Lemon Syrup
Wash and wipe the lemons and squeeze out all the juice, and rub the yellow rind over some of the sugar. Measure the juice and allow six pounds of granulated sugar to every quart. Put the sugar in a porcelain kettle, add the stiffly beaten whites of two eggs, and dilute gradually with a quart of cold water. Stir until the sugar is dissolved and boil for fifteen or twenty minutes. Skim until perfectly clear. Add the strained juice of the lemons, cover, and boil ten minutes longer. Pour into bottles that have been well rinsed. Dip corks in sealing wax. This will keep indefinitely.
A clarified lemon syrup of the old soda-fountain type, meant to be diluted at the glass rather than drunk straight. Nothing here is difficult, but the proportions are enormous by modern standards and a couple of the steps assume equipment most kitchens no longer have.
- Scale it down firstA quart of juice means roughly 20 to 30 lemons, and six pounds of sugar to it yields well over three quarts of finished syrup. A quarter batch works cleanly: 1 cup juice, 1 1/2 lb (about 3 1/3 cups) sugar, 1 cup water, and an egg white (half a white is impractical to measure, so a whole one is the usual compromise).
- Rub the rind first, and do not skip itRubbing the zest over sugar draws the peel oil into the crystals, which is where nearly all the lemon aroma lives. Juice alone gives sourness without perfume. This is the same step bartenders now call oleo-saccharum; a zester and a bowl do the job faster than a whole lemon rubbed over loose sugar.
- The egg white is a clarifying raftBeaten white stirred into cold syrup coagulates as it heats, trapping scum and cloudy matter so it can be lifted off. It must go in before the syrup is hot or it will set into shreds. By the end of fifteen to twenty minutes at a boil there is no raw egg left in the pan.
- Porcelain kettleThat means an enamelled cast-iron or enamel-on-steel pot, not stoneware and not the modern baked casserole. Any non-reactive pan works; bare aluminium or unlined copper will dull the colour and take on a metallic edge from the acid.
- Juice goes in last for a reasonThe long first boil is for the sugar and the clarification only. Lemon juice loses its fresh top notes fast under heat, so the ten minutes after it is added is the outer limit. Cook it longer and you get sweet-sour syrup that tastes cooked.
- Sealing wax and "keeps indefinitely"At this sugar concentration the syrup is genuinely inhospitable to spoilage, which is what the claim rests on. Waxed corks are no longer worth the trouble: bottle it hot into clean bottles with screw caps, and once a bottle is opened keep it in the refrigerator, where surface mould is the only real risk.
- ServingThe book gives no dilution ratio. Start at about one part syrup to five or six parts cold or sparkling water, and adjust; it is also the base for lemonade punches and for pouring over shaved ice.
Clarifying sugar syrup with beaten egg white was long-standing confectioners' practice, and a bottled lemon syrup was the practical answer to lemons being seasonal, expensive and perishable while the craving for lemonade was not.