This week I finished a final goodbye read of the collected tales of Edgar Allan Poe, and encountered this interesting passage:
Place a platina crucible over a spirit lamp, and keep it a red heat; pour in some sulphuric acid, which, though the most volatile of bodies at a common temperature, will be found to become completely fixed in a hot crucible, and not a drop evaporates- being surrounded by an atmosphere of its own, it does not, in fact, touch the sides. A few drops of water are now introduced, when the acid, immediately coming in contact with the heated sides of the crucible, flies off in sulphurous acid vapor, and so rapid is its progress, that the caloric of the water passes off with it, which falls a lump of ice to the bottom; by taking advantage of the moment before it is allowed to remelt, it may be turned out a lump of ice from a red-hot vessel.
I was going to ask readers here about the thermodynamics, but a quick search of the internet today led me to a page at Physics Stack Exchange that discussed this very same passage. The site provices additional citations of similar experiments in the nineteenth century:
M. Boutigny, by means of sulphurous acid, first froze water in a red-hot crucible; and Mr. Faraday subsequently froze mercury, by means of solid carbonic acid...
A reader there provided some clarification re the reagents -
What they were calling "sulphurous acid" back then is not what we would call an acid today. It was anhydrous sulphur dioxide which has a boiling point of −10∘C.When liquid sulphur dioxide was poured into the red-hot vessel, due to the Leidenfrost effect, it would form itself up into globules and float on a layer of its own vapour. In this state the temperature of the globules would be just below that of its boiling of −10∘C as it evaporates away at a now greatly reduced rate. Pouring in a small amount of water, which freezes at 0∘C, while the sulphur dioxide is in this state results in it freezing within a few seconds. Once all the sulphur dioxide has evaporated off, the ice will quickly melt again before being brought up to just below its boiling point of 100∘C as it assumes its spheroidal form due to the Leidenfrost effect. If one is quick, before all the liquid sulphur dioxide has disappeared one can throw out a small lump of ice from a red-hot crucible!
Sounds like a demonstration that would make an alchemist proud.