BUTTER AND CHEESE 391 



290. Cream Separators. The old method of placing the 

 milk in stone crocks and allowing it to stand for a day or 

 two for the cream to rise is too slow and tedious a process 

 for a large dairy. A separator was invented to take the 

 cream at once and quickly. A cream separator is what 

 we call a centrifuge a type of centrifuge which in this 

 case contains a few horizontal disks revolving on an up- 

 right axis. Cream is lighter than the rest of the milk. 



GERMS OF THE DAIRY. 



The left-hand dish was exposed out of doors for five minutes ; the 

 right-hand dish in a cow-barn during milking for only five seconds. 

 Note the difference in the number of bacteria in each. 



As the whole milk enters the separator when that machine 

 is in rapid motion, the heavy part of the milk is thrown 

 toward the circumference of the disks, and the lighter part 

 (or cream) is drawn off near the center. With a modern 

 separator, operated either with an engine or by hand, the 

 cream in several hundred pounds of milk can be quickly 

 and conveniently gathered, under the most sanitary con- 

 ditions, immediately after the milking. 



291. Butter and Cheese. Cream only is used in making 

 butter. Commonly the cream is first ripened, that is, it 



