178 



BUTTER-MAKING. 



over the heating-surface only by force of its own gravity, a 

 heavy layer of curd usually adheres. This is due to the fact 

 that certain portions of the milk are exposed to the excessive 

 heating too long, while if caused to move rapidly it does not 

 remain in contact with one portion of the heating-surface long 

 enough to cause it to adhere to so great an extent. 



FIG. 118. The Simplex regenerative pasteurizer (assembled). 



The condition of the milk or cream has some influence upon 

 the degree of adhesiveness of curd on the heating-surface. 

 Sour and coagulated milk adheres or burns on to a greater 

 extent than does milk or cream in good condition. This is 

 evidently due to the lesser fluidity of the sour milk, and, as a 

 consequence, it does not move over the heating-surface so 

 rapidly, and therefore burns on. Milk which contains a great 

 deal of air or scum also adheres to the heating-surface much 



