182 BUTTER-MAKING. 



lieve that the last few degrees the milk is being heated are the 

 most expensive; but if the steam is properly guarded from 

 being condensed, or wasted, it does not cost any more to heat 

 the milk the last few degrees than it does to heat the first degrees. 

 While the temperature on the milk side is low, much more 

 steam is consumed, and it is also used more rapidly. During 

 the last heating of the milk or cream less steam is being con- 

 densed and the condensing proceeds more slowly. 



When the temperature on the steam side is 220 F. and on 

 the milk side is 40 F. during the same time, twice as much 

 heat will pass through the heating wall as if the temperature 

 of the milk side were 130 F. In the first case the difference 

 in temperature on both sides would be: 220-40=180 F. In 

 the second instance it would be: 220 ^130 = 90.- F. 



(5) Proper Utilization of Steam Turned into- the Pasteurizer. 

 The cost of pasteurization will evidently vary under different 

 conditions and with different kinds of pasteurizers. In order 

 to reduce the . cost of pasteurization to the minimum, it is 

 essential that all steam turned into the pasteurizer be properly 

 utilized. The pasteurizer, as well as the steam-pipes, should 

 be properly insulated in order to prevent unnecessary conden- 

 sation of steam. According to experiments carried on by 

 Dr. Storch, all steam contains more or less air. By making 

 a device on the pasteurizer for the escape of this air better 

 results were obtained. By the use of such a vent it was made 

 possible to heat 1890 pounds of water from 52 F. to 185 F., 

 while without this air device, and with the same amount of 

 heat, only 1467 pounds of water were heated. That is, by 

 this device he made a gain of 30% in the heating efficiency 

 of the pasteurizer. The contrivance used was simply a pipe 

 attached to the bottom of the pasteurizer and extending down 

 below the pasteurizer about 2 feet, then turned or bent, and 

 brought up vertically a few inches above the bottom of the 

 pasteurizer. The mouth of the pipe was then turned over. 

 This pipe accomplishes two purposes. It removes condensed 

 water from the pasteurizer, and also the accumulated air. It 



