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.
Use one pound of rhubarb to each two pounds of peaches. The preserve will be better if only the tender ends of the rhubarb are used. Peel and quarter the peaches, and peel and cut up the rhubarb in inch lengths. Place in a preserving kettle with just enough water to start the juice flowing, and simmer slowly until the fruit is tender; then add the sugar after it has been heated in the oven, using a pound of sugar to each pound of fruit. Boil to the right consistency for preserves.
If you wish to keep the fruits whole, make a syrup with sugar and water, and boil down to a thick syrup. Add enough currant juice to make it a pretty pink color. Then add the peaches and rhubarb, a small quantity at a time, and boil just long enough in the syrup to cook thoroughly. Fill into the preserve jars with a strainer or spoon. Cook the juice until it begins to jelly, and pour over the fruit in the jars.
This makes a pretty as well as delicious preserve. If you do not have the currant juice, cranberry juice can be used, or a glass of currant jelly. Pears and rhubarb may be combined in the same manner.