Various receipts for indelible inks have at different times been published. Dr. Nor mandy asserts that the ink obtained by the following combination cannot he obliterated or defaced by any known chemical agent: 24 lbs. of Frankfort black (which is supposed to be a charcoal obtained from grape and vine lees, peach kernels, and bone shavings) must be ground with mucilage, formed by adding 20 lbs. of gum arable to. 00 galls. of water, and the mixture strained through a coarse flannel; four lbs. of oxalic acid are then added, together with as much decoction of cochineal or sulphate of indigo as will give the required shade.
Red Inks are of two kinds, one variety consisting essentially of the tinctdruil matter of Brazil-wood, and the other being prepared from cochineal or carmine. Stephens's red ink, which is one of the best of these preparations, is obtained as follows: " Add to a quantity of common carbonate of potash, soda, or ammonia, twice its weight of crude argot in powder. the effervescence has ceased, decant or filter the solution from the insoluble matter. To this fluid add by measure half its quantity of oxalate of alum Ma, prepared by dissolving damp, newly precipitated alumina in as small a quantity as possible of reconcentrated solution of oxalic acid. The mixture thus prepared is next colored, when cold, with bruised or powdered cochineal, and after standing for 48 hours, is strained, when it is fit for use." (Muspratt's C".emistry, vol. ii. p. 378.) Blue Inks are now chiefly made either directly or from Prussian blue. Stenhens's unchangeable blue ink is formed by dissolving this salt (which should be first well washed in a 'dilute mineral acid) in an aqueous solution of oxalic acid. Ink of which Prussian blue is the basis. is unaffected by any of the numerous physical causes which operate injuriously on black ink, unless it be exposed to a strong light, when the iron (which exists as a sesquioxide in Prussian blue) becomes deoxidized, and causes the color of this ink to fade; but on removing the writing from the influence of light, the color is restored.
Purple, green, and yellow inks have been formed by various chemists, but they are not of sufficient importance to claim a notice in this article.
'Pim/pathetic Inks leave no trace of color upon the paper, but when exposed to heat or chemical action•of some kind, become more or less distinctly apparent. The following are a few of the principal kinds of this class of compounds. On writing with a solution of sugar (acetate) of lead or of ternitrate of bismuth, and washing the paper with a sold tion of hydrosulpheric acid (sulphureted hydrogen), the letters come out black. On writing with a solution of nitrate of cobalt, and washing the paper with a solution of oxalic acid, the letters come mit blue. On writing with a solution of subaceude of lead, and washing the' Paper with La solution of iodide Of.,.potassium, thelettCrs come out yet low; or on writing with a dilute solution of chloride of copper, and gently heating the paper, the letters which were previously invisible assume a beautiful yellow tint, which disappears on cooling. On writing with a solution of arsenite of potash, and washing the paper with a solution of nitrate of copper, the letters come out green.
2. Printing Ink is a soft glossy compound, altogether different in its composition from the inks which have been already described. The following are, according to Mr. Underwood (in the paper already referred to). the necessary conditions of a good print ing ink: 1. it must distribute freely; 2. It must have much greater affinity for the paper
than for the type; 3. It must dry almost immediately on the paper, but not dry at all on the type or rollers; this is a great desideratum, especiallyfor newspapers; 4. It should be literally proof against the effects of time and chemical reagents, and should never change color. It is prepared by boiling the best linseed oil in an iron pot, kindling and allow ing it to burn for it short time; by this operation the oil acquires the necessary drying quality. After being again boiled resin is dissolved in it, in order to communicate body to the fluid, which now somewhat resembles Canadian balsam. The coloring matter— which is lampblack for black ink; carmine, lake, vermilion, etc., for red ink; indigo or Prussian blue for blue ink; lemon and orange chrome (chromate and biehromate of lead), or gamboge, for yellow ink, etc.—is then added to the hot mixture, and the whole is drawn off. and finally- ground into a smooth uniform paste.
In lithography a writing and a printing ink are employed, both of which differ alto. gether from the compounds already described. The writing ink is composed, according to Muspratt, of the following materials: shellac, soap, white wax, and tallow in certain proportions, to which is added a strongsolution of gum-sandarach, and it is colored with lampblack; while the printing ink, wnich is employed to take impressions on paper from engraved plates, with a view to their transference to the stone, is composed of tallow, wax, soap, shellac, gum-mastic, black pitclf, and lampblack.
INK (ante). Ancient Inks.—The inks of the ancients had nothing in common with ours except the color and the gum employed for obviating too great fluidity. Employ in broader-pointed pens than ours they required thicker inks, and though the compo .
salon of these inks is not fully understood, yet it is certain that they excelled ours in both richness and stability of color. Ample testimony to these characteristics is borne by existing papyri, whose age is more than 4,000 years, and by the brown leather and white vellum MSS., of an age exceeding 3,000 years, which are now treasured in the musetuns of Europe. While some of these inks were pigments, like the India and Chinese inks of to-day, others seem to have been actual dyes of iron and acids, with the addition of a good deal of ivory-black, lampblack, soot. or other form of carbon. Front Persins and Aisonius, we learn that the Romans made use of the juice of the (untie-fish, or sepia, which abounded in the Mediterranean. Most elegant manuscripts written in golden and silver inks have come down to our day; and also a few written wholly in red ink, made of vermilion, purple, or cinnabar, though red was more frequently used for headings of books, chapters, and pages. The emperors of Constantinople were wont to sign the acts of their sovereignty with red ink, and their lust secretary was gnardian of the vase cow:ain't]; the cinnabar or vermilion, which only the emperor might use. Green ink, though rarely found in charters, often occurs in Latin mannseripts. especially those of hater years It was also used by the guardians of the Greek emperors. before their wards obtained their majority. Blue or yellow inks, fortunately, were seldom employed in manuscripts; and in his Origin and Prof/rem qf Writing, Thomas Astle said that he bad neither found nor heard of the use of yellow ink during the past 600 years.