The Production of Anthocyanins and Anthocyanidins. 331 



in the aqueous acid layer, provided that sufficient ether is added. The 

 ethereal layer contains much of the unchanged flavonol derivatives and these 

 may be more completely removed from the aqueous acid solution by repeated 

 extraction with ether. 



In the preparation of extracts from flowers, dried and powdered petals are 

 more convenient to use than fresh flowers. 



With the red pigments — all of which were shown by the amyl-alcohol 

 reaction to be glucosides — obtained by reduction from extracts of the 

 following flowers, viz. : daffodil, primrose, viola (yellow) and wallflower 

 (lemon-yellow), the following experiments were carried out, viz. ■ — 



(1) The stability of the pigments in aqueous or alcoholic acid solutions was 

 examined. In every case they were stable, no decolorisation was observed, 

 even after standing for many days. 



(2) An acid (HC1) solution (aqueous or alcoholic) of the pigment was 

 separated into two portions : (a) kept for comparison ; (b) shaken with excess 

 of powdered calcium carbonate, whereby all excess of acid was removed, 

 colour passed from red to violet, solution then became decolorised — all traces 

 of red or violet disappeared, solution being a faint brownish yellow. The red 

 colour was restored quantitatively on acidification by 2-3 drops of concentrated 

 HC1 (concentrated used to prevent unnecessary dilution) whether the 

 acidification took place immediately after decolorisation or after allowing the 

 decolorised solution to stand over ] ight. 



(3) The absorption spectra were examined, with results already mentioned. 

 Thanks to the generosity of Prof. A. G-. Perkin, F.K.S., in placing at his 



disposal a quantity of crude rutin — a pigment consisting of quercetin 

 combined with a disaccharose residue, and identical with viola-quercitrin* — 

 the author was enabled to carry out similar experiments using the pigment 

 derived by reduction from this flavonol disaccharide of known constitution. 

 The red pigment remained almost quantitatively in aqueous sulphuric acid 

 (about 2N) when shaken with amyl alcohol, only traces passing into the 

 alcohol. When hydrolysed by boiling with hydrochloric acid (about 20 per 

 cent.) it yielded a sparingly soluble non-glucoside, which, when shaken in 

 dilate sulphuric acid solution with amyl alcohol, passed quantitatively into 

 the alcoholic layer, yielding a fine red solution. On shaking the solution 

 with sodium acetate, the colour changed to violet, remaining, however, in the 

 alcoholic layer. On shaking with sodium carbonate solution it became blue- 

 green and passed quantitatively to the aqueous layer. 



The series of observations (1, 2, and 3) as above was repeated with the 

 pigment obtained from rutin, and in every way similar results obtained. 

 * Of. A. G. Perkin, ' Chem. Soc. Journ.,' 1910, p. 1776. 



VOL. LXXXV1II. — B. 2 B 



