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Lemon Sponge
Soak one ounce of gelatine in one teacupful of water for two hours. Pour the juice of four lemons on one breakfast cupful of powdered sugar; beat the yolks of four eggs, and mix them with the remains of one pint of water allowing for the quantity used to soak the gelatine, add to this the sugar and lemon, and cook in a double boiler until it begins to thicken, then put in the gelatine. Strain all through a fine hair-sieve into a basin, stand the basin in a larger one containing iced-water, and whisk now and then until the sponge has cooled but not hardened. Beat in the whites of the eggs not previously beaten, and continue beating until the mixture is so thick that it is difficult to stir it, then turn it into a mould and set it away to harden. When ready to serve, dip the mould in tepid water, wipe it, and turn the contents onto a dish. Serve with powdered sugar and cream.
A moulded gelatine sponge of the sort that filled hotel dessert menus around 1900. The method has one flaw that cannot be worked around within the recipe as written, so the notes below are for reading it rather than cooking it.
- Raw whites are the problemThe whites go in unheated, after the custard base has already been cooled over iced water, and the finished sponge is only chilled to set. Nothing in the recipe brings the whites anywhere near a temperature that would deal with Salmonella, and the acid from four lemons does not sterilise them. A current recipe using pasteurised whites or an Italian-meringue method should be used instead.
- The yolk base is also marginal"Cook in a double boiler until it begins to thicken" describes a lemon custard that may only reach 165-170F, but the instruction is a visual cue with no temperature and no time, and the base is then immediately cooled. It is not a safeguard for the whites added afterwards.
- One ounce of gelatineAbout 28 g, or four standard quarter-ounce envelopes of powdered gelatine. Period gelatine is generally reckoned to have been more variable in strength than modern granulated gelatine, so an ounce here may not set the same volume it would today.
- Teacupful and breakfast cupfulNot the same measure. A teacupful is roughly 6 fl oz; a breakfast cup is larger, around 8-10 fl oz. The sugar is measured by volume.
- "The remains of one pint of water"The pint is the total water: the teacupful used to soak the gelatine is subtracted from it, and what is left goes with the yolks.
- Hair-sieveA fine sieve woven from horsehair, used before fine tinned wire mesh was common; it is often said to have been preferred for acid mixtures because it would not react with them. Any fine nylon or stainless sieve is the equivalent.
- UnmouldingA brief dip in tepid water, not hot, then wipe the mould dry before inverting. Hot water melts the outer layer and the sponge slumps on the dish.
Lemon sponge belongs to the family of whisked gelatine desserts -- sponges, snows, and whips -- that were a common feature of the sweet course in late nineteenth-century hotels and ambitious households. The distinction from a plain jelly is the aeration: egg white beaten into a setting gelatine base traps air, increasing the volume and turning a clear jelly opaque and light. These desserts became practical for ordinary kitchens once refined sheet and powdered gelatine were sold commercially, from the middle of the nineteenth century onward, replacing the long labour of boiling down calves' feet for stock jelly. Oscar Tschirky, maitre d'hotel at the Waldorf from its opening in 1893, compiled his 1896 cook book from the hotel's working repertoire alongside more domestic material, and moulded lemon sponge sits squarely in that repertoire: cheap in ingredients, showy on the plate, and made in quantity a day ahead.