Madder is cultivated in many countries. The roots, which vary from the thickness of a quill to that of a finger, are cleansed from adherent earth, carefully sorted according to size, and dried. In commerce a distinction is made between stripped and unstripped madder. The cortex of the root contains but little colouring matter and is generally removed by mill-stones moving at some distance apart. The stripped roots are finely ground, and are then known commercially as madder. Merchants distinguish a large number of varieties, which are designated according to the place of production. In addition to ground madder there are a number of madder preparations which contain the colouring matter in concentrated form, and are consequently used in smaller quantity. The most important of these preparations are garancin, garanceux, and the madder extracts. ”Refined madder” is made from the natural substance by subjecting it to a process of fermentation, by which the substances accompanying the colouring matters are largely decomposed, and the product becomes relatively richer in colouring matter. ”Flowers of madder,” which have double the colouring power of madder, are made by treatment with very dilute sulphuric acid. Madder is stirred with five or six times its quantity of water to which about 1 per cent. of sulphuric acid has been added. After leaving the mixture in a fairly warm place for five to six days alcoholic fermentation takes place, and many substances which would be injurious in dyeing are decomposed. The residue becomes in consequence richer in colouring matter. When the fermentation is finished the residue is filtered off, subjected to powerful hydraulic pressure, and the mass broken up and very thoroughly dried at a temperature of 60° to 70° C. If it is not thoroughly dried it soon becomes mouldy. This method of treating madder, due to Julians, is simple, and has the advantage that from the alcoholic liquid spirit may be obtained. In some respects this process is more rational than the one immediately following: certain substances which are destroyed in the manufacture of garancin are made useful, and also the process requires little outlay. =Garancin= is obtained from madder by treatment with sulphuric acid, which decomposes the glucoside, and also sets free the colouring matter united to lime and magnesia, which would otherwise be lost. In addition, the warm acid radically attacks the nitrogenous compounds, the greater portion of which is destroyed. Thus the residue contains relatively more colouring matter, and the removal of substances which accompany the colouring matter considerably facilitates the dyeing process.