29 



Reactions of coloring matters according to Leeds method. 



d. SPECIAL TESTS (SAFFRON, TURMERIC, MARIGOLD, ANNATTO). 

 1. Martin test 



Add gradually 2 parts carbon bisulphid, with gentle agitation, to 15 parts of alcohol 

 or wood spirits. Five grams of the butter to be tested, which need not be previously 

 clarified, is shaken with 25 cc of this solution. On standing for a few minutes, the 

 mixture separates into two layers, the lower of which is a solution of the fat in carbon 

 disulphid while the upper alcoholic stratum will be yellow if any artificial coloring 

 matter be present. If the butter be but slightly colored a larger amount should be 

 employed. The alcoholic stratum will give a greenish coloration with nitric acid, 

 and a red with hydrochloric acid and sugar if saffron be present. A brownish color 

 with ammonia indicates turmeric, and a blackish coloration with silver nitrate mari- 

 gold. If the alcoholic solution be evaporated to dryness, and the residue treated 

 with concentrated sulphuric acid, annatto will be indicated by a greenish blue, and 

 saffron by a blue, coloration. On adding a few drops of boric-acid solution and again 

 evaporating turmeric will be indicated by a bright brownish-red coloration, changed 

 to blue, green, or violet by caustic alkalies. 



2. Carotin test (Moore) . & 



When a butter colored with carotin is dissolved in carbon disulphid and shaken 

 with alcohol, as prescribed by Martin, the alcohol remains colorless, while the lower 

 layer is deeply colored, but on adding a drop of a dilute solution of ferric chlorid and 



Analyst, 12, 70; Allen, tf, (1), 354. 



''Analyst, 12, 163. 



