34 PRESERVATION OF FOOD. 



process in spite of all care ; (3) a drying-out of the rubbers and hence 

 a breaking of the seal. 



In some factories where foods are canned in glass jars racks 

 are made for holding the jars upside down in an inclined position, 

 thus keeping the liquid constantly in the top of the can and pre- 

 venting the rapid drying of the rubber. 



