DETECTION OF ADULTERATION 51 
Leffmann has found that several commercial 
photographic developers, ¢. 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. Thelowerlayer, 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, 
