220 BUTTER-MAKING. 
containing the milk into cold water,—covering the jar so as 
to prevent outside contamination,—and then heat up the 
water gradually. Care should be taken not to insert these 
bottles suddenly into scalding hot water, or to let the steam 
strike them, for either is likely to crack the bottles. Care 
should be taken also to exclude water from milk used for 
starters. It is advisable to heat this milk, for the starterline, 
as high as possible in scalding water, say up to about 200° F. 
The sample may assume a cooked taste, but this will soon 
disappear after the starter has been carried on a few days. 
The milk should be left at this high temperature for about ten 
or fifteen minutes. A longer time does no harm. Then the 
milk is gradually cooled to about 80° F. This high temperature 
is desirable, because the germs present in the commercial cul- 
ture may be somewhat dormant. This high temperature would 
tend to revive them more quickly than a lower temperature. 
Great care should always be taken to cool the milk previous to 
inoculating it with the pure culture, otherwise the germs present 
in the pure culture will be destroyed. 
Inoculation.—The next step is to inoculate the prepared 
milk with the pure culture obtained from the laboratory. The 
bottle which contains the pure culture is carefully opened, then 
the bottle containing the culture is turned over and emptied 
into the pasteurized milk. The bottle should be held down 
closely to the mouth of the jar containing the sterile milk, in 
order to prevent too much contamination from the air. Then 
the milk containing the pure culture is thoroughly stirred and 
set away in a room where the temperature is about 70° F. 
This will gradually cool the milk from 80° to 70° F., and in 
about twenty to forty hours the milk will sour and coagulate. 
Germs in nearly all of the liquid cultures are rather slow in 
acting upon the milk, undoubtedly due to the dormancy of the 
germs, and to a comparatively few of them being present in 
the pure culture. When the powdered cultures are used, a 
little more care is essential to get the powder thoroughly min- 
gled with the milk. It is a trifle more difficult to get the 
