STERILIZATION OF MILK 191 



that unusual types of bacteria have developed to great 

 extent and have probably made it unwholesome. 



4. Use of Preservatives. The facts given elsewhere 

 concerning the use of preservatives apply equally in the 

 case of milk. The use of any preservative is always to 

 be deprecated, and, so far as concerns the housewife, the 

 rule should be that no preservatives should ever under 

 any circumstances be used in milk. 



It should be borne in mind that none of these devices 

 remove dangerous disease germs. They make it pos- 

 sible to keep the milk longer, but do not make it more 

 wholesome if it chances at the outset to contain any 

 mischievous bacteria. 



5. Sterilization. Sterilization of milk has become 

 extremely common in the last fifteen years. It has been 

 recommended widely by physicians, it has been introduced 

 by milk-supply companies, and it has very frequently been 

 adopted in private families. In our large cities, during 

 hot weather, families unable to obtain ice protect their 

 milk by heating it. The most common method is that 

 of simple boiling, a boiling temperature being sufficient 

 to kill most of the bacteria present. Not all of the bac- 

 teria are killed by this method, and hence the milk is 

 not strictly sterilized, for this term means the destruc- 

 tion of all bacteria. But the boiling does destroy most 

 of them, and since it is an extremely easy method to use, 

 the boiling of milk is a very general practice. Absolute 

 sterilization is possible by using a heat higher than that of 

 boiling, but this cannot be done in the ordinary kitchen. 

 In common use sterilizing simply means boiling, and we 

 $hall so use the word, although it is not strictly correct, 



