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Rock, Snowy
Take a pound of loaf sugar, clarify it, and boil it till it reaches the degree of crackled; then add a table-spoonful of vinegar. A few drops of either the essence of lemon or the oil of peppermint may also be mixed in. When the ingredients are thoroughly incorporated, pour the mixture out on a slightly-oiled marble slab; whilst cooling it may be twisted, rolled, moulded, or made up into any shape at pleasure.
This is pulled sugar work — a one-pound batch of hard candy taken to the crack stage, acidulated, then aerated by hand until it turns opaque white. The whole outcome depends on hitting the right temperature and working fast.
- The hinge: "crackled"The old "crackle" or crack degree corresponds to about 300-310F (150-155C) on a sugar thermometer, tested by dropping a little into cold water where it should set brittle and snap rather than bend. Under-boiled syrup will never set hard; past about 320F it begins to caramelise and the finished rock will be beige rather than snowy.
- Loaf sugarLoaf sugar was refined sugar sold in cones and broken up as needed. Ordinary granulated white sugar is the equivalent, and one pound is a little over two cups.
- Clarifying is now unnecessaryNineteenth-century sugar carried impurities that were skimmed off after dissolving it with a little beaten egg white. Modern refined sugar needs none of this: dissolve it in roughly a cup of water, brush the pan sides down, and boil without stirring.
- Why the vinegarA spoonful of acid added near the end inverts a portion of the sucrose, which discourages the syrup from crystallising into a grainy mass while it is being pulled. Cream of tartar or a squeeze of lemon does the same job; add it at the end of the boil, as the original directs (the recipe says only to add it once the crack degree is reached, not to take the pan off the heat), since acid added early can invert too much sugar and leave the candy sticky.
- Flavouring oilsOil of peppermint is a concentrated essential oil, not the alcohol-based extract sold for baking; 'essence of lemon' in this period usually meant lemon oil dissolved in spirit. A few drops is literal — an eighth of a teaspoon of peppermint oil will flavour a pound of sugar assertively. Alcohol extracts largely flash off in syrup this hot.
- Marble and oilMarble is specified because it draws heat quickly and evenly; a heavy granite slab or a chilled steel sheet works, and a silicone mat is the modern substitute. Oil it very lightly with a neutral oil — too much and the candy slides rather than gathers.
- Getting it snowyThe white colour comes from pulling, not from any ingredient. Once the mass is cool enough to handle, fold and stretch it repeatedly; the trapped air turns the clear sugar to satin white. Wear clean cotton gloves or work with well-oiled hands, and stop while the mass is still pliable, because it stiffens abruptly.
- Yield and keepingA pound of sugar gives roughly a pound of finished rock. Cut or twist it before it hardens fully, and store airtight with a desiccant if possible — pulled sugar takes up moisture from the air and goes tacky within a day or two in a humid kitchen.
"Rock" in Victorian confectionery meant boiled sugar pulled and shaped by hand, the family that includes seaside rock, humbugs and peppermint sticks; "snowy" describes the opaque white that appears when the clear syrup is aerated by repeated stretching over a hook or between the hands. The recipe is really a lesson in sugar boiling ote cl: clarify, take it to a named degree, acidulate, and cool on marble ote dash with the flavouring left to the cook's pleasure. Peppermint and lemon are often said to have been the standard choices, peppermint oil being, by tradition, cheap and widely traded by the middle of the nineteenth century, and both are generally reckoned to have survived the boiling temperatures better than the fruit flavours of the day. The named degrees of sugar (thread, ball, crack, caramel) were judged by hand and eye with cold water long before thermometers were common in domestic kitchens, and a book of this period expected its readers to know the tests by feel.