DETECTION OF ADULTERATION 5 1 



Leflfmann has found that several commercial 

 photographic developers, e. g., amidol, are ap- 

 plicable in this test with about, the limitations 

 above noted. 



At critical temperatures, however, the results 

 with all the reagents depend materially on the 

 length of the heating. 



Colors. — ^Annatto, turmeric, and some coal-tar 

 colors are much used. Caramel is occasionally 

 used, saffron and carotin but rarely. Annatto 

 may be detected by rendering the sample 

 slightly alkaline by acid sodium carbonate, im- 

 mersing a slip of filter-paper, and allowing it to 

 remain over night. Annatto will cause a reddish- 

 yellow stain on the paper. 



Leys gives the following method for detecting 

 annatto; 50 c.c. of the sample are shaken with 

 40 c.c. of 95% alcohol, 50 c.c. of ether, 3 c.c. of 

 water, and 1.5 c.c. of ammonium hydroxid 

 solution (sp. gr. 0.900), and allowed to stand for 

 twenty minutes. The lower layer, which in pres- 

 ence of annatto will be greenish-yellow, is tapped 

 off and gradually treated with half its measure of 

 10% solution of sodium sulfate, the separator 

 being inverted without shaking, after each addi- 

 tion. When the casein separates in flakes that 

 gather at the surface, liquid is tapped off, strained 

 through wire gauze, and placed in four test- 

 tubes. To each of these amyl alcohol is added, 



