PHYTOSTERYL ACETATE TEST. 259 



Bomer's Phytosteryl Acetate Method for Detection of 

 Vegetable Oils. While butter fat and other animal fats 

 contain cholesterol, vegetable oils are free from this alcohol, 

 and contain phytosterol. There is a difference in crystalline 

 form and other properties between these alcohols, but the most 

 striking and reliable difference is the melting point of the acetates. 



Fifty grammes of butter fat are saponified with 100 c.c. of 

 alcoholic caustic potash (200 grammes per litre), 200 c.c. of 

 water are added, and the solution shaken out three times with 

 ether, 500 c.c. being used for the first extraction, and 250 c.c. 

 for the others. A larger amount of butter fat may be taken, 

 and shaken out three times with an equal volume of warm alcohol, 

 the alcohol evaporated, and the residue saponified with 20 c.c. 

 of caustic potash, the solution diluted with 50 c.c. of water, 

 and shaken out three times with 100 c.c. of ether ; sufficient 

 of the unsaponifiable alcohol is thus extracted for the test, and 

 the manipulation is easier. 



The ether is evaporated, and the residue again saponified with 

 a little alcoholic potash solution, diluted with twice the volume of 

 water, and shaken out with three or four successive quantities 

 of ether. The ethereal solution is washed three times with 5 c.c. 

 of water, filtered, and the ether evaporated. 



The residue is transferred to a small basin (this may be accom 

 plished by distilling off not quite the ether, and pouring the 

 ethereal solution left into the basin), the solvent completely 

 evaporated, and the residue treated with 2 or 3 c.c. of acetic 

 anhydride, and covered with a watch-glass. The acetic anhy- 

 dride is boiled for about a quarter of a minute, and the excess 

 evaporated on the water-bath. 



The acetate is dissolved in sufficient alcohol to prevent im- 

 mediate crystallisation on cooling, and the solution left to crystal- 

 lise ; when about two-thirds of the alcohol has evaporated, the 

 crystals are separated by filtration, washed with a very little 

 95 per cent, alcohol, redissolved in hot alcohol, and recrystallised : 

 the recrystallisation is repeated five to seven times, and the 

 melting point of the crystals determined after the third and 

 subsequent recrystallisations. 



Marcusson and Schilling use digitonin to separate the cholesterol 

 or phytosterol. Fritzsche recommends that 50 grammes of the 

 melted fat be stirred for five minutes at 60 to 70 with 20 c.c. 

 of a 1 per cent, solution of digitonin, 20 c.c. of chloroform added, 

 and the mixture filtered on a Buchner filter, the residue washed 

 twice with 4 c.c. of hot chloroform and then six times with 5 c.c. 

 of ether. The digitonide is dried for five minutes at about 40 

 C., dissolved in 2 c.c. of hot glacial acetic acid, and boiled for 

 five minutes and then filtered through cotton wool. The tube 



