CHAPTEK III. 



THE PASTEURIZING HEATER. 



In writing the history of the apparatus which have been and are 

 used practically, I find it impossible to mention them in their proper 

 chronological order. 



It must always be remembered that a pasteurizing apparatus 

 must consist of a heater and a cooler unless indeed the same appara- 

 tus is used for both as in Prof. Reessell's, John Boyd's and others. 



In Denmark the first heat- 

 er used was the one constructed 

 by the late Prof. Fjord for heat- 

 ing the milk for the separators 

 Fig. 4. This consists of a 

 strong wooden barrel D in 

 which a tinned copper vessel c 

 is inserted. A stirring appara- 

 tus K prevents the milk, which 

 enters at M through H, from 

 scorching on the side. Steam is 

 introduced by F if exhaust and 

 E if direct steam is used. Con- 

 densed water escapes through G. 

 The milk outlet not shown in 

 the illustration, is above the 

 the wood. The cooler used is 

 generally of the Lawrence 

 type. 



Fi - *- In Sweden the first Laval 



Pasteurizer (see Fig. 14, page 21) represents another principle. The 

 milk is pumped up over a series of disks, the upper ones being heat- 

 ed by steam, the lower ones cooled by water. 



Both these were designed originally for pasteurizing the skim 

 milk, a practice to which the economical sense of the Scandinavian 

 farmers insisted on soon after the introduction of the separators. 



The Fjord heater has the advantage of holding the milk a little 



