CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 419 



KOH. After dilution with water, the soap was extracted with ether. 

 The ether was washed, filtered and evaporated into absolute alcohol. 

 The alcohol was diluted to an 80 per cent solution and extracted with 

 petroleum ether (b.p.3O-5oC.) until no more color was extracted. The 

 alcohol layer was left with quite a little color, but by far the greatest 

 part of the color was in the petroleum ether extracts. The petroleum 

 ether soluble pigment gave a deep red carbon bisulphide solution which 

 showed 3 absorption bands, the third being faint. The measurements 

 of the band are given in Table No. 2. 



The 80 per cent alcohol soluble pigment showed no clear absorp- 

 tion bands. 



Experiment III. 



Fifty cubic centimeters of the same serum was mixed to a thick 

 paste with plaster of Paris, and the pasty mass shaken thoroughly 

 with 700 c.c. of hot 95 per cent alcohol. All the color was extracted, 

 a second extraction with fresh alcohol being colorless. The yellow 

 extract was concentrated to 100 c.c. An equal volume of 10 per cent 

 alcoholic potash was added and the solution boiled on the steam bath 

 for one hour. No aldehyde resin pigments formed. The alkaline 

 solution was diluted with 3 volumes of distilled water and extracted 

 with two-thirds of its volume of ether. All the color was extracted 

 by the one extraction. After washing and filtering, the golden-yellow 

 extract was evaporated to dryness and the residue taken up at once 

 with petroleum ether (b.p.3O-5oC.) This solution was now thor- 

 oughly shaken with 80 per cent alcohol until no more color was ex- 

 tracted. Fresh petroleum ether extracted a little color from the alco- 

 holic extract, which was not re-extracted by fresh 80 per cent alcohol. 

 The blood serum lutein was now divided into a major and minor 

 pigment, the major being insoluble in 80 per cent alcohol in the pres- 

 ence of petroleum ether and the minor being insoluble in petroleum 

 ether in the presence of 80 per cent alcohol. 



The petroleum ether soluble pigment had a blood-red color in CS 2 

 solution and showed 3 absorption bands, the measurements of which 

 are given in Table No. 2. 



Analyzed chromotographically it passed through CaCO 3 un- 

 adsorbed as a beautiful rose-colored area, leaving no adsorbed zones. 



The 80 per cent alcohol soluble pigment was transferred to ether 

 by diluting its alcoholic-ether solution with much water, and from 

 the ether to carbon bisulphide after evaporation of the former. In 

 carbon bisulphide it gave an orange-yellow solution showing two 

 absorption bands in the 25 m.m. cell. The measurements of the bands 

 are given in Table No. 2. 



