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Raspberry jam
Mash a quantity of fine ripe dry raspberries, strew on them their own weight of loaf sugar, and half their weight of white currant juice. Boil them half an hour over a clear slow fire, skim them well, and put them into pots or glasses; tie them down with brandy papers, and keep them dry. Strew on the sugar as quick as possible after the berries are gathered, and in order to preserve their flavour they must not stand long before boiling them.
A straightforward equal-weight jam whose one unusual element — white currant juice — is doing the work a bottled pectin would do today. The instructions assume berries picked that morning and a copper pan over embers.
- The currant juice is the setThe currant juice reinforces the set -- Raspberries carry only moderate pectin, though they are acidic; white currants are rich in both pectin and acid. The half-weight of juice is what makes this jam gel firmly; without currants, expect a softer preserve, or use a recipe written for added pectin.
- Loaf sugarRefined sugar sold in a hard cone, broken and crushed before use. Ordinary granulated sugar is the direct equivalent, weight for weight.
- Weigh, do not measure"Their own weight" means equal weights of fruit and sugar — 1 lb berries to 1 lb sugar. Volume measures will not give the same ratio, since raspberries pack loosely.
- Half an hour is longModern practice boils raspberry jam hard for 5 to 15 minutes and stops at 220F (105C), or when a spoonful wrinkles on a chilled plate. A slow half-hour boil over a weak fire darkens the fruit and dulls the flavour; watch the set rather than the clock.
- "Clear slow fire"A bright, smokeless fire without flare-ups, kept gentle: "clear" means no smoking, "slow" means low heat rather than fierce. Use a wide pan so evaporation happens fast at a lower temperature.
- Dry berries"Dry" means not rain-wet or washed. Surface water thins the jam and forces a longer boil; if you rinse the fruit, spread it out to dry first.
- Brandy papersRounds of paper soaked in brandy and laid on the hot surface, then a second paper tied over the rim — the spirit discouraged mould. It is not a seal. Fill sterilised jars and either process them in a boiling-water bath or keep the jam refrigerated and eat it within a few weeks.
- SkimmingSkim the pink foam as it rises rather than at the end; it clouds the finished jars and is largely trapped air.
- YieldPer pound of berries with sugar and currant juice, expect roughly two to three half-pint jars, depending on how far the boil is taken.
Equal-weight fruit-and-sugar preserving is one of the standard formulas in English household books, and the sugar is there as a preservative as much as a sweetener: at that concentration little will grow in it. The instruction to strew the sugar on "as quick as possible after the berries are gathered" belongs to a kitchen supplied from its own canes rather than a shop, and raspberries do lose aroma and deteriorate quickly after picking. The white currant juice does the work bottled pectin does now; commercial pectin extracts did not reach domestic cooks until the early twentieth century, so cooks leaned on high-pectin fruit and juices, apple or currant, to set the low-pectin ones. Brandied paper covers were common before the screw-band jar, and the spirit appears to have been used to discourage the surface moulds that were the chief enemy of a jam pot in a damp larder.