320 MISSOURI AGR. EXP. STA. RESEARCH BULLETIN No. 9. 



C 26 H 38 , and the iodine derivative C 26 H 38 I 2 . He also gave a detailed 

 description of the spectroscopic absorption of carotin. In ether and 

 carbon-bisulphide he measured three bands : 



In ether In carbon bisulphide 



I 49<>475 A I 510-485 * 



II 455-445 * II 470-458 * 



III 430-418 ^ III 437-425 A 



Carotin is laevorotatory, according to Kohl, D at 15 in chloroform 

 being 30.17. 



Schunck * in his spectroscopic study of the yellow pigments of 

 leaves and flowers, described the properties of carotin. Schunck also 

 photographed the absorption bands of crysophyll (carotin) from the 

 daffodil leaf, from spinach, from the carrot and from grass, in alcoholic 

 solution. All of the carotin preparations showed the same three pro- 

 nounced bands situated between F and H the first band of which 

 lay almost directly upon the F line. 



The most recent detailed investigation of the carotin of green 

 plants is that of Willstatter 2 and Meig, and a study of their data shows 

 that their results are to be accepted as the final proof of the chemical 

 constitution and properties of this pigment. 



Willstatter and Meig describe the properties of carotin as follows : 

 Its crystals are copper colored plates of almost quadratic form, and 

 melt at 167.5 to 168 C. Its crystals are soluble with great difficulty 

 in hot ethyl alcohol and almost insoluble in cold ethyl alcohol, and 

 in methyl alcohol they are still less soluble; one gram of the crystals 

 requires 1.5 liters of petroleum ether (b. p. 30-50 C.) for solution and 

 about 900 c.cm. of hot ethyl ether ; the crystals are difficultly soluble in 

 acetone, easily soluble in benzol, very easily soluble in chloroform 

 and instantly soluble in carbon bisulphide; the crystals are soluble in 

 concentrated sulphuric acid with an indigo blue color and are pre- 

 cipitated as green flakes on dilution with water. 



The carotin obtained by Willstatter and Meig crystallized from 

 its deep red carbon bisulphide solution on addition of absolute alcohol, 

 but analysis showed that the crystals contained ^2 to ^ of a molecule 

 of alcohol of crystallization. The carotin showed the composition of 

 a pure hydrocarbon only after crystallization from low boiling point 

 petroleum ether. From this solvent the preparation of Willstatter 

 and Meig showed the composition C 5 H 7 . A preparation of carotin 

 which the same authors obtained from the carrot showed the same 



1. Proc. Roy. Soc. 72, p. 170 (1903). 



2. Ann. der Chemie, 355, p. 1 (1907). 



