Dr. Schunck on Rubian and its Products of Decomposition. 503 



Some emulsine prepared in this manner was placed in a solution 

 of rubian, and well mixed up with it. The mixture was allowed 

 to stand in a warm place for some days. By degrees the liquid 

 became almost colourless, while the emulsine acquired a yellow 

 colour. It was filtered and evaporated, when it left a quantity 

 of emulsine. The yellow mass on the filter was treated with 

 boiling alcohol, which became yellow, while the residue lost almost 

 the whole of its colour. The alcoholic liquid was filtered and 

 spontaneously evaporated, when it left a yellowish-red mass, 

 among which crystals of alizarine were discernible. This mass 

 was treated with cold water, in which a part dissolved with a 

 yellow colour. The liquid after filtration and evaporation left a 

 quantity of unchanged rubian. The part insoluble in water was 

 dissolved again in alcohol, and to the solution was added acetate 

 of alumina, which produced a red precipitate. This precipitate, 

 after filtration and washing with alcohol, was decomposed with 

 muriatic acid, and the yellow flocks left by the acid were dis- 

 solved in alcohol, on the spontaneous evaporation of which there 

 was left a mass of pure alizarine in well-defined yellow crystals. 

 The liquid filtered from the alumina precipitate was evaporated 

 to dryness, and the residue left was treated with water and mu- 

 riatic acid, when a brown mass was obtained, which after filtering 

 and washing was treated with cold alcohol. The alcohol left 

 undissolved a brown powder, consisting probably of verantine, 

 and after filtration and evaporation left a brown resinous sub- 

 stance, easily fusible when thrown into boiling water, and con- 

 sisting doubtless of rubiretine. The quantity of alizarine formed 

 seemed to be much larger in proportion to the rubian employed, 

 and to the quantity of other substances formed, than in the case 

 of the ferment of madder. Nevertheless, I must state, that on 

 repeating the experiment I was unable to attain the same result, 

 the ahzarine being formed in much smaller proportion and giving 

 place to other products of decomposition. 



Lastly, I resolved to examine what efi'ect, if any, would be pro- 

 duced on rubian by some fermentative substance derived like that 

 of madder from a vegetable root. For this purpose I chose the 

 albuminous substance described by Braconnot as existing in the 

 root of the Helianthus tuber osus^. I selected this substance, 

 because it has, like the ferment of madder, the property of 

 causing a solution of sugar to undergo an acetous fermentation. 

 It was prepared in the following manner. The tubers were cut 

 into slices, then pounded in a mortar with a little water until 

 the lumps had disappeared. The mass was then placed on a 

 ^ piece of calico, and the liquor expressed with the hands. The 

 muddy liquid which ran through was then mixed with a con- 

 * Ann, de Chem. et de Phys. xxv. 358. 



