188 PRINCIPLES AND PRACTICE OF MILK HYGIENE 
cidal power is active (see page 43). As a general rule, 
however, it is best to run the milk over a cooler immedi- 
ately after it is drawn from the cow. When the milk 
is emptied from the milk pail directly into the tank of the 
cooler and passes from the cooler into a bottling machine, 
it is important to milk the cows in such order that milk 
of low fat per cent. and milk of higher fat per cent. 
will be mixed in passing through the bottling machine. 
After being cooled, the milk should be stored in a 
cool place, such as a refrigerator, ice-water tank, or 
spring house, until sent to the railroad station. The in- 
spector should note the facilities provided for this pur- 
pose. Milk can be kept cooler in a tank of ice water 
than in a compartment in which the air is cooled by ice, 
unless the latter is well insulated. ‘The temperature 
of air in an ice-cooled refrigerator is usually not much 
below 50° F., whereas the temperature of water in which 
ice is floating is generally as low as 40° F., and often 
lower. 
While being hauled to the station, the milk should be 
protected from the heat in summer. This is usually 
done by covering the cans with a woolen blanket. A 
wet blanket is more effective than a dry one. Jackets 
of hair enclosed in canvas are sometimes used to cover 
the cans. Ice in small pieces should be placed in the 
boxes in which bottled milk is shipped. 
The surface of the milk cooler and the inner sur- 
face of all milk vessels should be examined for cleanli- 
ness, rusted areas, and open seams. Uncleanliness is 
indicated by an odor of sour or putrid milk and by the 
presence of particles of coagulated milk. These parti- 
cles may be very small, sometimes no larger than a pin’s 
head. All surfaces with which milk comes in contact 
