MILK-PLANT EQUIPMENT. 
21 
have been heated to the desired temperature to the point where cool- 
ing is begun. The heating with the in-the-bottle pasteurizer is 
usually accomplished by passing sprays of hot water over the bottles. 
(See figs. 11 and 12.) Either a special cap is used on the bottle 
or the bottles are covered with a specially constructed pan. In the 
latter case the hot water usually flows through small holes in this 
pan and forms a thin film around the bottles. Where the special 
cap is used the pans are not required. The cooling is accomplished 
by changing from hot water to cold. After the milk is heated, held, 
and cooled it may remain, in some types, in the machine and be kept 
at a low temperature until time for delivery. With some types of the 
in-the-bottle pasteurizer the milk in the bottles is heated by live 
steam and the cooling is accomplished by immersing the bottles in 
clean, cold water. With other types the bottles are heated by im- 
mersing in vats containing hot water. 
Fig. 12. — Front view of in-the-bottle pasteurizer, showing the fine sprays of hot water 
used in heating the milk. 
