240 GENERAL SCIENCE 



solution. A perfectly fresh egg will sink; if several days old, it will 

 swim just immersed in the liquid; if stale, it will float on the surface. 



Shake an egg, holding it near the ear. The contents of a fresh 

 egg should not move. If a slight movement can be detected, it is 

 somewhat stale; if it rattles, the egg is spoiled. 



Open the egg and observe the odor and taste. If there is a 

 tendency for the white and yolk to run together, the egg is not fresh, 

 or the hen has been improperly fed. 



Milk Test for Bacteria. Curd Test: The presence of a large 

 number of bacteria in milk indicates staleness or an unsanitary 

 condition. The following test will give some indication of its 

 degree of impurity: 



Place 1 pint of milk in a pan surrounded by hot water. When the milk is 

 heated to body temperature, add one junket tablet which has been dissolved in 

 one tablespoonful of warm water. Stir until thoroughly mixed and then wait 

 until the milk has clotted well. Cut the curd in cross-sections with a knife, 

 and carefully pour off the whey. From time to time draw off the whey as it 

 : accumulates. When the curd is compact, cut it with a knife and observe its 

 .condition. If it is firm and smooth, with but few holes, the milk does not con- 

 tain an abnormal number of bacteria. If the curd has a spongy appearance, 

 bacteria are present which have produced gas. Place a tablespoonful of the 

 curd in water; if it sinks, the milk is comparatively clean; if it floats, the 

 milk is stale or in an unsanitary condition. 



Oleomargarine. Oleomargarine is made by churning oleo oil, 

 neutral oil, cotton seed oil, and peanut oil, with milk. Oleo oil is 

 obtained from beef fat. Neutral oil is melted lard. This food has 

 as much food value as butter, and is slightly more digestible. It 

 is sometimes colored with coal tar dye to resemble Gutter. 



Renovated Butter. Renovated butter is made from old and 

 rancid butter. Air is blown through the fat to remove the un- 

 pleasant odor. The liquid fat is then churned with milk to produce 

 the butter. 



Butter Test. To distinguish between genuine butter, renovated 

 or process butter, and oleomargarine, the " spoon " test may be used. 



Heat in a tablespoon a piece of butter about the size of a cherry, stirring 

 with a match. On boiling, genuine butter makes little noise, but produces 

 much froth; renovated butter boils noisily with a small amount of foam, 

 while oleomargarine boils with more or less sputtering, and produces no foam. 



