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Lemon Sponge
Put an ounce of isinglass or gelatine into a pint of water, add the rind and juice of two lemons, and half a pound of loaf sugar, and simmer gently for half an hour. Strain into a bowl, and when the mixture is cold and beginning to set, which may be known by its becoming thick, stir in the whites of two eggs beaten to a firm froth, and whisk it briskly until it is of the consistency of sponge. Pour it into a damp mould, and turn it out before serving. A few drops of cochineal may be put in with the eggs, if liked, to give a pink appearance. Time, half an hour to whisk the sponge. Probable cost, 1s. 8d. Sufficient for a pint and a half mould.
A Victorian moulded jelly whisked to a foam, of the same family as snow pudding and lemon whip. The reason it cannot be recommended as written is the egg, but several other details are worth understanding.
- Raw egg white, never heatedThe lemon and gelatine mixture is simmered, then cooled, and the whites go in only once it has begun to set — so they are never brought anywhere near a temperature that would kill Salmonella, and nothing in the recipe pasteurises them afterwards. The sugar and lemon acid do not make the mixture safe. Anyone wanting a lemon sponge today should follow a current recipe built around pasteurised egg white or aquafaba.
- IsinglassCollagen extracted from the swim bladders of fish, principally sturgeon, and the standard setting agent before commercial leaf and powdered gelatine displaced it. It is still used to fine beer and wine but is essentially gone from domestic kitchens; note that it is not vegetarian, and neither is gelatine.
- An ounce to the pint is very strongModern gelatine, whether leaf or powder, sets a pint firmly at roughly a quarter of that weight. Victorian isinglass and gelatine varied in strength, and a heavy dose also gives the firm set needed to hold a whisked foam in a mould.
- Loaf sugarRefined sugar sold in a hard cone and broken up with nippers, valued because it was clean and dissolved to a clear syrup. Ordinary granulated sugar is its direct descendant; half a pound is 8 oz, about 1 cup plus 2 tablespoons.
- CochinealA red colouring made from the dried bodies of the Dactylopius coccus insect, sold in Victorian kitchens as a liquid tincture. It survives on labels as carmine or E120, is not vegetarian, and is a recognised though uncommon allergen.
- Damping the mouldRinsing the mould with cold water and leaving it wet, rather than oiling it, was standard for jellies: the film of water breaks the seal and lets the set sponge drop cleanly without leaving a greasy surface.
- Half an hour of whiskingWith a hand whisk on a mixture that is thickening as you go, this is a realistic figure rather than an exaggeration.
- Cost and size1s. 8d. is twenty pence in pre-decimal money, with the isinglass or gelatine likely the largest single item. A pint-and-a-half mould is about 850 ml, serving six to eight as a light dessert.
Lemon sponge belongs to the large Victorian family of moulded, whisked jellies — snow pudding, lemon soufflé — that turned an expensive setting agent into something showy for the dinner table. Its interest is largely technical: whipping air into a jelly at the exact moment it begins to thicken produces a pale, opaque foam that holds a mould's pattern while eating far lighter than a plain jelly, and books of the period repeatedly stress catching that moment. Isinglass had been the prestige setting agent since the eighteenth century, when the alternative was calf's-foot stock boiled down at home over many hours; by the time Cassell's was compiled, manufactured gelatine was steadily replacing it, and the recipe's casual "isinglass or gelatine" catches the changeover in progress. The optional cochineal reflects a period taste for tinted food.