26 BULLETIX 240, U. S. DEPARTMENT OF AGRICULTURE. 
2. Bottles should be steamed at least two minutes before being 
filled with milk in order to destroy beat -resist ant types of organisms 
which might survive the pasteurizing temperature and thereby in- 
crease the bacterial count. 
3. Care must be taken to record the temperature in the bottom of 
the bottle during the heating process. When milk at an initial 
temperature of 50° F. is heated in bottles without agitation in water 
at about 146 = F. the temperature of the milk in the top of the 
bottle will reach 140 ~ F. about nine minutes before that in the bot- 
tom. The temperature of the milk during the process of pasteuriz- 
ing in the bottle should be recorded by placing a thermometer in a 
control bottle with the bulb of the thermometer about one-half inch 
from the bottom. The milk should be heated for 30 minutes at 
115 c F. 
4. When bottles are heated and cooled under water care should 
be taken not to use bottles with chipped or otherwise imperfect tops, 
since the seal caps may allow leaks during the process of pasteuriz- 
ing. It is advisable for the users of patented seal caps to assure 
themselves that the caps are water-tight, since leaking caps may 
cause dangerous infections, particularly if the cooling water is pol- 
luted. 
5. The process of bottling pasteurized milk while hot in hot 
steamed bottles causes equally good bacterial reductions as does 
pasteurization in bottles. Even with the same length of exposure 
of 30 minutes and the same temperature of 145° F. the bacterial 
reductions are often much greater than those produced by pas- 
teurization in bottles. 
6. In the process of bottling hot. bottle infection is eliminated, 
even when several cubic centimeters of old. sour milk are added to 
bottles before filling. The two-minute steaming period to which 
the bottles are subjected before filling with hot milk is sufficient to 
destroy the contamination, at least so far as bacteriological methods 
can detect. 
7. Laboratory experiments indicate that milk may be pasteurized, 
bottled hot. capped with ordinary cardboard caps, and cooled by a 
blast of cold air. 
8. It is probable that if milk is cooled from 145° to 50 c F. within 
five hours no more bacterial increase will take place during the slow 
cooling than would take place if the milk were cooled immediately 
to 50° F. TThether or not this will be true under commercial con- 
ditions can be determined only by future experiments. 
9. So far as the laboratory experiments indicate, when milk is 
heated to 145° F. for 30 minutes, the bottling of the hot pasteurized 
milk followed by slow, gradual cooling has no more appreciable 
