39. PROCESSING.--The purpose of the water bath is to process the food contained in the jars before they are thoroughly sealed. Therefore, when the jars are filled, proceed to place them in the water bath. The water, which was placed in the sterilizer during the preparation of the food, should be boiling, and there should be enough to come 2 inches over the tops of the jars when they are placed in this large vessel. In putting the jars of food into the sterilizer, place them upright and allow them to rest on the rack in the bottom. If the filled jars have cooled, they should be warmed before placing them in the sterilizer by putting them in hot water. On account of the boiling water, the jars should be handled with a jar lifter, as in Fig. 14. However, if the sterilizer is provided with a perforated part like that in Fig. 15, all the jars may be placed in it and then lowered in place.
When the jars are in place, put the tight-fitting cover on the sterilizer and allow the water to boil and thus cook and sterilize the food in the jars. The length of time for boiling varies with the kind of food and is given later with the directions for canning different foods. The boiling time should be counted from the instant the water in the sterilizer begins to bubble violently. A good plan to follow, provided an alarm clock is at hand, it to set it at this time, so that it will go off when the jars are to be removed from the sterilizer.
40. SEALING THE JARS.--After processing the food in this manner, the jars must be completely sealed. Therefore, after the boiling has continued for the required length of time, remove the jars from the water with the aid of the jar lifter or the tray and seal them at once by clamping or screwing the covers, or lids, in place, as in Fig. 16. Sometimes, the food inside the jars shrinks so much in this process that the jars are not full when they are ready to be sealed. This is illustrated in Fig. 17. Such shrinkage is usually the result of insufficient blanching, or poor packing or both. However, it will not prevent the food from keeping perfectly. Therefore, the covers of such jars of food must not be removed and the jars refilled; rather, seal the jars tight immediately, just as if the food entirely filled them. If, in sealing jars removed from the water bath, it is found that a rubber has worked loose, shove it back carefully with the point of a clean knife, but do not remove the cover.
As the jars are sealed, place them on their sides or stand them upside down, as in Fig. 18, to test for leaks, in a place where a draft will not strike them and cause them to break. If a leak is found in any jar, a new rubber and cover must be provided and the food then reprocessed for a few minutes. This may seem to be a great inconvenience, but it is the only way in which to be certain that the food will not be wasted by spoiling.
