27 



CHAPTER II. 



THE PASTEURIZING HEATER. 



Continuous Heater. 



In writing the history of the apparatus which have been 

 and are used practically, I try to mention them in their proper 

 chronological order, but lay more stress on grouping them to- 

 gether according to the principles involved. 



It must always be remembered that a pasteurizing ap- 

 paratus must consist of a heater and a cooler unless indeed 

 the same apparatus is used for both as in Prof. Russell's, John 

 Boyd's, Potts' and others. 



CONTINUOUS HEATER. 



In Denmark the first 

 heater used was the one 

 constructed by the late 

 Prof. Fjord for heating 

 the milk for the separa- 

 tors Fig. 13. This con- 

 sists of a strong wooden 

 barrel D in which a 

 tinned copper vessel C is 

 inserted. A stirring ap- 

 paratus K prevents the 

 milk, which enters at M 

 through H, from scorch- 

 ing on the side. Steam 

 is introduced by F if ex- 

 haust and E if direct 

 steam is used. Con- 

 densed water escapes 

 through G. The milk 

 outlet not shown in the illustration, is above the wood. When 



