Ink, a black fluid employed in Writing, and usually prepared with an infusion of galls, copperas, and gum-arabic.

The chief requisites for the making of good ink, are, 1. Limpidity, so that it may flow freely from the pen. 2. A deep, uniform and black colour. 3. Durability, so that the letters be not liable to be effaced by age ; and 4. It should be divested of any corrosive quality, by which the substance of the paper may be destroyed, or the writing rendered in any degree illegible. No ink, however, hitherto used, possesses all these properties ; hence several ingenious chemists have been induced to make experiments, in order to render it more perfect.

M. Ribaucourt, in the " Annales de Chimie" directs eight ounces of Aleppo galls, and four ounces of logwood, to be boiled in twelve pounds of water, till the quantity is reduced to one half; when the liquor should be strained through a linen or hair sieve into a proper vessel. Four ounces of sulphate of iron (green vitriol); three ounces of gum-arabic ; one ounce of sulphate of copper (blue vitriol); and a similar quantity of sugar-candy, are now to be added : the liquid should be frequently shaken, to facilitate the solution of the salts. As soon as these ingredients are perfectly dissolved, the composition is suffered to subside for twenty-four hours ; when the ink may be decanted from the gross sediment, and preserved for use in glass or stone bottles, well stopped.

This ink exhibits a purplish-black colour in the bottles ; but the writing performed with it, is said to be of a beautiful black cast, which it retains, unaltered, fur a considerable length of time.. Each quart of the preparation contains : ox. drs, gyi.

Of galls - - 2 5 20

Green vitriol 1 2 40

Logwood 1 2 40

Gum - - 1 0 O

Blue vitriol - O 2 40

Sugar-candy 0 2 40

M. Ribaucourt is of opinion, that ink thus prepared, may be preserved several years in a state of perfection, without depositing either galls or iron.

The ink commonly used, is manufactured by stationers, according to Dr. Lewis's recipe; but it is ill calculated for keeping, as it deposits a black sediment, while the fluid itself is of a pale colour. Each quart of this ink contains : oz. drs. grs.

Of galls - - 3 0 O

Green vitriol 1 0 O

Logwood - 0 5 24

Gum - - 1 0 0

Neither blue vitriol nor sugar are employed in this preparation. As, however, both the ink made after the latter method, and that compounded according to other recipes, are not adapted to resist the effects of acids, and are consequently by no means fit for records, deeds, and other documents, M Westrumb recommends the following ingredients, as being well calculated to remedy this inconvenience. He directs one ounce of Brazil-wood, and a similar quantity of gall-nuts, to be boiled in forty-six ounces (somewhat less than three pints) of water, till the whole be reduced to thirty-two ounces, or about two quarts. This decoction is to be poured, while hot, upon half an ounceof copperas, or green vitriol; a quarter of an ounce of gum-arabic, and a similar quantity of white sugar. As soon as a perfect solution of these substances has taken place, one ounce and a quarter of indigo finely pulverized is to be added; together with three quarters of an ounce of the purest lamp-black, previously diluted in one ounce of the best brandy. The whole is to be well incorporated; and, after it has subsided, Mr. Westrumb asserts that it will form an ink absolutely indestructible by acids.

A more simple composition, is that proposed by M. Bosse, who directs one ounce of Brazil-wood to be boiled in twelve ounces of water with half an ounce of alum, till the liquid be reduced to eight ounces; when one ounce of calcined manganese is to be mixed with half an ounce of gum-arabic, and added to the liquor, which should be previously decanted, in order to render it perfectly limpid. This preparation is said to possess the property of being indelible by the use of any kind of acid, and to be superior to that proposed by M. Westrumb.

A durable ink may also be prepared by washing paper, parchment, etc. with the Prussic acid, which will not in the least injure either of these substances. The materials, thus prepared, may be written on with common ink, and a ground of Prussian blue will be formed beneath every stroke, which will remain long after the black has decayed by the influence of the air, or been destroyed by acids.

The latest, and perhaps most simple, preparation of black ink, is that contrived by Van Mons, who observed that sulphate of iron, or green vitriol, when calcined till it became while, uniformly afforded a very beautiful black precipitate. According to his experiments, the following ingredients produced an excellent writing ink : four ounces of galls, two ounces and a half of calcined vitriol of iron perfectly white, and two pints of water. The whole was infused in a cold place for twenty-four hours ; adding ten drams of pulverized gum-arabic, and preserving it in a glass bottle, or glazed earthen vessel, slightly covered with paper.

Indian Ink, a valuable black for water-colours, imported from China, and other parts of the East Indies, generally in oblong square cakes, impressed with Chinese characters. The preparation of Indian ink was discovered by Dr. Lewis. according to whom it consists of lamp-black and animal glue. In order to imitate it, he directs as much lamp-black to be mixed with the glue, as will be sufficient to give it a proper tenacity for making it into cakes. This composition is said fully to answer the different purposes to which the genuine Indian ink is subservient, both with regard to the colour, and the facility with which it may be applied. Dr. Lewis farther found that ivory-black, and other blacks obtained from charcoal finely levigated, may be advantageously substituted for lamp-black: ivory and charcoal, however, are generally sold in so gross a state, as to prove gritty when worked, and to separate too spee-dily from the water.

