At high altitudes the boiling point of water is below 212°
F. At moderate elevations satisfactory results may be obtained in the use of
the hot-water bath by increasing the time of sterilization 10 per cent for
every 500 feet above 1000. To insure best results in very high altitudes,
however, a steam pressure canner or aluminum pressure cooker is recommended
to be used. This type of canner produces a temperature up to 250 ° F. at 15
lbs. pressure, insuring proper sterilization and also saving time and fuel.
A steam pressure canner may be bought around $20. Several families may use
one, and divide the cost.
Fig. 7. Home canner and steam
cooker holding 14 quart jars. Requires same time as hot-water bath.
OPERATION OF PRESSURE
CANNERS AND ALUMINUM COOKERS
1. Have water in the canner up
to the false bottom, but not above it. Keep this water boiling during the
time that packed jars are being placed in the canner, and add water
occasionally to prevent its boiling dry.
2. To prepare product follow instructions in "Steps in the Single
Period Cold-pack Method" on pages 8 and
9. As each jar is packed, set it at
once, partially sealed, into the canner. The cover of the canner may be put
in position, but not clamped.
3. When all of the filled jars are placed in the canner, put on the
cover, and fasten opposite clamps moderately tight; then tighten each pair
of clamps fully.
4. The petcock should be left open until live steam escapes from
it. The canner should be steam-tight, and no steam should escape except
through the open petcock. When live steam escapes, close the petcock
5. Begin to count time when the steam gauge registers the required
6. Maintain a uniform pressure during the sterilizing period by
setting the weight on the arm, when the proper pressure is registered on the
steam gauge, so that surplus stem will escape at that desired pressure. A
uniform temperature may be maintained also, by turning down the flame or
moving the canner to a less hot part of the stove.
7. When the sterilization period is complete, do not allow steam
to escape, but allow the canner to cool until the steam gauge registers
8. Open petcock, remove the cover of canner, and take out the jars.
As each jar is removed, complete seal at once.
For home use glass jars are more satisfactory for canning
than tin. This is especially true this year when there is a shortage of tin
cans. Tin cans are used chiefly for canning on a large scale for commercial
There are many jars of different styles and prices on the market;
and provided the seal is not defective, equally good results may be obtained
from all. Glass is a popular household choice because one can see through it
and thus have some idea as to the condition of the contents. Glass jars may
be used for years if properly cared for.
All types of jars which seal readily may be use. Jars having glass
tops held in place by bails are especially easy to handle while hot.
Screw-top jars are serviceable. Glass caps held in place by separate metal
screw bands are now on the market, as well as the one-piece sort of former
years. Vacuum seal jars are very easily managed. Tops for Economy jars
should be purchased each year. The composition material. which takes the
place of rubber, should have a rubber-like texture. If of mealy consistency
it is unfit for use and the top will not make a tight seal.
The color and shape of jars are not of first moment, but are to be
considered. Containers made of white glass should be used if the product is
to be offered for sale, as blue or green glass detracts from the appearance
of the contents. Wide-mouthed jars are best for packing whole products and
are easiest to clean. Small-necked bottles can be used for fruit juices.
Large-mouthed bottles can be used for jams, marmalades and jellies.
Fig. 8 Rack for jars.
TESTS FOR JARS
Jars should be tested before they are used. Some of the
important tests are here given:
1. Glass-top Jars.––First examine for cracks. Then
run a finger around the edge of necks of jars, and if there are sharp
projections, file them off, or scrape them off with an old knife. If left on
they may cut rubbers and interfere with perfect sealing. Place a top on a
jar. It will slip from side to side, but should not rock, when tapped.
Rocking tops will not make a tight seal. Sometimes the fault is with the top
and sometimes with the neck. Defective jars and tops when discarded for
canning purposes may be used as containers for jams, etc. The top-bail
should go into position with a light snap. If too loose it should be taken
off and bent slightly inward in the center. If too tight bend outward.