330 



bih'ter. 



Small quantities of paraffin wax are occasionally added, and 

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

 alcohol should be crystallised from petroleum ether. 



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 

 O'l c.c. of the reagent ; a red coloraticui indicates the presence 

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

 conclusive. Certain colouring matters — e.*/., turmeric and certain 

 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 tinj^e 

 gradually appearing must not be taken to indicate sesame oil. 

 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. 



8prink, Jleyer, and AVagner 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 

 satujated baryta water to the residue, and evaporate. The 

 residue is extracted several times with petroleum ether, which 

 is evapiorated, and the test performed on the residue. They 

 claim that O'l per cent, of sesame oil can thus be detected. 



Becchi's Test for Cottonseed Oil. — This test was originally 

 performed by heating the fat with a solution containing silver 

 nitrate, alcohol, ether, nitric acid, amyl alcohol, and rape oil. 

 The reagent has been frequentlj' modified. Bevan prepares the 

 reagent by boiling silver nitrate with amyl alcohol, and cooling 

 the solution. Equal parts of this solution and of the fat are 

 heated in a test tube on a boiling water-bath for ten minutes ; 

 a brown or black coloration indicates cottonseed oil. This test 



