LIVE-STOCK AND DAIRYING. 379 



other components of butter, viz., water, casein, and a 

 little milk sugar or acid. The buttermilk is allowed to 

 drain off and the butter is washed with cold water, 

 salted to suit the taste of the consumer and worked on 

 a butter worker, or in a combined churn and worker; it 

 is then ready to be packed into tubs or made into pack- 

 ages weighing a pound each (" point butter "). Ordi- 

 nary market butter has the following average compo- 

 sition : 



Water 12.0 per cent., fat 84.2 per cent., casein and 

 milk sugar 1.3 per cent., and ash (salt) 2.5 per cent. 



Butter made from sweet cream is usually not salted, 

 and contains somewhat more water, fat and casein 

 than sour-cream butter, and only about one-tenth of a 

 per cent, of ash. Under the Federal pure-food law 

 butter must contain at least 82.5 per cent, of fat and 

 not more than 16 per cent, of water. A small amount 

 of butter color is added to the cream in order to secure 

 butter of a uniform color through the entire year. 



Cheese. Numerous kinds of cheese are made from 

 milk. We shall here only mention two types com- 

 monly made in this country, viz., Cheddar cheese and 

 cottage cheese. 



Cheddar or American Cheese is made by adding a 

 small amount of rennet extract to the milk. The ren- 

 net contains a ferment which causes the milk to curdle. 

 The curd is cut into small cubes and carefully heated 

 in the cheese vat so that it contracts and hardens. The 

 whey is then strained off, and the curd salted, put into 

 forms and pressed. The cheese is placed in a curing 

 cellar where it is kept at an even temperature for a 

 period ranging from a few weeks to half a year or 

 more. American cheese is often sold only a couple of 

 weeks old when it has not yet ripened into a nutritious, 

 easily digested food; it takes several months for cheese 

 to ripen properly. 



Cottage Cheese. Instead of adding rennet to curdle 

 the milk, this may be allowed to sour spontaneously at 

 ordinary room temperature, which will occur within 



