67 



easily be removed by "a ground joint like an ordinary sink 

 plug." They are submerged in a tank which is filled with 

 water, which also passes through the inner cylinder as indi- 

 cated in the illustration. 



With this cooler and cold water the milk can be reduced 

 from 25 to 40, says the professor. 



I have show r n how Hochmuth and Lawrence protected 

 the milk against the air by a mantel, and the exacting Prof. 

 Bitter protected the Smith cooler, Fig. 68, by a cover. 



Indeed nearly all these surface coolers are easily cov- 

 ered at a slight expense for those who so desire, and unless the 

 air is pure it is certainly safer. 



A. H Barber & Co. makes coolers similar to the Hill 

 heater, and on the same principle are the Miller coolers de- 

 scribed with his heater on page 36. 



CENTRIFUGAL COOLERS. 



THE BERGEDORFER Machine works (Germany) make 

 a cream cooler illustrated in Fig. 71. It consists of an in- 

 verted cone of cast iron 

 in which revolves a simi- 

 lar shaped drum driven 

 by P. The cream enters 

 from C, the lower bear- 

 ing of the drum, and 

 escapes through the per- 

 forated upper part of the 

 drum into the gutter 

 and leaves at CR. 



The water enters at 

 W and overflows through 

 the siphon O. 



The cream is here, as 

 in the centrifugal heat- 

 ers, spread in a thin film 

 over the drum. The speed 

 given is 800 revolutions 

 per minute. 



If the friction of the 

 water be not a too great 

 objection to this system 

 in larger apparatus, it 

 seems to me there are 

 great possibilities in de- Fig. 71. 



