CHAPTER III 



HOLDERS 



As previously stated, the New York City De- 

 partment of Health was the pioneer among health 

 authorities to require that milk, in order to be offi- 

 cially considered to be pasteurized, must be held, 

 after heating for a definite length of time. When 

 this regulation was adopted no holding device was 

 upon the market which was suitable to be used on 

 a commercial basis. Since that time most of the 

 manufacturing firms making milk-handling ma- 

 chinery have constructed and placed upon the mar- 

 ket one or more forms of holding apparatus. These 

 differ in detail, and to a considerable extent in the 

 efficiency with which they operate. In general, 

 however, it may be said they are naturally divided 

 into two classes: 



First, those which may be termed absolute 

 holders, and 



Second, those which are of the continuous or 

 flow type. 



Absolute Holders 



The absolute holders are so called for the rea- 

 son that the milk, after being heated, is all held 



