=Madder Carmine= is not often found in commerce; it consists of the almost pure lakes of alizarin and purpurin. The process by which this valuable pigment is produced is based upon the great stability of the madder colouring matters. The following is the process on the large scale: Good madder, very finely ground, is spread out in small heaps in a room, the temperature of which is about 16° to 18° C.; the heaps are moistened with water and left for several days. The mass ferments and gives off a peculiar smell; in the fermentation not only is the glucoside decomposed, but also many of the other compounds contained in the madder, consequently the mass becomes dark and considerably diminishes in weight. The end of the fermentation process may be recognised by a little practice with tolerable certainty by the disappearance of the peculiar smell; the mass is broken up and transferred to a lead-lined vessel, in which it is mixed with three or four times its weight of ordinary sulphuric acid. The acid is allowed to act for several hours, the plant fibres are almost completely charred, and the mixture becomes black. When the charred residue has settled, the liquid is filtered through pure quartz sand or powdered glass, and mixed with a large quantity of water. The carmine, which is insoluble in water, separates as a red powder; it is then washed and dried. The colour of madder carmine is of such beauty that it can only be compared with that of good cochineal carmine, but it is incomparably more permanent than the latter and may be used in all varieties of painting. CHAPTER LVI. MANJIT (INDIAN MADDER). The roots of the East Indian _Rubia mungista_ contain purpurin and another characteristic colouring matter, manjistin. This material is a rarity in German commerce, but is imported into England from India in tolerable amount and used in dyeing. Manjistin may be extracted by boiling manjit repeatedly with a solution of aluminium sulphate, uniting the liquids and acidifying strongly with hydrochloric acid. In twenty-four hours a red precipitate forms in the liquid; it is dried and treated with boiling carbon disulphide, which extracts purpurin and manjistin and leaves undissolved a dark resin. The residue, after distilling off the carbon bisulphide, gives up purpurin to dilute acetic acid, manjistin remaining undissolved. When the purpurin has been completely extracted, the residue is treated with a little boiling alcohol and repeatedly recrystallised; manjistin is finally obtained in golden yellow crystals of the composition C₁₄H₁₅O₂(OH)₂.CO₂H. When a solution of manjistin in a little alcohol is mixed with water no precipitate occurs; on then adding aluminium hydrate and long boiling an orange red lake is produced. Lead acetate produces a deep orange red lake when used in just sufficient quantity; with excess a fine scarlet lake is obtained.