22 



C. SPECIAL TESTS FOR VEGETABLE COLORS. 



A great man} T tests for vegetable colors are given, depending largely 

 on color reactions with different reagents, but these must be used with 

 very great discrimination, as they depend very largely on a fine judg- 

 ment of shades of colors, which many eyes are not able to distinguish. 



A great deal of work has been done on detection of vegetable colors/' 

 but only in a very few cases are the reactions specific enough to be 

 decisive. 



a. DETECTION OF CARAMEL AMTHOR TEST. 



U. S. Dept. Agr., Div. of Chem., Bui. 65, p. 120; Modification, Bui. 90, p. 226; Zts. 

 anal. Chem., 1885, 24, 30. 



6. DETECTION OF TURMERIC. 



U. S. Dept. Agr., Div. of Chem., Bui. 51, p. 131; Bui. 65, p. 120. 

 c. TEST FOR CHERRY JUICE. & 



Windisch found that all cherries examined by him contained hydrocyanic acid, as 

 did also the fermented juice with or without the stones. From this fact he proposes 

 the following test: 



Distill 20-30 cc of the liquid until 2 cc have been collected, and to this distillate 

 add a drop of guaiacum tincture, together with a drop of copper sulphate solution. 

 A blue color indicates hydrocyanic acid. The color is fugitive, and if very faint may 

 be intensified by shaking out with chloroform in which it is soluble. Unfortunately, 

 however, a negative test does not prove the absence of cherry juice. 



d. KERMESE c (Phytolacca). 



Add lead acetate, kermese gives red- violet precipitate; add barium hydrate, ker- 

 mese gives blue-violet flocks. 



II. Brandy, Bum, Liqueurs, Vinegar, etc. 

 GENERAL DISCUSSION. 



Coal-tar colors may be examined for in the usual way as under 

 wines, after previously boiling out excess of alcohol and filtering off 

 any .coloring matter precipitated. The color of brand} T may be due to 

 the presence of caramel or a deepening of the tint by coloring matter 

 due to the cask. Arrack is nearly colorless, but maj T have a slight 

 tinge of yellow or brown due to long storing in casks. Liqueurs are 

 often brightly colored by vegetable coloring matters such as chloro- 

 phyll, turmeric, cochineal, etc. Absinthe is yellowish-green in color, 



Girard and Dupre, Analyse des matieres alimentaires, etc., 580-581, also 169; A. 

 W. Blythe, Foods, Their Composition and Analysis, pp. 91-109; Allen, Commercial 

 Organic Analyses, 3, (1) ; E. Brucher, Falsification des substances alimentaires, p. 162; 

 W. Lenz, Zts. anal. Chem., 1885, 24, 285. 



&Zts. Nahr. Genussm., 1901, 817. 



cBujard and Baier, Hilfsbuch, etc., p. 296. 



