40 CAROTINOIDS AND RELATED PIGMENTS 



it from a spcetroscopic standpoint. Besides chrysophyll, the only 

 member of the "xanthophylls" which he was able to obtain in crystal- 

 line form, Schunck separated two other xanthophylls from green leaves 

 by shaking the alcoholic chlorophyll-free 1 solution with successive 

 equal portions of carbon disulfide, each volume of carbon disulfide 

 being equal to about one-lialf the volume of the crude solution experi- 

 mented upon. This was continued until no more color was extracted, 

 three or four extractions being sufficient as a rule to accomplish this 

 result. 



With the exception of the first carbon disulfide extract, which con- 

 tained the crystallizable chrysophyll as well as one of the xantho- 

 phylls, Schunck erroneously believed that the various carbon disul- 

 fide fractions represented more or less pure solutions of individual 

 xanthophylls with varying degrees of relative solubility in alcohol and 

 carbon disulfide. 



The various carbon disulfide fractions were now allowed to evapo- 

 rate spontaneously, the residue was taken up again in alcohol and 

 the spectroscopic alt-orption bands photographed. The effect on these 

 bands of adding rmuviitrated HC1, HNO :! , H 2 S0 4 , H 2 2 and nascent 

 hydrogen was studied, as well as the effect of these reagents on the 

 color of the alcoholic solution. Certain marked differences were 

 observed with the various fractions. 



The first fraction from green leaves contained, besides ehrysophyll, 

 a pigment which Schunck called L. xanthophyll, whose spectroscopic 

 absorption bands differed from those of chrysophyll by being shifted 

 only slightly towards the ultra-violet and whose solution, like chryso- 

 phyll, changed to a green tint before fading on addition of HC1 or 

 HN0 3 , the absorption bands disappearing. 



The subsequent rarbon disulfide extracts contained a second xan- 

 thophyll, called B. xanthophyll, which differed from the first in two 

 respects, (1) the absorption bands (Schunck observed three distinct 

 bands for all his "xanthophylls") were shifted slightly more towards 

 the ultra-violet, (2) the effect of acids on the alcoholic solution was 

 to produce a brilliant green color which gradually changed to a beau- 

 tiful peacock blue, then purple, and gradually bleached entirely. 

 Especially striking was the observation that the addition of ammonia 



1 This was obtained by one of two methods, either by adsorbing the chlorophyll on 

 animal charcoal, which does not remove the "xanthophylls," according to Schunck, or 

 by saponifying the alcoholic leaf extract and extracting the soap with ether, the latter 

 taking out the yellow pigments. After evaporation of the ether the pigments were taken 

 up in alcohol for the "xanthophyll" separations. 



