16 
BULLETIX 240. U. 5. DEPARTMENT OF AGBICE'LTirBE. 
the amount of infection introduced by placing milk in an infected 
bottle. It is evident that in only two samples. Xos. 28 and 35. was 
the infection entirely destroyed. 
Table 5. — Destruction of bottle infection during the process of pasteurization in 
bottles. 
Sample Xo. 
Raw milk. 
Milk pasteux- Sorties in- , ni , ^„ „*_„ 
feetedwiTh M ^P a ?I eux - 
ized in clean 
previouslv 
borrles. 
sour milk and 
ized in 
filled with ^fd 
raw milk. : botTles - 
A 
B 
c 
Bacteria 
Bacteria 
Bacteria 
Bacteria 
per c. c. 
■per c. c. 
per c. c. 
per c. c. 
24.900 
570 
3. 700. 000 
2.090 
94.000 
2,2 : 
3.300.000 
6.200 
235.000 
7,600 
760.000 
9,500 
176,000 
11,400 
- 650,000 
11,000 
97,000 
8,350 
530, 000 
20,000 
230,000 
5.500 
645.000 
20,900 
124,000 
1.500 
400.000 
28.600 
190,000 
9.300 
230,000 
9.600 
38, 000 
5.600 
92.000 
17.700 
24.. 
25.. 
27i. 
28.. 
29i 
30i 
31i 
351 
1 Bottle infected with, old, sour, pasteurized milk. 
It is quite possible that infection from unclean bottles might be- 
come a serious factor in bottle pasteurization. TThen one considers 
that in pasteurization in the bottle the bacteria which are left are 
either heat-resistant vegetative cells or spores, it is easy to see that 
if a large number are left in a bottle and it is again filled with milk 
and pasteurization again performed in the bottle these same bacteria 
will again survive and increase the number left. It is advisable to 
steam the bottles at least two minutes before filling with milk for 
pasteurization in the bottles. 
COOLING MILK WHICH HAS BEEN BOTTLED ROT. 
When a water-tight cap is used it is. of course, possible to bottle 
the milk while hot and cool by submerging in cold water, but experi- 
ments have been made with a process by which the milk may be 
cooled in bottles capped with ordinary cardboard caps. Briefly 
stated, the process consists in exposing the hot bottled milk to an air 
blast. The air-blast system is used at present in the hardening rooms 
in ice-cream plants, but. so far as known, this system has never been 
applied to the cooling of milk. 
Several experiments were tried on a laboratory scale which gave 
promising results. When a bottle of hot milk is allowed to cool in 
still air a film of warm air forms about it which can move away only 
by convection, and. naturally, the cooling process is slow. If some 
means were provided for moving the film of warm air and forcing 
