MILK AND ITS CARE. 183 



proportion, due to the large amount of fat 

 present. 



Cream is separated from milk for food pur- 

 poses, and as a matter of convenience and econ- 

 omy in making butter. Butter can be made, 

 and is made in some countries, by churning 

 milk. Cream may contain from 12 to 60 per 

 cent, of butter fat. Cream as sold at retail 

 usually has from 1 8 to 20 per cent., and a very 

 rich cream has from 35 to 45 per cent, of fat. 

 The apparent thickness of cream is not a reli- 

 able means of judging its real quality. Cream 

 is separated from milk by taking advantage of 

 the difference in specific gravity between the 

 fat globules and the remainder of the milk. 

 We have two general systems of separating 

 cream. Both take advantage of the difference 

 in specific gravity already mentioned. 



i. By Gravity. If milk be allowed to remain 

 undisturbed in a vessel of any kind, the fat glob- 

 ules, being slightly lighter than the other con- 

 stituents, gradually rise to the top. This is the 

 oldest and, until recent years, the only method 

 of separation in use. 



There are two methods of gravity creaming 

 in common use : shallow pans, and deep setting. 



(i) SHALLOW PANS. Although the oldest 



and least effective in every way, this is still the 



most common method used in many localities. 



" As generally used, the milk is placed in shallow 



