258

DYEING AND CALICO PRINTING.

has it ever served the use of dyeing. All that has ever been done with thecomparatively small quantity made has been its extraction, either with alcoholor a boiling solution of alum, to prepare what has been called the colorin ofMessrs. Lagier and Thomas. M. Henri Schliimberger has, however, trieddyeing with this chcirbon sulfurique , and found that it gave the red, violet, andblack tints perfectly well, while the white portions of the tissue were almostunsoiled. No action ensued until the boiling-point of the liquid in the dye-beck was nearly reached.

In 1828, Lagier, Robiquet, and Colin took out a patent, from the text ofwhich it is quite clear that they intended to produce from madder a moreeasily manageable suustance by means of sulphuric acid. They proposed(and actually carried out) a preliminary washing of the madder with water,in order to remove from it all soluble matter. In consequence, the quantityof sulphuric acid was decreased, since, by the previous washing out of aportion of the sugar, that substance no longer neutralised the effeCt of theacid, although the addition of the concentrated acid to a thoroughly moistmass would, of course, cause its dilution to some extent. More water wasadded to the acid previous to its addition to the washed and moist madder,which immediately after was heated, by means of steam, to ioo°. This is,briefly related, the original method of making garancin. This substance hasonly very gradually come into use.

At present garancin is made as follows :—Madder is mixed with fromeight to ten times its weight of water, acidulated with sulphuric or hydro-chloric acid; from 1 to 2 kilos, of acid for every 100 kilos, of powdered madderbeing a sufficient quantity. As regards the acids, it is essential that the sul-phuric acid should be, as far as possible, free from nitric acid or nitrouscompounds, and should not contain metallic substances in solution. Thehydrochloric acid ought not to contain any free chlorine, and should be alsofree from metallic compounds. These particulars are too often overlooked,yet experience, especially in Holland, has proved that the goodness of theacids influences the goodness of the garancin produced. This washingprocess is executed in large wooden tanks, fitted with a stout flannel lining,resting upon a false or perforated bottom, as already described for the prepa-ration of fleur de garance.

In the case of garancin the madder is left steeping in the acidulated waterfor about seven to twelve hours, after which the liquid is run off. This fluidalso serves for the manufacture of alcohol. The mass in the tank is trans-ferred to another wooden tank, and sufficient water is added to make a thinpaste of the whole, to which there is then added—for every 100 kilos, of madderoriginally taken—30 kilos, of strong sulphuric acid or 40 kilos, of stronghydrochloric acid. After this mixture has been well stirred up the cover ofthe tank is closed, and, by means of a lead pipe, steam is introduced into themagma, which is kept boiling for three or four hours. When ebullition hasbeen kept up for that time, the contents of the tank—while yet hot—arebrought over into a very large tank, lined with flannel and provided with aperforated false bottom, This tank is partly filled with cold water, the purerthe better, the water having a decided influence upon the goodness of the-resulting garancin. After all the material is transferred from the boiling tankinto the filtering basin, the water contained is run off and fresh water added,