Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 3, 1802).djvu/33

15&#93; INK vlnys to a warm teniiXTatiirp, and stir it occasionally: after having extrai5tcd the colouring matter, lil- tre the solution, and suiter it to stand in the open air tor several weeks, in a vessel slig'.uly covered. A sediment will then be gradually formed ; which, after removing the mouldy skin from the top of the liquor, should be carefully col- lected. Hot water is next poured on this sediment, wlien 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 evajwra- tion. If one dram of this salt of galls be triturated v, ith an equal quan- tity of the purest vitriol of iron, and about twenty grains of perfe6tly dry gum-arabic, a composition v/ill be obtained, which, on adding a proportionate quantity of warm water, instantly atfords an excel- lent black ink. Blue Ink. One ounce of the finest indigo is first levigated in a glass mortar j 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 liours, in a moderately warm place, this dense mixture must be diluted with water ; not by adidng this fluid to the composition, but by Lntroducing small portions of the latter into a vessel containing such a quantity of water as may be re- IN:K [T5. qui lite to produce a lighter or dirk- er shade. In general, from 30 to 40 parts of water will be necessary to reduce it to a fine blue li<juid. This diluted solution of indigo is, however, in too caustic a state to be employed either as a bluer dye, or as writing ink. Hence the vitriolic acid ought to be divested of its corrosive quality, by raeansi 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 he sumcient to add inilverized chalk in small portions, til it cease to effervesce J because a large quan- tity 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 suifered to stand for 24 hours, then filtred through blotting paper, and preserved in bottles. — If, hoA^ever, this preparation be designed for dyeing silk, such as stockings, ^'c. it will be preferable to neutralize the vitriolic acid by the addition of aluminous eartli, 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 pr. viously mixed with gum traga- canth. Green Ink. Take a glass re- tort containing about one quart ; pour into it one pint of distilled vinegar ; place it over a sand heat, and wdien it begins to boil, intro- duce into the liquid small portions of powdered verdigrease, till a sa- turated solution is obtained, or till no more colouring matter can be diisolved. In order to keep the iaUcr