Loquat Marmalade

This is a second-run recipe: it assumes you have just made loquat jelly and are left with a kettle of cooked, drained fruit. A few things the single sentence takes for granted.

• What "the fruit pulp left from the jelly" isLoquat jelly of this period is typically made by simmering halved, seeded fruit with water and straining it through a jelly bag. The solids left in the bag are what this recipe uses. They are already soft and carry no sugar of their own, so all the sugar in the marmalade comes from this step.
• Remove the seeds firstLoquats carry two to four large glossy seeds, and the seeds and leaves contain cyanogenic compounds. They should be taken out before the fruit is ever cooked, not sieved out afterward. Sieving hot pulp that still contains cracked seeds is the one thing to avoid here.
• Equal quantity means by weightEqual quantity probably means by weight -- Many preserving books of this period match sugar to fruit by weight, though volume measures were also common. Weighing the sieved pulp and matching it pound for pound is the safer reading; cup-for-cup measuring changes the sugar-to-fruit ratio and will give a looser set.
• "The right consistency"For a spreadable marmalade of this type, cook to about 220F/104C, or until a spoonful dropped on a chilled plate mounds and wrinkles when pushed. Because the pectin was largely extracted into the jelly, this will set as a thick fruit butter rather than a firm jelly, and that is the correct result.
• Use a wide, heavy pan and stirSieved pulp is dense and scorches far more readily than the thin juice used for jelly. A wide preserving pan, moderate heat and near-constant stirring in the last ten minutes will keep the flavor clean; a burnt bottom taints the whole batch.
• Sieve while warmPush the drained pulp through a medium sieve or food mill while it is still warm and soft. Cold pulp is gluey and much of it stays in the mesh.
• Brightening the flavorMuch of the loquats' acid passes into the juice during the first cooking, so the leftover pulp can taste flat. A tablespoon or two of lemon juice per pound of pulp restores balance and helps whatever pectin remains.
• Yield and keepingA quart of sieved pulp with its sugar gives several half-pint jars. The recipe says nothing about how to put it up; refrigerate it and use within a month, or process filled half-pints in a boiling-water bath for 10 minutes.