METHODS OF ISOLATION OF CAROTlNOlDS 201 



form. The carotin was precipitated from the chlorntnnn by an excess 

 of absolute alcohol and purified by recrystallization i'roni petroleum 

 ether. Kohl found that a very good yield of crystals could be secured 

 by omitting the saponification process and merely allowing the con- 

 centrated ether extract to evaporate spontaneously. The crystals 

 secured in this manner could be purified further by washing with cold 

 ether followed by cold absolute alcohol. 



On forming a concentrated chloroform solution of this residue and 

 adding three volumes of absolute alcohol, the impurities which pre- 

 cipitated immediately could be removed by a quick filtration. On 

 allowing the solution to stand for about 24 hours, pure carotin crystal- 

 lized out. Kohl does not tell what yields he secured by this method, 

 but he assures us that the product was of a high degree of purity. 



A method somewhat similar to that of Kohl was followed by Euler 

 and Nordenson (1908). Fresh carrots in 25 kg. lots were boiled in 

 water for several hours and then pressed. The press cake was ground 

 with sand and dried in thin layers at 50 C., which took about a day. 

 The dried residue was extracted twice with carbon disulfide at 20 C., 

 presumably by agitating with the solvent. The volume of solvent 

 used was not stated. The carbon disulfide was pressed out of the 

 dried carrot pulp and the solvent distilled off of the filtrate, at the 

 last with the addition of much ether. The carrot pulp was now treated 

 with 8 liters of alcohol for several hours, which became deep red with 

 extracted pigment. By diluting with much water and shaking with 

 ether the pigment was transferred to the latter solvent. The two 

 ether solutions of pigment were treated alike. They were first evapo- 

 rated to dryness and then taken up in a little petroleum ether and 

 three volumes of alcohol added. The precipitated phosphatides were 

 filtered off and the filtrates evaporated to dryness. The combined 

 yields of crude pigment amounted to 26 grams. 



The most satisfactory yields of pure pigment were reported by 

 Escher (1909) who obtained 125 grams from 472 kgs. of dried (5,000 

 kgs. fresh) carrots. The complete details of the method used have 

 not been accessible to the writer. In general, however, Escher dried 

 the carrots without previous cooking, using a low heat. The dried 

 pulp was ground to a powder and the pigment completely extracted 

 by petroleum ether in a continuous extractor. This extract was con- 

 centrated to a low volume under diminished pressure at 40 C. On 

 standing, the carotin crystallized out together with a large amount of 

 colorless impurities. Purification was carried out by fractional pre- 



