This section is from the book "Preserving And Pickling", by Mary M. Wright. Also available from Amazon: Preserving and Pickling: Two Hundred Recipes for Preserves, Jellies, Jams, Marmalades, Pickles, Relishes and Other Good Things.
To each three pounds of tart apples pared, cored, and quartered, add one cupful of water, an ounce of ginger root, and the juice and grated rinds of two lemons. Stew until tender, then pass through a coarse sieve. Add four pounds of sugar to this amount, and if preferred a few finely chopped almonds may be added, or English wal nut meats. Boil to the consistency of marmalade, and pour into glasses or jars.
Boil the plums and press through a sieve, pare the apples, slice very thin, add to the plum pulp and boil, stirring constantly, until the apples are soft; then add the sugar in the proportions of one pound of sugar to each pint of pulp if tart apples are used; and from two-thirds to one-half, if sweet apples are used. Cook until fine and thick, and then fill glasses or jars and seal.