FROM THE PRACTICAL VIEWPOINT 



ing the milk to flow in a thin layer over pipes 

 which are heated to about 162 to 165. The milk 

 is then immediately cooled. It is claimed that bac- 

 teria which are resistant to 142 temperature are 

 nevertheless considerably weakened by this heat- 

 ing,, and are completely destroyed at the brief 

 heating of 162. It is also claimed that the cream 

 rises in a more satisfactory manner when the ad- 

 ditional heating is employed. The feature of ap- 

 plying a brief superheating temperature to milk 

 already pasteurized has been covered by a patent. 



It must be evident, when a little thought is 

 given to the matter, that in order for any con- 

 tinuous holder to be reliable, the rate of milk flow 

 must be uniform. In very few forms of appara- 

 tus is there any attempt to properly control the 

 rate of flow. When milk flows by gravity, the 

 rate at which it flows into the heater will depend 

 partly upon the volume of the fluid in the tank 

 which feeds the machine. W T hen a pump is used 

 to supply the heater, its rate of delivery may be 

 influenced by the steam pressure, or by the degree 

 to which the steam valve is opened, or by the con- 

 dition of the valves and pistons. In places where 

 a gravity flow is employed, it is not a difficult mat- 

 131 



