CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 351 



were all plainly visible, this solution showed three distinct absorption 

 bands. (See Table 3.) 



The carbon bisulphide solution was evaporated to dryness at the 

 lowest possible temperature, the residue taken up in 50 c. c. of hot 

 ninety-five per cent alcohol and hot one per cent digitonin in ninety 

 per cent alcohol added until no more precipitate came down. The 

 digitonin-cholesteride was filtered off, the filtrate evaporated to dry- 

 ness, and the residue dissolved once more in carbon bisulphide. The 

 solution still showed the three bands. On evaporation it left a golden 

 yellow oil which solidified on cooling to a reddish yellow salve. Con- 

 centrated H 2 SO 4 added to the residue gave a blue green color which 

 slowly changed to a purple color. 



The alcoholic solution. This was evaporated to dryness. When 

 very concentrated it showed a little color, and the carbon bisulphide 

 solution of the residue had a light orange color when it had a volume 

 of i % c. c. When viewed in a 25 m. m. cell this solution showed 

 three absorption bands. (See Table 3.) 



TABLE 3. ABSORPTION BANDS OF BUTTERFAT PIGMENTS. 



The striking results of this experiment were the remarkable 

 similarity of the solubility and spectroscopic properties of the main 

 butter fat pigment to carotin, and the indications of a secondary minor 

 constituent of the butter fat pigment, whose solubility and spectro- 

 scopic properties were strikingly similar to xanthophyll. 



It at once became evident that should these observations be con- 

 firmed, it would be not only profitable, but essential to ascertain 

 whether the presence of secondary xanthophyll-like pigments is nor- 

 mal to butter fat under other conditions of coloration, such as in 

 light colored butter fat, colostrum butter fat and other conditions. 



That the presence of a secondary pigment in the fat under inves- 

 tigation was confirmed and its character more clearly identified is 

 shown by the following experiment. 



