ir BUTTER 163 



fat consists of cholesterine, whilst phytosterine is obtained from 

 a vegetable fat. Salkowksi l first proposed to make use of this 

 fact as a means of detecting the admixture of vegetable fats 

 with animal fats. It has been proved, chiefly through the 

 researches of A. Bomer, that phytosterine is always a constituent 

 of plant fats, whilst cholesterine, on the other hand, is always 

 found in animal fats. If, therefore, the presence of phytosterine 

 can be proved in an animal fat butter, for example it is 

 certain that adulteration with a vegetable fat has taken place. 



As in the manufacture of margarine vegetable oils are always 

 used; they being indispensable for obtaining the right con- 

 sistency, it is easy to see that an addition of margarine to 

 butter can be detected by the presence of phytosterine. 



To distinguish phytosterine from cholesterine A. Bomer 2 has 

 worked out a method the main features of which are as follows 

 The non-saponifiable portion from a certain quantity of fat 

 is separated as completely as possible, and then allowed to 

 slowly recrystallise from alcohol. In the original method the 

 crystals obtained in this way were examined under the 

 microscope, and the characteristic crystalline formation of the 

 phytosterine or the cholesterine could be detected if either 

 were present. When a mixture was being dealt with either 

 the phytosterine crystallised out, or the crystals had a new 

 and characteristic shape (Fig. 64). 



This method, however, requires a certain proficiency in 

 crystallographic measurements, and in addition it is difficult, 

 where there is much cholesterine and only a little phytosterine, 

 to detect the latter. Bomer, therefore, uses the acetate as a 

 means of distinguishing the two substances, for the melting 

 point of cholesterine acetate does not rise above 115'4, whilst 

 that of the phytosterine acetate lies between 125 and 127 . 3 Even 

 a small admixture of phytosterine acetate is recognised by the 

 raising of the melting point. When making the test, 50 g. of 

 butter are saponified with 100 c.c. of alcoholic caustic potash 

 (200 g. of caustic potash, and 1 litre of 70 vol. per cent, alcohol), 

 and then poured into a separating funnel with 200 c.c. of water. 



1 Zeitschrift fur analytischeChemie, Vol. XXVI, p. 557. 



2 Zeitschrift fiir Untersuchung dtr Nahr.- und Qenussmittel, 1898, 1901, 



3 Siegfeld gives the melting point of phytosterine acetate as still higher. 

 Zeitschrift fur Unter.mch. der Nahr.- und Gennssmittel, 1904, No. 10, p. 577. 



M 2 



