XANTHOFHYLL 



243 



stances erythrophyll and chrysophyll described by Bougarel 

 and Schunck respectively. 



It absorbs 34 3 per cent of its weight of oxygen, being 

 converted into a colourless substance. With iodine it forms 

 the compound C^f^Hr^^h, which crystallizes in dark violet 

 prisms. 



XANTHOPHYLL C4oH5g02. 



This substance is closely related to carotin, having the 

 molecular formula C4oH5u02. Ewart * has, indeed, shown that 

 xanthophyll may be converted into carotin by the action of 

 zinc dust or magnesium powder and water. 



It is a neutral substance, reacting neither as an alcohol nor 

 as an acid. 



It absorbs 36'5 5 per cent of its weight of oxygen, and 

 forms an additive compound with iodine of the formula 

 C4oH5,;02l2, which crystallizes in dark violet tufts. 



The more important physical constants and solubilities of 

 carotin and xanthophyll are given in the appended table, 

 compiled b)^ Willstatter : — 



Carotin. Xanthophyll. 



. Copper coloured leaflets. Pleochroic dark reddish- 



Appearance 



Colour by transmitted 

 light .... 



Melting-point . 



Solubility in light pe- 

 troleum 



Solubility in alcohol 



Solubility in acetone 

 Solubility in carbon di 

 sulphide 



Red. 



167-5-168°. 



brown plates. 



Yellow to orange. 

 172°. 



Appreciably soluble. Insoluble. 



Practically insoluble in Sparingly soluble in cold ; 



cold; very sparingly fairly readily soluble in 



soluble in hot. hot. 



Very sparingly soluble. Readily soluble. 



Very readily soluble. 



Sparingly soluble. 



FUCOXANTHIN C,nH„0« 



This substance was first isolated from fresh brown algs by 

 Willstatter and Page.f It is more difficult to extract this 

 substance from dried alga;. Fucoxanthin is a brownish-red 

 substance, which crystallizes from methyl alcohol or light 

 petroleum, and melts at I59'5 to i6o"5". It absorbs iodine 



• Ewart: " Proc. Roy. Soc," 1915 [B], 89, i. 

 t Willstatter and Page: " Annalen," 1914, 404, 237. 

 16* 



