43. For canning foods by steam pressure, special equipment is necessary.
In one of the steam-pressure methods, what is known as a _water-seal
outfit_ is required, and in the other a device called a _pressure
cooker_ is employed. The work of getting the containers ready, preparing
the food for canning, packing it into the jars, and sealing and testing
the jars is practically the same in the steam pressure methods as in the
cold-pack methods. The difference lies in the cooking and sterilization
of the foods after they are in the jars and partly sealed and in the
rapidity with which it may be done.

44. CANNING WITH A WATER-SEAL OUTFIT.--A water-seal outfit, which may be
purchased in stores that sell canning supplies, consists of a large
metal vessel into which fits a perforated metal basket designed to hold
jars of food. This vessel is also provided with a tight-fitting cover
having an edge that passes down through the water, which is placed in
the bottom of the vessel. When heat is applied to the bottom of the
vessel, the water inside of it is changed into steam. The cover prevents
the steam from passing out, and it collects in and around the metal
basket supporting the jars of food. Enough steam is generated in this
outfit to raise the temperature about 4 to 6 degrees above the boiling
point. Thus, the water-seal outfit will cook the food in the cans in
about one-fourth less time than will the water bath of the one-period
cold-pack canning method.

[Illustration: FIG. 20]

45. CANNING WITH A PRESSURE COOKER.--For canning by steam pressure, a
number of different kinds of pressure cookers are to be had, but in
principle they are all alike and they are always made of heavy material,
so as to withstand the severe steam pressure generated in them. In Fig.