FROM THE PRACTICAL VIEWPOINT 



by means of the paddles also has a tendency to 

 break up the fat globules into smallei particles, 

 which do not so readily rise to the surface. 



It is difficult to maintain a uniform temperature 

 with this type of machine, since the amount of 

 heating fluid is comparatively small, and when 

 there is either a fluctuating flow of milk or a vary- 

 ing milk temperature, there is no automatic con- 

 troller which can be made to respond to sudden 

 changes in temperature quickly enough to check 

 or increase the flow of steam into the heating 

 chamber. 



As a general proposition, also, the introduction 

 of steam directly into a heating chamber is to be 

 avoided, since there is always the possibility that 

 certain portions of the steam will strike the heat- 

 ing surface before becoming condensed, and will 

 therefore heat these portions to an abnormally 

 high point. 



Second Type. There are several heating de- 

 vices made by different firms, and having certain 

 variations in the details of their construction, 

 which embody the same general principles. These 

 are illustrated in Figs. 3, 4, 5. In all of these 

 the milk flows between two or more upright, heated 



47 



