CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT. 319 



dark blue coloration with concentrated H 2 SO 4 , and bleached very 

 quickly in the sunlight. 



Sorby, using carbon bisulphide as the separator in place of benzo- 

 line, was the first to show that there is more than one yellow pigment 

 associated with chlorophyll. 



Hansen's method of isolating the yellow pigments was still dif- 

 ferent. He treated the alcoholic extracts with caustic alkali, evaporated 

 the liquor to dryness and extracted the yellow pigment from the 

 residue with ether, the spectroscopic study of which led him to believe 

 that it exhibited three absorption bands. He believed also that it was 

 identical with the pigment of the carrot. 



E. Schunck 1 obtained from all crude alcoholic chlorophyll ex- 

 tracts minute sparkling red crystals which deposited on standing, and 

 which he considered identical with the crystals which Bougarel 2 had 

 called erythrophyll, and which Hartsen 3 has called crysophyll. This 

 pigment showed two absorption bands. 



Tschirch 4 using Hansen's method, found two yellow coloring 

 matters, to which he gave the name xantho-carotin, showing three 

 bands, and xanthophyll proper which showed no bands. 



Returning now to Arnaud's 5 work, we find that he identified 

 the red orange crystalline pigment which he obtained from spinach 

 leaves with the carotin of the carrot, both as regards to crystalline 

 form, melting point and chlorine derivatives. 



We are indebted to Immendorff 6 for the confirmation of Arnaud's 

 results indicating that the carotin of green plants is identical with 

 the carotin of the carrot. Immendorff gave the pigment the formula 

 which Arnaud found for carotin, namely C 26 H 38 . He states, however, 

 that the percentage composition of the pure pigment corresponded best 

 with Zeise's formula, C 5 H 8 . Immendorff believed that carotin was 

 the only yellow pigment accompanying chlorophyll in the green leaf. 



One of the most extensive publications in regard to carotin is 

 that by F. G. Kohl 7 This author also gives one of the best and most 

 voluminous compilations of the carotin literature that is to be found, 

 besides a large amount of experimental data. The literature is also 

 excellently reviewed by Tammes. 8 Kohl gave carotin the formula 



1. Proc. Roy. Soc. 44, p. 449. 



2. Ber. Chem. Gessel, 10, p. 1173 (1877). 



3. Arch. Pharm. 207, p. 166 (1875). 



4. Botan. Zeitung. 42, p. 817 (1884); Ber. der Deutsch. Botan. Ges. 14, pt. 

 2, p. 76 (1896). 



5. Compt Rend. 100, p. 751 (1885). 



6. Landwirtschaftliche Jahrbiicher 18, p. 507 (1889). 



7. Untersuch, Tiber d. Karotin, Leipzig. 1902. 



8. Flora, p. 205 (1900). 



