Although the preparation of garancin was recommended in 1828, it was much later before the prejudice which prevented its general employment was completely overcome, and garancin recognised as a very valuable material for the dyer. The simplest process for preparing garancin is as follows: Madder is several times washed with water, then pressed, and the residue mixed with dilute sulphuric acid in a lead-lined vessel. To 100 parts of madder 50 parts of sulphuric acid and 50 parts of water are taken, the mixture is heated by steam to 100° C., and maintained at this temperature for half an hour. By the action of sulphuric acid of this strength considerable charring occurs, and in particular the cell walls of the madder are attacked, so that in the succeeding process the colouring matter is readily dissolved; in consequence of the charring, the garancin acquires a deep brown to black colour. When the action of the acid is finished, it is drawn off and the residue washed with water until it is free from acid, when it is dried. The process here described is the original method; it has been much modified, hydrochloric acid, zinc chloride, alkalis, soap solution, etc., being used in the manufacture of garancin. The colour maker will rarely require to make garancin himself, so that it is sufficient for our purpose to indicate what is understood by garancin, and in what manner it is made. =Garanceux.=—Madder which has been once used in dyeing still retains some quantity of colouring matter; this is utilised by treating it by the same process which is used to obtain garancin from fresh madder. The treatment with sulphuric acid almost entirely destroys the cellular structure, so that the residual colouring matter is made accessible to solvents, and consequently the garanceux may be again used for dyeing.