230 CAROTINOIDS AXD RELATED PIGMENTS 



the crystals show only very slight solubility in petroleum ether. When 

 its petroleum ether or carbon disulfide solutions are analyzed by means 

 of the chromatograph the pigment shows very little adsorption affinity 

 for CaC0 3 , its adsorption zone preceding all the others in a chromnto- 

 graphic analysis of extracts obtained from leaves in which the pig- 

 ment abounds, like the winter foliage of arbor vita? (Thuja orientalis). 

 When carbon disulfide is employed as solvent the rhodoxanthin zone 

 has a characteristic ruby red color. 



Solutions of rhodoxanthin show three absorption bands in a char- 

 acteristic position in the spectrum, being shifted farther towards the 

 red than any of the other carotinoids. The position of the bands, 

 taken from the observations of Monteverde and Lubimenko (1913b), 

 which appear to be the most accurate, are as follows: 



In petroleum In carbon 



ether (M.J.I) disulfide (nn) 



Band I 530-513 575-553 



Band II 495-480 535-515 



Band III 470-455 500 480 



The relation of these bands, when in carbon disulfide, to the bands 

 of the other carotinoids in the same solvent is shown in Figure 1. 



The effect of mineral acids upon the alcoholic solution of rhodoxan- 

 thin has apparently not been determined. 



Fucoxanthin. This carotinoid. which is characteristic of the brown 

 algae, gives well colored solutions in practically all the organic solvents. 

 Although the pure crystals are completely insoluble in petroleum 

 ether, the presence of lipoids makes it possible to obtain colored solu- 

 tions in this solvent also. This is likewise true of methyl alcohol in 

 which the pure crystals are very sparingly soluble. The ether solu- 

 tion of fucoxanthin is orange yellow, the alcoholic solutions have a 

 somewhat rusty, or brownish yellow tinge, and the carbon disulfide 

 solution is deep red. Fucoxanthin is a more intense pigment than 

 either carotin or crystalline xanthophyll. Willstatter and Page (1914) 

 have stated that a comparison of 5 x 10~ 5 molar solutions of the three 

 pigments in ether shows that 50 mm. of fucoxanthin is equal in color 

 to 80 mm. of the carotin and 108 mm. of xanthophyll. 



The effect of adsorbents on petroleum ether and carbon disulfide 

 solutions of fucoxanthin has not been studied, but the very low solu- 

 bility of the pigment in petroleum ether suggests that it would be 

 readily adsorbed from this solvent by CaC0 3 . 



Solutions of fucoxanthin show two well defined absorption bands, 



