GEORGE W. PUTNAM 



421 



to operate, owing to having to heat and cool successively the glass bottles, cases, and 

 parts of the machine in addition to the milk itself. The consumer must also become 



Fig. 2. — Pocket-type pasteurizer; equipped withleak-protector inlet and outlet valves; external 

 surface cooler (above). 



accustomed to receiving bottles which are not completely filled, since an empty space, 

 I inch deep, remains at the top of the bottle, owing to the difference in volume be- 

 tween the hot milk during pasteurization and the cold milk after cooling. A real ad- 



