27 



It will be seen from these two tables that amyl alcohol, as a rule, 

 extracts fruit coloring matter from acid solution, while ether does 

 not. Neither amyl alcohol nor ether extracted any color from the 

 alkaline solution of the fruit juices. 



Desmouliere a found that amyl alcohol extracts a yellow color from 

 macerated apricots in the presence of acid or alkali. The yellow resi- 

 due with sulphuric acid gives an indigo-blue color changing to brown 

 violet. This reaction is identical with that for carotin. The color 

 does net dye silk or wool. 



DETECTION OF COCHINEAL. 



Girard and Dupre", Analyse des matures alimentaires, etc.^p. 580; U. S. Dept. 

 Agr., Bureau of Chemistry, Bui. 65, p. 120. 



VI. Dairy Products, Fats, Oils, etc. 

 A. NATURAL AND ARTIFICIAL COLORS IN MILK. 



In examining for the presence of added coloring matters it is well to 

 consider first the nature of the natural coloring in milk and, conse- 

 quently, in butter. The natural coloring matter of milk is "lacto 

 chrome," which may be precipitated from milk whey by nitrate of 

 mercury in bright red orange resin-like masses, softening at 100 C., 

 freely soluble in water and hot alcohol, separating from the latter on 

 cooling (Blyth). Cholesterin occurring in milk is soluble in hot alco- 

 hol, ether, bisulphid of carbon, and chloroform, and gives characteris- 

 tic color reactions with certain reagents, as follows: 



5 parts sulphuric acid and 1 part water, colored carmine red, then violet. Mole- 

 schott's test. 



1 part sulphuric acid and 1 part chloroform, colored blood red, violet, or purple. 

 Salkowsky's test. 



The coloring matter of certain plants when eaten by cows imparts 

 colors to milk, which, though not natural, may be present through 

 natural means. Such are 



Marsh marigold and saffron, coloring yellow; rhubarb, opuntia, and madder, 

 coloring red; buckwheat and forgetmenot, coloring blue. Certain bacteria in milk 

 develop a blue color which turns cherry red on addition of caustic alkali, returning 

 to blue on addition of acids (Blyth). 



Among the artificial coloring matters which may be considered are 

 the following: 



Vegetable colors. Saffron, rocou, alkanet, carrot juice (carotin), aspergeoire berries, 

 marigold and carthamus flowers, chelidoine juice, ranunculus, turmeric, annatto, etc. 



Coal-tar colors. Spirit yellow R, nitrosamine red, aurantia, phosphin, Martius 

 yellow, picric acid, Mikado yellow, Mikado gold yellow, naphthol yellow S, naphthol 

 yellow RS, victoria yellow, coralline yellow, acid yellow, methyl orange, orange IV 

 and similar azo colors, amidoazobenzol, anilin yellow (amidoazobenzol hydrochlorid), 

 butter yellow (benzinazodimethyl anilin), diazobenzol, etc. 



Ann. chim. anal., 1902, 7, 323. 



