BUTTER 95 
afew 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 moisten- 
ing 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 phos- 
phoric 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 
