184 PRINCIPLES AND PRACTICE OF MILK HYGIENE 



lower part of this space and discharges at the top. The 

 milk is poured into a reservoir or tank at the top of 

 the corrugated metallic sheets and, passing out through 

 perforations in the bottom of the reservoir, flows slowly 

 downward in a thin layer over the corrugated surfaces 

 to a trough at the bottom, from which it passes into the 



Fio. 19. Corrugated type of cooler. 



collecting can or bottling apparatus. A late model of 

 the corrugated type of cooler is conical in form and is 

 provided with a metal cover to protect the milk from 

 contamination while it is passing over the cooling sur- 

 face. 



(c) The tubular cooler (Fig. 20) consists of a num- 

 ber of pipes arranged horizontally, one under the other 



