A substance very extensively employed in dyeing; it is the root of a trailing plant that grows very abundantly in the south of Europe. It is cultivated in England and Holland also; but the best is said to be that brought from Smyrna and Cyprus. The roots of the plant are carefully peeled, dried in the air, and afterwards in a kiln, in the same way as hops are dried in Kent. They are then chipped and pulverized. The best roots are about the thickness of a goose-quill; semi-transparent, of a reddish colour and strong smell. The red colouring matter of madder is soluble in alcohol, which, on evaporation, leaves a residuum of a deep red. Fixed alkali forms in this solution a violet, the sulphuric acid a fawn coloured, and the sulphate of potash a fine red precipitate. A variety of shades are obtained by the addition of alum, chalk, nitre, sugar of lead, and the muriate of tin.