Chemistry of Madder.

Scientific American 14, 21.12.1850

We have seen a number of articles in exchange papers, relative to the cultivation of madder in America. We have heard that a considerable quantity of madder is raised every year in Ohio, but we not know how much. There can be no doubt but it can be grown profitably in many of our States. Madder is a dye drug and paint, (in the form of a lake,) and has long been known and used for these purposes. Madder root grows on light soils and is reaped every three years in France, and every five in Turkey. The roots are dried in the open air or in stoves, and then either ground or merely deprived of their dirt, fibres, &c. by rubbing and winnowing. When the roots are ground they bear the name of madder; when they are in their entire state they are called Turkey roots. The coloring principles are not diffused throughout the root, but are found between the outside root and the middlefibrous parts.

It is grown in various countries, Turkey, France, Holland &c. Dutch madders, although inferior to French, for red or pink dyeing are nevertheless good for chocolates or purples: they are generally recognised by being coarser ground than the French. Dutch madder improves in quality by being kept two or three years: after that time it gradually losses its properties.

Madder, when kept for a long time in casks, ferments and sometimes increases sufficient in bulk to burst them; and it becomes so hard by long keeping, that it is necessary to have recourse to pickaxe to remove it from them. One hundred parts of madder root gives on an average about twenty parts of madder. Boiling water does not dissolve all the coloring matter of madder, a certain amount remaining fixed; but alcohol removes nearly all the coloring matter.

It was formerly believed that there were three coloring principles in madder: the red, alizarine; the purple, purpurine; and the yellow, xanthine. In 1837, a French botanist discovered, by microscopical investigation, that there is but one coloring principle in madder, which is yellow, and that the other colors are produced by oxifation of this yellow principle: Mr. Girardin afterwards confirmed this statement by chemical investigations.

Alizarine is the red coloring substance and the important one. It crystalizes in fine needles slightly soluble in cold and boiling water, and is freely soluble in alcohol, ether, and the alkalies; it communicates to the latter solutions a splendid purple color, which can be removed by precipitating it, unchanged, with an acid. Rubiacine, which is sidentical with the purpurine of Robiquet, and with the pink of Persoz, does not communicate ny color to mordanted cloth. Rubian, the bitter principle of madder, is volatile, and does not crystalize. Xanthine, the yellow coloring substance, is very soluble in water, and gradually oxidised, it becomes brown; and it is this coloring principle which plays a great part in dyeing with madders, for if in excess, it removes a part of the mordant, and thus it injures the colors, on account of which it is often necessary to neutralise it in the dye-baths by adding chalk; this is to be done with some species of madders, for all do not require chalk, seeing that they already contain a sufficient amount in their roots. A good quality of madder gives nine per cent., a middling quality about twelve per cent., of residue; if a much larger amoubnt is obtained, it is a sign of adulteration.

The way to try madder is to test that suspected to be adulterated with one of a known quality. Of each of these a given quantity is taken, and put into eqal bulks of water, together with equal weights of mordanted cloth: thus for example, 150 grains of each madder is put into one pint of water with a hank of yarn or strip of cotton cloth weighing 80 grains; the temperature of the water is gradually raised, during two hours, to the boiling point, when the whole is then boiled for ten minutes. The fents are taken out, washed in cold water soaped once or twice (with or withour muriate of tin), washed, dried, and compared.

Within a few years, a substance produced from madder, termed garancine, has come into somewhat extensive use in calico madder printing. Two French chemists, Messrs. Robiquet and Caventon, were the first who manufactured garancine, in 1827. It was regarded for many years as a purely scientific produvt; but after several successful applications of it in one or two houses, it became generally used as a dyeing matter in 1839, since which time its application in the art of calico printing has extensively increased.

Garancine is made by treating madder with sulphuric acid the washed product of which is garancine.

In dying Turkey-red, the residue of the madder bath was a dead loss. In some works, the refuse was piled up in useless huge banks. This is now no more all loss: it is treated with sulphuric acid in a steam box and garancine is the result. This useful discovery was made by Mr. Schwartz, a chemist, who secured a patent for its manufacture in France, in 1843.

