OLEOMARGARINE 287 



Detection of Oleomargarine. — The spoon test: This 

 test is described in the chapter on " Renovated Butter." 



Waterhouse test: Add about 5 grams of the sample to 

 be tested to 50 cubic centimeters of hot skim milk, cool 

 slowly, and stir with a small wooden stick while cooling. 

 In solidifying, the fat, if oleomargarine, will mass into a 

 lump or clot; but if butter, it will not, but will remain 

 in small particles distributed throughout the milk. 



Chemical tests: In the chemical laboratory oleomar- 

 garine may be distinguished from butter by determining 

 the amount of volatile and soluble acids in each. 



The Reichert-Meisel number (number of cubic centi- 

 meters N/io alkali required to neutralize the volatile 

 acids in 5 grams of fat) is the most reliable indication of the 

 kind of fat. The Reichert-Meisel number for butter may 

 vary from 25 to 32 ; for oleomargarine, from .5 to 10, depend- 

 ing upon the percentage of butter used in the process of 

 manufacture. 



In butter fat the soluble acids constitute from 3 to 6 per 

 cent of the whole: in oleomargarine, from .1 to 1.5. 



Butyro-refractometer reading: Owing to the difference 

 in the refractive indices of various fats and oils, butter 

 may be distinguished from oleomargarine by means of 

 the butyro-refractometer. This is a very simple method, 

 requires but little time, and, with few exceptions, is re- 

 liable. The refractometer reading of butter is normally 

 50 to 54 at 25° C. Higher readings indicate the presence 

 of oleo oil. According to Wollny, samples having a reading 

 higher than 54 will, upon chemical analysis, be found to 

 be adulterated. Pure oleomargarine will show a reading 

 of 58 to 66. 



