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Mr. A. E. Everest. 



produced in a manner similar to that propounded by Miss Wheldale, but 

 they part company with that author in regard to the process necessary 

 subsequent to hydrolysis of the glucosides, for they maintain that the 

 oxidation must be preceded by reduction of the non-glucoside flavone or 

 flavonol derivative. 



The result of work already published on the pigment of the cornflower,* 

 and consideration of the work of Keeble, Armstrong, and Jones, have led 

 the author to the conclusions (1) that if the anthocyans are produced from 

 the yellow glucosides, then it must be by some interaction in which the 

 glucosides and not the hydrolysed glucosides take part ; and (2) that all 

 evidence obtained in dealing with the above-mentioned pigments tends 

 to show that the anthocyan pigments would prove to be, not oxidation, 

 but reduction products of the yellow glucosides. 



That luteolin and morin give red pigments on reduction in acid alcoholic 

 solution by means of sodium amalgam has been known for many years.f 

 Quite recently Watson]: has obtained a red pigment from quercetin by the 

 same means, and, lastly, since the present work was completed, the author's 

 attention has been drawn to a paper by E. Combes,§ who describes the 

 production by the same means from the yellow pigment of the green leaves 

 of Ampclopsis hederacea of a pigment which he shows to be identical with 

 the red pigment (anthocyan) which he obtained from the red leaves of the 

 same plant. He does not, however, give definite information whether his 

 pigments are anthocyanins or anthocyanidins. The author is able to confirm 

 the production of anthocyan pigments by reduction of flavone or flavonol 

 derivatives, and to explain the observations of Keeble, Armstrong, and Jones. 

 Being one of the most commonly occurring of the flavonol class, and readily 

 obtained, quercitrin (Kahlbaum) was taken for the starting point. 



Quercitrin by reduction with zinc (fine granulated) and dilute acids (2NHC1) 

 or by electrolytic reduction, even cold, gave only anthocyanidin. 



The pigment production took place equally well when the aqueous acid 

 was covered with a layer of ligroin, so precluding all possibility of oxidation 

 by the air following reduction. As, however, no anthocyanin could be 

 obtained from quercitrin (this is a monoglucoside from bark, not a flower 

 pigment, at least some flowers are known to contain a diglucoside of 

 quercitrin, e.g., viola contains viola quercitrin) — a result which at first 

 appeared to support Miss Wheldale's hydrolysis hypothesis — the author 



* Willstatter and Everest, loc. cit. 



t Cf. Eupe, ' Die Chemie der natiirlichen Farbstoffe,' vol. 1, pp. 77 and 85. 

 X ' Chem. Soc. Proc.,' 1913, p. 349. 



§ 'Compt. Eend.,' vol. 157, p. 1002 (1913) ; 'Chem. Zentr.,' 1914, p. 158. 



