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Powders, Soda-Water
Place thirty grains of bicarbonate of soda in each blue paper, and twenty-five grains of tartaric acid or twenty-four grains of citric acid in each white paper. To use, empty the contents of each paper separately into about half a glassful of water; mix the two and drink at once. This is a cooling, wholesome summer drink, but it should not be partaken of to excess.
A two-part effervescing powder of the kind chemists once sold folded into coloured papers. It still works exactly as described, though the units belong to the apothecary's counter rather than the kitchen.
- Grains into gramsAn apothecaries' grain is 64.8 mg. Thirty grains of bicarbonate is about 1.9 g, twenty-five grains of tartaric acid about 1.6 g, twenty-four grains of citric acid about 1.55 g. A jeweller's or coffee scale reading to 0.1 g is the only practical way to measure these.
- Why two papersBlue and white were the trade convention for distinguishing alkali from acid so the two never met while dry. The colours carry no other meaning; any two marked containers do the same job, provided both stay bone dry.
- Dissolve separately, then combineThis is the hinge of the recipe. If the powders are tipped into one glass together the reaction runs off before you can drink it and the water goes flat. Dissolve each in its own half-glass, pour together, drink immediately.
- Tartaric or citric, not bothThe recipe offers a choice. Tartaric gives a sharper, slightly more mineral edge; citric tastes lemony. Use food-grade acid sold for brewing or preserving rather than the descaling grade sold in hardware shops.
- The sodiumTwo grams of bicarbonate carries roughly 530 mg of sodium, about a quarter of a day's sensible intake, and the reaction leaves sodium tartrate or citrate in the glass. Anyone on a sodium-restricted diet or with kidney trouble should leave it alone.
- YieldOne pair of papers makes a single glassful, though the recipe gives no volume beyond 'about half a glassful' of water for each powder. Sweetening is not part of the formula, but a little sugar syrup or lemon in the acid half makes it more palatable.
- StorageFold or seal the papers airtight and keep them dry. Bicarbonate slowly absorbs moisture and loses fizz; the acids cake. Made-up powders are best used within a few months.
Effervescing powders sit on the border between the kitchen and the dispensary, which is where much of Victorian soft-drink making lived. Before bottled aerated water was cheap and universal, a household could raise its own fizz by combining an alkali and an acid in water, and chemists sold the components ready-weighed into folded papers of contrasting colours so the customer could not confuse them. The best-known relative is the Seidlitz powder, a similar two-paper preparation using Rochelle salt that was taken as a mild aperient rather than for refreshment; the plainer soda powder here is its purely thirst-quenching cousin. The warning against excess reflects a period awareness that habitual dosing with alkali upsets the stomach, an observation that modern advice on sodium bicarbonate has largely borne out.