PASTEURIZING MILK. 
15 
milk bottles for each sample were inoculated with equal amounts of 
sour milk. One of these infected bottles was then steamed for two 
minutes and filled with hot pasteurized milk and the other contami- 
nated bottle not heated was filled with some of the same pasteurized 
milk, which had been previously cooled in a sterile bottle. An exami- 
nation of Table 4 shows, when the figures in columns A and C are 
compared, that the infectious material added to the bottle was en- 
tirely destroyed by the method of bottling, at least so far as bac- 
teriological methods can detect, since any marked increase in column 
C would show infection. Column B shows the bacterial counts 
obtained by putting cold pasteurized milk into infected bottles. From 
these results it is evident that the process of bottling hot pasteurized 
milk in hot, steamed (two minutes) bottles entirely eliminates the 
factor of bottle infection, which may often be serious in the ordinary 
processes of pasteurization on a commercial scale. 
Table 4. — Destruction of bottle infection during the process of bottling hot 
pasteurized milk. 
Sample No. 
Raw milk. 
Hot pasteur- 
ized milk in 
hot steamed 
bottles. 
Cold pasteur- 
ized milk in 
cold infected 
bottles. 1 
Hot pasteur- 
ized milk in 
steamed in- 
fected bot- 
tles.* 
A 
B 
C 
24 
Bacteria 
per c.c. 
24, 900 
94, 000 
235, 000 
176,000 
97,000 
230, 000 
124, COO 
190, 000 
Bacteria 
per c.c. 
380 
860 
5,400 
2,200 
5,900 
6,300 
920 
7,500 
Bacteria 
per c.c. 
6, 400, 000 
5, 600, 000 
1,330,000 
1,510,000 
235, 000 
355,000 
305,000 
Bacteria 
per c. c. 
460 
25 
27 2 
600 
4,800 
2,400 
4,100 
28 
29 2 
30 2 .... 
5,800 
950 
31 2 
35 2 
8,800 
1 Bottles had been previously infected with several cubic centimeters of sour milk. 
2 Bottle infected with old, sour, pasteurized milk. 
The question naturally arose as to whether or not pasteurization 
in bottles would destroy infection in bottles specially infected before 
being filled with raw milk, To determine this point nine samples 
of milk were pasteurized which had been previously steamed and 
cooled. The results are shown in Table 5. One bottle for each 
sample was steamed, cooled, infected with several cubic centimeters 
of sour milk, and filled with some of the original raw milk. Samples 
were then plated from this bottle to show the extent of the infection, 
the results of which may be found in column B of the table. The 
bottle of infected raw milk was capped with a seal cap- and the milk 
pasteurized directly in the bottle. Plates were made directly after 
the heating and the bacteriological results are shown in column C. 
Any increase in the counts in column C over those in column A shows 
