64 MILK ANALYSIS 



is drawn off, and part of it tested by adding to it 2 c.c. of a mix- 

 ture of i part crystallized phenol in 2 parts carbon tetrachlorid. 

 To this add 5 drops of hydrobromic acid (sp. gr. 1.19). The 

 test is best performed in a porcelain basin and the contents 

 mixed by agitating gently. Palm oil gives almost immediately 

 a bluish-green liquid. 



Liebermann-S torch method. 10 c.c. of the filtered fat are 

 shaken with an equal volume of acetic anhydrid, one drop of 

 sulfuric acid (sp. gr. 1.53) is added and the mixture shaken 

 for a few seconds. If palm oil be present, the heavier layer 

 separating will be blue with a tint of green. 



Egg-yolk has been proposed as a color for oleomargarin, and 

 although its use is unlikely, the possibility of it should be borne 

 in mind. To detect it, about 10 grams of the filtered fat should 

 be shaken with warm alcohol, the liquid drawn off as closely 

 as possible and evaporated to dryness. The coloring matter 

 of egg-yolk is soluble in alcohol, but insoluble in water. It 

 may be distinguished from turmeric by moistening it with a 

 few drops of a mixture of boric and hydrochloric acids, and 

 drying at a gentle heat. Turmeric becomes brown; egg-color 

 is not affected. Egg-yolk contains considerable lecithin, a 

 phosphoric acid derivative. Pure fats contain no phosphorus 

 compound. If, therefore, a few grams of the fat, carefully 

 freed from water or curd, are charred and the mass extracted 

 by boiling with nitric acid, the filtered solution should not 

 give an appreciable precipitate with ammonium molybdate. 



Vegetable colors may be detected by boiling up the filtered 

 fat with water, drawing off the watery liquid, adding a few 

 drops of hydrochloric acid and heating the mixture with a 

 piece of clean, undyed wool. True butter colors will not dye 

 wool under these circumstances. 



Caramel may be detected by shaking the watery solution with 

 fuller's earth and filtering. The filtrate is notably paler if 



