676 
In order to satisfy public health requirements pasteurizers must 
be efficient in operation, permitting a definite quantity of milk to be 
heated to a definite temperature for a definite time (Russell). They 
must be easy of control, the milk must be heated uniformly through- 
out, the apparatus must be simple in construction, easily cleaned, eco- 
nomical in use, and arranged to safeguard against reinfection of the 
milk. Finally, proyision must be made for rapid cooling. Giyen 
an apparatus of proper construction more depends upon the intelli- 
gence and care with which it is run than upon the machine. Xo pas- 
teurizer is automatic. For instance. I haye found that the milk 
pasteurized in a standard machine contained many more bacteria 
after the process than before. This was not the fault of the machine, 
but due to ignorance and uncleanliness. 
The following figures show the efficiency of a commercial pasteur- 
izer operated under intelligent though not skilled superyision : 
I ! 
Colonies per cubic cen- 
timeter. 
Colonies per cubic cen- ! 
timeter. 
Before pas- 
teurization. 
After pas- ' 
teuriza- 
tion. 
Before pas- 
teurization. 
After pas- 
teuriza- 
tion. 
92,000 
2,200 
380,000 
83,000 
142,000 
6,000 ! 
214,000 
87,000 
71,000 
6,000 
6,700 
28,200 
93,000 
6,900 
900,000 
100,000 
105,000 
38,000 
7,000,000 
70,000 i 
1,680,000 
80,000 ■ 
74,000 
35,000 
The aboye figures were obtained from a type of machine known as 
a “ Flash pasteurizer,'* in which the milk is heated momentarily at 
73° to 71° C. ■ ^ 
The pasteurization of milk is such an important public health 
measure that it should be under the immediate and constant super- 
yision of the health officer. The milk should be heated a definite 
temperature for a definite time and then promptly cooled and prop- 
erly labeled. 
RESUME ADVANTAGES AND DISADVANTAGES. 
Pasteurization sayes liyes and preyents sickness. tVeighing against 
this great merit we have certain disadyantages connected with the 
heating of milk. That there are two sides to the question may be 
judged from the fact that those who haye giyen the matter careful ^ 
consideration come to diametrically opposite conclusions. From a 
theoretical standpoint some belieye pasteurization to be an unsatis-- 
factory and yery feeble way out of a yery difficult situation. From 
a practical standpoint, others find in pasteurization our only practi- 
