MILK 209 



then less care to keep the bottles upright will be needed. But corks 

 must be firmly tied down, when sterilizing is done, to prevent their 

 being forced out. 



To heat the milk in these bottles, it is necessary to put them into 

 a boiler upon a perforated false bottom or platform to keep them 

 from direct contact with the bottom of the boiler. Water is poured 

 in around the bottles to the same level as the milk. This water is 

 heated, and as the temperature of the milk lags some ten or more 

 degrees behind that of the water, the latter must be raised to the 

 boiling point, when the bottles can be removed and cooled, gradually, 

 to prevent their cracking. As it is advantageous to cool the milk 

 rapidly, the use of tin cans of similar shape as the bottles is recom- 

 mended. Such cans may be put at once in iced water. The part of 

 the bottles above the milk is not pasteurized, and hence the bottles 

 should be kept upright to prevent contamination. 



At 170, water begins to steam, and simmer; while boiling be- 

 gins at 190 to 195, at which time the milk in the bottles has 

 reached 185. ^ 



If it is desired to pasteurize at a lower temperature, say at 155, 

 the water must be held at this point for half an hour, and at 140 

 for about an hour. This will take more care and time than the 

 method described. 



To use this boiler as a sterilizer it is only necessary to boil the 

 water for about ten minutes to half an hour, or longer. The time 

 will depend on whether the bottles are taken out and cooled at once 

 or left in the hot water to cool gradually. In the latter case the 

 boiling can be shorter. 



The boiler can also be used as a steamer, by putting less water 

 in and putting on the cover. When bottles are plugged with cotton 

 it is necessary to remove the cover when the steaming is completed 

 to prevent the plugs from getting wet by the condensing steam. In 

 this case the plugs and upper parts of the bottles become sterilized. 

 If desired, the plugs may be withdrawn after sterilizing, and steril- 

 ized corks substituted, care being exercised to prevent the finger from 

 touching the bottom of the corks or the lips of the bottle. Or, the 

 cotton plugs can be made impervious by saturating them with melted 

 paraffine. This, of course, must not be done until after the steaming 

 is completed. (N. J. B. 152.) 



Supposed Effect of Thunderstorms. A consideration of the 

 subject of the souring of milk would not be complete without refer- 

 ence to the effect of electricity. The popular belief that thunder- 

 storms will sour milk is so widespread that it would seem as if there 

 must be some foundation for it. It has been asserted by many that 

 the ozone produced in the air by electricity causes the milk to be- 

 come sour. In experiments in which electric sparks were discharged 

 over the surface of the milk, however, little or no effect has been 

 produced upon it. The conclusion is that electricity is not of itself 

 capable of souring milk or even of materially hastening the process. 

 Nor can the ozone developed during the thunderstorm be looked 

 upon as of any great importance. It seems probable that the connec- 



