Mr W. H. Perkin’s patent is similar in principle to that of Messrs Caro, Graebe, and Liebermann, and is dated only one day later.
The following is an outline of a patent taken out in France in May, 1869, by MM. Brœnner and Gutzkon, for the manufacture of artificial alizarin. One part of anthracen is heated with two parts of nitric acid, sp. gr. 1·3 to 1·5. The anthraquinone thus produced is washed and dissolved at a moderate heat in sulphuric acid. Mercuric nitrate is now added, which converts the anthraquinone into alizarin, The mass thus formed is dissolved in an excess of alkali, which precipitates the oxide of mercury, and retains the colouring matters in solution. The alkaline liquor is decanted and neutralised with sulphuric acid, and the precipitate thus formed is washed and collected. If not quite pure the treatment with alkali must be repeated. (The complete specification of this patent is published in the ‘Moniteur Scientifique,’ vol. xi, p. 865.)
In England a large quantity of artificial alizarin is manufactured by the process of Mr Perkin, and is used as a substitute for madder and madder extract, in Turkey red dyeing and topical styles. The largest makers of artificial alizarin on the continent are Messrs Gessert Frères, of Ebelfort, Messrs Maister, Lucius and Co., of Hæchst, near Frankfort, and the Badische Anilin und Soda Fabric, Mannheim.
The following recipes for printing with artificial alizarin are extracted from Mr Crookes’ ‘Practical Handbook of Dyeing and Calico Printing’:
Reds.
5 lbs. alizarin paste (10 per cent.); 16 lbs. thickening; 1 lb. acetate of alumina, at 15° Tw.; 1⁄2 lb. acetate of lime, at 25° Tw.
Pinks.
The above diluted with 2 or 3 parts of thickening.
For double printing, when deep red is printed on first, the goods must be steamed one hour before the second printing takes place. After the second printing the goods are again steamed for one hour, and aged for twenty-four hours; they are then passed through one of the following baths, at from 120 to 140 F., remaining in the bath not longer than 1 to 11⁄2 minute:—
250 gals. water; 60 lbs. chalk; 3 lbs. tin crystals. Or, 250 gals. water; 40 lbs. chalk; 10 lbs. arseniate of soda.