Discoveries and Inventions Abroad. / Red Dyes. Aniline Blues, Lilacs and Drabs.

Scientific American 3, 14.1.1860


Red Dyes..—A patent has been taken out in England by R. A. Brooman (as a communication from abroad) for the preparation of red colors for textile fabrics from aniline. A mixture of aniline and anhydrous bichloride of tin are first heated up together to the boiling point and then boiled for fifteen minutes. At first the mixture is of a yellowish tint, but it finally becomes a beautiful red when held up to the light, althought, in a very large quantity, it appears to be of a blackish crimson color. When hot, to liquor maintains its liquid condition; but on becoming cold, it assumes a jelly slate. While still warm, the liquor is to be filtered to free the coloring matter from several impurities. By adding the tartrate of potash or the acetate of lead to the liquor while hot all the coloring matter is precipitated, and when it becomes cold it may thus to obtained solid, to be used like the extract of logwood in dyeing. The red solution of aniline thus obtained may be used with pyroligneous mordant, or the nitrate and acetate of lead in dyeing. To print calicoes with this preparation of aniline a very concentrated extract is required, which is mixed with dextrine or gum to make it into a printing paste. Acetic acid and alcohol will also precipitate the extract. The bichloride of mercury (corrosive sublimate), the protochloride of copper and the perchloride of iron can also be embployed to mix with the anyline as substitutes for the bichloride of tin.

Aniline Blues, Lilacs and Drabs. — A patent has also been lately secured by Messrs. J. T. Beale and T. N. Kirkham, of England, for aniline in dyeing and printing. This invention consists in treating salts of aniline, or an acid solution of it, with hypochlorite of lime or common bleaching powder, to obtain fat colors. They take the nitrate of aniline, or the acetate, or a saturated solution of aniline in water, and add an equal quantity by measure of acetic acid. To this solution some hypochlorite or bleaching powder is also added, and a change in the color of the solution at once takes place. The shade of the liquor indicates the shade of color to be produced by it on textile fabrics. By varying the quantities of these substances different shades may be produced, from a blue to a lilac, purple, violet, slate and drab. It In well known to dyers that, by using the same substances in dyeing (only in different quantities—strong and weak), browns, drabs, &c., are colored; and so it is with using aniline of different degrees of strength, according to the shades desired. When prepring aniline for dyeing, the chlorite must be added very cautiously until the proper shade is attained, because it is the reagent which "tones" the colors. The following is the method of practically using the aniline:—Dissolve as much aniline as can be taken up in a certain quantity of water—say one gallon, and to this add one gallon of strong acetic acid and a pint of the hypochlorite of lime. The whole is then carefully stirred and the color of the liquor becomes a violet of an intensity proportioned to the amount of chlorine used, the greater the quantity of the latter the lighter the shades produced. According to the quantity of hypochlorite used, the shades of aniline will vary from a violet to a drab. With aniline liquors thus prepared, silk may be dyed various shades without mordants; with mordants, both wool and cotton fabrics may be dyed with the aniline thus prepared; and strong extracts may be employed for printing. We had been informed that aniline—which is a preparation of indigo with dilute nitric acid, and formerly called indigotic acid—had gone out of use, but these two patents afford evidence of it becoming more extended in Europe. None of these colors, so far as we know, have yet been introduced into this country.


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