The Production of Anthocyanins and Anthocyanidins. 257 



to air to blue, violet, then orange yellow;* moreover, in the presence of 

 other yellow sap-pigments, a green colour passing to a brown-yellow is 

 observed when myricetin is present. In this way its presence, together with 

 quercetin, is shown in the colouring matter obtained from Thuja occidentalis. 

 The known glucoside of myricetin, on the other hand, gives only a yellow 

 coloration with dilute alkalis. 



Now whilst the identity of quercetin, or any similar sap-pigment of the 

 flavonol group, would have to be established by isolation and characterisa- 

 tion, pending time for further investigation, the presence of myricetin 

 would be almost conclusively proved if the above-mentioned characteristic 

 'colour changes could be observed under proper conditions. 



From the observations made in the course of the present investigations, 

 and described below, there can now be no doubt that, unless gossypetin is 

 present, which is unlikely, there is present in the Viola " Black Knight " 

 (Sutton's), a glucoside of myricetin side by side with a glucoside of 

 delphinidin. 



Thus the presence in one flower of an anthocyan pigment and of the 

 flavonol derivatives from which it would be produced by reduction, is shown 

 for the first time. 



Experimental. 



Isolation of the Anthocyan Pigntent of the Purple-Black Viola. 



The dry powdered petals of Sutton's " Black Knight " (25 grm.) were 

 extracted with alcoholic hydrochloric acid (200 c.c. of a mixture made up in 

 the proportion 95 c.c. of 96-per-cent. EtOH ; 5 c.c. of 2N aqueous HOI ; and 

 1 c.c. cone. aq. HCl), and after standing some hours the extract filtered off 

 and the residue further extracted with the same solvent. (As stated by 

 Willstatter and Weil, MeOH may, with advantage, replace EtOH.) The 

 combined filtrates were mixed — good agitation — with 2-2|- times their 

 volume of ether, whereby most of the anthocyan pigment was precipitated 

 as a sticky mass from which the liquors were readily decanted ; the liquors 

 were then filtered and worked up for the yellow pigment which they 

 contained. 



Prior to the publication of Willstatter and Weil's paper on the blue-black 

 Pansy {loc. cit.), the crude anthocyan pigment — after one reprecipitation 

 from alcoholic hydrochloric acid by means of ether — was fractionally pre- 

 cipitated from the same solvent by ether, then finally crystallised by 

 solution in acidified alcohol, addition of aqueous acid (HCl) to the solution, 

 and slow evaporation of the alcohol, as described by Willstatter and Everest, 



* A. G. Perkins, ' Journ. Cheni. Soc.,' 1899, p. 1289. 



