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Peach Jam or Marmalade
Take the peaches when quite ripe; skin, stone, and divide them into quarters, put these into a preserving-pan, and stir the fruit over the fire until it is quite soft. Rub the pulp through a coarse sieve, beat it well until no lumps remain, weigh it, and mix with it an equal weight of powdered loaf sugar and a fourth part of the kernels, blanched and bruised. Boil the mixture for a quarter of an hour, stirring and skimming constantly. Pour the jam into jars, cover these in the usual way, and store in a cool, dry place. Time, about half an hour to reduce the peaches to pulp; a quarter of an hour to boil them with the sugar. Probable cost, uncertain.
This is a straightforward sugar-preserve in every respect but one: it directs the cook to add bruised peach kernels, the seeds inside the stones. That single instruction puts the recipe out of reach today.
- The kernels are the problemPeach kernels contain amygdalin, a cyanogenic glycoside. Once the kernel is crushed and wetted, the plant's own enzyme releases hydrogen cyanide — the same chemistry that makes bitter almonds dangerous. Bruising the kernels into the wet pulp, as directed here, is exactly the condition under which that happens.
- The quantity is not trivial"A fourth part of the kernels" is ambiguous — most plausibly a quarter of the kernels from the stones taken out, though the wording does not make the basis of the fraction explicit. On any reading a quantity of pounded kernel is spread through a jar that will be eaten a spoonful at a time over weeks, with no way to gauge what any single serving contains.
- Boiling does not fix itA quarter-hour boil with sugar will drive off some hydrogen cyanide, but this is a short boil in a thick, sugar-saturated pulp rather than a long thin simmer, and the amount remaining is unpredictable. This is not a hazard that can be reliably managed by adjusting the time.
- Why it was thereThe kernels were added for flavour, not preservation — they give the almond-and-stone-fruit note commercial peach products still imitate with natural or artificial almond flavouring. Nothing about the set or the keeping of the jam depends on them.
- Loaf sugar"Powdered loaf sugar" is refined sugar broken from a cone and crushed fine — ordinary granulated or caster sugar in modern terms, not icing sugar and not confectioner's sugar with its cornstarch.
- "Cover in the usual way"In Cassell's period this meant a disc of brandy-soaked or waxed paper laid on the hot surface and a paper or bladder cover tied over the rim. It is not a modern sealed-jar process, and it assumed a cool larder and reasonably prompt use.
- If you want peach jamUse a current tested recipe with a proper jar-sealing method. The fruit-to-sugar ratio here — equal weights of sieved pulp and sugar — is unremarkable and still recognisable; the kernels are what cannot be carried forward.
Peach kernels, apricot kernels and bitter almonds were interchangeable flavourings in nineteenth-century English confectionery, all three prized for the same almond bitterness and all three now understood to share the same cyanogenic chemistry. Cassell's New Dictionary of Cookery, which grew out of the firm's Dictionary of Cookery of the 1870s and was reissued over many years, reflects a kitchen in which the stone of a fruit was simply another part of the fruit: ratafia creams, noyau, macaroons and blancmanges all leaned on kernel flavour, and period cookery writers rarely remarked on the practice. Warnings did exist — poisoning cases from kernel-flavoured preparations were reported during the century — but they did not reliably reach the recipe books. The rest of the method is orthodox preserving of its era: reduce the fruit to a pulp, sieve it, weigh it, match it pound for pound with sugar, and boil hard while skimming. "Probable cost, uncertain" stands out because the book gives costings for a great many entries; why the compilers declined to price this one is not stated.