Page:Encyclopædia Britannica, Ninth Edition, v. 13.djvu/89

 I N K I N K 79 cedure Act of 1854, and by other statutes in special cases, a limited power of injunction was conferred on the courts of common law. But the Judicature Act, by which all the superior courts of common law and chancery are con solidated, enacts that an injunction may be granted by an interlocutory order of the court in all cases in which it shall appear to be just or convenient ;. . . . and, if an in junction is asked either before or at or after the hearing of any cause or matter, to prevent any threatened or appre hended waste or trespass, such injunction may be granted whether the person against whom it is sought is or is not in possession under any claim of title or otherwise, or if not in possession does or does not claim to do the act sought to be restrained under colour of any title, and -whether the estates claimed are legal or equitable. An injunction obtained on interlocutory application during the progress of an action is superseded by the trial. It may be continued either provisionally or permanently. In the latter case the injunction is said to be perpetual. The distinction between &quot;special&quot; and &quot;common&quot; injunc tions the latter being obtained as of course is now abolished in English law. The practice as to injunctions obtains in the United States of America. &quot; In the courts of the United States, as injunctions are grantable only on notice to the adverse party, all interlocutory injunctions are regarded as within the class of special injunction ; and this is believed to be also the practice of the State courts generally &quot; (Abbott s Law Dictionary], For the analogous Scotch practice see INTERDICT. INK (French, encre ; German, Tintc), in its widest signification, is the medium employed for producing graphic tracings, inscriptions, or impressions on paper or similar materials. The term includes two distinct conditions of pigment or colouring matter : the one fluid, and prepared for use with a pen or brush, as writing ink ; the other a glutinous adhesive mass, printing ink, used for transferring to paper impressions from types, engraved plates, and other like surfaces. The latter class may be more properly dealt with under LITHOGRAPHY and PRINTING- (q.v.). Writing inks are fluid substances which contain colouring matter either in solution or in suspension, and very com monly partly in both conditions. They may be prepared in all shades of colour, and contain in their composition almost every pigment which can be dissolved or suspended in a suitable medium ; but by far the most important of all varieties is black ink, after which red and blue are the colours most commonly employed. Other colours are only occasionally employed ; but apart from colour there are special qualities which recommend certain inks for limited applications, such as marking inks, ineradicable ink, sym pathetic ink, &c. Black ItiL Among the qualities which should char acterize a good black ink for ordinary purposes, the follow ing are important. Ifc should continue limpid, and flow freely and uniformly from the pen ; it should not throw down a thick sludgy deposit on exposure to the air ; nor should a coating of mould form on its surface. It should yield distinctly legible characters immediately on writing, which ought to become a deep blue-black, not fading or decaying with age ; and the fluid ought to penetrate into the paper without spreading, so that the characters will neither wash out nor be readily removed by erasure. Further, it is desirable that ink should be non-poisonous, that it should as little as possible corrode steel pens, that characters traced in it should dry readily on the applica tion of blotting paper without smearing, and that the writing should not present a glossy varnished appearance. To obtain these characteristics is the chief object of the ink manufacturer ; and upon the whole they have hitherto been found best combined in ink prepared from galls, or other sources of tannin, and a salt of iron, with the addition of some colouring matter. Such a compound indeed forms the staple black ink of commerce, which is essentially a ferroso-ferric gallate in extremely fine division held in sus pension in water. The essential ingredients of this ordinary black ink are- first, tanniu-yieldiug bodies, for which Aleppo or Chinese galls are the only eligible materials ; second, a salt of iron, the ferrous sulphate (green vitriol) being alone employed ; and third, a gummy or mucilaginous agent to keep in suspension the insoluble tinctorial matter of the ink. For ink-making the tannin, from whatever source obtained, has first to be transformed into gallic acid ; and, as has been shown by Viedt, in the case of Aleppo galls that change takes place by fermentation when the solution of the galls is exposed to the air, the tannin splitting up into gallic acid and sugar (see GALLIC ACID, vol. x, p. 41). Chinese galls, which formerly were considered unsuitable for the manufacture of ink, do not contain the ferment necessary for inducing this change; and therefore to induce the process yeast must be added to their solution. To-prepare a solution of Aleppo galls for ink-making, the galls are coarsely powdered, and intimately mixed with chopped straw. This mixture is thrown into a narrow deep oak vat, provided with a perforated false bottom, and having a tap at the bottom for drawing off liquid. Over the mixture is poured lukewarm water, which, percolating down, extracts and carries with it the tannin of the galls. The solution is drawn off and repeatedly run through the mixture to extract the whole of the tannin, the quantity of water used being in such proportion to the galls as will produce as nearly as possible a solution having 5 per cent, of tannin. The object of using straw in the extraction process is to maintain the porosity of the mixture, as powdered galls treated alone become so slimy with mucilaginous extract that liquid fails to percolate the mass. For each litre of the 5 per cent, solution about 45 grammes of the iron salt are used, or about 100 parts of tannin for 90 parts of crystallized green vitriol. These ingredients when first mixed form a clear solution, but on their exposure to the air oxidation occurs, and an insoluble blue-black ferroso- ferric gallate in extremely fine division, suspended in a coloured solution of ferrous gallate, is formed. To keep the insoluble portion suspended, a mucilaginous agent is employed, and that most available is gum Senegal. An ink so prepared develops its intensity of colour only after some exposure ; and after it has partly sunk into the paper it becomes oxidized there, and so mordanted into the fibre. But, as the first faintness of the characters is a dis advantage, it is a common practice to add some adventitious colouring matter to give immediate distinctness, and for that purpose either extract of logwood or a solution of indigo is used. When logwood extract is employed, a smaller proportion of extract of galls is required, from the fact that logwood itself contains a large percentage of tannin. Black ink in which the provisional colouring matter is indigo was introduced about the year 1856, under the name alizarin ink, although the substance alizarin has nothing whatever to do with the preparation. The indigo for this ink is dissolved in strong sulphuric acid, and the ferrous sulphate, instead of being used direct, is prepared by placing in this indigo solution a proper quantity of scrap iron. In order to free the solution from excess of uncom- bined acid, chalk or powdered limestone is added, whereby the free acid is fixed and a deposit of sulphate of lime formed. A solution so prepared, mixed with a tannin solution, yields a very limpid sea-green writing fluid, and as all the constituents remain in solution, no gum or other suspending medium is necessary. In consequence the ink flows freely, is easily dried, and is free from the glossy