On rubian and its products of decomposition

After adverting to the obscurity in which the inquiry concerning the state in which the colouring matter of Madder originally exists in this root is involved, the author refers to the change which takes place in the root, especially if in a state of powder, during the lapse of time, and to the little light which has been thrown by chemical investigations on the nature of the process by which the change is effected. He states that it has been suspected by several chemists that there exists originally some substance in madder, which, by the action of fermentation, or oxidation, is decomposed, and gives rise by its decomposition to the various substances endowed either with a red or yellow colour, which have been discovered during the chemical investigations of this root. In his papers on the colouring matter of madder, he has described four substances derived from madder, only one of which is a true colouring matter, but all of them capable under certain circumstances, as for instance in combination with alkalies, of developing red or purple colours of various intensity.