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.
Lady blush or fall pippins are best for jelly. The first make a bright-red jelly, and the latter an almost white jelly.
Wipe the fruit, cut it into pieces without paring or removing the seeds. Put into a porcelain-lined kettle and barely cover with cold water; cover the kettle, and boil slowly until the apples are very tender; then drain them through a flannel jelly-bag - do not squeeze, or the jelly will be cloudy. To every pint of this juice allow one pound of granulated sugar. Put the juice into a porcelain-lined kettle, and bring it quickly to a boil; add the sugar, stir until the sugar is dissolved, then boil rapidly and continuously until it jellies, skimming the scum as it comes to the surface; twenty minutes is usually sufficient, but sometimes I have boiled it thirty-five minutes before it would jelly properly. It is wise to commence testing after fifteen minutes' boiling. To do this, take out one teaspoonful of the boiling jelly, pour it into the bottom of a saucer, and stand it in a cold place for a moment; then scrape it one side with a spoon - if jellied, the surface will be partly solid; if not, boil a few minutes longer, and try again. As soon as it jellies, roll the tumblers quickly in boiling water, then fill them with the boiling liquid. Stand aside until cold and firm (about twenty-four hours). Then, if you have jelly-tumblers, put on the lids; if not, cover with two thicknesses of tissue paper, and paste the edges of the paper down over the edge of the tumbler. Then moisten the top of the paper with a sponge dipped in cold water. This moistening stretches the paper, so that when it dries again it shrinks and forms a covering as tight and smooth as bladder skin. I do not recommend jelly being covered with brandied paper, as in my hands it has never been satisfactory. The jelly, in cooling, forms its own air-proof covering, and if the top of the tumbler be well secured, it is all that is necessary. Keep in a cool, dark place.
Cut the large Siberian crab apples into halves, and then into quarters, and to every five pounds of apples allow one pint of water. Proceed and finish precisely the same as for Apple Jelly.
The uncultivated blackberries are best for jelly, and should be rather under- than over-ripe. Put the berries into a stone jar, stand it in a kettle of cold water, cover the top of the jar, and boil slowly for one hour, or until the berries are quite soft. Now put a small quantity at a time into your jelly-bag, and squeeze out all the juice. Measure the juice, and to each pint allow one pound of granulated sugar. Turn the juice into a porcelain-lined kettle, and stand over a brisk fire. Put the sugar into earthen dishes and stand them in the oven to heat. Boil the juice rapidly and continuously for twenty minutes, then turn in the sugar, hastily stirring all the while until the sugar is dissolved. Dip your tumblers quickly into hot water, watch the liquid carefully, and, as soon as it comes again to a boil, take it from the fire and fill the tumblers.
If the fruit is over-ripe, your jelly will never be firm, no matter how long you boil it.
Follow these directions carefully, and you will never fail.
 
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