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To clarify Beer
Put in a piece of soft chalk, as big as two hen's eggs to a barrell, which will disturb the liquor and cause it to fine, and will draw brisk, though it was flat before.
A brewer's remedy rather than a dish: a lump of chalk dropped into a dull cask to settle the haze and put some life back into it. The chemistry is real, but the effects are not quite what the writer thought.
- What size barrelThe English beer barrel was nominally 36 gallons (the ale barrel 32), and gallon measures varied before the imperial standard, so the cask size is approximate; 36 imperial gallons is about 164 litres or 43 US gallons. Scaled down, the dose is well under a gram of chalk per litre.
- How much chalkTwo hen's eggs of soft chalk is on the order of 100-120 ml by volume; the weight depends on how dense and porous the chalk is and could be well over twice that figure in grams. Comparisons to eggs are a common way of giving quantities in receipt books; a modern brewer would weigh it.
- Soft chalk means calcium carbonateNatural whiting or precipitated chalk, sold today as food-grade calcium carbonate for brewing water treatment. Blackboard and craft chalk is usually calcium sulphate or gypsum plaster with binders and pigments, and has no place in a cask.
- Why it fizzesThe "brisk" draw is carbon dioxide released as the carbonate reacts with the acids in the beer. It is a short-lived effervescence rather than carbonation in the modern sense.
- What it does to flavourChalk raises pH and strips acidity. In a sour, thin, tired beer that reads as an improvement; in anything hoppy or pale it flattens the finish and can leave a chalky dullness.
- "Fine" and "disturb"To fine is to clear. Stirring the cask rouses the yeast and suspended protein so it can flocculate and drop again, which is why the instruction expects the beer to be cloudier before it is clearer.
- What a brewer uses nowIsinglass, gelatin, Irish moss in the boil, or simply cold-crashing at 1-3C for a few days. All of these clear beer without shifting its pH.
Domestic and publican's manuals of the seventeenth and eighteenth centuries are full of cask remedies of this kind, sitting alongside kitchen receipts because beer was brewed and kept at home like any other provision. Chalk was often recommended for beer gone sharp. Some of these cellar tricks were harmless and some were not, and by the early nineteenth century writers on food adulteration were attacking the more dangerous ones, particularly bitterants and narcotics such as cocculus indicus. Chalk sits at the innocent end of that tradition: a cheap mineral that genuinely neutralised acid, though the brief fizz it produced was often mistaken for a return of the beer's condition.