Prepare, weigh, and boil the plums for forty minutes; stir to them half their weight of good sugar beaten fine, and when it is dissolved continue the boiling for ten additional minutes, and skim the preserve carefully during the time. This is an excellent marmalade, but it may be rendered richer by increasing the proportion of sugar. The blanched kernels of a portion of the fruit-stones will much improve its flavour, but they should be mixed with it only two or three minutes before it is taken from the fire. When these plums are not entirely ripe, it is difficult to free them from the stones and skins: they should then be boiled down and pressed through a sieve, as directed for greengages, in the receipt above.
Mogul plums, skinned and stoned, 6 lbs: 40 minutes. Sugar, 3 lbs.: 5 to 8 minutes.
Pare the plums, but do not remove the stalks nor stones; take their weight of dry sifted sugar, lay them in a deep dish or bowl, and strew it over them; let them remain thus for a night, then pour them gently into a preserving-pan, with all the sugar, heat them slowly, and let them just simmer for five minutes; in a couple of days repeat the process, and do so again and again at an interval of two or three days, until the fruit is tender and very clear; put it then into jars, and keep it in the syrup, or drain and dry the plums very gradually, as directed for other fruit. When they are not sufficiently ripe for the skin to part from them easily, they must be covered with spring water, placed over a slow fire, and just scalded until it can be stripped off easily.
Put them into jars, or wide-necked bottles, with half a pound of good sugar, rolled or pounded, to twice the weight of fruit; set them into a very cool oven for four and five hours; or if more convenient place them, with a little hay between them, in a pan of cold water, and boil them gently for rather more than three hours. Leave them in the syrup for a few days, and finish them as directed for the drying of other fruits. Tie a bladder over the necks of the jars or bottles before they are placed in the pan of water, and fasten two or three folds of paper over the former, or cork the bottles when the fruit is to be baked. The sugar should be put in after the fruit, without being shaken down; it will then dissolve gradually, and be absorbed by it equally.
To each pound of plums, 8 ounces pounded sugar: baked in cool oven 4 or 5 hours, or steamed 3 hours.