190oJ Group of Yellow Colouring Matters. 169 



of HC1 will confirm their presence, and so sensitive is the reaction that 

 the admixture of very small quantities of B. and Y. with L. can be 

 easily detected. The alcoholic extract, after the carbon-bisulphide 

 separation, besides containing the yellow colouring matters which are 

 soluble in water and absorb the violet and ultra-violet rays will 'also 

 contain some xanthophyll, but the bands of the latter are generally so 

 obscured by the former, that only in cases where there is but little 

 obscuration is an examination possible, but a certain amount of clearing 

 up of the spectrum may be effected by adding water and ether, the 

 xanthophylls being more soluble in ether than these colouring matters. 

 If the fatty waxy deposit which, as mentioned before, forms on cooling 

 from the extracts, and is deeply impregnated with pigment be dissolved 

 in alcohol and examined, it will be found to contain the xanthophyll 

 group only and in cases of mixtures to contain the L. xanthophyll free 

 from the B. and Y. which points to the fact that in the presence of fats 

 the former is less soluble in alcohol than the latter. 



In contradistinction to the B. and Y. the L. xanthophyll is more or 

 less stable, its alcoholic solutions showing but little change even after 

 the lapse of several weeks when kept away from the light, and is in 

 fact, more stable than chrysophyll under the same conditions. Towards 

 acids, H 2 2 and nascent H both appear to behave in a very similar 

 manner though chrysophyll withstands the action of HC1 to a greater 

 extent. This similarity together with the close resemblance of their 

 spectra, the slight shift in the bands being the only difference, 

 indicates but a slight difference in their chemical constitution, and 

 though in none of the flowers experimented with was any chrysophyll 

 obtained, yet under certain conditions it may be that chrysophyll is 

 elaborated from the L. xanthophyll. 



With HC1 no colour reaction is produced in alcoholic solutions of 

 chrysophyll and L. xanthophyll, but with the B. and Y. a striking 

 effect is produced. Taking fairly concentrated solutions and adding a 

 little concentrated HC1, after a short time a deep green coloration is 

 produced which changes to peacock blue, purple and then gradually 

 fades, the solutions becoming colourless in a day or two, the reaction 

 being more rapid in the case of the Y. and the colour effect being 

 slightly more brilliant.. On the addition of ammonia the original 

 yellow colour though less intense is produced, the blue colour 

 reappearing on acidifying and vice versd. Sorby* mentions this 

 reaction in connection with his " Yellow Xanthophyll," and is, I believe, 

 the first to have noticed it. If the blue solutions be examined spectro- 

 scopically, but a faint indication of bands is discernible, but after the 

 addition of alkali the spectra produced by the action of acid upon the 

 B. and Y. xanthophylls are exhibited, so that it appears the action of 

 -acid first produces these two yellow colouring matters from the B. and 



* Loc. dt. 



