ii2 CLEAN MILK 



warm milk for this period without great increase in germs, the 

 only way is to cool each pailful as soon as it is milked. 



Then the milk may be kept an hour or more before it is mixed 

 and bottled. I started out prejudiced in favor of cooling milk by 

 immersion of cans or bottles in ice water, but did not find it 

 practicable, except under certain conditions (see p. 118). There is 

 no doubt but that the cooler and all apparatus, not necessary in 

 handling milk, should be abandoned when possible. The oftener 

 milk touches objects the more likely will contamination result, es- 

 pecially by aeration in a dusty atmosphere. But immediate cooling- 

 is essential. 



"When milking begins, as soon as a milk pail is filled, the milk 

 should be taken directly to the milk house and the milk poured into 

 the strainer, which is placed in the receiving tank of the cooler. 

 The milk runs over the cooler and is received in the shipping can, 

 which, when filled, should be immersed in a tank of cold or iced 

 water above the shoulder of the can with the cover of the can left 

 off until shipping time. The milk should be cooled below 50 F. 

 Two types of coolers or aerators are in common use. Aeration, or 

 exposure of the milk to air, is not essential if the milk is with- 

 drawn from the cow in a cleanly manner, but if the milk is more 

 or less contaminated with manure, by impure air or by odors caused 

 by imperfect feeding, aeration frees it to an extent of so-called 

 animal odor. Aeration is inadvisable, in so far as the milk is ex- 

 posed to germs in the air during the process. The coolers in ordi- 

 nary use do, however, aerate the milk at the same time that the 

 milk is cooled. The conical cooler (Fig. 15) may be employed when 

 a moderate quantity of milk is to be handled, but requires more 

 labor, as, in order to cool the milk satisfactorily, the water in the 

 aerator must be constantly stirred to continually change the layer 

 of water lying against the inner surface of the tin over which the 

 milk runs. This aerator is fitted with an inflow and outflow pipe. 

 for running water, at either side of the' base of the aerator, but. 



