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CITY MILK SUPPLY 



from the heater or holder to heat the cold raw milk on its way to the heater. 

 There are several ways of arranging the apparatus to do this; the 

 heating of the cold milk may take place within the heater or in the cooler. 

 If it is done within the heater the pasteurized hot milk in the course of its 

 passage to the cooler through the machine is forced over a surface against 

 the other side of which the incoming cold flows. So the hot milk gives 

 up heat to the cold milk. In case a holder is used with such machines 

 the hot milk from it is returned to the heater and following the usual 

 course to the cooler heats the raw milk on the way. Where the regenera- 



Courtesy of Robert Burnett. 



FIG. 42. Pasteurizing milk in the bottle at Deerfoot Farms, Southboro, Mass. 



tion is accomplished in the cooler, the pasteurized hot milk passes from 

 either the heater or holder to the cooler and flowing down on the outside 

 of the cooler warms the cold milk which in some types of coolers passes 

 through the inside of the cooler and in others runs down one side of the 

 cooler while the hot milk runs down the other. By the regenerative 

 process the temperature 'of the cold raw milk on its way to the cooler is 

 raised through 40F. or more while the hot milk that is passing over the 

 cooler is chilled a like amount; thus a saving of both steam and ice is 

 effected. 



The invention of the Dacro metal cap by William Painter in 1892 an 



