When canning in tin we cap and tip the cans at once.  The tin will bulge out, but is strong enough to withstand the pressure, and when the contents cool the can will come back into shape.

The jars are now ready for the canner.  Tomatoes sterilized under boiling water require twenty-two minutes; in condensed-steam cooker, twenty-two minutes; in water-seal, eighteen minutes; in steam-pressure, with five pounds, fifteen minutes, and in the pressure cooker, at ten or fifteen pounds, ten minutes.

If you use the homemade outfit or any water-bath outfit be sure the water is boiling when the jars of tomatoes are lowered into the canner.  Time lost in bringing the contents to the point of sterilization softens the tomatoes and results in inferior goods.  Use the ordinary good sense with which you have been endowed in handling the jars and you will have no breakage.  At the end of the sterilizing period, remove the jars.

In taking canned goods from boiling hot water, care is needed to see that they are protected from drafts.  If necessary close the windows and doors while lifting the jars out, for a sudden draft might break them.

Examine rubbers to see that they are in place.  Sometimes, if the covers are screwed down too tight, the pressure of the steam from the inside causes the rubber to bulge out.  Simply loosen the cover a thread or two, push the rubber back into place and then tighten.  In case the rubber does not seem to fit well or seems to be a poor rubber, it should be replaced by a new one and the jar returned to the cooker for five minutes.

The jars should be sealed tight—­covers screwed down, clamps put in place—­immediately after they are removed from the cooker.

Invert to test the joint and cool.  If the seal is not perfect, correct the fault, and return the jar to the cooker for five minutes if hot, ten minutes if jar is cold.

Do not invert vacuum-seal jars.  These should be allowed to cool and then tested by removing the spring or clamp and lifting the jars by the cover only.  Lift the jar only a half inch, holding it over the table so that, in case the lid does not hold, the jar and contents will not be damaged.  Or, better still, tap round the edge of the cover with a ruler.  An imperfect seal will cause a hollow sound.

Tomato Puree.  Small, misshapen, unevenly ripened tomatoes may be converted into tomato puree.  The tomatoes should be washed, run through a colander to remove skins and cores, concentrated by cooking to about half the original volume, and packed in the jars.  Rubbers and tops should then be placed in position and the product sterilized for the same length of time as for canned tomatoes. Puree even may be kept in bottles sealed with sterilized corks and dipped several times in paraffin.

HOW OTHER VEGETABLES ARE CANNED

All other vegetables are canned exactly like tomatoes, with two exceptions.  Tomatoes are scalded.  All other vegetables are blanched.  We scald tomatoes to loosen the skins and to start the flow of the coloring matter, which is later arrested or coagulated by the cold-dip.