Chemical Science. 219 



Supposing that this substance might contain a principle analo- 

 gous to that latterly observed by M. Pelletier in logwood, &c. a 

 portion of it was dissolved in strong alcohol, the solution evapo- 

 rated until very concentrated, and then poured into cold water, an 

 agglomerated spongy substance was precipitated, which, after being 

 washed with cold water and filtered, was triturated with water 

 containing -Xf^^th of sulphuric acid, and exhibited traces of chemi- 

 cal action at a temperature of 22° (61°. 6 F.) It then deposited 

 a substance upon the sides of the vessel, and the liquid became 

 yellow and very acid. The sediment, being carefully washed with 

 water, was of a fine red colour, varying according to the state of 

 aggregation ; it had no taste or smell ; was flexible between the 

 fingers, and was quite fluid at 55° (131° F.). This substance, 

 which the author has called Dracine, has some analogy with the 

 vegeto-alkalis, although its affinity for acids is but slight. The sul- 

 phate may be obtained, he says, by adding sulphuric acid diluted 

 with alcohol to an alcoholic solution of dracine^ precipitating the 

 mixture by cold water, and then applying a little heat; the sulphate 

 of dracine collects at the bottom, is to be washed with cold water 

 until the latter no longer reddens litmus paper, and then dissolved 

 in hot water. This solution becomes red by the smallest quantity 

 of alkalis, and may be used as a very sensible test of their presence. 

 Dracine is also a good test for acids, assuming a yellow colour with 

 them. The small quantity of carbonate of lime in filtering paper 

 may be detected by sulphate of dracine, the yellow solution in- 

 stantly becoming red from its action, and thus showing its presence, 

 —Bull. Univ. C. xi. p. 157. 



37. Purification of Madder, hy the Separation of its Yellow 

 Colouring Matter.— 1^\\Q experiments of MM. Kuhlman, Colin, and 

 Robiquet*, have induced M. G. H. de Kurrerto pubHsh the means 

 which he has resorted to for the purification of madder, by the 

 separation of the yellow colouring matter from it; and thus render- 

 ing it more fit to supply the various red, lilac, violet, and brown 

 colours which are required upon wool, silk, cotton and linen. Three 

 tubs or vessels are placed by the side of each other; in summer they 

 may be in the open air under shelter, but in the winter should be 

 placed in an airy cellar where the temperature may be retained at 

 18° or 20° R. (73° to 77° F.). The first is that in which the soaking 

 and fermentation is to be effected : it should be 2 feet 8 inches deep, 

 and 2 feet 6 inches in diameter, for from fifty to fifty-five pounds of 

 madder. The second, or washing vessel, should be 5^^ feet deep, 

 and 3 feet in diameter; it should have three wooden cocks fixed into 

 it, the first 2 feet, the second 3 feet, and the third 4 feet from the 

 bottom. The third tub is for deposition ; its height should be 44 

 feet, and it should have a cock at 1^ foot from the bottom. 



* See page 289 of (he last volume, 



