40 DAIRY LABORATORY GUIDE 



off buttermilk. Rinse once, using one-quarter of the 

 churnful of sterile water, or as pure as can be ob- 



FIG. 31. Churning and Cream Ripening Department of the 

 Model Dairy of the Louisiana Purchase Exposition, 

 showing machinery operated by a 5-horse-power dy- 

 namo. This is the most sanitary source of power ob- 

 tainable for a creamery. One of the most important 

 precautions for the beginner in the use of a dynamo is 

 that of starting and stopping. In starting the current 

 is first connected with the switch. Then the crank or 

 starting rheostat is moved slowly over the controlling 

 box to the magnet which holds it in place, while the 

 current is on. If the starting rheostat is moved over 

 quickly the field in the controlling box does not "catch 

 up ' ' with the current immediately and a fuse may be 

 blown out, or the field overstrained. In stopping the 

 dynamo, disconnect current by merely throwing off 

 switch. Never try to move starting rheostat back while 

 current is on. Use nothing but insulated copper-wire 

 for connections, and see that they are kept clean and 

 tight. 



tained, revolving the churn about three times. Draw 

 off, and if water still has milky color rinse again, 

 otherwise not. Add salt, depending on the market 



