INK. 



Besides these additions others are 

 made by the printers, of which the most 

 important is generally understood to he 

 a little fine indigo in powder, to improve 

 the beauty of the colour. 



Red printers' ink is made, by adding to 

 the varnish about half its weight of ver- 

 milion. A little carmine also improves 

 the colour, (Encycl. Arts & Metiers, vol. 

 iii. p. 518.) 



INKS, coloured. Few of these are used 

 except red ink. The preparation of these 

 is very simple, consisting either of decoc- 

 tions of the different colouring or dyeing 

 materials in water, and thickened with 

 gum-arabic, or of coloured metallic ox- 

 ides, or insoluble powders, merely diffus- 

 ed in gum-water. The proportion of 

 gum-arabic to be used may be the same 

 as for black writing ink. All that applies 

 to the fixed or fugitive nature of the se- 

 veral articles used in dyeing may be ap- 

 plied, in general, to the use of the same 

 substance as inks. 



INK, red, is usually made by boiling 

 about two ounces of Brazil wood in a 

 pint of water for a quarter of an hour, 

 and adding to the decoction the requisite 

 quantity of gum, and about half as much 

 alum. The alum both heightens the co- 

 lour and makes it less fugitive. Proba- 

 bly a little madder would make it more 

 durable. 



INK, blue, may be made by diffusing 

 Prussian blue or indigo through strong 

 gum-water. 



INK, yellow, may be made by a solution 

 of gamboge in gum-water. 



Most of the common water-colour 

 cakes, diffused in water, will make suffi- 

 ciently good coloured inks for most pur- 

 poses. 



Inks of other colours may be made 

 from a strong decoction of the ingredi- 

 ents used in dyeing, mixed with a little 

 alum and gum-arabic. For example, a 

 strong decoction of Brazil wood, with as 

 much alum as it can dissolve, and a little 

 gum, forms a good red ink. These pro- 

 cesses consist in forming a lake, and re- 

 tarding its precipitation by the gum. See 

 LAKE. 



On many occasions it is of importance 

 to employ an ink indestructible by any 

 process, that will not equally destroy the 

 material on which it is applied. Mr. 

 Close has recommended for this purpose, 

 25 grains of copal in powder dissolved in 

 200 grains of oil of lavender, by the as- 

 sistance of gentle heat, and then mixed 

 with 2^ grains of lamp-black, and half a 

 grain of indigo: or 120 grains of oil of 

 lavender, 17 grains of copal, and 60 grains 



of vermilion. A little oil of lavender, or 

 of turpentine, may be added, if the ink 

 be found two thick. Mr Sheldrake sug- 

 gests, that a mixture of genuine asphal- 

 tum, dissolved in oil of turpentine, am- 

 ber varnish, and lamp-black, would be 

 still superior. 



When writing with common ink has 

 been effaced by means of oxygenated 

 muriatic acid, the vapour of sulphuret of 

 ammonia, or immersion in water impreg- 

 nated with this sulphuret, will render it 

 again legible. Or if the paper that con- 

 tained the writing be put into a weak so- 

 lution of prussiate of potash, and when 

 it is thoroughly wet, a sulphuric acid be 

 added to the liquor, so as to render it 

 slightly acidulous, the same purpose will 

 be answered. 



Mr. Haussman has given some compo- 

 sitions for marking pieces of cotton or li- 

 nen, previous to their being bleached, 

 which are capable of resisting every ope- 

 ration in the processes both of bleaching 

 and dyeing, and consequently might be 

 employed in marking linen for domestic 

 purposes. One of these consists of asphal- 

 tum 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 consist- 

 ence for printing with types. Another, 

 the blackish sulphate left after expelling 

 oxygen gas from 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 

 solution of gum tragacanth, and the cloth 

 marked with this is to be dipped in a so- 

 lution of potash or soda, mild or caustic, 

 in about ten parts of water. 



Among the amusing experiments of the 

 art of chemistry, the exhibition of sym- 

 pathetic inks holds a distinguished place. 

 With these the writing is invisible, until 

 some reagent gives it opacity. We shall 

 here mention a few out of the great num- 

 ber, that a slight acquaintance with che- 

 mistry may suggest to the student. 1. If 

 a weak infusion of galls be used, the writ- 

 ing will be invisible till the paper be 

 moistened with a weak solution of sul- 

 phate of iron. It then becomes black, 

 because these ingredients form ink. 2. 

 If paper be soaked in a 'weak infusion of 

 galls, and dried, a pen dipped in the so- 

 lution of sulphate of iron will write black 

 on that paper, but colourless.on any other 

 paper. 3. The *'. luted solutions of gold, 

 silver, or mercury, remain colourless up- 

 on- the paper, till exposed to the sun's 

 light, which gives a dark colour to the 

 oxides, and renders them visible. 4. 



