378 



FUNDAMENTALS OF AGRICULTURE. 



in which this is done is called a cream separator or 

 centrifuge. These are either hand or power ma- 

 chines. Hand separators are 

 used on dairy farms, while only 

 steam-power centrifuges are 

 used in butter factories (cream- 

 eries). The largest of these 

 machines separate 

 the cream from the 

 skim milk at the rate 

 of 5,000 pounds, or 

 about 2,500 quarts, 

 of milk per hour. 

 Cream is used for 

 table or culinary pur- 

 poses, and for the 

 manufacture of but- 

 ter. 



Butter. In the 

 manufacture of but- 



A HAND CREAM SEPARATOR. 



ter the cream is either al- 

 lowed to sour (ripen) be- 

 fore being placed in the 

 churn, or is churned di- 

 rectly without ripening. 

 The former method gives 

 us the ordinary market 

 butter (sour-cream but- 

 ter), the latter method 

 sweet-cream butter. 

 When cream of a tem- 

 perature of 50 to 60 

 degrees Fahrenheit is 

 stirred or agitated in a 



churn for twenty minutes or more, the butter fat will 

 gather into granules or small lumps which also contain 



A BARREL CHURN. 



