TESTING MILK FOR ADULTERATIONS 149 



ADULTERATIONS OF BUTTER 



The most common adulteration of butter is substi- 

 tution, in part or in whole, of fat other than butter- 

 fat, such as products from beef-fat and lard. Occa- 

 sionally preservatives are found, such as occur in milk. 

 "Renovated" or "process" butter is made from refuse 

 butter that can not be disposed of otherwise on the 

 market. Excessive water or casein should be regarded 

 as an adulteration. Harmless coloring matter has been 

 universally allowed. The absolute identification of 

 such adulterants as oleomargarin requires somewhat 

 elaborate chemical methods. Only simple tests can 

 be given here. 



Foam-test for oleomargarin and "renovated" but- 

 ter. Melt in an ordinary tablespoon a piece of the 

 suspected butter about the size of a small chestnut, 

 holding it over a small flame, a candle flame will do. 

 Stir the fat, while melting, with a match or similar 

 stirrer. Then lower the spoon into the flame and let 

 the fat boil vigorously, stirring thoroughly several 

 times during the boiling and not neglecting the outer 

 edges. Oleomargarin and "renovated" butter boil 

 with marked noise, sputtering more or less and pro- 

 ducing little or no foam. Genuine butter generally 

 boils with much less noise and foams up vigorously. 



Milk-Test for oleomargarin. In a tin measuring- 

 cup take about one gill of sweet milk or water, heat 

 to about 140 F. and then add a slightly rounded tea- 

 spoonful of the suspected sample. Stir with a small 

 piece of wood, about the size of a match or smaller, 

 until the fat is melted. Then immerse the cup to about 

 one-third of its height in a pan of water in which there 



