610 • Dr. Schunck on Rubian and its Products of Decomposition 



rine alone, and that consequently all substances derived from 

 madder, if endowed with any such power, owe it to their con- 

 taining alizarine; and after having isolated and examined the 

 primitive substance, from which all the bodies in madder endowed 

 with a red or yellow colour, or capable of producing these colours, 

 are derived, and after having exposed this substance to the in- 

 fluence of all the reagents with which madder itself under ordi- 

 nary circumstances is brought into contact, I find myself entirely 

 confirmed in my opinion. I should indeed think it unnecessary 

 to add anything confirmatory of the conclusions which must 

 suggest themselves at once from the perusal of the preceding 

 pages, but as Messrs. Wolff" and Strecker have made it one of 

 the special objects of their investigation to prove the exist- 

 ence of more than one colouring matter in madder, I think it 

 may not be out of place here to add a few remarks to show 

 how, in my opinion, these chemists, as well as their predeces- 

 sors, have been misled, and also to give an account of some 

 experiments still further confirmatory of the opinion which I 

 have always held. 



The second colouring matter, which, according to the chemists 

 just mentioned, exists in madder in addition to alizarine, and 

 which has received at various times the names of purpurine, 

 madder-purple, and oxylizaric acid, possesses, according to those 

 observers, the property of being easily soluble with a red colour 

 in boiling alum liquor. Wolff" and Strecker assert that this sub- 

 stance is peculiarly a product of fermentation, and in order to 

 prepare it, they mix madder with water and yeast, allow the 

 mixture to stand in a warm place until the effervescence pro- 

 duced by fermentation has ceased, and the liquid has acquired a 

 strong acid reaction and contains alcohol, after which they strain 

 the liquid through a cloth, wash the mass on the cloth with 

 water, and then treat it with boiling alum liquor. From the bright 

 red solution a substance separates on cooling in red flocks, which, 

 as well as the orange-coloured flocks produced by adding sul- 

 phuric acid to the liquid, consist, according to them, entirely of 

 purpurine without any trace of alizarine. They purify it by cry- 

 stallization from alcohol. Now I have shown above that the 

 fermentation of madder, which is in fact synonymous with the fer- 

 mentation of rubian, is due to the action of a peculiar substance, 

 which I have called erythrozym, on rubian ; that the action of 

 this substance is very rapid ; that it is not accompanied by any 

 disengagement of gas; that it is terminated long before any 

 effervescence or any acid reaction of the liquid begins to appear ; 

 that the products of the action do not diff'er essentially from 

 those due to the action of acids and alkalies ; that the formation 

 of alizarine in about the same proportion as when acids or alka- 



