This section is from the book "Philadelphia Cook Book: A Manual Of Home Economies", by Sarah Tyson Heston Rorer. Also available from Amazon: Philadelphia Cook Book.
The process of canning the different kinds of fruit varies but little, except in the amount of sugar used. None but perfectly sound and fresh fruits should be used for this purpose. They may be canned with or without sugar, as the sugar takes no part whatever in their preservation. The fruit should not be cooked sufficiently long to destroy its natural flavor, and while boiling hot should be sealed in air-tight glass jars, filled to overflowing to exclude every particle of air, then quickly sealed. The jars should be thoroughly heated before filling, filled through a wide-mouthed funnel, and should, during this process, stand on a folded damp towel, to prevent breakage. Large-mouthed glass jars, with porcelain-lined or glass tops only, should be used. After filling and screwing on the tops, stand the jars in a warm part of the kitchen, where the air will not strike them, over night. In the morning you will be able to give the tops another turn. Then wipe the jars carefully, and put them away in a cool (not cold) dark closet. In a week or two examine them carefully; if the liquid has settled, and you see no small air bubbles, or the porcelain-lined tops slightly indented, you may be sure that the fruit is keeping; if you find the opposites, the fruit is beginning to ferment, and the jars will burst if not opened.
Re-cook and use them at once for stewed fruit, as it is never satisfactory to return them to the jars. All large fruits should be thrown into cold water as soon as pared, to prevent discoloration, then boiled in clear water, in which has been dissolved a quarter-teaspoonful of powdered alum to every quart of water, until tender, then drained and boiled a few moments in the syrup. Cook only enough to fill one or two jars at a time; have the jars hot and everything ready as soon as the fruit is done. Fill the jars quickly, run a silver spoon handle around the inside of the jar to break any air bubbles that may be there, and then screw on the tops without delay.
Small fruits are best sugared one or two hours before cooking, and then if you add the same proportion of alum, they will be clear and keep their shape. They should just be brought to boiling point, skimmed, and sealed immediately.
The surplus juice that exudes from strawberries and plums may be strained and boiled for jelly.
By following these directions religiously, and using the quantities given in the recipes that follow, success is sure.
1 pound of sugar 4 pounds of apples
The grated yellow rind of one lemon
1 quart of water
Pare the apples, throw them into cold water. When you have enough to fill one or two jars, take them from the water, put them in a porcelain-lined kettle, cover with boiling water, stand them on the back part of the fire, where they will scarcely bubble, until tender. While they are cooking, put the sugar and water in another kettle, stir the sugar until it is dissolved, add the lemon rind, and boil three minutes. When the apples are sufficiently tender to admit a straw, lift them carefully with a strainer from the water into the syrup, bring to boiling point, skim, and can as directed.