Garancine is an amorphous reddish brown powder, nearly insoluble in cold and boiling water; and although it is also insoluble in acids, it becomes soluble in water if an alkali is present, viz. potash, lime, chalk, &c. Alum acts rapidly upon garancine, by dissolving the coloring matter. Alcohol, or spirits of wine, by repeated boiling, is capable of dissolving all the coloring matter of garancine: it is made from good madder as follows:
After washing the madder with acidulated water, which dissolves the gum, sugar, xanthine, and pectic acid, the mass is pressed, ad one part of vitriol diluted with one part of water, should be mixed with it, the temperature not being allowed to rise above from 140° to 170° Fahr., for if it does, some of the coloring matter will be destroyed; the aount of vitriol must vary in accordance with the species of madder employed, as they contain various amounts of alkaline earths; nevertheless, after having kept the mass at the said temperature for several hours, it must be washed with water until nearly all the acid is removed chalk and carbonate of soda re added to neutralize the last portions of acid, and after being washed, dried, ground, and sifted, it constitutes commercial garancine.

Garancine, or garanceaux, as it is sometimes called, which is made from spent madder, is produced as follows:
The grounds of the liquor fro the madder bath are treated with weak sulphuric acid to prevent them fermenting, after which the liquor is drained off, the stuff well pressed, and for every 400 lbs. of it, 50 lbs. of the oil of vitriol is added; these, after being well mixed together are placed in a double-bottomed lead cistern, the leaden plate of which is perforated with holes, and placed five or six inches from the bottom. A current of steam is introduced between the leaden plate and the bottom, and is passed through the acid mass for two or three hours; then the residue is first washed with water, and secondly, with water containing a little chalk or carbonate of soda; lastly, it is again washed with water alone, dried, ground and sifted.

Garancine has several advantages over madder in dyeing. First, it does not soil the white parts of the print and make them of such a dirty brown color as madder - consequently the dyer has not so many consecutive processes to have recourse to in order to remove the coloration of the white parts, since in dyeing with garancine the whites are very little colored, and it is only necessary to pass the pieces into bran and water, heated to 70° Fahr., to have them perfectly clear. Secondly, a further econpomy is effected, on account of one part of garancine having as much tinctorial power as about three parts of madder. Lastly, the colors produced by garancine are much brighter than those by madder, the pinks and reds having none of the yellow appearance sometimes to be observed in madder colors, and the chocolate color produced by garancine is far superior to that from madder.

Still, there is one disadvantage in these colors, which is, that they are not so fast as those of madder, tand they cannot withstand the action of boiling soap and water. The quantity of garancine required to dye a piece of cloth varies from one to two pounds and a half, according to the style of pattern to be dyed.

The process of dyeing is nearly the same as with madder, the pieces being put into the dyebecks when the water is heated to about 100°; the temperature is afterwards gradually raised to 170° for an hour and a half, when the bath is boiled for a few minutes. To finish them, it is only necessary to wash them with hot water, or to heat them in a bath of water and bran to 170&drg;, allowing them to remain in until their white parts are perfectly clear.

Altlhough it still remains a disputed question as to the beneficial influence of chalk in dyeing with some kind of madders, the influence of alkalies in the case of garancine is sufficiently marked to prevent any doubts upon the subject, for when it is attempted to dye with alkaline waters, it is impossible to obtain good genuine colors; if, for example, the water contains bicarbonate of lime, it immediately colors those parts which should remain colorless, and the colored parts are inferior. In order to remove the difficulty with the white parts, the cloth has to be subjected to several boilings &c., which tend not only to injure the cloth, but also the colors fixed upon it.

When garancine is well prepared, neutral water is the best to make use of; but when the garancine is acid, a certain amount of chalk must be employed to neutralize the acid. When the water is alkaline, acertain amount of acid can be advantageously made use of. Oxalic acid is the one principally employed, owing to its property of forming with lime an insolube and inert compound. Madder lakes for painting are generally prepapred by first washing the madder, to free it from all soluble substances, and then boiling it with alum; caustic potash or soda is then added with great caution. The coloring matter which combines with the alumina is thus precipitated, which is then carefully washed and dried - this deposit is the ordinary madder lake.

Madder is used to dye drabs, salmons, and many colors. The above relates principally to its employment in the art of Calico Printing.

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