4 Perkin, CJiemical Researches of Edward ScJiimck. 



tained in the madder root as such, but was present in 

 combination with sugar or some similar substance. 

 Schunck, in 1847, carefully investigated this matter, and 

 was successful in isolating a bitter substance which he 

 called riibian, and he showed that this substance, on 

 boiling with dilute sulphuric acid, is decomposed with 

 formation of alizarin and a sugar, and he was thus able 

 to confirm Zenneck's suggestion. 



A few years later (in 185 1) Rochleder succeeded in 

 obtaining this glucoside in a crystalline condition, and he 

 then named it ruberythriuic acid. Gra^be and Lieber- 

 mann were the first to show that this crystalline 

 ruberythrinic acid, when hydroly.-ed by boiling with 

 dilute hydrochloric acid, yields, besides alizarin, glucose 

 as the sugary constituent, and they represent the decom- 

 position as taking place according to the equation 



CaeHj^Ou + 2H2O = CuHsOi + 2C6H12O6. 

 In 1876 Schunck discovered that, when anthraquinone 

 disulphonic acid is fused with soda, a new dihydroxy- 

 anthraquinone was formed, which he named anthraflavic 

 acid. He subsequently isolated this same substance from 

 the bye-products which had accumulated in the manu- 

 facture of artificial alizarin, and by fusing anthraflavic 

 acid with potash he obtained a new and very interesting 

 trihydroxyanthraquinone which he cdWed Jlavopurpurin. 



Schunck submitted both anthraflavic acid and flavo- 

 purpurin to an exhaustive examination, and converted 

 them into a number of beautifully crystalline derivatives, 

 all of which he obtained in a state of great purity. 



In the year 1876 Schunck associated himself with 

 Roemer, and together they published an important series of 

 papers on some of the di- and tri-hydroxyanthraquinones. 

 They worked out a method for preparing pure purpurin or 



