When wool is to be dyed with this sulphate of indigo-blue, it must be first boiled in alum, than treated with blue liquor, and thus several times alternate ly, in order to produce a uniform blue color. Too long continuance of boiling is injurious to the beauty of the dye. In this operation the woollen fibres get im pregnated with the indigo-blue sulphate of alumina.
With sulphate of indigo, not only blues of every shade are dyed, but also green, olive, gray, as also a that ground to log wood-blues ; for the latter purpose the preparatory boil is given with alum, tar tar, sulphates of copper and iron, and the blue solution ; after which the goods are dyed up with a logwood bath con taining a little potash.
I N K. The colored liquid used for writing, is made usually by the action of the tannin of vegetable substances upon salts of iron. In the case of black ink, nut-galls, sulphate of iron, and gum, are the only substances necessary ; others being added to modify the shade, or diminish the cost. Those which contain most eallic acid or tannin acid are most valnahle, and the reverse. To make 12 gallons of ink, Dr. Uro directs to take 12 lbs. of Nut-galls, 5 lbs. of Green Sulphate Iron, 5 lbs. of Gum Senegal, 12 gallons of Water.
The nut-galls and water are put into a copper and well boiled, replacing the water lost : it is then poured into a tub, let to settle, and strained. The gum is then dissolved, strained, and added to the gall liquor. The copperas is also dis solved and added, when the whole be comes gradually black. It should be bottled before it attains its full black ness. A few bruised cloves added in, prevents mouldiness. Sumach logwood, i and oak-bark, are often used instead of galls, or in addition to it, to diminish the cost of manufacture; but the ink is deteriorated by their use. Logwood requires less copperas than galls. The foregoing ink is much stronger than that commonly sold, and it may be diluted with an equal quantity of water to form an ink of similar strength to that usually sold. A good black ink should write pale and become black afterwards in the paper : that which writes black at once and shines on the surface of the paper, easily rubs off and is not as permanere. Japan ink, as such is called, is not lasting.
Inks are of almost every shade, and generally are solutions of chemical salts. Bed ink. Take a strong decoction of Brazil wood and a little gum-water, and add some alum with a few drops of the chloride of tin.
A still better red ink is a decoction of cochineal, to which a little water of am monia bas been added : or an extempo raneous red ink may be made by rubbing up carmine in strong water of ammonia, diluting the solution down to the desired shade, and adding mucilage.
Green ink. Dissolve distilled verdi gris is strong vinegar, and make into a proper consistency for writing with a so lution of gum arabic: or boil 2 parts of verdigris, 8 parts of water, and 1 part of cream of tartar together down to one half, let settle, strain, and bottle.
Yellow ink. A little alum added to saffron and water, makes a very good yellow ink—thicken with gum: or boil 8 parts of alum, 100 parts of water, and 25 parts of Persian berries together, strain and add mucilage ; or dissolve gamboge' in water.
The different dye-stuffs and solutions, afford inks of any desired shade.
Mr. I. Deck has recommended a new mode of making black ink, which affords a good color and is remarkably cheap. The process is this: boil 1 part of log wood in 100 parts of water until the liquor is pretty strong, and to one quart of it put in one quarter of an ounce of chromate of potash, and set it apart, shaking it frequently, for about three weeks. At first the appearance of the ink will be a little greenish, but after it is exposed to the sun and air for some time, it gets beautiful, is very fast, and does not injure steel pens.
Ink powder. Blue galls, 2 ounces ; gum arabic, t an ounce; sulphate of iron, 8 ounces—all powdered and well mixed together.
Indelible inks. These used to have for a basis nitrite of silver, which, in a strong solution, thickened with gum and color ed, was laid with a pen on the cloth pre viously soaked with carbonate of soda— which reduced the oxide of silver in the tissue of the stuff. More recently, the nitrate of silver has been dissolved in water of ammonia and laid on the cloth without any further treatment : this ink is not now indelible, its stain is removed by chlorine and water of ammonia, and of course it does not resist the bleaching powder used in laundries. Fine gold powder,. rubbed up with genuine China ink, resists the action of chlorine, oxalic acid, and washing off with water. Char coal, rubbed up with acetic acid and thickened, furnishes a very permanent ink.