Page:The New International Encyclopædia 1st ed. v. 10.djvu/718

INK. 632 INK. vrhich are then crushed and treated with distilled water for several days, after which the clear liquid is carefully drawn off and to it is added a clear mucilage, made by previously dissolving the gum in hot water and filtering. Kiniilly. dissolve separately the ferrous sulphate ami mix with the foregoing solutions. Some authorities recommend instead of a solution of ferrous sul- phate that clean iron filings be adiled to a por- tion of nutgalls and gum and the li(|uid agitated until it U'come.s deep black in color. In either case the color is due to the oxidation of the iron salt and its combination with the gallic acid in the solution. In the manufacture of conunercial inks, nutgalls are fre(|uently sub- stituted by logAvood. oak bark, and sumach. It has been determined that the proportion of three parts of the galls to one part of the ferrous sul- phate yields a satisfactory ink, but in actiial practice more ferrous sulphate is usually added. The use of the foregoing ingredients has been conceded to result in the production of a writing fluid which is jet black at the time of ise. flows freely in the pen, and is practically permanent. In order to obtain a deeper black, logwood and indigo extracts are sometimes added. Runge in 1S4!) described a chrome ink which he made by adding one part of potassium chronuite to one thousand parts of a sohition of logwood, made by exhausting one pound of logwood with 6 quarts of boiling water. The potassium chro- mate is added gradually when the solution is cooled, the mixture being constantly stirred dur- ing the achlition. This ink is cheap, permanent on paper, and unaffected by exposure to water or aciils. The use of ammonium vanadate, with an infusion of nutgalls. has been recommended as producing an exceedingly black writinglluid, but the expense of the vanadium salt lias pre- vented its common use. Certain aniline blacks, especially nigrosin, owing to their fluidity, and the fact that they form no sediment, have been extensively used in fountain pens. Rkd Writixg-Ink. Red inks are commonly prepared from Rrazilwood. cochineal, or car- mine: those nuide from Brazilwood are re- garded as more permam-nt. while tho.se from cochineal yield the most brilliantly colored fluids. An excellent quality of red ink may be had by boiling 2 ounces of Brazilwood in .'i2 oiinces of water and by adding to that solution, after straining, one half an ounce of stannous chloride (tin salt) and 1 dram of gum arabic. This mix- ture is then boiled down to a pint. The modem red ink is frequently little more than a solution of some aniline color, such as cosin red or rosein. BLfE Writixo-Ink. Ordinary blue ink is a preparation of Prussian blue, and may be made by triturating"G parts of this substant« and 1 part of oxalic acid with a little water to a per- fectly smooth paste, and diluting the mass with a sulhcient quantity of distilled water. An ex- cellent blue ink is made by dis.solving soluble Paris blue ("cornflower blue") in alcohol. Ami.ine Writixg-Ixks. The general formula for making aniline inks is to dissolve l.i parts of any aniline color in 150 parts of strong alco- hol in a glass vessel, and. after allowing the solu- tion to stand for three hours, adding 1000 parts of distilled water; the liquid is then heated gently for some hours, or until the color of the alcohol has quite disappeared, whereupon it is mixed with a solution of CO parts of powdered gum arabic in 250 parts of water. This formula may bi- followed for the ordinary violet or purple ink, as well as for the many other colors, such as green, yellow, etc., which are sometimes used. .MfrTALLlc Ink.s. Gold, silver, and similar metallic inks may be maile by taking e<|ual parts of the metal in leaf and triturating with honey until the metal is reduced to the finest possible state of ilivision : thin agitating with .'JO parts of hot water, allowing to settle, diianling tlie water, repeating the washing several times, and finally drying the metal anri mixing it with a little weak giuu arabic water for use. Si'Ei'iAi. Inks. Copying-ink is made by adding a thickening substance, such as gum arabic, gum dextrin, or glycerin, to ordinary ink. The ordi- nary marking or indelible inks are maih' by dis- solving a silver salt, usually the nitrate, in water and ammonia, to which a small quantity of gum is added. Such inks may be removed by treat- ment with potassium cyanide. More permanent inks may be made by using solutions of gold or platinum chloride. Sy.mpatiietic or Secret Ixks. These are fluids which produce colorless writing U|K>n paper: but, when the latter is sul>sei|uently ex- posed to heat or proper chemical a<'tion, the writing becomes colored and clearly readable. Among the favorite secret inks m.iy be mentioned solutions of lead acetate, whose invisible marks on paper turn black on exposure to sulphureted hydrogen, owing to the formation of sulphide of lead. Cobalt nitrate solution furnishes another favorite secret ink, its marks on paper turning blue on treatment with oxalic acid. A solution of either cobalt chloride or the nitro-chlorifle will yield characters whidi are green when heated, but which disappear on cooling; also a weak soluti(m of nickel and cobalt chlorides will produce green tracings. Ink-Powders. These are nothing but the common constituents of ink in a ilry state. Black ink-powder may be made by mixing 4 parts of powilered nutgalls. 2 parts of ferrous suiphat"', and one part of gum arabic. The dry aniline colors may be similarly used. Printi.ng-Inks. Any ink used in printing is essentially a pigment of the rci|uired color, mixed with an oil or varnish, .lohn Underwood in lS,i7 before the Society of Arts described the pron- ertics es.sential to a good printing ink as fol- lows: Jt must distribute freely and easily and work sharp and clean ; it must not have too nnich tenacity for the type, but come off freely and adhere to the pajxT; it must dry almost immediately on the paper, and not dry at all on the type or rollers: it should be practically proof against the effects of time and chemical reagents, and never change color. The pigment used for th» best black ink is lampblack, and the vehicle is usually linseed oil. Mineral pigments are generally used to produce the different colored printing-inks. Details concerning the manufac- ture of printing-inks may be found in any of the larger handbooks on printing. In lithography, the writing-ink for drawing on the stone may consist of equal parts of tallow, wax, soap, and shellac, mixed up with a sutlicient quantity of Paris black. The printing-ink used to take the impression of engraved plates, with a view to transference to the stone, may consist of equal parts of tallow, wax, soap, shellac, and pitch. Consult : Spon, Workshop Receipts I London,