60s SCIENCE PROGRESS 



lised, yielding glucose, and the non-glucoside pigment which 

 separated from the aqueous acid, also as chloride, in the form of 

 long needles. 



They introduced a reaction whereby it is easy to decide 

 whether the glucoside, the non-glucoside, or a mixture of the 

 two is present in any specimen of anthocyan pigment. This was 

 based upon the fact that the glucosides remain entirely in dilute 

 acid solution (preferably sulphuric acid) when shaken with amyl 

 alcohol, whereas the non-glucoside anthocyans, when similarly 

 treated, pass quantitatively into the alcoholic layer, producing a 

 red solution. Moreover, when shaken with sodium acetate 

 solution, the red amyl alcoholic solution so obtained becomes 

 violet — or red-violet — but the pigment remains in the alcohol ; 

 when shaken with sodium carbonate solution, it turns blue, or 

 blue-green, and the colour descends quantitatively to the aqueous 

 layer. 



By means of this reaction they were able to show that in 

 every anthocyan containing flower, leaf, or fruit examined, the 

 anthocyan was present entirely as glucoside. This generalisation, 

 which so completely reversed the views of previous authors, has 

 been further confirmed by Willstatter's later work. To prevent 

 confusion these authors proposed the terms Anthocyanins and 

 Anthocyanidins for the glucoside and non-glucoside pigments 

 respectively, and in agreement with this assigned to the 

 glucoside present in the cornflower the name introduced by 

 Fremy and Cloez, Cyanin, whereas to the sugar-free pigment 

 obtained by hydrolysis of cyanin the name Cyanidin was 

 given. 



By careful oxidation of cyanidin with hydrogen-peroxide, a 

 yellow crystalline product was obtained which, in its reactions, 

 closely resembled the pigments of the flavonol series. 



It is surprising, in view of the fact that the crystalline nature 

 of several of the anthocyan pigments had been established, and 

 that the papers in which they were prepared are even cited by 

 her, that Miss Wheldale {Biochem. Journ. 1914, 8, 204) further 

 published work in which she concluded that the fact that she 

 failed to obtain a crystalline pigment, and that her product had 

 no melting-point, was evidence of the high molecular weights 

 of the anthocyan pigments. By comparison with the case of 

 cyanidin chloride, the melting-point evidence collapses at once, 

 and it appears as though the non-crystalline condition of her 



