260 THE CHEMICAL ANALYSIS OF BUTTER FAT. 



and wool are washed twice with J c.c. of hot alcohol, and 

 the filtrate and washings evaporated on the water-bath, and 

 the residue crystallised from alcohol as before. Klosterman 

 prefers to add the digitonin to the ethereal solution after saponi- 

 fication. 



Cholesteryl acetate melts at 1154 C. (corrected), and phyto- 

 steryl acetate at 127, if on continued recrystallisation the melting 

 point rises above 117 the presence of phytosteryl acetate is 

 certain. 



Small quantities of paraffin wax are occasionally added, and 

 this interferes somewhat with the test ; if this is the case, the 

 cholesterol should be crystallised from petroleum ether before 

 acetylation. 



Although this method only detects vegetable oils, these are 

 so largely used in the manufacture of margarine that this is a very 

 reliable test. 



Specific Colour Tests for Adulterants. 



Baudouin's Test for Sesame Oil. This test consisted, 

 originally, in shaking the melted fat with a solution of cane 

 sugar in hydrochloric acid. Villavecchia and de Fabris have 

 modified this by using a solution of 2 grammes of furfuraldehyde 

 in 100 c.c. of alcohol to replace the sugar ; 10 c.c. of the melted 

 fat are shaken thoroughly with 10 c.c. of hydrochloric acid and 

 0-1 c.c. of the reagent; a red coloration indicates the presence 

 of sesame oil. This reaction is very delicate, but is not entirely 

 conclusive. Certain colouring matters e.g., turmeric and some 

 aromatic dyes give a red coloration with hydrochloric acid 

 alone, and, in the presence of these, sesame oil cannot be detected, 

 as the colour due to sesame oil would be masked by that yielded 

 by the dye. Furfuraldehyde and hydrochloric acid alone, after 

 some time, yield a reddish colour ; hence a slight pinkish tinge 

 gradually appearing must not be taken to indicate sesame oil, 

 especially if it turns black on standing. Spampani and Daddi 

 have shown that the milk of goats fed with sesame oil yields 

 butter which gives this test. Hehner, Faber, and others were, 

 however, unable to obtain it with butter prepared from the 

 milk of cows fed on sesame cake. 



Sprink, Meyer, and Wagner modify this test, and extract 

 100 c.c. of butter fat twice with 20 to 30 c.c. of glacial acetic 

 acid at 60 C., evaporate the acid, and test the residue by Bau- 

 douin's test. 



To remove the colouring matters which give a red colour with 

 hydrochloric acid they add 10 c.c. of alcohol and 5 c.c. of 

 saturated baryta water to the residue, and evaporate. The 