Ink-powder is prepared chiefly from the acid salt of galls, which may be obtained by the following process : Take two ounces of pulverized galls, and infuse them in twelve ounces of rain or river-water ; expose the whole for a few days to a warm temperature, and stir it occasionally: after having extracted the colouring matter, fil-tre the solution, and suffer it to stand in the open air for several weeks, in a vessel slightly covered. A sediment will then be gradually formed; which, after removing the mouldy, skin from the top of the liquor, should be carefully collected. Hot water is next poured on this sediment, when it is again filtred and evaporated to dryness : thus, a grey crystalline salt will be produced, that is the essential ba-sis of black ink ; and which may be still more purified by repeated solution, filtration, and evaporation.

If one dram of this salt of galls be triturated with an equal quantity of the purest vitriol of iron, and about twenty grains of perfectly dry gum-arabic, a composition will be obtained, which, on adding a proportionate quantity of warm water, instantly affords an excellent black ink.

Blue Ink. One ounce of the finest indigo is first levigated in a glass mortar; then four ounces of the most concentrated vitriolic acid are very gradually poured on the powder; and, on every addition, it is stirred with a glass pestle, so that the whole mixture will require several hours. Such precaution is indispensable, as otherwise the heat generated on adding the vitriolic acid, would impair the brightness of the colour.

After standing from 12 to 18 hours, in a moderately warm place, this dense mixture must be diluted with water; not by aduing this fluid to the composition, but by introducing small portions of the latter into a vessel containing such a quantity of water as may be requisite to produce a lighter or darker shade. In general, from 30 to 40 parts of water will be necessary to reduce it to a fine blue liquid. This diluted solution of indigo is, however, in too caustic a state to be employed either as a blue dye, or as writing ink. Hence the vitriolic acid ought to be divested of its corrosive quality, by means . of such a substance as may form a chemical combination with the acid, and not precipitate the indigo. If the solution be intended merely for colouring or writing on paper, it will be sufficient to add pulverized chalk in small portions, til it cease to effervesce; because a large quantity of this powder, at a time, would cause the liquid to rise above the brim of the vessel. It is easy to ascertain the point of saturation ; for, when the powder of chalk scattered on the surface no longer produces any bubbles, the solution should be suffered to stand for 24 hours, then filtred through blotting paper, and preserved in bottles.-It', however, this preparation be designed for dyeing' silk, such as stockings, etc. it will be preferable to neutralize the vitriolic acid by the addition of aluminous earth, instead of chalk, as the former renders the colour more durable. And, if the solution is to be used for painting on silk, it ought to be previously mixed with gum traga-canth.

Green Ink. Take a glass retort containing about one quart; pour into it one pint of distilled vinegar ; place it over a sand heat, and when it begins to boil, introduce into the liquid small portions of powdered verdigrease, till a saturated solution is obtained, or till no more colouring matter can be dissolved, la order to keep the latter suspended, and prevent the formation of crystals, it will be requisite to add about the sixth part of gum-arabic, in proportion to the verdigrease.

For preparing red and yellow ink, see the articles Red and Yellow.

Printing, or Printers' Ink, differs greatly from every other species. It is an oily matter of the consistence of an ointment, the composition of which is, at present, very imperfectly known, excepting to the few who are employed in its manufacture. The following recipe, however, has been found to make printing ink of a tolerable good quality : Let two quarts of linseed-oil be boiled in a vessel capable of holding a triple quantity, over a strong fire, till it emit a thick smoke. It is then to be kindled with a piece of paper, and suffered to burn for the space of a minute, when the flames must be extinguished, by closing the vessel. As soon as the oil becomes cool, two pounds of black resin, and one pound of hard soap, cut into thin slices, are. to be added; the mixture again placed over the fire ; and, when the ingredients are perfectly dissolved, a pound of lamp black, previously sifted, must be incorporated with the mixture; after which the whole is to be finely ground on a marble stone.

This method of making printers' ink is acknowledged to be preferable to the different recipes hitherto published. It is, however, much inferior in beauty of colour to the ink generally used, and is apt to adhere to the types, so as to make an indistinct impression. Good printers' ink, which is easily worked, without daubing or tearing the paper, while it imparts a line colour, is a desideratum that will amply repay the attention and time bestowed upon its preparation.- See Printing.

Sympathetic Ink, aliquor employed for writing on paper, so that it may retain its natural whiteness after the letters are formed, till it is held near the fire, rubbed with another liquor, or some other expedient is used to render the characters legible.

Sympathetic inks are prepared from various substances, such as bismuth, lead, etc. Thus, a solution of common sugar of lead in water, if employed with a clean pen, will remain concealed till it is wetted with a solution of the liver of sulphur, or is exposed to the vapours of such liquid ; in which case it will assume a deeper or lighter brown shade, in proportion to the strength of the sulphureous" gas. By the same process, words written with a solution of bismuth in spirit of nitre, will appear of a deep black colour.

Another sympathetic ink may be easily prepared, by diluting oil of vitriol with a sufficient quantity of water, to prevent the paper from being corroded. Letters drawn with this fluid are invisible when dry, but, on being held near the fire, they assume a perfectly black colour. The juices of lemons, or onions; a solution of sal ammoniac, etc. will answer a similar purpose, though their application is more difficult, and they afterwards require a greater degree of heat.

On the subject of removing or discharging spots, occasioned by different inks on linen, silk, or woollen cloth, we shall treat under the article Spots.