s 
BULLETIN 240, U. S. DEPARTMENT OF AGEICULTUKE. 
machines is shown in figure 3. The machine consists of a large tank 
divided into two compartments and two smaller tanks. These con- 
tain water at different temperatures. Bottle-holding frames are car- 
ried through these compartments on an endless chain in the manner 
shown in the drawing. The raw milk is bottled and capped with 
water-tight caps, then placed on the bottle-holding frames of the 
machine on the loading end. The bottles of milk are then carried 
through the preheating compartment into the pasteurizing compart- 
ment where they remain for about 30 minutes. From the pasteuriz- 
ing tank the bottles are carried to the cooling tank, then to the 
refrigerating tank, after which they are removed from the machine. 
The process is continuous, the bottles of milk being loaded at one 
I h. p. motor 
UNLOAD 
Fig. 3. — Machine for continuous pasteurization of milk in bottles. The bottles have 
water-tight caps and are conveyed on an endless chain through water compartments 
of various temperatures. 
end, heated, held, and cooled, then unloaded at the other end of the 
machine. The temperature of the water in this machine is auto- 
matically controlled. 
There are other machines on the market which differ in the man- 
ner in which the bottles are carried through the tanks of water, but 
the principle is about the same. 
In other types of pasteurizers the bottles are not submerged in 
water and consequently water-tight caps are not necessary. The 
bottles of milk are heated and cooled by sprays of water and ordinary 
caps are used and protected from water by a metal covering. One 
of this type of in-the-bottle pasteurizers is shown in figure 4. The 
