STERILISATION 



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the inside of each jar, being no greater, except when 

 cooling, than in the retort on the outside of the 

 packages, there is less danger of the jars bursting. 

 Retorts admit steam at the bottom, having an es- 

 cape valve at the top of the opposite end. If prop- 

 erly constructed, they withstand fifteen pounds to 

 the square inch, representing a temperature of 250 

 degrees Fahrenheit. A convenient sized retort will 

 hold fifty cases, or one hundred dozen pound jars of 

 preserves. 



The principal danger in sterilizing glass goods is 

 from cracking, which will surely happen to a great 

 many jars if a direct draft of outside air reaches 

 them while hot, for they must cool very slowly. 

 Even tin will burst if the retort is suddenly opened 

 while at a high temperature, for the preserves con- 

 tinue to develop steam inside the cans, while the 

 sudden removal of pressure around them withdraws 

 its resistance to that within, and their sides give 

 way. 



The crop from a few acres may easily be pre- 

 served with gasoline heat. The first step in such 

 case is to make a frame of half -inch pipes to hold 

 galvanized iron tubs about two feet above the floor. 

 The tubs should be fourteen inches deep, twenty 

 inches wide, and six feet long. A couple of smaller 

 ones for syrup and other special uses will be conve- 

 nient. For a thousand trees in full bearing six tubs 

 will do very well. Under them place a double row 



