PROPERTIES AND METHODS OF IDENTIFICATION 231 



but the positions of the bands arc not sufficiently characteristic to 

 distinguish the pigment sharply from carotin or xanthophyll. The 

 bands of the alcoholic solution, containing 5 mg. per liter arc given 

 by AVillstattrr and his co-workers as follows: 



Fucojcanlhin in ulrohol ((J,|x) 



6mm. layer in nun. In HIT ,. J u mm. layer 



Kami I isii 469 492-476 498-473 



Bainl II 455-440 467-451 462443 



Knd Absorption 440-. . . 



One of the most characteristic properties of fucoxanthin solutions 

 which can be used as an aid in identification as well as a means of 

 separation of the pigment from other carotinoids is the fact that 70 

 per cent methyl alcohol will quantitatively extract the pigment from 

 its solution in petroleum ether ethyl ether (1:1). This fact has al- 

 ready been pointed out in connection with the isolation of the caroti- 

 noids, and is especially useful in the quantitative estimation of fuco- 

 xanthin as will be shown in the next chapter. 



Fucoxanthin solutions are very much less stable than those of the 

 other carotinoids, particularly in the light. Benzene solutions bleach 

 especially readily. Ether solutions of fucoxanthin give a reaction 

 with HC1 which resembles in many respects the action of mineral 

 acids on alcoholic solutions of xanthophyll (3. When the ether solu- 

 tion of pigment is shaken with 30 per cent HC1 solution the pig- 

 ment bleaches and the acid layer takes on a magnificent blue-violet 

 or sky-blue color. The latter is due to a stable salt containing 4 

 atoms of HC1, which is probably an oxonium compound. Its solu- 

 bility in the aqueous layer is due only to the ether which is dis- 

 solved in the acid solution. On regeneration of the yellow pigment 

 with alkali, the hydrochloride still persists and retains one atom of 

 HC1. Fucoxanthin apparently unites with other substances as well 

 as HC1 for Willstatter and Stoll state that ether solutions dried over 

 CaCl 2 yield a pigment showing 3 to 4 per cent CaO. 



Another especially characteristic property of fucoxanthin is the 

 action of alkalis on its solutions, or rather on the pigment itself when 

 in solution. The pigment apparently has no acid properties but 

 under certain conditions it is attacked by alkali. Metallic sodium, 

 solid Ba(OH) 2 and 50 per cent KOH have no effect upon it. It is 

 dissolved, however, by strong aqueous KOH solutions, and cannot 

 be extracted from this solution by ether. This is also true of con. 



