-lo- 

 in 1872 the partition of leaf pigments between benzene hydrocarbons 

 and aqueous alcohol was reported independently by Kraus and by Konrad, 

 And in 1873 Sorby re-examined the chloroplast pigments by partition be- 

 tween alcohol and carbon disulfide and found a series of yellow xantho- 

 phylls in addition to the chlorophylls. He regarded the separation of 

 the chloroplast pigments by partition and their description by spectro- 

 scopic studies as different from the usual analytical investigations. 

 He, therefore, proposed a new name for these studies of the pigments; 

 namely, comparative vegetable chromatology ■' . 



By 1877 Sachsse utilized aqueous alcohol end petroleim ether for 

 the separation of the chloroplast pigments. And in I9I5 WillstStter 

 and Stoll summarized the large scale partition and crystallization pro- 

 cedures that they had employed for the preparation of solid chlorophyll 

 a and b, crystalline carotene and crystalline xanthophyll ' ' . 



Efficient as the partition procedure proved to be, it failed to 

 separate the carotenes from the chlorophyll a^. It also failed to sepa- 

 rate the carotenes from one another. It required repeated application 

 to effect a partial separation of the xanthophylls from one another. 

 Unless special care was exercised some of the xanthophylls were lost in 

 the aqueous layers that were discarded . 



Separations by Ch emical Reactions Plus Partition between Immiscible 

 Solvents 



Chemical alteration of the green pigments followed by partition 

 of the alteration products between immiscible solvents has long facili- 



7 R TO 



tated the separation and isolation of the carotenes and xanthophylls'' * . 

 In I860, four years before Stokes' partial separation of the chloroplast 



