pasteuriza¬ 
tion 
66 HOUSEHOLD BACTERIOLOGY 
resisting microbe destroyed, a third steaming is given. 
This is called intermittent sterilization. No. 5 should 
keep indefinitely. It will, of course, dry away slowly 
through evaporation. 
No. 6 is like No. 5, only closed from the air which 
passes through the cotton wool, and if the cork was 
sterilized it is impervious to dust. Some corks are not 
solid enough to keep the bacteria from growing 
through the cavities. Such corks need to be dipped 
in melted paraffin. They are then as tight as a glass 
stopper. No. 6 should keep, as well as No. 5. 
The woman who put up her grape juice in corked 
bottles, to find some years after that she had grape 
wine, either did not thoroughly sterilize the juice, the 
bottles and the corks, or the latter allowed dust to pass 
or mold to grow through. She should have covered 
the corks with melted paraffin to prevent such a pos¬ 
sibility. 
No. 7 varies from No. 5 only in the time and the 
degree of heat to which it was subjected. In the case 
of milk—where the process is most commonly used— 
this is called Pasteurization. It is sufficient to kill 
most if not all the souring bacteria and all the disease- 
producing or pathogenic germs. It does not affect as 
unfavorably the digestibility of the milk as steriliza¬ 
tion, 212 0 F, or higher is found to do. 
Pasteurized milk will spoil eventually because not 
all the germs are killed. Pasteurization is valuable for 
protection from disease germs and to improve the keep- 
