The Nature of the Agitation 213 



length of time will give butter of the best quality. 

 The lower the temperature at which the butter is 

 churned, other things being equal, the more com- 

 pletely will the butter be removed from the butter- 

 milk, the longer will be the time required for churn- 

 ing, and the less casein will be found in the. butter. 

 The nature of the agitation. It is generally be- 

 lieved that the best results follow from agitating 

 the cream in such a way that the particles of fat 

 are subject to more or less concussion, though it 

 is not at all necessary that this concussion should 

 take place. Mere gentle stirring of the cream, if 

 continued long enough, will bring butter, and agi- 

 tating the cream by passing bubbles of air through 

 it will also cause it to churn. Many churns have 

 been devised which bring about the churning by 

 agitating the cream with floats or paddles, and in 

 the old-fashioned dasjh churn there was a minimum 

 amount of concussion, the motion being largely that 

 of stirring. Where the agitation is brought about 

 by the use of paddles or stirring instruments, the 

 texture of the butter is usually injured, because of 

 the effect of the stirring motion upon the grain of 

 the first particles of .butter formed. The best churns, 

 then, are entirely hollow vessels, barrel or box, 

 which bring about agitation of the cream through 

 concussion of the particles upon the sides of the 

 rotating churn. The churning depends, also, upon 

 the rate of agitation; the faster the motion to 

 which the particles of cream are subjected, the 

 quicker will be the churning. In this respect the 



