Method of Treating Madder.

Scientific American 18, 8.6.1859

J. Wright, of London, Eng., has recently invented a new process of treating madder for printing and dyeing. He takes madder in the ordinary raw state, and mixes it with water, or bran water, in the proportion of about one (by weight) of madder to about five of water. After allowing it to steep for a little time he puts the mass into a coarse calico bag, and subjects it to pressure in an ordinary press, receiving the expressed liquor into a vessel, which afer standing for some time, forms a jelly, and afterwards separates into a solid and liquid form. He then washes thoroughly the resulting coloring with clear water, and strains it off. This, upon being reduced to a proper consistancy with gum or mucillage in the usual manner, is ready to dye or print with. Instead of treating the jelly in the last described manner with cold water, it may be treated with dilute sulphuric acid, or any vegetable substance containing an acid, or even with common salt. Afterwards it must be thoroughly washed, so as to remove all trace of the acid, then strained, and pressed so as to get rid of the water. Upon being reduced to the proper consistency, as before, it is ready to dye or print with, or the water may be all evaporated, and a dry powder formed. He then takes the refuse madder left fro the last operation, and treats it in a similar manner, that is, obtaining a jelly extract, using, however, less water than in the previous operation. Finally, he mixes the refuse madder remaining after these two operations, with warm water, and after allowing it to stand for a short while, boils it; a precipitate is thus formed, which, after running off the clear supernatant water, he treats with caustic potash, then washes well and strains. He  precipitates the coloring matter from the mass of water by means of sulphuric acid after boiling; and care should be taken to wash out of the precipitate every trace of the acid. It may be advisable in some cases to neutralize it by means of an alkali. The residuum or precipitate thus obtained may be added to the products of coloring matter obtained from the first or second described operations. Instead of treating the refuse madder in the way described, it may be converted into garancine in the usual manner. Again, when he wishes to obtain a crimson, or darker shade of red color, he takes the product resulting from either of the two first-mentioned operations, and converts it into garancine in the usual manner. Furthermore, he proposes to form garancine of any precipitate or extract of madder, either using them separately, or with the garancine results last described. The invention includes other details.

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