210 THE MILK QUESTION 



Emphasis is laid on the fact that only fresh, clean milk, which 

 has been kept cold, should be used. 



After the bottles have been thoroughly cleaned they are placed 

 in the tray (A) and filled to the neck. Then put on the corks or 

 patented stoppers without fastening them tightly. 



The pot (B) is now placed on the wooden surface of the table or 

 floor and filled to the supports (C) with boiling water. 



Place the tray (A) with filled bottles into the pot (B) so that the 

 bottom of the tray rests on the supports (C), and put cover (D) 

 on quickly. 



After the bottles have been warmed up by the steam for five 

 minutes, remove the cover quickly, turn the tray so that it drops 

 into the water, replace the cover immediately. This manipulation 

 is to be made as rapidly as possible to avoid loss of heat. Thus it 

 remains for twenty-five minutes. 



Now take the tray out of the water and fasten the corks or 

 stoppers airtight. Cool the bottles with cold water and ice as 

 quickly as possible, and keep them at this low temperature until 

 cold. 



Use the milk from the bottles and do not pour it into another 

 vessel. 



The milk must not be used for children later than twenty-four 

 hours after pasteurization. 



The attempt is frequently made to pasteurize milk in the 

 home by simply placing the bottle of milk as it is received 

 in a pot of water. The water is then brought to the boiling- 

 point for a variable length of time and finally cooled. At 

 first glance this appears to be an entirely satisfactory pro- 

 cedure, but in some experiments upon the subject I have 

 shown that the depth of the water in which the bottle is 

 immersed markedly affects the results. The neck of the 

 bottle must always project above the water, and unless the 

 pot has a lid the upper layers of the milk may therefore 

 escape heating, especially if the contents have not been well 

 shaken up, for the thick cream prevents circulation of the 

 liquid. Therefore, contrary to what might be expected 

 from the physics of fluids, the top layers of the milk in the 



