CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 395 



fat pigment with the pigment from maize, with the result that, "The 

 maize pigment gave the lipochrome reaction faintly with H 2 SO 4 , 

 distinctly with HNO 3 while the fat pigment gave no lipochrome re- 

 action. In other respects, in tint, solubility, etc., the pigments closely 

 resembled each other." The experience of this station in studying 

 the lipochrome properties of the milk fat pigment seems to indi- 

 cate that Newbigin's results were due to the fact that he was work- 

 ing with decomposed pigment. Nevertheless particular attention was 

 paid to the lipochrome properties of the body fat pigment. 



Method of Isolation. 



The method was the same as that used for isolating the milk 

 fat pigment. It consisted in careful saponification of the fat with 

 alcoholic potash (2 c.c. of 20% solution per gram of fat) and sub- 

 sequent extraction of the unsaponifiable matter from the diluted 

 soap (3 volumes of water to one of soap) with ether. The ether ex- 

 tract was sometimes purified by re-saponification and re-extraction 

 with ether, and sometimes was freed from cholesterol with digitonin. 

 Only small amounts of fat were used for each test, i. e., 25 to 30 

 grams, as the studies of the milk fat pigment showed that the best 

 results could thus be obtained. 



Identification of Pigments. 



Only two typical experiments showing the character of the body 

 fat pigments will be reported. 



Experiment I. 



Twenty-five to thirty grams of pure rendered kidney fat from 

 a Jersey cow was used for this experiment. The fat had a high 

 yellow color testing in the one-inch tintometer cell 54 yellow, 2.3 red. 

 The unsaponifiable matter of the fat had a golden yellow color in 

 ether solution and a blood red color in carbon bisulphide solution. 

 The carbon bisulphide solution left no adsorbed zone in the CaCO 3 

 when analyzed chromotographically, but passed through unadsorbed 

 as an orange-red or rose colored zone. A very small amount of 

 pigment was left in the column, however, which was readily washed 

 out by a stream of alcoholic petroleum ether. 



The main pigment was now examined with respect to its solu- 

 bility relations toward petroleum ether and 80 per cent alcohol. A 

 very minor constituent was thus obtained more soluble in 80 per 



