11 



pigments by partition alone, Frfemy had observed that strong hydrochloric 

 acid and ether acting upon the residue from an alcohol extract of leaves 

 yielded a yellow ether solution and a blue acid solution of the altered 

 green pigments. This partition procedure with chemical reaction was 

 soon modified through use of alkalies as the reagents for alteration of 

 the chlorophyll „ By saponification of the chlorophylls with caustic 

 alkalies and partition of the products between diethyl ether and aqueous 

 alcohol, the yellow carotenoids could be transferred to the ether while 

 the green saponified chlorophyll remained in the aqueous layer„ In an- 

 other modification, the green pigments were saponfied in alcohol, the 

 xanthophylls and carotenes were transferred to petroleum ether, and then 

 the xanthophylls were separated from the carotenes by extraction from 

 the petroleum ether with aqueous methanolc Numerous modifications of 

 these saponification plus partition methods have been adapted to the 

 preparation and estimation of the xanthophyll mixture and the carotene 

 mixture in extracts of leaves7>8,9, 10,11^ g^^ with some of the algae, 

 as the brown algae, the principal xanthophylls are also decomposed by 

 alkalies along with the chlorophylls j hence saponification followed by 

 partition is not a universally applicable procedvire for the isolation 

 of carotenes and xanthophylls^o 



Separations by Batchwise Selective Absorption 



Selective absorption of chlorophylls from extracts of leaves per- 

 mitted the separation of the green pigments from the carotenoids^ o 

 Stokes observed in 186i4. that the addition of sorptive alximinum hydrox- 

 ide to leaf extracts removed the green pigments and left the yellow 

 oneso In the next year Frftmy observed that both magnesium hydroxide 



