v] CONSTITUTION OF ANTHOCYANINS 77 



105 C. The formula is then found to be C 15 H n 6 Cl from the following 

 analyses : 



C H Cl 



From cyanidin chloride ... (i) 5540% 3-62% 10-75% 



(ii) 55-77% 3-60% 

 Calculated for C 15 H U 6 C1 55-81% 3-41% 11-01% 



Flower-pigment of Rosa gallica. 

 This pigment is found to be a diglucoside of cyanidin. 



Pigment from fruit of Cranberry. 



This pigment idaem is found to be a galactoside of cyanidin, 

 formed from one molecule of cyanidin and one molecule of galactose. 



Calculated for C 31 H 21 O n Cl Found 



Galactose 37-2 ... 33-4 



Cyanidin chloride ... ... ... 66-6 ... 67-5 



Pigment (Oenin) from grapes. 



The method employed for preparation was as follows. The skins 

 of dark blue grapes are extracted in the cold with glacial acetic, and 

 the dark red nitrate precipitated with ether. A sticky precipitate is 

 obtained which, after washing with ether, is put into an excess of water 

 picric acid solution, and warmed for a short time. On cooling, the 

 picrate crystallises out from the solution in long prisms of a fine red 

 colour. By changing the solution to methyl-alcohol-hydrochloric acid, 

 it yields the solution of the pigment chloride, which is precipitated with 

 ether-petrol-ether and crystallised from water-alcohol-hydrochloric acid, 

 in the form of hard beetle-green prisms. On hydrolysis, oenin decom- 

 poses into oenidin C 17 H 14 7 and one molecule of glucose. 



Pigment (Myrtilliri) from the Bilberry (Vaccinium Myrtillus). 



The skins of the berries are used after being dried and ground. 

 The pigment is extracted rapidly by warming with ethyl alcohol, which 

 contains a small percentage of hydrochloric acid, and the solution is 

 precipitated with ether. The precipitate, mixed with a large quantity 

 of a colourless product, is separated, by taking up in water, from many 

 of its impurities. By addition, with cooling, of a double weight of 

 concentrated hydrochloric acid, the chloride is precipitated almost 

 pure, and quite pure by repetition of the operation. For crystallisation, 

 a third of its volume of 9 % hydrochloric acid is added to the solution 



