Cherry Conserve

A two-fruit conserve with an unusually low sugar ratio for its era, which makes the finish point the whole job.

• The fruit measures are by volumeThree pints of pitted sour cherries is roughly 2 1/2 lb of fruit as prepared; a pint of black raspberries is about 12 oz. Measure after pitting, not before.
• Sugar weight2 2/3 cups granulated sugar is about 1 lb 3 oz. That is well under half the weight of the fruit, so expect a soft, loose set rather than a firm jam, and a shorter keeping life once opened.
• "Thick and clear" means 220F"Thick and clear" is the only finish cue given -- the recipe names no temperature. 220F at sea level is the usual set point for a soft spread, or use the sheet test on a chilled spoon; a wide, heavy pan makes the change easier to see than a deep pot.
• Stir once it thickensWith this little sugar the mixture scorches easily in the last few minutes. Keep it moving across the bottom of the pan and drop the heat as it comes together.
• Sour cherriesMontmorency or another pie cherry is what is meant, not sweet Bing types, which lack the acid the set depends on. Frozen pitted sour cherries work; thaw and include the juice.
• Black raspberriesThese carry a lot of seeds. If black raspberries are unavailable, ordinary raspberries or blackberries substitute, though the colour and perfume change noticeably.
• SkimmingBoth fruits foam. Skim before jarring or the finished conserve looks cloudy rather than the "clear" the recipe asks for.
• Yield and storageRoughly five or six half-pint jars, depending on how far it is reduced. The original gives no sealing method; follow current water-bath processing guidance for soft spreads, or refrigerate and use within about three weeks.