Madder, a plant (rubia tinctorum), the roots of which are employed as a red dye. It was known and used by the ancients, and a correct description of the plant is given by Dioscorides under the name of ereuthodanon. The plant belongs to the natural order rubiacece, is a native of the south of Europe, and is largely cultivated in France, Asia Minor, and Holland; experiments have been made in cultivating it in some parts of this country, but it has not yet found a place in our agriculture. The roots are perennial, and throw up annual slender, quadrangular, jointed stems, a few feet in length, and furnished with prickles, by which they are held in climbing upon other plants. The leaves are produced in whorls at the joints, at which point the branches are borne in pairs; the flowers are in clusters at the ends of the branches, have a rotate yellow corolla, and are succeeded by a small, globular, two-lobed, juicy berry. The roots, proceeding from a central head, are long succulent fibres. Those esteemed the best for dyers' use are from the size of a goose quill to that of the little finger, and of the second or third year's growth. When stripped of the dark bark which covers them, they appear semi-transparent, are of a reddish color, and possess a bitter taste and a strong peculiar odor.

The plants are propagated by shoots, which are planted in August about a foot apart, and left to grow for two years, being kept free from weeds. They are also raised from seed. When the roots are dug, they are dried in the air and in kilns, threshed with a flail to remove the cuticle, and several times winnowed and sifted with sieves of increasing fineness; the dust and sand which pass through the last sieve are rejected, and the fibrous portions which remain are further cleaned and assorted. The coarsest fibres are esteemed the best. They are again dried in stoves until they break easily when squeezed in the hand; and after this they are cut up by a machine furnished with knives, and then ground between millstones, and the powder is bolted. In commerce the powdered roots only are called madder, the whole roots being known by the name of lizari; the variety called mulle or bilon is of inferior quality, consisting of the fibres and epidermis of the larger roots, earthy impurities, and the refuse from the sieves. The best varieties are those from Bakir and other places in the vicinity of Sinope. At Smyrna, whither most of the Turkish product is brought for shipment, the roots are sorted and packed by means of hydraulic presses into bales of 6 to 7 cwt. each.

The annual product varies with the prices, the growers refusing to dig the roots when the price is low, and when it is high they often take them up when they are only two years old. They should be in the ground three or four years, according to the sort. The European madders are distinguished as Dutch, Alsatian, and of Avignon, or of the Comtat. The qualities are very variable. Many sorts are prepared without removal of the epidermis, and are consequently of darker hue than those denominated "stripped." The powders are improved by being kept from one to three years in the cask; they undergo in this time a process of fermentation, the particles agglomerating and expanding, often with sufficient force to cause the heads of the casks to swell out. The madder becomes so hard that it can be removed only by cutting it out with chisels. - In dyeing, the common reds employed for cottons are prepared from madder, and in calico printing this dye is particularly convenient on account of the variety of tints it affords when used with different mordants.

The composition of madder is exceedingly complicated, from the great number of organic and inorganic substances it contains. (See Alizarine.) - Madder is often adulterated, sometimes with earthy substances, the presence of which is easily detected by the grittiness of the article when chewed; but more frequently with saw dust, as of pine bark, mahogany, logwood, etc, substances that seriously impair its qualities as a dye, and are very difficult of detection and separation. Hence, to judge of the value of samples of madder, it is necessary to submit them to actual trial upon pieces of cloth prepared with different mordants in order to determine their tinctorial power and peculiar hues. - A singular property possessed by madder was first noticed by John Belchier, an English surgeon, in 1736, and subsequently attracted much attention from physiologists, especially Haller and Hunter. He observed that the bones of pork served at table were of a red color, and on investigation traced the cause to the hogs having been fed on bran which had been boiled with printed calicoes in order to brighten their colors. It was afterward ascertained that the color of madder was very rapidly deposited on the external portion of bones of animals that partook of the dye in their food.

No point of ossification in the system escaped its action. Pigeons soon exhibited a red circle round the iris of the eye, where in birds there exists a circle of minute osseous pieces. Flourens in 1839, by a series of experiments upon pigs fed alternately with food mixed with madder and food free from it, was led to very interesting conclusions as to the manner of growth and absorption of bones, the former resulting from external accretion, and the latter taking place on the inner surface, except in the teeth, in which the operations are reversed. The milk of cows that feed upon it is said to be tinged of a reddish color, which is imparted to the butter. But there is little ground for the opinion of Beckmann, that Virgil in his fourth Eclogue referred to madder under the name of sandyx, in the line: Sponte sua sandyx pascentes vestiet agnos, there being no authentic case recorded of either wool or hair made red by an introduction of madder in food. - East India madder, known also as mun-jeet, is the roots of rubia munjista, a species found in Bengal, Nepaul, etc.; it has different foliage from the common madder, and its roots are longer and thinner. The root is sent out in the whole state in bundles about 2 ft. long and the thickness of one's wrist.

Its uses are the same as the common madder, but it is but little employed; the annual supply received in England from all sources is less than 100 tons.