haussman has given some compositions for marking pieces of cotton and linen, previous to their being bleached, which are capable of resisting every operation in the processes both of bleaching and dyeing, and consequently might be employed in marking linen for domestic purposes. One
of these consists of asphaltum, dissolved in about four parts of oil of turpentine, and with this is to be mixed lamp-black or black-lead in fine powder, so as to make an ink of a proper consistence for printing with types. Another,—the blackish sulphate left after expelling oxygen gas fiow oxide of manganese with a moderate heat ; being dissolved and filtered, the dark grey pasty oxide left on the filter is to be mixed with a very little of a solution of gum tragacanth, and the cloth marked with this is to be dipped in a solution of potash or soda, mild or caustic, in about ten parts of water. The anacardium, or cashew nut, it is well known, yields an inflammable caustic liquor, which alone forms a very useful marking ink, as any thing written on linen or cotton with it is of a brown colour, which gradually grows blacker, and is very durable. The ordi nary marking ink sold in our shops is made in the following manner:—Take lunar caustic (nitrate of silver), 5 scruples ; gum arabic, 5 scruples; sap-green, 1 scruple ; water, 1 ounce ; put these together in a small bottle, and the ink is formed. In using it, the linen is first wetted with the following mordant ;— 1 ounce of soda to 2 ounces of water. The marking ink should not be used until the mordant has dried upon the linen.
12. Sympathetic, Invisible, or Secret Inks, are such as do not appear after they are written with, but which may be made visible at by certain means used for that purpose. They are of considerable antiquity ; for it appears that Ovid recommends the maidens of his days, who wished to correspond secretly with their lovers, to write with fresh milk, which when dried might be made visible by rubbing over it ashes or rust. Pliny, who was better informed than Ovid in such arts, though probably less inclined to practise them, recom mended the milky juice of certain plants for the purpose ; but the use of such things is superseded by the discoveries of modern chemists, who have intro duced to our notice a great variety of secret inks, the best of which we find selected in the Oxford Cyclopedia ; they are as follow :—Dissolve some sugar of lead in water, and write with the solution. When dry, no writing will be visible. When you want to make it appear, wet the paper with a solution of alkaline sulphuret (liver of sulphur,) and the letters will immediately appear of a brown colour. Even exposing the writing to the vapours of these solutions will render it apparent.—Write with a solution of gold in aqua-regia, and let the paper dry gently in the shade : nothing will appear ; but draw a =e over it, wetted with a solution of tin in aqua-regia, the writing will imm appear of a purple colour.—Write with an infusion of galls, and when you wisl the writing to appear, dip it into a solution of green vitriol ; the letters will appear black.—Write with diluted sulphuric acid, and nothing will be visible. To render it so, hold it to the fire, and the letters will instantly appear black.— Juice of lemons or onions, a solution of sal ammoniac, green vitriol, &c. will answer the same purpose, though not so easily, nor with so little heat.