This section is from the book "Everywoman's Canning Book", by Mary B. Hughes. Also available from Amazon: Everywomans canning book; the A B C of safe home canning and preserving.
It is claimed that eighty-five per cent of all human ailments are caused by improper diet. Four months of the year, when there is an abundance of fresh fruits and vegetables, we eat plenty of them; the remainder of the year our diet is highly concentrated, with an excess of protein foods. The fiber, mineral salts, and acids found in fruits and vegetables are a daily requirement of the body if health is to be maintained. Home canning should be so planned that the family will have a jar of fruit and a jar of vegetables every day when fresh supplies cannot be obtained. In the beginning of the season, if the housewife will purchase two jars for each day of the winter months (pints or quarts, according to the size of the family), she will then have her goal set ahead of her, and will take delight in reaching it by the end of the season.
"What kind of jar is best?" is frequently asked. This is a matter of individual preference. Jars with wide necks and straight sides are easily packed and cleaned. Whether the glass is green or white makes no difference in the keeping of the product. The green glass does not prevent bleaching when the products are exposed to light. Fruits and vegetables have a much finer appearance when packed in a good, clear, colorless glass.
Do not buy cheap jars, as invariably they are defective or of poor glass, and crack easily. A cheap jar is most expensive in the end. Every jar, before being packed, should be examined carefully for defects. Run the finger around the edge to see if the glass is chipped; also fill the jar with water and watch for tiny air holes. Air bubbles will be seen to rise from the side of the jar when there is a defect in the glass. Discard every defective jar.
If screw-top jars are used, care must be taken to see that the cap is not bent and that the rim is perfect. Adjust the rubber and screw on the cap tightly. Invert. If there is leakage, try a cap which has never been used. When a bail is used, test it with the rubber and top adjusted, to see if it works properly, before filling the jar.
The quality of rubber ring used is of the greatest importance. A jar cannot be air-tight, or remain so for any length of time, unless the rubber ring is of the proper texture. After the contents are processed, the possibility of keeping the jar air-tight depends on the rubber used. A good ring must be both wide and thick, and of such rubber that it can be stretched ten inches or more, when it will snap back into shape and not break or crack. It is never safe to use the same rubber more than once. Use the rings which come with the jars only for pickles and preserves, which keep without an airtight seal. Never buy cheap rubbers.
For those who wish to do canning for commercial purposes, steam pressure outfits are to be recommended. They save time, labor, and fuel, and give excellent results. They are, however, by no means essential to success, and the wash boiler is all that is necessary for family use. When only a few jars are to be processed at a time, it is more economical to use a smaller container, thereby eliminating the heating of unnecessary water. A lard pail or a new garbage can, or a stew kettle with a tight cover and a false bottom, makes a good sterilizer.
Other items of equipment are cheesecloth, plenty of clean towels, several large bowls, paring knives, teaspoon, wooden spoon, colander and pestle, cake racks, scales, and timepiece. Plenty of fresh, clean water is essential.
Always read general directions