This section is from the book "A Textbook Of Domestic Science", by Matilda G. Campbell. Also available from Amazon: A textbook of domestic science for high schools.
Only those fruit juices which contain at least one-half per cent of acid and one per cent of pectin will form a jelly when cooked with sugar. Almost all fruits contain the requisite amount of pectin, but sweet fruits, such as peaches, pears, blackberries, contain too little acid; for this reason, acid must be added in order to make them jelly; an acid fruit, lemon juice, or tartaric acid may be used for this purpose. As before stated, the pectin is in the best condition for jelly making when the fruits are underripe or just ripe.
Fruits should not be overripe ; the more perfect the fruit, the clearer will be the jelly. Berries, currants, and grapes require no water. Apples and quinces must be cooked in water before straining.
Use a porcelain-lined or granite kettle. Drain the fruit juice through a jelly bag made of cotton flannel or double thickness of cheesecloth. Do not squeeze the bag, but let the juice drip for several hours or over night. Measure equal quantities of juice and sugar. Boil the juice ten to twenty minutes; add the heated sugar and boil five minutes or until it forms a jelly. Pour into sterilized glasses; let stand twenty-four hours and cover with melted paraffine. Put tin covers on the glasses or cover them with wrapping paper to keep out the dust.
Wash apples, cut in pieces, but do not pare nor remove the seeds. Cover with cold water. Boil until soft. Strain as directed, boil juice twenty minutes, add an equal volume of heated sugar, boil five minutes or until it jellies. Finish as in directions for jelly making.
Select grapes that are not fully ripe, wash, and remove from stems. Put into a kettle, mash well, and cook about thirty minutes. Strain. Add 3/4 c. hot sugar to every c. juice, and proceed .as in directions for jelly making.
Marmalade, Etc. Plum Conserve
4 qt. plums 1 1/2 lb. sugar
3 oranges and 1 lemon chopped 1 lb. raisins
1/2 lb. nuts coarsely chopped
Remove stones from the plums, add the other ingredients with the exception of the nuts. Cook until it becomes thick; add the nuts and cook a few minutes longer. Put in glasses and seal as directed.
8 lb. pears 4 lb. sugar
25 cent jar preserved ginger cut fine
Peel the pears and cut them fine; add a little water and cook until they soften; add the sugar and the ginger with the juice. Cook until thick like a marmalade. Put in glasses and seal as directed.
Wash grapes, remove from stems; squeeze the pulp into a stewpan. Cook pulp and rub through a strainer to remove seeds. Add the grape skins to pulp and 3/4 lb. sugar to every pound of fruit. Cook slowly until it thickens. Put in glasses and seal as directed.
Wash grapes and remove seeds as above. To every 7 lb. grapes (pulp and skins) add 3 lb. sugar, 1 pt. vinegar, ground spices to taste. Boil until the skins are tender and the mixture thickens. Put in glasses, sealing as directed.
Peel peaches and slice fine. Add 1 pt. sugar to every quart of peaches. Let stand three or four hours; cook quickly twenty-five minutes. Put in glasses and seal as directed.
 
Continue to: