1915] Clarence J. West i53 



mother liquor, from which it was precipitated by alcohol. This 

 gave a much larger yield, 0.15-0.20 gm. per k. of dry leaves. 



The preparation from cärrots was carried out by extracting the 

 dry material with petroleum ether in a percolator and purifying as 

 above; 5000 k. of fresh carrots (473 k. of dry material) gave 125 

 gm. of pure Carotin. 



Carotin forms quadratic or four-sided reddish-yellow plates, 

 which exhibit the phenomenon of dichroism, being orange-red by 

 transmitted Hght and greenish-blue in refracted Hght. Dilute Solu- 

 tions are yellow, conc. Solutions orange-red but Solutions in carbon 

 disulfid, or in other solvents upon the addition of carbon disulfid, are 

 red. Analyses of carefully purified products indicate the formula 

 (C5H7)x, which, from molecular weight determinations, becomes 

 C40H56. Earlier workers gave C^Hg," Ci8H240,^ CzßHgs« and 

 other formulae.'^ It should be mentioned that in the precipitation 

 with absolute alcohol, a product is obtained which contains from 

 Yz io Yz oi 2. molecule of alcohol ; this may be removed by recrys- 

 tallization from petroleum ether. With conc. sulfuric acid it gives 

 an indigo-blue color; upon diluting this Solution, green flakes pre- 

 cipitate. Solutions of Carotin readily absorb oxygen. Willstätter 

 found that Carotin took up 34.3 percent of its weight (11 atoms), 

 forming a colorless Compound. Various other values, from 21 

 percent to 37.8 percent, have been given. Shaken with ^ of its 

 weight of iodin in ether, a di-iodid is formed, C40H56I2; rosettes of 

 dark violet prisms. However, if benzene, carbon disulfid or carbon 

 disulfid-ether is used, and a larger amount of iodin, a tri-iodid^ re- 

 sults; dark violet leaflets, melting at 136-7°. Carotin, shaken with 

 bromin at 0°, and then allowed to stand at room temperature, forms 

 a bromid, C4oH36Br22, decomposing about 171-174°. During the 

 process, about 20 molecules of hydrobromic acid are evolved, so that 

 probably 2 atoms of bromin are added and 20 atoms of hydrogen 

 substituted by bromin. 



*Zeise: Ann. d. Chem., 62, 380, 1847. 



ßHusemann: Ihid., 117, 200, 1861. 



«Arnaud: Compt. rend. acad. sc, 100, 75, 1885; Bull. soc. chint., 48, 641, 



1887. 



7 Immendorf : Landwirtschaftliche Jahrb., 18, 507, 1889. 



»Arnaud: Compt. rend. acad. sc, 102, 11 19, 1886. Willstätter and Escher: 

 Ztschr. f. physiol. Chem., 64, 59, 1910. 



