122 Chemistry of MendeUan Factoi'sfor Floiver-Coloiir 



pigment with sodium amalgam in presence of hydrochloric acid. Hence 

 the anthocyanin is a reduction product of the flavone. 



(3) The anthocyanin can be converted into a yellow pigment, 

 identical with the natural flavone, by means of hydrogen peroxide. 

 Hence the flavone is an oxidation product of the anthocyanin. 



As regards the formation of anthocyanin from the flavone in 

 Ampelopsis, the method of procedure was as follows (Combes, 9) : 



" La solution dans I'alcool a 90° du compos6 jaune brun, acidifiee 

 par I'acide chlorhydrique et soumise a Taction de I'hydrogene naissant 

 fourni par I'amalgame de sodium, prend j^rogressivement une coloration 

 rose violace qui devient de plus en plus foncde. Filtr^e et neutralisee, 

 la liqueur obtenue foumit par evaporation une substance pourpre. 



Ce corps, comme I'anthoeyane naturelle extraite des feuilles rouges, 

 cristallise en aiguilles pourpres gi-oupees en rosettes. Apres deux 

 cristallisations dans I'alcool et trois cristallisations dans I'eau, le pigment 

 artificiel obtenu en partant du compose jaune natural, aussi bien que le 

 pigment anthocyanique naturel, commencent a se decomposer au bloc 

 Maquenne a 165° ; la fusion instantanee a lieu a 212° — 215°, tandis que 

 le compose jaune commence a se decomposer a 182°, et fond instantan^- 

 ment a 226°— 229°." 



The artificial anthoeyaiiiu had, moreover, the same qualitative 

 reactions as the natural anthocyanin, i.e. it turned red on addition 

 of acid and green, becoming brown-yellow, with alkali. It gave a green 

 precifjitate with lead acetate and a green-black coloration with ferric 

 chloride. On addition of sodium bisulphite, the colour of the artificial 

 anthocyanin disappears, but reappears on acidification with sulphuric 

 acid, a reaction which is also characteristic of the natural pigment. 



By the sodium amalgam method. Combes (11) was also able to 

 obtain, in several cases, artificial anthocyanin identical as far as qualita- 

 tive reactions are concerned with the natural product. The materials 

 used were : 



(a) A crystalline yellow-brown j)igm('iit isolated from Privet 

 {Ligustrmn) leaves. The resulting anthocyanin crystallised in needles. 



(h) A yellow-brown crystalline pigment isolated from leaves of a 

 variety of Vine which duos not redden naturally. Crystalline antho- 

 cyanin resulted. 



(c) A crystalline pigment from Narcissus incomparabilis; the 

 resulting pigment had properties of anthocyanin. 



