Chemical Analysis of Milk and Its Products. 243 



(or a small tin dish) at a low heat, stirring with a splin- 

 ter of wood. The heat is increased until as brisk a boil 

 as possible, and after boiling has begun, the melted mass 

 is stirred thoroughly two or three times, always shortly 

 before boiling ceases. Oleomargarine and renovated 

 butter will boil noisily, sputtering like a mixture of 

 grease and water when boiled, and will produce but 

 little or no foam. Renovated butter produces usually a 

 very small amount of foam, while genuine butter boils 

 with less noise and produces an abundance of foam. 



284. The Waterhouse test for distinguishing oleo- 

 margarine and renovated butter. 1 Half fill a 100 cc. 

 beaker with sweet skim milk (or distilled water), heat 

 nearly to boiling and add 5 to 10 grams of butter or 

 oleomargarine. Stir with a small wooden stick of about 

 the size of a match until the fat is melted ; the beaker is 

 then placed in ice water, and the milk (or water) stirred 

 until the temperature falls sufficiently for the fat to 

 congeal. If oleomargarine, the fat can now be easily 

 collected into one lump by means of the stick, while if 

 genuine or renovated butter, the fat will granulate and 

 can not be so collected. 2 



D. CHEESE. 

 For method of sampling, see par. 104. 



285. a. Water. Five grams of cheese cut into very 

 thin slices are weighed into a small porcelain dish filled 

 about one-third full with freshly-ignited stringy asbes- 



exnmination of renovated or "process" butter, see also Cochrnn, Journ 

 Franl-1. 7n.s/.. 180!). p. 94 : Analyst, 1899, p. 88. 



1 Farmers' Bulletin No. 131, p. 7. 



2 For tests for artificial coloring matter in oleomargarine, see Circ. 

 629, Com. of Internal Rev., Treasury Dept. 



