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 shown 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 

 \V 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 . 



