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Acid Drops
Put three pounds of loaf sugar in a sugar-boiler with one teaspoonful of cream of tartar, and two breakfast cupfuls of water, and boil them to the crack. When the pan is removed from the fire, stir in a few drops of essence of lemon, pour the sugar onto an oiled marble slab, sprinkle over one tablespoonful of powdered tartaric acid and work it in. Place it on an oiled tin sheet to keep warm; take a small quantity at a time, roll it out to the shape of a pipe-stem, cut it into small pieces with a pair of scissors, roll them round in the hands, or the paste may be passed through a drop-machine; dust over with fine sugar, and put them away in boxes.
A hard-boiled sugar sweet of the old confectioner's type, worked by hand on a slab. Nothing here is dangerous, but the sugar work is unforgiving and the timing is everything.
- "Boil to the crack"This is the hard-crack stage, 300-310F (149-154C) on a candy thermometer. Below about 295F the drops will be sticky and chewy rather than glassy; much above 315F the sugar begins to colour and taste of caramel, which fights the lemon.
- Loaf sugarRefined sugar sold in a cone or block, broken up for use. Ordinary granulated white sugar is the same thing and needs no adjustment. Three pounds is roughly 6 3/4 cups.
- Sugar-boilerAn unlined copper or heavy brass pan with a pouring lip. Use the heaviest-bottomed saucepan you own, deep enough that the syrup at full boil comes no more than a third of the way up.
- Breakfast cupfulA breakfast cup runs 8 to 10 fluid ounces; two of them is about 2 to 2 1/2 cups. The exact figure hardly matters, since all the surplus water boils off before the crack.
- Cream of tartarNot a leavener here. It inverts a little of the sucrose during boiling so the finished sweet stays clear and glassy instead of turning grainy. Keep the sides of the pan washed down with a wet brush for the same reason.
- Essence of lemonPeriod essence was lemon oil in alcohol, far stronger than modern supermarket extract. Use a few drops of pure lemon oil if you can get it; with ordinary extract you will need closer to a teaspoon, added off the heat so the flavour does not flash off.
- Tartaric acidStill sold for confectionery and winemaking. It is what makes the drop sour, and it also continues inverting sugar, so work it in quickly and get the batch cut before the mass goes soft and sticky.
- The slab and the workingA marble or granite slab lightly wiped with a flavourless oil, chilled if the kitchen is warm. Keep the reserve mass over gentle warmth on the oiled tray, as directed, while you rope and cut, or it sets before you finish.
- StoringHard sugar drops pull moisture from the air and weld themselves into a single lump. Dust with fine sugar as directed, cool completely, and keep them in a genuinely airtight tin. Yield is in the region of three pounds of sweets.
Acid drops are a British boiled sweet of the early nineteenth century, the sourness coming from tartaric acid, a by-product of winemaking that became cheap and widely available to confectioners in that period. Oscar Tschirky's book carries a run of such formulas. A drop machine, a hand-cranked pair of engraved rollers, stamped a rope of hot sugar into uniform lozenges. The instruction to roll them between the hands is the older, smaller-scale alternative, and a reminder of how recently this was all handwork.