THE PASTEURIZATION OF MILK 



exact time at which the last milk enters any sin- 

 gle compartment of the holder, and then observ- 

 ing the exact time at which the first milk flows 

 from the same tank. The difference indicates the 

 minimum holding time. Of course, some of the 

 milk is held for a longer time than that which is 

 thus indicated, but we are sure that none is held 

 for a less time. 



It will be found that the time as observed in 

 this way is nearly equal to that which we obtain 

 by calculation, allowances being made for varia- 

 tions in the mechanical exactness with which the 

 machine operates. 



It will be seen from the illustration that the 

 various holding tanks are insulated by a cork 

 jacket, so that little heat is lost during the hold- 

 ing period. It will be noted, however, that the 

 pipes leading from the holding tanks to the cen- 

 tral valve are not insulated, and in this condition 

 the milk which lies in these pipes during the time 

 of revolution may, and probably will, become 

 cooled, and the effectiveness of the bacterial de- 

 struction will be impaired. This having been 

 brought to the attention of the manufacturers, they 

 provided insulating jackets for the pipes as well 

 104. 



