DETECTION OF ADULTERATION 53 



and the curd separated from the whey. The 

 curd will often collect in a mass; but if this does 

 not occur, it must be freed from whey by straining 

 through muslin. The curd is macerated for 

 several hours in a closed flask, with occasional 

 shaking, with ether to extract fat. Annatto 

 will also be removed by it. The ether and curd 

 are separated and treated as foUows: 



The ether is evaporated, the residue mixed 

 with a little weak solution of sodium hydroxid, 

 and passed through a wet filter; and when this 

 has drained, the fat is washed off and the paper 

 dried. An orange tint shows annatto, which 

 may be confirmed by a drop of solution of 

 stannous chlorid, which makes a pink spot. 



If the curd is colorless, no foreign coloring- 

 matter is in it; if orange or brown, it shotild be 

 shaken with strong hydrochloric acid in a test- 

 tube. 



If the mass turns blue gradually, caramel is 

 probably present. The whey should be ex- 

 amined for caramel (see page 95). 



If the mass turns pink at once, an azo-color 

 is indicated. 



Falsification of the "Cream-line." — The use of 

 glass bottles for retail delivery of milk enables 

 purchasers to make approximate estimations of 

 the richness of the sample by the depth of cream 

 formed after standing for some time, this being 



