DAIRYING 



stand twenty or thirty minutes before placing it in the cold water. 

 When the cans of milk are set in cold water immediately, the 

 sudden chilling of the milk next to the walls of the can by the 

 cold water seems to prevent the groups of fat globules in the 

 milk from attaching themselves to the walls of the can and hastens 

 the cream rising, even though the interior temperature may not 

 be brought to 40 degrees or lower for some little time thereafter. 

 224. These comparisons of the blood corpuscles with the fat 

 globules, together with a knowledge of the fact that the fat in 

 .milk is suspended and not dissolved in the milk serum, help to 

 make clear the reasons for some of the manipulations and arrange- 

 ments that are commonly used in the various methods of cream 

 separation. It is obvious that the thinner the layer of milk the 

 quicker the fat will rise to the surface, and since the serum cools 

 faster than the fat, cooling has a tendency to hasten the rising of 

 the cream because it increases the difference between the specific 

 gravity or weight of the butter fat and that of the milk serum. 

 Heat, however, has the opposite effect and retards the rising of 

 the cream. 



A. SEPARATING CREAM BY GRAVITY. 



225. Cream is usually obtained from milk in one of two ways, 

 first, by the so-called "gravity processes," and second, by means of 

 centrifugal force. The "gravity processes" have passed through 

 two stages of development during the years they have been in 

 use, starting with ''shallow setting" and progressing to the "deep 

 setting" process. 



a. "Shallow Setting." 



226. The first method of cream separation, historically speak- 

 ing, is the shallow setting of milk into tin pans or in earthen 

 vessels. The details of this process of creaming milk are very 

 simple. Directly after milking the fresh, warm milk is strained 

 into tin pans which are about fifteen inches in diameter and four 

 inches deep. The pans have floating sides and are filled two- 

 thirds full of milk. These pans of milk are set in the pantry, the 

 buttery, or some other convenient place about the house and left 



