28 FIRST LESSONS IN DAIRYING 



force generated depends on the diameter of the 

 bowl and number of revolutions per minute. A 

 bowl of large diameter need not be run so rapidly 

 as a bowl of smaller diameter in order to do the 

 same work. The speed recommended by the manu- 

 facturer should be maintained. If necessary, a 

 slight increase of speed will increase the thorough- 

 ness of separation. 



Rate of inflow. This is usually fixed by the 

 manufacturers of hand separators. However, if the 

 inflow of milk is not sufficient, the cream may be- 

 come too thick and clog the machine. 



Temperature. Milk separates easiest when sep- 

 arated quickly after drawn from the cow. If for 

 any reason it is cooled to a temperature below 80, 

 or with some machines below 70, it should be 

 warmed by placing the vessel of milk in warm 

 water. Milk that is slightly curdled cannot be suc- 

 cessfully separated. 



Thickness of cream. The thickness of the cream 

 is regulated in most machines by a screw which 

 determines either the size of the cream outlet or 

 its distance from the center of the bowl, usually 

 the latter. The nearer the center, the thicker the 

 cream will be. Most hand separators will do effi- 

 cient work and skim cream varying in richness from 

 15 to 40 per cent., and in several cases to 50 per cent., 

 of butter fat. An increase in the speed of the 

 machine increases the richness and lessens the 

 amount of cream, while a decrease in the speed in- 

 creases the volume of cream and lessens its per cent, 

 of fat. For ordinary purposes the cream screw 



