CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 345 



is added adsorption material only sufficient to destroy the fluorescence, 

 both the carotin and xanthophylls remain in solution," and can be 

 separated by means of a differentiation between the petroleum ether 

 and eighty per cent alcohol, or, "By treating the solution with more 

 adsorption material, after pouring it away from the first, and the 

 xanthophylls then freed from combination with the adsorption material 

 by means of alcoholic petroleum ether/' In addition to the above, 

 Tswett made the interesting discovery that the pigments which are 

 adsorbed by the various materials suggested, can to a certain extent 

 displace one another in the adsorbing material. As an example one 

 finds that, "If a petroleum ether solution of the mixed pigments is 

 filtered through a column of adsorption material (such as CaCO 3 

 packed tight in a glass tube) the pigments will be separated from one 

 another from top to bottom in differently colored zones, proportion- 

 ately to their degree of adsorption." This 

 separation will be complete if a stream of 

 pure solvent is put through the column 

 after the pigment has been adsorbed in 

 the upper part of the column. As stated 

 by Tswett, "Like the rays of light in the 

 spectrum, so the different components of 

 a pigment mixture are actually separated 

 in the CaCO 3 column, and may thus be 

 qualitatively estimated." Tswett calls 

 such an experiment a "chromotogramm." 

 He found carbon bisulphide to be one of 

 the most useful solvents for a chromoto- 

 graphic analysis, on account of the bril- 

 liant color which all pigments show in 

 this solvent. 



In describing the technique for the 

 chromotographic analysis, the author 

 mentions the following essential points. 

 A very finely divided material with not 

 too strong adsorption properties should 

 be used for the adsorbator. (CaCO 3 was 

 found to answer these qualifications 

 best.) A glass tube is now prepared 10 to 

 20 m. m. in diameter and 15 to 20 c. m. 

 long, one end of which is drawn out to 



a narrow diameter, at which end the opening is fused in a little to 

 form a base for the deposition of the adsorbing material. A small 



FIGURE I. 



