420 Dr. Schunck on Rubian and its Products of Decomposition, 



spots, consisting of long hair-like crystals, are sometimes dis- 

 cernible. If, after twenty-four hours, the jelly on being mixed 

 with cold water still yields to the latter any yellow colour, it is 

 a sign that the rubian is not entirely decomposed, and more 

 ferment must be added, the mixture being again allowed to stand 

 until the liquid has become tasteless and colourless. During 

 this process none of the usual signs of fermentation are mani- 

 fested. The liquid remains perfectly neutral, and no gas of any 

 kind is disengaged. In order however to be perfectly sure of 

 the latter point, I took a solution of rubian in water, mixed it 

 with ferment, poured the mixture into a graduated glass tube, 

 and inverted the latter over mercury. After standing in this 

 way for several days, not a particle of gas had collected at the 

 top of the tube, notwithstanding which the rubian was entirely 

 decomposed, and on examination the products of decomposition 

 were found to be precisely the same as those formed in the usual 

 manner. This experiment proves not only that no gas is evolved 

 during the fermentation of rubian, but also that, as Higgin has 

 observed, the access of atmospheric air is not necessary during 

 the process. 



The decomposition of the rubian being completed, a little water 

 is added to the mass, and the gelatinous substance left undissolved 

 by the water is placed on a filter and slightly washed with cold 

 water. The percolating liquid is almost colourless. The gela- 

 tinous mass on the filter now consists partly of the ferment 

 employed, and partly of substances formed by the decomposition 

 of the rubian. These substances are six in number, of which three 

 are bodies previously described, and three are new. They are, — 

 1st, Alizarine ; 2ndly, Verantine ; 3rdly, Rubiretine ; 4thly, a sub- 

 stance closely resembling rubiacine, which I shall call Rubiafine ; 

 5thly, a substance very similar to rubianine and rubiadine, to 

 which I shall give the name of Rubiagine ; and, 6thly, a peculiar 

 fatty substance w^hich I shall denominate Rubiadipine. These 

 substances are separated in the following manner. The mixture 

 is treated with boiling alcohol. The alcohol, which assumes a 

 dark reddish-yeUow colour, is filtered, and the substance on 

 the filter is treated again with boiling alcohol, until the latter 

 acquires thereby only a light yellow colour. The substance left 

 on the filter consists of the ferment, which has undergone no 

 apparent change either in quantity or properties. To the alco- 

 hohc liquid there is now added acetate of alumina, which pro- 

 duces a dull yellowish-red precipitate. This precipitate, which 

 consists of alizarine, verantine and rubiafine in combination with 

 alumina, is separated by filtration and decomposed with boiling 

 muriatic acid, which leaves undissolved a quantity of orange- 

 coloured flocks. The liquid filtered from the alumina precipitate 



