2572. Aniline Black for Dyeing

2572.     Aniline Black for Dyeing. According to Mr. Köchlin, aniline black is produced as follows: Water, 20 to 30 parts; chlorate of potassa, 1 part; sal ammoniac, 1 part; chloride of copper, 1 part; aniline, hydrochloric acid, of each 1 part, previously mixed together. Several other formula for producing aniline blacks have been devised for dyeing purposes. It is essential in each of them, and always, that the preparation shall be acid, and the more acid it is, the more rapid is the production of the blacks. The action, of course, if it be excessive, will be likely to injure the fibre of the fabric.

2573. Aniline Black on Wool

2573.    Aniline Black on Wool. For 2 pounds of wool. a bath is prepared of 20 quarts water, 3 ounces permanganate of potassa, 41/4 ounces sulphate of magnesia. The use of sulphate of magnesia has for its object, to prevent the formation of caustic alkali, and has already been proposed by Tessi'e du Mothay. The wool is impregnated with this solution, and left in it until the fluid has become colorless, or nearly so, whereby it is colored dark-brown and covered with brown oxide of manganese. This process takes place easily in the cold, but it is best to dissolve the permanganate in hot water. The wool is now pressed out, and, without washing, conveyed into a bath of 12 ounces commercial aniline oil, 21 ounces commercial hydrochloric acid, and 8 quarts water, where it is moved about in the cold; it attains here directly a dark green-black color. It is pressed out again, washed in water containing a little soda, and treated with a weak solution of 1/3 ounce bichromate of potassa in 10 quarts water. The color becomes now dark black, when the wool is washed with water and dried.

2574. Persoz's Aniline Black for Wool or Silk

2574. Persoz's Aniline Black for Wool or Silk. Steep the silk or wool for 1 hour at a boiling heat, in a bath consisting of 5 grammes (77 grains) bichromate of potassa, 3 grammes (46 grains) sulphate of copper, and 2 grammes (31 grains) oil of vitriol, for each litre (21/10 pints) of water used. It is then thoroughly washed, and afterward passed through a solotion of oxalate of aniline marking 1° to 2° Baum6, in which it at once assumes a black color. In case the fabric contains a vegetable fibre, the first bath must be replaced by a series of baths resulting in chromate of lead. This is effected by successive passages through a solution of nitrate or acetate of lead, then through a hot one of sulphate of soda; and lastly through a cold bath of from 5 to 20 grammes (77 to 300 grains) bichromate of potash to the litre (21/10 pints) of water.

2575. To Prepare Magenta for Dyeing

2575.     To Prepare Magenta for Dyeing. This color, which is also called rosein, fuchsine, and aniline red, is the best known of the series. It is better adapted for the preparation of a liquid dye than any other. In the hands of the amateur it can be used with economy, and the results obtained are generally satisfactory. It is readily soluble in alcohol, and to some extent in water. The latter property is taken advantage of by dyers, the dye bath being prepared directly from the crystals. It is, however, preferable to use alcohol for dissolving the color, as the solubility in water is not always the same with different samples. To 1 pound of the crystals add 21/2 gallons of spirit .8200 specific gravity. The solution may be conveniently made in an ordinary 5-gallon tin. Agitate frequently, and add 21/2 gallons of hot water. This product will be suitable for sale as a liquid dye, but for dyers' use, where a large quantity of water is admissable, 11/2 gallons of spirit will be found sufficient. It is sometimes necessary to filter before using.