APPENDIX 



Since the previous chapters were written, further work has been 

 published by Willstatter, Bolton, Mallison, Martin, Mieg, Nolan, 

 Zechmeister and Zollinger on the anthocyanins. These publications 

 give, in the main, more detailed accounts of the isolation and properties 

 of the pigments already mentioned in Chapter v. The following is 

 a short summary of the additional methods of preparation contained 

 in the later papers. 



The flower-pigment of Rosa gallica (Willstatter & Nolan, 643). 

 This pigment was found to be identical with the cyanin of the Corn- 

 flower. The dried and powdered petals are digested with methyl- 

 alcohol-hydrochloric acid (2-5 %). From the extract the colouring 

 matter is precipitated with ether, and the precipitate contains impure 

 cyanin chloride. After purification, the crystalline product was found 

 on analysis to yield cyanidin and two molecules of dextrose. 



The pigment from the fruits of the Cranberry, Vaccinium Vitis-idaea 

 (Willstatter & Mallison, 638). The skins of the berries are digested with 

 glacial acetic acid for several days, and the extract precipitated with 

 ether. The crude precipitate is again taken up in glacial acetic, and 

 fractionally precipitated with ether; the second fraction is dissolved 

 in water and picric acid added. A precipitate of the picrate of the 

 pigment is formed which is extracted with methyl alcohol, reprecipitated 

 by ether, and finally crystallised from water. Analysis proved the 

 pigment, idaeiin, as previously stated, to be a monogalactoside of 

 cyanidin. The picrate is converted into the chloride by treatment 

 with methyl-alcohol-hydrochloric acid. The difference in the attached 

 sugar molecule, i.e. galactose instead of glucose, causes idaei'n to differ 

 in properties (solubilities and behaviour with alkalies) from cyanin. 



The floiver-pigment of Pelargonium (Willstatter & Bolton, 637). 

 The fresh flowers are digested for several days with alcohol (96 %), 

 and to the extract alcohol-hydrochloric acid (20 %) is added together 

 with ether. The precipitate of pigment is dissolved in boiling methyl- 

 alcohol-hydrochloric acid (2 %), and to the solution hydrochloric acid 



