156 Miss Wheldale, On the nature of anthoci/anin. 



From this we see that the pigment insohible in alcohol is an oxi- 

 dation product and a glucoside of the pigment sohible in alcohol. 



Heise^-' obtained a pigment — Heidelbeerf'arbstoff — from the 

 Bilberry which was differentiated into two portions : — 



Colouriug matter (A) Colouring matter (B) 



Insoluble in cold water, soluble in alcohol Soluble in water and alcohol 



CHH14O7 C20H24O12 



The relationship is shown as : — 



C.3„H,,0,, + H,0 = C,H,A- f C„H,A . 



glucoside 



Gautier" also extracted two pigments from the red leaves 



of the Vine — Verfarbungroth der Rebblatter — and termed them 



respectively : — 



a-ampelochi'oic acid |3-ampelochroic acid 



Insoluble in cold water, 



soluble in hot water Soluble in cold water 



Green precipitate with Green precipitate with 



basic lead acetate basic lead acetate 



Dark green with iron salts Dark violet with iron salts 



CioHieOjo C26H24O15 



The results obtained from Ligustrum, Althaea and Vitis seem 

 to point to purple anthocyanin as being sometimes a mixture 

 of a red and bluer portion, the former giving a green-, the latter 

 a blue-iron reaction. The bluer portion is more soluble in water 

 and is generally present in greater quantity; this may explain 

 the iron-blueing reaction of some purple forms of anthocyanin. 



The analyses made by Grafe and by Gautier suggest that 

 the bluer pigment is more highly oxidised, and the change from 

 red to blue anthocyanin may possibly be one of oxidation 

 resembling the change which causes the colourless chromogen 

 to become red. 



The separation of purple pigments into red and bluer con- 

 stituents is most obvious in the anthocyanin of certain allied orders, 

 i.e.Amarantaceae, Nyctaginaceae,Phytolaccaceae, and Portulacaceae. 

 The pigment of these genera differs in its reactions from the usual 

 type of anthocyanin* and is at the same time more readily 

 separable into two portions distinguished by means of their 

 respective solubilities in alcohol. 



Pigment soluble in both 



alcohol and water Basic lead acetate Alkalis Iron salts 



Amaranthus sp yellow precipitate yellow green 



Mirahilis Jalapa orange-yellow precipitate ,, ,, 



BoiigainviUea glabra ... orange ,, green ,, 



Phytolacca decandra orange-red „ yellow ,, 



Portulaca grandifora orange ,, ,, „ 



* Wheldale 20. 



